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NAME

       crypto - Crypto Functions

DESCRIPTION

       This module provides a set of cryptographic functions.

         Hash functions:

           SHA1, SHA2:
              Secure Hash Standard [FIPS PUB 180-4]

           SHA3:
              SHA-3  Standard:  Permutation-Based  Hash and Extendable-Output Functions [FIPS PUB
             202]

           BLAKE2:
             BLAKE2 — fast secure hashing

           MD5:
             The MD5 Message Digest Algorithm [RFC 1321]

           MD4:
             The MD4 Message Digest Algorithm [RFC 1320]

         MACs - Message Authentication Codes:

           Hmac functions:
              Keyed-Hashing for Message Authentication [RFC 2104]

           Cmac functions:
              The AES-CMAC Algorithm [RFC 4493]

           POLY1305:
              ChaCha20 and Poly1305 for IETF Protocols [RFC 7539]

         Symmetric Ciphers:

           DES, 3DES and AES:
             Block Cipher Techniques [NIST]

           Blowfish:
              Fast Software Encryption, Cambridge Security Workshop Proceedings (December  1993),
             Springer-Verlag, 1994, pp. 191-204.

           Chacha20:
              ChaCha20 and Poly1305 for IETF Protocols [RFC 7539]

           Chacha20_poly1305:
              ChaCha20 and Poly1305 for IETF Protocols [RFC 7539]

         Modes:

           ECB, CBC, CFB, OFB and CTR:
              Recommendation for Block Cipher Modes of Operation: Methods and Techniques [NIST SP
             800-38A]

           GCM:
              Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode  (GCM)  and
             GMAC [NIST SP 800-38D]

           CCM:
              Recommendation for Block Cipher Modes of Operation: The CCM Mode for Authentication
             and Confidentiality [NIST SP 800-38C]

         Asymetric Ciphers - Public Key Techniques:

           RSA:
              PKCS #1: RSA Cryptography Specifications [RFC 3447]

           DSS:
              Digital Signature Standard (DSS) [FIPS 186-4]

           ECDSA:
              Elliptic Curve Digital Signature Algorithm [ECDSA]

           SRP:
              The SRP Authentication and Key Exchange System [RFC 2945]

   Note:
       The actual supported algorithms and features depends on their availability in  the  actual
       libcrypto used. See the crypto (App) about dependencies.

       Enabling FIPS mode will also disable algorithms and features.

       The  CRYPTO  User's Guide has more information on FIPS, Engines and Algorithm Details like
       key lengths.

DATA TYPES

   Ciphers, new API
       cipher() = cipher_no_iv() | cipher_iv() | cipher_aead()

       cipher_no_iv() =
           aes_128_ecb | aes_192_ecb | aes_256_ecb | blowfish_ecb |
           des_ecb | rc4

       cipher_iv() =
           aes_128_cbc | aes_192_cbc | aes_256_cbc | aes_128_cfb128 |
           aes_192_cfb128 | aes_256_cfb128 | aes_128_cfb8 |
           aes_192_cfb8 | aes_256_cfb8 | aes_128_ctr | aes_192_ctr |
           aes_256_ctr | aes_ige256 | blowfish_cbc | blowfish_cfb64 |
           blowfish_ofb64 | chacha20 | des_ede3_cbc | des_ede3_cfb |
           des_cbc | des_cfb | rc2_cbc

       cipher_aead() =
           aes_128_ccm | aes_192_ccm | aes_256_ccm | aes_128_gcm |
           aes_192_gcm | aes_256_gcm | chacha20_poly1305

              Ciphers known by the CRYPTO application when using the new API.

              Note that this list might be reduced if the underlying libcrypto does  not  support
              all of them.

   Ciphers, old API
       block_cipher_with_iv() =
           cbc_cipher() | cfb_cipher() | blowfish_ofb64 | aes_ige256

       block_cipher_without_iv() = ecb_cipher()

       stream_cipher() = ctr_cipher() | chacha20 | rc4

       aead_cipher() = aes_gcm | aes_ccm | chacha20_poly1305

       cbc_cipher() =
           aes_128_cbc | aes_192_cbc | aes_256_cbc | blowfish_cbc |
           des_cbc | des_ede3_cbc | rc2_cbc |
           retired_cbc_cipher_aliases()

       cfb_cipher() =
           aes_128_cfb128 | aes_192_cfb128 | aes_256_cfb128 |
           aes_128_cfb8 | aes_192_cfb8 | aes_256_cfb8 | blowfish_cfb64 |
           des_cfb | des_ede3_cfb |
           retired_cfb_cipher_aliases()

       ctr_cipher() =
           aes_128_ctr | aes_192_ctr | aes_256_ctr |
           retired_ctr_cipher_aliases()

       ecb_cipher() =
           aes_128_ecb | aes_192_ecb | aes_256_ecb | blowfish_ecb |
           retired_ecb_cipher_aliases()

              Ciphers known by the CRYPTO application when using the old API.

              Note  that  this list might be reduced if the underlying libcrypto does not support
              all of them.

       retired_cbc_cipher_aliases() =
           aes_cbc | aes_cbc128 | aes_cbc256 | des3_cbc | des_ede3

       retired_cfb_cipher_aliases() =
           aes_cfb8 | aes_cfb128 | des3_cbf | des3_cfb | des_ede3_cbf

       retired_ctr_cipher_aliases() = aes_ctr

       retired_ecb_cipher_aliases() = aes_ecb

              Alternative, old names of ciphers known by the CRYPTO application  when  using  the
              old  API.  See  Retired cipher names for names to use instead to be prepared for an
              easy convertion to the new API.

              Note that this list might be reduced if the underlying libcrypto does  not  support
              all of them.

   Digests and hash
       hash_algorithm() =
           sha1() |
           sha2() |
           sha3() |
           blake2() |
           ripemd160 |
           compatibility_only_hash()

       hmac_hash_algorithm() =
           sha1() | sha2() | sha3() | compatibility_only_hash()

       cmac_cipher_algorithm() =
           aes_128_cbc | aes_192_cbc | aes_256_cbc | blowfish_cbc |
           des_cbc | des_ede3_cbc | rc2_cbc | aes_128_cfb128 |
           aes_192_cfb128 | aes_256_cfb128 | aes_128_cfb8 |
           aes_192_cfb8 | aes_256_cfb8

       rsa_digest_type() = sha1() | sha2() | md5 | ripemd160

       dss_digest_type() = sha1() | sha2()

       ecdsa_digest_type() = sha1() | sha2()

       sha1() = sha

       sha2() = sha224 | sha256 | sha384 | sha512

       sha3() = sha3_224 | sha3_256 | sha3_384 | sha3_512

       blake2() = blake2b | blake2s

       compatibility_only_hash() = md5 | md4

              The  compatibility_only_hash()  algorithms  are  recommended only for compatibility
              with existing applications.

   Elliptic Curves
       ec_named_curve() =
           brainpoolP160r1 | brainpoolP160t1 | brainpoolP192r1 |
           brainpoolP192t1 | brainpoolP224r1 | brainpoolP224t1 |
           brainpoolP256r1 | brainpoolP256t1 | brainpoolP320r1 |
           brainpoolP320t1 | brainpoolP384r1 | brainpoolP384t1 |
           brainpoolP512r1 | brainpoolP512t1 | c2pnb163v1 | c2pnb163v2 |
           c2pnb163v3 | c2pnb176v1 | c2pnb208w1 | c2pnb272w1 |
           c2pnb304w1 | c2pnb368w1 | c2tnb191v1 | c2tnb191v2 |
           c2tnb191v3 | c2tnb239v1 | c2tnb239v2 | c2tnb239v3 |
           c2tnb359v1 | c2tnb431r1 | ipsec3 | ipsec4 | prime192v1 |
           prime192v2 | prime192v3 | prime239v1 | prime239v2 |
           prime239v3 | prime256v1 | secp112r1 | secp112r2 | secp128r1 |
           secp128r2 | secp160k1 | secp160r1 | secp160r2 | secp192k1 |
           secp192r1 | secp224k1 | secp224r1 | secp256k1 | secp256r1 |
           secp384r1 | secp521r1 | sect113r1 | sect113r2 | sect131r1 |
           sect131r2 | sect163k1 | sect163r1 | sect163r2 | sect193r1 |
           sect193r2 | sect233k1 | sect233r1 | sect239k1 | sect283k1 |
           sect283r1 | sect409k1 | sect409r1 | sect571k1 | sect571r1 |
           wtls1 | wtls10 | wtls11 | wtls12 | wtls3 | wtls4 | wtls5 |
           wtls6 | wtls7 | wtls8 | wtls9

       edwards_curve_dh() = x25519 | x448

       edwards_curve_ed() = ed25519 | ed448

              Note that some curves are disabled if FIPS is enabled.

       ec_explicit_curve() =
           {Field :: ec_field(),
            Curve :: ec_curve(),
            BasePoint :: binary(),
            Order :: binary(),
            CoFactor :: none | binary()}

       ec_field() = ec_prime_field() | ec_characteristic_two_field()

       ec_curve() =
           {A :: binary(), B :: binary(), Seed :: none | binary()}

              Parametric curve definition.

       ec_prime_field() = {prime_field, Prime :: integer()}

       ec_characteristic_two_field() =
           {characteristic_two_field,
            M :: integer(),
            Basis :: ec_basis()}

       ec_basis() =
           {tpbasis, K :: integer() >= 0} |
           {ppbasis,
            K1 :: integer() >= 0,
            K2 :: integer() >= 0,
            K3 :: integer() >= 0} |
           onbasis

              Curve definition details.

   Keys
       key() = iodata()

       des3_key() = [key()]

              For keylengths, iv-sizes and blocksizes see the User's Guide.

              A key for des3 is a list of three iolists

       key_integer() = integer() | binary()

              Always binary() when used as return value

   Public/Private Keys
       rsa_public() = [key_integer()]

       rsa_private() = [key_integer()]

       rsa_params() =
           {ModulusSizeInBits :: integer(),
            PublicExponent :: key_integer()}

              rsa_public() = [E, N]

              rsa_private() = [E, N, D] | [E, N, D, P1, P2, E1, E2, C]

              Where E is the public exponent, N is public modulus and D is the private  exponent.
              The longer key format contains redundant information that will make the calculation
              faster. P1,P2 are first and second  prime  factors.  E1,E2  are  first  and  second
              exponents. C is the CRT coefficient. Terminology is taken from  RFC 3447.

       dss_public() = [key_integer()]

       dss_private() = [key_integer()]

              dss_public() = [P, Q, G, Y]

              Where P, Q and G are the dss parameters and Y is the public key.

              dss_private() = [P, Q, G, X]

              Where P, Q and G are the dss parameters and X is the private key.

       ecdsa_public() = key_integer()

       ecdsa_private() = key_integer()

       ecdsa_params() = ec_named_curve() | ec_explicit_curve()

       eddsa_public() = key_integer()

       eddsa_private() = key_integer()

       eddsa_params() = edwards_curve_ed()

       srp_public() = key_integer()

       srp_private() = key_integer()

              srp_public() = key_integer()

              Where is A or B from SRP design

              srp_private() = key_integer()

              Where is a or b from SRP design

       srp_gen_params() =
           {user, srp_user_gen_params()} | {host, srp_host_gen_params()}

       srp_comp_params() =
           {user, srp_user_comp_params()} |
           {host, srp_host_comp_params()}

              srp_user_gen_params() = [DerivedKey::binary(), Prime::binary(), Generator::binary(), Version::atom()]

              srp_host_gen_params() = [Verifier::binary(), Prime::binary(), Version::atom() ]

              srp_user_comp_params() = [DerivedKey::binary(), Prime::binary(), Generator::binary(), Version::atom() | ScramblerArg::list()]

              srp_host_comp_params() = [Verifier::binary(), Prime::binary(), Version::atom() | ScramblerArg::list()]

              Where  Verifier is v, Generator is g and Prime is N, DerivedKey is X, and Scrambler
              is u (optional will be generated if not provided) from SRP design Version =  '3'  |
              '6' | '6a'

   Public Key Ciphers
       pk_encrypt_decrypt_algs() = rsa

              Algorithms for public key encrypt/decrypt. Only RSA is supported.

       pk_encrypt_decrypt_opts() = [rsa_opt()] | rsa_compat_opts()

       rsa_opt() =
           {rsa_padding, rsa_padding()} |
           {signature_md, atom()} |
           {rsa_mgf1_md, sha} |
           {rsa_oaep_label, binary()} |
           {rsa_oaep_md, sha}

       rsa_padding() =
           rsa_pkcs1_padding | rsa_pkcs1_oaep_padding |
           rsa_sslv23_padding | rsa_x931_padding | rsa_no_padding

              Options for public key encrypt/decrypt. Only RSA is supported.

          Warning:

              The RSA options are experimental.

              The exact set of options and there syntax may be changed without prior notice.

       rsa_compat_opts() = [{rsa_pad, rsa_padding()}] | rsa_padding()

              Those  option  forms  are kept only for compatibility and should not be used in new
              code.

   Public Key Sign and Verify
       pk_sign_verify_algs() = rsa | dss | ecdsa | eddsa

              Algorithms for sign and verify.

       pk_sign_verify_opts() = [rsa_sign_verify_opt()]

       rsa_sign_verify_opt() =
           {rsa_padding, rsa_sign_verify_padding()} |
           {rsa_pss_saltlen, integer()} |
           {rsa_mgf1_md, sha2()}

       rsa_sign_verify_padding() =
           rsa_pkcs1_padding | rsa_pkcs1_pss_padding | rsa_x931_padding |
           rsa_no_padding

              Options for sign and verify.

          Warning:

              The RSA options are experimental.

              The exact set of options and there syntax may be changed without prior notice.

   Diffie-Hellman Keys and parameters
       dh_public() = key_integer()

       dh_private() = key_integer()

       dh_params() = [key_integer()]

              dh_params() = [P, G] | [P, G, PrivateKeyBitLength]

       ecdh_public() = key_integer()

       ecdh_private() = key_integer()

       ecdh_params() =
           ec_named_curve() | edwards_curve_dh() | ec_explicit_curve()

   Types for Engines
       engine_key_ref() =
           #{engine := engine_ref(),
             key_id := key_id(),
             password => password(),
             term() => term()}

       engine_ref() = term()

              The result of a call to engine_load/3.

       key_id() = string() | binary()

              Identifies the key to be used. The format depends  on  the  loaded  engine.  It  is
              passed to the ENGINE_load_(private|public)_key functions in libcrypto.

       password() = string() | binary()

              The password of the key stored in an engine.

       engine_method_type() =
           engine_method_rsa | engine_method_dsa | engine_method_dh |
           engine_method_rand | engine_method_ecdh |
           engine_method_ecdsa | engine_method_ciphers |
           engine_method_digests | engine_method_store |
           engine_method_pkey_meths | engine_method_pkey_asn1_meths |
           engine_method_ec

       engine_cmnd() = {unicode:chardata(), unicode:chardata()}

              Pre and Post commands for engine_load/3 and /4.

   Internal data types
       crypto_state()

       hash_state()

       hmac_state()

       mac_state()

       stream_state()

              Contexts  with  an internal state that should not be manipulated but passed between
              function calls.

   Error types
       run_time_error() = no_return()

              The exception error:badarg signifies that one or more arguments are of  wrong  data
              type, or are otherwise badly formed.

              The  exception  error:notsup  signifies  that  the  algorithm  is  known but is not
              supported by current underlying libcrypto  or  explicitly  disabled  when  building
              that.

              For a list of supported algorithms, see supports/0.

       descriptive_error() = no_return()

              This is a more developed variant of the older run_time_error().

              The exception is:

                     {Tag, {C_FileName,LineNumber}, Description}

                      Tag = badarg | notsup | error
                      C_FileName = string()
                      LineNumber = integer()
                      Description = string()

              It is like the older type an exception of the error class. In addition they contain
              a descriptive text in English. That text is targeted to a developer.  Examples  are
              "Bad key size" or "Cipher id is not an atom".

              The exception tags are:

                badarg:
                  Signifies  that  one  or more arguments are of wrong data type or are otherwise
                  badly formed.

                notsup:
                  Signifies that  the  algorithm  is  known  but  is  not  supported  by  current
                  underlying libcrypto or explicitly disabled when building that one.

                error:
                  An  error  condition  that  should  not  occur, for example a memory allocation
                  failed or the underlying cryptolib returned an error code, for  example  "Can't
                  initialize  context, step 1". Thoose text usually needs searching the C-code to
                  be understood.

              To catch the exception, use for example:

                     try crypto:crypto_init(Ciph, Key, IV, true)
                     catch
                         error:{Tag, {C_FileName,LineNumber}, Description} ->
                                 do_something(......)
                         .....
                     end

NEW API

EXPORTS

       crypto_init(Cipher, Key, EncryptFlag) ->
                      State | descriptive_error()

              Types:

                 Cipher = cipher_no_iv()
                 Key = iodata()
                 EncryptFlag = boolean()
                 State = crypto_state()

              As crypto_init/4 but for ciphers without IVs.

       crypto_init(Cipher, Key, IV, EncryptFlag) ->
                      State | descriptive_error()

              Types:

                 Cipher = cipher_iv()
                 Key = IV = iodata()
                 EncryptFlag = boolean()
                 State = crypto_state()

              Part of the new API. Initializes a series of encryptions or decryptions and creates
              an  internal  state  with  a  reference  that is returned. The actual encryption or
              decryption is done by crypto_update/2.

              For encryption, set the EncryptFlag to true. For decryption, set it to false.

              See  examples in the User's Guide.

       crypto_update(State, Data) -> Result | descriptive_error()

              Types:

                 State = crypto_state()
                 Data = iodata()
                 Result = binary()

              Part of the new API. It does an actual crypto operation on a part of the full text.
              If  the  part  is less than a number of full blocks, only the full blocks (possibly
              none) are encrypted or decrypted and the remaining bytes  are  saved  to  the  next
              crypto_update  operation.  The  State  should  be  created  with  crypto_init/3  or
              crypto_init/4.

              See  examples in the User's Guide.

       crypto_dyn_iv_init(Cipher, Key, EncryptFlag) ->
                             State | descriptive_error()

              Types:

                 Cipher = cipher_iv()
                 Key = iodata()
                 EncryptFlag = boolean()
                 State = crypto_state()

              Part of the new API. Initializes a series of encryptions or decryptions  where  the
              IV   is   provided   later.   The  actual  encryption  or  decryption  is  done  by
              crypto_dyn_iv_update/3.

              For encryption, set the EncryptFlag to true. For decryption, set it to false.

       crypto_dyn_iv_update(State, Data, IV) ->
                               Result | descriptive_error()

              Types:

                 State = crypto_state()
                 Data = IV = iodata()
                 Result = binary()

              Part of the new API. Do an actual crypto operation on a part of the full  text  and
              the   IV   is   supplied   for   each  part.  The  State  should  be  created  with
              crypto_dyn_iv_init/3.

       crypto_one_time(Cipher, Key, Data, EncryptFlag) ->
                          Result | descriptive_error()

              Types:

                 Cipher = cipher_no_iv()
                 Key = Data = iodata()
                 EncryptFlag = boolean()
                 Result = binary()

              As crypto_one_time/5 but for ciphers without IVs.

       crypto_one_time(Cipher, Key, IV, Data, EncryptFlag) ->
                          Result | descriptive_error()

              Types:

                 Cipher = cipher_iv()
                 Key = IV = Data = iodata()
                 EncryptFlag = boolean()
                 Result = binary()

              Part of the new API. Do a complete encrypt or decrypt  of  the  full  text  in  the
              argument Data.

              For encryption, set the EncryptFlag to true. For decryption, set it to false.

              See examples in the User's Guide.

       crypto_one_time_aead(Cipher, Key, IV, InText, AAD,
                            EncFlag :: true) ->
                               Result | descriptive_error()

       crypto_one_time_aead(Cipher, Key, IV, InText, AAD, TagOrTagLength,
                            EncFlag) ->
                               Result | descriptive_error()

              Types:

                 Cipher = cipher_aead()
                 Key = IV = InText = AAD = iodata()
                 TagOrTagLength = EncryptTagLength | DecryptTag
                 EncryptTagLength = integer() >= 0
                 DecryptTag = iodata()
                 EncFlag = boolean()
                 Result = EncryptResult | DecryptResult
                 EncryptResult = {OutCryptoText, OutTag}
                 DecryptResult = OutPlainText | error
                 OutCryptoText = OutTag = OutPlainText = binary()

              Part  of  the  new API. Do a complete encrypt or decrypt with an AEAD cipher of the
              full text.

              For encryption, set the EncryptFlag to true  and  set  the  TagOrTagLength  to  the
              wanted  size  of the tag, that is, the tag length. If the default length is wanted,
              the crypto_aead/6 form may be used.

              For decryption, set the EncryptFlag to false and put the tag to be checked  in  the
              argument TagOrTagLength.

              See examples in the User's Guide.

       supports(Type) -> Support

              Types:

                 Type = hashs | ciphers | public_keys | macs | curves | rsa_opts
                 Support = Hashs | Ciphers | PKs | Macs | Curves | RSAopts
                 Hashs =
                     [sha1() |
                      sha2() |
                      sha3() |
                      blake2() |
                      ripemd160 |
                      compatibility_only_hash()]
                 Ciphers = [cipher()]
                 PKs = [rsa | dss | ecdsa | dh | ecdh | ec_gf2m]
                 Macs = [hmac | cmac | poly1305]
                 Curves =
                     [ec_named_curve() | edwards_curve_dh() | edwards_curve_ed()]
                 RSAopts = [rsa_sign_verify_opt() | rsa_opt()]

              Can  be  used  to  determine  which  crypto  algorithms  that  are supported by the
              underlying libcrypto library

              See hash_info/1 and  cipher_info/1  for  information  about  the  hash  and  cipher
              algorithms.

       mac(Type :: poly1305, Key, Data) -> Mac | descriptive_error()

              Types:

                 Key = Data = iodata()
                 Mac = binary()

              Short for mac(Type, undefined, Key, Data).

       mac(Type, SubType, Key, Data) -> Mac | descriptive_error()

              Types:

                 Type = hmac | cmac | poly1305
                 SubType =
                     hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined
                 Key = Data = iodata()
                 Mac = binary()

              Computes a MAC (Message Authentication Code) of type Type from Data.

              SubType depends on the MAC Type:

                * For hmac it is a hash algorithm, see Algorithm Details in the User's Guide.

                * For  cmac it is a cipher suitable for cmac, see Algorithm Details in the User's
                  Guide.

                * For poly1305 it should be set to undefined or the mac/2 function could be  used
                  instead, see Algorithm Details in the User's Guide.

              Key  is the authentication key with a length according to the Type and SubType. The
              key length could be found with the hash_info/1 (hmac) for and cipher_info/1  (cmac)
              functions.  For  poly1305  the  key length is 32 bytes. Note that the cryptographic
              quality of the key is not checked.

              The Mac result will have a default length depending on the Type and SubType. To set
              a shorter length, use macN/4 or macN/5 instead. The default length is documented in
              Algorithm Details in the User's Guide.

       macN(Type :: poly1305, Key, Data, MacLength) ->
               Mac | descriptive_error()

              Types:

                 Key = Data = iodata()
                 Mac = binary()
                 MacLength = integer() >= 1

              Short for macN(Type, undefined, Key, Data, MacLength).

       macN(Type, SubType, Key, Data, MacLength) ->
               Mac | descriptive_error()

              Types:

                 Type = hmac | cmac | poly1305
                 SubType =
                     hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined
                 Key = Data = iodata()
                 Mac = binary()
                 MacLength = integer() >= 1

              Computes a MAC (Message Authentication Code) as mac/3 and mac/4 but MacLength  will
              limit  the  size  of  the  resultant  Mac  to at most MacLength bytes. Note that if
              MacLength is greater than the actual number of bytes returned from  the  underlying
              hash, the returned hash will have that shorter length instead.

              The max MacLength is documented in Algorithm Details in the User's Guide.

       mac_init(Type :: poly1305, Key) -> State | descriptive_error()

              Types:

                 Key = iodata()
                 State = mac_state()

              Short for mac_init(Type, undefined, Key).

       mac_init(Type, SubType, Key) -> State | descriptive_error()

              Types:

                 Type = hmac | cmac | poly1305
                 SubType =
                     hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined
                 Key = iodata()
                 State = mac_state()

              Initializes the context for streaming MAC operations.

              Type determines which mac algorithm to use in the MAC operation.

              SubType depends on the MAC Type:

                * For hmac it is a hash algorithm, see Algorithm Details in the User's Guide.

                * For  cmac it is a cipher suitable for cmac, see Algorithm Details in the User's
                  Guide.

                * For poly1305 it should be set to undefined or the mac/2 function could be  used
                  instead, see Algorithm Details in the User's Guide.

              Key  is the authentication key with a length according to the Type and SubType. The
              key length could be found with the hash_info/1 (hmac) for and cipher_info/1  (cmac)
              functions.  For  poly1305  the  key length is 32 bytes. Note that the cryptographic
              quality of the key is not checked.

              The returned State should be used in one or more subsequent calls to  mac_update/2.
              The MAC value is finally returned by calling mac_final/1 or mac_finalN/2.

              See  examples in the User's Guide.

       mac_update(State0, Data) -> State | descriptive_error()

              Types:

                 Data = iodata()
                 State0 = State = mac_state()

              Updates  the  MAC  represented by State0 using the given Data which could be of any
              length.

              The State0 is the State  value  originally  from  a  MAC  init  function,  that  is
              mac_init/2,  mac_init/3  or  a  previous  call of mac_update/2. The value State0 is
              returned unchanged by the function as State.

       mac_final(State) -> Mac | descriptive_error()

              Types:

                 State = mac_state()
                 Mac = binary()

              Finalizes the MAC operation referenced by State. The Mac result will have a default
              length depending on the Type and SubType in the mac_init/2,3 call. To set a shorter
              length, use mac_finalN/2 instead. The default length  is  documented  in  Algorithm
              Details in the User's Guide.

       mac_finalN(State, MacLength) -> Mac | descriptive_error()

              Types:

                 State = mac_state()
                 MacLength = integer() >= 1
                 Mac = binary()

              Finalizes the MAC operation referenced by State.

              Mac  will  be  a  binary  with  at  most MacLength bytes. Note that if MacLength is
              greater than the actual number of bytes returned  from  the  underlying  hash,  the
              returned hash will have that shorter length instead.

              The max MacLength is documented in Algorithm Details in the User's Guide.

API KEPT FROM PREVIOUS VERSIONS

EXPORTS

       bytes_to_integer(Bin :: binary()) -> integer()

              Convert binary representation, of an integer, to an Erlang integer.

       compute_key(Type, OthersPublicKey, MyPrivateKey, Params) ->
                      SharedSecret

              Types:

                 Type = dh | ecdh | srp
                 SharedSecret = binary()
                 OthersPublicKey = dh_public() | ecdh_public() | srp_public()
                 MyPrivateKey =
                     dh_private() | ecdh_private() | {srp_public(), srp_private()}
                 Params = dh_params() | ecdh_params() | srp_comp_params()

              Computes  the  shared secret from the private key and the other party's public key.
              See also public_key:compute_key/2

       exor(Bin1 :: iodata(), Bin2 :: iodata()) -> binary()

              Performs bit-wise XOR (exclusive or) on the data supplied.

       generate_key(Type, Params) -> {PublicKey, PrivKeyOut}

       generate_key(Type, Params, PrivKeyIn) -> {PublicKey, PrivKeyOut}

              Types:

                 Type = dh | ecdh | rsa | srp
                 PublicKey =
                     dh_public() | ecdh_public() | rsa_public() | srp_public()
                 PrivKeyIn =
                     undefined |
                     dh_private() |
                     ecdh_private() |
                     rsa_private() |
                     {srp_public(), srp_private()}
                 PrivKeyOut =
                     dh_private() |
                     ecdh_private() |
                     rsa_private() |
                     {srp_public(), srp_private()}
                 Params =
                     dh_params() | ecdh_params() | rsa_params() | srp_comp_params()

              Generates a public key of type Type. See also public_key:generate_key/1. May  raise
              exception:

                * error:badarg: an argument is of wrong type or has an illegal value,

                * error:low_entropy:   the   random  generator  failed  due  to  lack  of  secure
                  "randomness",

                * error:computation_failed:  the  computation  fails  of  another   reason   than
                  low_entropy.

          Note:
              RSA  key generation is only available if the runtime was built with dirty scheduler
              support. Otherwise,  attempting  to  generate  an  RSA  key  will  raise  exception
              error:notsup.

       hash(Type, Data) -> Digest

              Types:

                 Type = hash_algorithm()
                 Data = iodata()
                 Digest = binary()

              Computes a message digest of type Type from Data.

              May  raise  exception  error:notsup in case the chosen Type is not supported by the
              underlying libcrypto implementation.

       hash_init(Type) -> State

              Types:

                 Type = hash_algorithm()
                 State = hash_state()

              Initializes the context for streaming hash operations. Type determines which digest
              to use. The returned context should be used as argument to hash_update.

              May  raise  exception  error:notsup in case the chosen Type is not supported by the
              underlying libcrypto implementation.

       hash_update(State, Data) -> NewState

              Types:

                 State = NewState = hash_state()
                 Data = iodata()

              Updates the digest represented by Context using the given Data. Context  must  have
              been generated using hash_init or a previous call to this function. Data can be any
              length. NewContext must be passed into the next call to hash_update or hash_final.

       hash_final(State) -> Digest

              Types:

                 State = hash_state()
                 Digest = binary()

              Finalizes the hash operation referenced by Context returned from a previous call to
              hash_update.  The size of Digest is determined by the type of hash function used to
              generate it.

       info_fips() -> not_supported | not_enabled | enabled

              Provides information about the FIPS operating status of crypto and  the  underlying
              libcrypto library. If crypto was built with FIPS support this can be either enabled
              (when running in FIPS mode) or not_enabled. For other builds this value  is  always
              not_supported.

              See enable_fips_mode/1 about how to enable FIPS mode.

          Warning:
              In  FIPS  mode  all  non-FIPS compliant algorithms are disabled and raise exception
              error:notsup. Check supports that in FIPS  mode  returns  the  restricted  list  of
              available algorithms.

       enable_fips_mode(Enable) -> Result

              Types:

                 Enable = Result = boolean()

              Enables (Enable = true) or disables (Enable = false) FIPS mode. Returns true if the
              operation was successful or false otherwise.

              Note that to enable FIPS mode succesfully, OTP must be  built  with  the  configure
              option --enable-fips, and the underlying libcrypto must also support FIPS.

              See also info_fips/0.

       info_lib() -> [{Name, VerNum, VerStr}]

              Types:

                 Name = binary()
                 VerNum = integer()
                 VerStr = binary()

              Provides the name and version of the libraries used by crypto.

              Name  is  the  name  of the library. VerNum is the numeric version according to the
              library's own versioning scheme. VerStr contains a text variant of the version.

              > info_lib().
              [{<<"OpenSSL">>,269484095,<<"OpenSSL 1.1.0c  10 Nov 2016"">>}]

          Note:
              From OTP R16 the numeric version represents the version of the OpenSSL header files
              (openssl/opensslv.h) used when crypto was compiled. The text variant represents the
              libcrypto library used at runtime. In earlier OTP versions both  numeric  and  text
              was taken from the library.

       hash_info(Type) -> Result | run_time_error()

              Types:

                 Type = hash_algorithm()
                 Result =
                     #{size := integer(),
                       block_size := integer(),
                       type := integer()}

              Provides  a  map  with  information  about  block_size,  size  and  possibly  other
              properties of the hash algorithm in question.

              For a list of supported hash algorithms, see supports/0.

       cipher_info(Type) -> Result | run_time_error()

              Types:

                 Type = cipher()
                 Result =
                     #{key_length := integer(),
                       iv_length := integer(),
                       block_size := integer(),
                       mode := CipherModes,
                       type := undefined | integer()}
                 CipherModes =
                     undefined | cbc_mode | ccm_mode | cfb_mode | ctr_mode |
                     ecb_mode | gcm_mode | ige_mode | ocb_mode | ofb_mode |
                     wrap_mode | xts_mode

              Provides a  map  with  information  about  block_size,  key_length,  iv_length  and
              possibly other properties of the cipher algorithm in question.

          Note:
              The  ciphers  aes_cbc,  aes_cfb8, aes_cfb128, aes_ctr, aes_ecb, aes_gcm and aes_ccm
              has no keylength in the Type as opposed to for example aes_128_ctr. They  adapt  to
              the  length of the key provided in the encrypt and decrypt function. Therefor it is
              impossible to return a valid keylength in the map.

              Always use a Type with an explicit key length,

              For a list of supported cipher algorithms, see supports/0.

       mod_pow(N, P, M) -> Result

              Types:

                 N = P = M = binary() | integer()
                 Result = binary() | error

              Computes the function N^P mod M.

       next_iv(Type :: cbc_cipher(), Data) -> NextIVec

       next_iv(Type :: des_cfb, Data, IVec) -> NextIVec

              Types:

                 Data = iodata()
                 IVec = NextIVec = binary()

              Returns  the  initialization  vector  to  be  used  in  the   next   iteration   of
              encrypt/decrypt  of  type  Type.  Data  is  the  encrypted  data  from the previous
              iteration step. The IVec argument is only needed for des_cfb as the vector used  in
              the previous iteration step.

       private_decrypt(Algorithm, CipherText, PrivateKey, Options) ->
                          PlainText

              Types:

                 Algorithm = pk_encrypt_decrypt_algs()
                 CipherText = binary()
                 PrivateKey = rsa_private() | engine_key_ref()
                 Options = pk_encrypt_decrypt_opts()
                 PlainText = binary()

              Decrypts  the  CipherText, encrypted with public_encrypt/4 (or equivalent function)
              using the PrivateKey, and returns the plaintext (message digest).  This  is  a  low
              level  signature  verification operation used for instance by older versions of the
              SSL protocol. See also public_key:decrypt_private/[2,3]

       private_encrypt(Algorithm, PlainText, PrivateKey, Options) ->
                          CipherText

              Types:

                 Algorithm = pk_encrypt_decrypt_algs()
                 PlainText = binary()
                 PrivateKey = rsa_private() | engine_key_ref()
                 Options = pk_encrypt_decrypt_opts()
                 CipherText = binary()

              Encrypts the PlainText using the PrivateKey and returns the ciphertext. This  is  a
              low  level  signature  operation  used  for  instance  by older versions of the SSL
              protocol. See also public_key:encrypt_private/[2,3]

       public_decrypt(Algorithm, CipherText, PublicKey, Options) ->
                         PlainText

              Types:

                 Algorithm = pk_encrypt_decrypt_algs()
                 CipherText = binary()
                 PublicKey = rsa_public() | engine_key_ref()
                 Options = pk_encrypt_decrypt_opts()
                 PlainText = binary()

              Decrypts the CipherText, encrypted with private_encrypt/4(or  equivalent  function)
              using  the  PrivateKey,  and  returns the plaintext (message digest). This is a low
              level signature verification operation used for instance by older versions  of  the
              SSL protocol. See also public_key:decrypt_public/[2,3]

       public_encrypt(Algorithm, PlainText, PublicKey, Options) ->
                         CipherText

              Types:

                 Algorithm = pk_encrypt_decrypt_algs()
                 PlainText = binary()
                 PublicKey = rsa_public() | engine_key_ref()
                 Options = pk_encrypt_decrypt_opts()
                 CipherText = binary()

              Encrypts  the  PlainText  (message  digest)  using  the  PublicKey  and returns the
              CipherText. This is a low level signature operation  used  for  instance  by  older
              versions of the SSL protocol. See also public_key:encrypt_public/[2,3]

       rand_seed(Seed :: binary()) -> ok

              Set  the  seed for PRNG to the given binary. This calls the RAND_seed function from
              openssl. Only use this if the system you  are  running  on  does  not  have  enough
              "randomness"   built   in.   Normally   this  is  when  strong_rand_bytes/1  raises
              error:low_entropy

       rand_uniform(Lo, Hi) -> N

              Types:

                 Lo, Hi, N = integer()

              Generate a random number N, Lo =< N < Hi. Uses  the  crypto  library  pseudo-random
              number generator. Hi must be larger than Lo.

       start() -> ok | {error, Reason :: term()}

              Equivalent to application:start(crypto).

       stop() -> ok | {error, Reason :: term()}

              Equivalent to application:stop(crypto).

       strong_rand_bytes(N :: integer() >= 0) -> binary()

              Generates N bytes randomly uniform 0..255, and returns the result in a binary. Uses
              a cryptographically secure prng seeded and periodically mixed with operating system
              provided entropy. By default this is the RAND_bytes method from OpenSSL.

              May  raise  exception  error:low_entropy in case the random generator failed due to
              lack of secure "randomness".

       rand_seed() -> rand:state()

              Creates  state  object  for  random  number  generation,  in  order   to   generate
              cryptographically  strong  random  numbers  (based on OpenSSL's BN_rand_range), and
              saves it  in  the  process  dictionary  before  returning  it  as  well.  See  also
              rand:seed/1 and rand_seed_s/0.

              When  using  the  state  object  from this function the rand functions using it may
              raise exception error:low_entropy in case the random generator failed due  to  lack
              of secure "randomness".

              Example

              _ = crypto:rand_seed(),
              _IntegerValue = rand:uniform(42), % [1; 42]
              _FloatValue = rand:uniform().     % [0.0; 1.0[

       rand_seed_s() -> rand:state()

              Creates   state   object  for  random  number  generation,  in  order  to  generate
              cryptographically strongly random numbers (based on OpenSSL's  BN_rand_range).  See
              also rand:seed_s/1.

              When  using  the  state  object  from this function the rand functions using it may
              raise exception error:low_entropy in case the random generator failed due  to  lack
              of secure "randomness".

          Note:
              The  state  returned from this function cannot be used to get a reproducable random
              sequence as from the other rand functions, since  reproducability  does  not  match
              cryptographically safe.

              The  only  supported  usage  is  to generate one distinct random sequence from this
              start state.

       rand_seed_alg(Alg) -> rand:state()

              Types:

                 Alg = crypto | crypto_cache

              Creates  state  object  for  random  number  generation,  in  order   to   generate
              cryptographically  strong  random  numbers,  and saves it in the process dictionary
              before returning it as well. See also rand:seed/1 and rand_seed_alg_s/1.

              When using the state object from this function the  rand  functions  using  it  may
              raise  exception  error:low_entropy in case the random generator failed due to lack
              of secure "randomness".

              Example

              _ = crypto:rand_seed_alg(crypto_cache),
              _IntegerValue = rand:uniform(42), % [1; 42]
              _FloatValue = rand:uniform().     % [0.0; 1.0[

       rand_seed_alg(Alg, Seed) -> rand:state()

              Types:

                 Alg = crypto_aes

              Creates a  state  object  for  random  number  generation,  in  order  to  generate
              cryptographically  unpredictable  random  numbers,  and  saves  it  in  the process
              dictionary before returning it as well. See also rand_seed_alg_s/2.

              Example

              _ = crypto:rand_seed_alg(crypto_aes, "my seed"),
              IntegerValue = rand:uniform(42), % [1; 42]
              FloatValue = rand:uniform(),     % [0.0; 1.0[
              _ = crypto:rand_seed_alg(crypto_aes, "my seed"),
              IntegerValue = rand:uniform(42), % Same values
              FloatValue = rand:uniform().     % again

       rand_seed_alg_s(Alg) -> rand:state()

              Types:

                 Alg = crypto | crypto_cache

              Creates  state  object  for  random  number  generation,  in  order   to   generate
              cryptographically strongly random numbers. See also rand:seed_s/1.

              If Alg is crypto this function behaves exactly like rand_seed_s/0.

              If  Alg is crypto_cache this function fetches random data with OpenSSL's RAND_bytes
              and caches it for speed  using  an  internal  word  size  of  56  bits  that  makes
              calculations fast on 64 bit machines.

              When  using  the  state  object  from this function the rand functions using it may
              raise exception error:low_entropy in case the random generator failed due  to  lack
              of secure "randomness".

              The  cache  size  can  be  changed  from its default value using the  crypto app's
              configuration parameter rand_cache_size.

              When using the state object from this function the  rand  functions  using  it  may
              throw  exception  low_entropy  in  case  the random generator failed due to lack of
              secure "randomness".

          Note:
              The state returned from this function cannot be used to get a  reproducable  random
              sequence  as  from  the  other rand functions, since reproducability does not match
              cryptographically safe.

              In fact since random data is cached some numbers may get reproduced if you try, but
              this is unpredictable.

              The  only  supported  usage  is  to generate one distinct random sequence from this
              start state.

       rand_seed_alg_s(Alg, Seed) -> rand:state()

              Types:

                 Alg = crypto_aes

              Creates a  state  object  for  random  number  generation,  in  order  to  generate
              cryptographically unpredictable random numbers. See also rand_seed_alg/1.

              To  get  a long period the Xoroshiro928 generator from the rand module is used as a
              counter (with period 2^928 - 1) and the generator states are scrambled through  AES
              to create 58-bit pseudo random values.

              The  result  should  be statistically completely unpredictable random values, since
              the scrambling is cryptographically strong and the period is ridiculously long. But
              the  generated  numbers  are  not  to be regarded as cryptographically strong since
              there is no re-keying schedule.

                * If you need cryptographically strong random numbers use rand_seed_alg_s/1  with
                  Alg =:= crypto or Alg =:= crypto_cache.

                * If you need to be able to repeat the sequence use this function.

                * If  you  do not need the statistical quality of this function, there are faster
                  algorithms in the rand module.

              Thanks to the used generator the state object supports the  rand:jump/0,1  function
              with distance 2^512.

              Numbers  are  generated in batches and cached for speed reasons. The cache size can
              be changed from its default value using the  crypto app's  configuration  parameter
              rand_cache_size.

       ec_curves() -> [EllipticCurve]

              Types:

                 EllipticCurve =
                     ec_named_curve() | edwards_curve_dh() | edwards_curve_ed()

              Can be used to determine which named elliptic curves are supported.

       ec_curve(CurveName) -> ExplicitCurve

              Types:

                 CurveName = ec_named_curve()
                 ExplicitCurve = ec_explicit_curve()

              Return the defining parameters of a elliptic curve.

       sign(Algorithm, DigestType, Msg, Key) -> Signature

       sign(Algorithm, DigestType, Msg, Key, Options) -> Signature

              Types:

                 Algorithm = pk_sign_verify_algs()
                 DigestType =
                     rsa_digest_type() |
                     dss_digest_type() |
                     ecdsa_digest_type() |
                     none
                 Msg = iodata() | {digest, iodata()}
                 Key =
                     rsa_private() |
                     dss_private() |
                     [ecdsa_private() | ecdsa_params()] |
                     [eddsa_private() | eddsa_params()] |
                     engine_key_ref()
                 Options = pk_sign_verify_opts()
                 Signature = binary()

              Creates a digital signature.

              The  msg  is  either  the  binary "cleartext" data to be signed or it is the hashed
              value of "cleartext" i.e. the digest (plaintext).

              Algorithm dss can only be used together with digest type sha.

              See also public_key:sign/3.

       verify(Algorithm, DigestType, Msg, Signature, Key) -> Result

       verify(Algorithm, DigestType, Msg, Signature, Key, Options) ->
                 Result

              Types:

                 Algorithm = pk_sign_verify_algs()
                 DigestType =
                     rsa_digest_type() | dss_digest_type() | ecdsa_digest_type()
                 Msg = iodata() | {digest, iodata()}
                 Signature = binary()
                 Key =
                     rsa_public() |
                     dss_public() |
                     [ecdsa_public() | ecdsa_params()] |
                     [eddsa_public() | eddsa_params()] |
                     engine_key_ref()
                 Options = pk_sign_verify_opts()
                 Result = boolean()

              Verifies a digital signature

              The msg is either the binary "cleartext" data to be signed  or  it  is  the  hashed
              value of "cleartext" i.e. the digest (plaintext).

              Algorithm dss can only be used together with digest type sha.

              See also public_key:verify/4.

ENGINE API

EXPORTS

       privkey_to_pubkey(Type, EnginePrivateKeyRef) -> PublicKey

              Types:

                 Type = rsa | dss
                 EnginePrivateKeyRef = engine_key_ref()
                 PublicKey = rsa_public() | dss_public()

              Fetches  the  corresponding  public key from a private key stored in an Engine. The
              key must be of the type indicated by the Type parameter.

       engine_get_all_methods() -> Result

              Types:

                 Result = [engine_method_type()]

              Returns a list of all possible engine methods.

              May raise exception error:notsup  in  case  there  is  no  engine  support  in  the
              underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

       engine_load(EngineId, PreCmds, PostCmds) -> Result

              Types:

                 EngineId = unicode:chardata()
                 PreCmds = PostCmds = [engine_cmnd()]
                 Result =
                     {ok, Engine :: engine_ref()} | {error, Reason :: term()}

              Loads  the  OpenSSL engine given by EngineId if it is available and then returns ok
              and an engine handle. This function is  the  same  as  calling  engine_load/4  with
              EngineMethods set to a list of all the possible methods. An error tuple is returned
              if the engine can't be loaded.

              The function raises a error:badarg if the parameters are in wrong  format.  It  may
              also  raise  the  exception  error:notsup in case there is no engine support in the
              underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

       engine_load(EngineId, PreCmds, PostCmds, EngineMethods) -> Result

              Types:

                 EngineId = unicode:chardata()
                 PreCmds = PostCmds = [engine_cmnd()]
                 EngineMethods = [engine_method_type()]
                 Result =
                     {ok, Engine :: engine_ref()} | {error, Reason :: term()}

              Loads the OpenSSL engine given by EngineId if it is available and then  returns  ok
              and an engine handle. An error tuple is returned if the engine can't be loaded.

              The  function  raises  a error:badarg if the parameters are in wrong format. It may
              also raise the exception error:notsup in case there is no  engine  support  in  the
              underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

       engine_unload(Engine) -> Result

              Types:

                 Engine = engine_ref()
                 Result = ok | {error, Reason :: term()}

              Unloads  the  OpenSSL  engine  given  by  Engine. An error tuple is returned if the
              engine can't be unloaded.

              The function raises a error:badarg if the parameter is in wrong format. It may also
              raise  the  exception  error:notsup  in  case  there  is  no  engine support in the
              underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

       engine_by_id(EngineId) -> Result

              Types:

                 EngineId = unicode:chardata()
                 Result =
                     {ok, Engine :: engine_ref()} | {error, Reason :: term()}

              Get a reference to an already loaded  engine  with  EngineId.  An  error  tuple  is
              returned if the engine can't be unloaded.

              The function raises a error:badarg if the parameter is in wrong format. It may also
              raise the exception error:notsup  in  case  there  is  no  engine  support  in  the
              underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

       engine_ctrl_cmd_string(Engine, CmdName, CmdArg) -> Result

              Types:

                 Engine = term()
                 CmdName = CmdArg = unicode:chardata()
                 Result = ok | {error, Reason :: term()}

              Sends  ctrl  commands  to  the OpenSSL engine given by Engine. This function is the
              same as calling engine_ctrl_cmd_string/4 with Optional set to false.

              The function raises a error:badarg if the parameters are in wrong  format.  It  may
              also  raise  the  exception  error:notsup in case there is no engine support in the
              underlying OpenSSL implementation.

       engine_ctrl_cmd_string(Engine, CmdName, CmdArg, Optional) ->
                                 Result

              Types:

                 Engine = term()
                 CmdName = CmdArg = unicode:chardata()
                 Optional = boolean()
                 Result = ok | {error, Reason :: term()}

              Sends ctrl commands to the OpenSSL engine given by Engine. Optional  is  a  boolean
              argument  that can relax the semantics of the function. If set to true it will only
              return failure if the ENGINE supported the given  command  name  but  failed  while
              executing  it, if the ENGINE doesn't support the command name it will simply return
              success without doing anything. In this case we assume the user is  only  supplying
              commands specific to the given ENGINE so we set this to false.

              The  function  raises  a error:badarg if the parameters are in wrong format. It may
              also raise the exception error:notsup in case there is no  engine  support  in  the
              underlying OpenSSL implementation.

       engine_add(Engine) -> Result

              Types:

                 Engine = engine_ref()
                 Result = ok | {error, Reason :: term()}

              Add the engine to OpenSSL's internal list.

              The  function  raises  a error:badarg if the parameters are in wrong format. It may
              also raise the exception error:notsup in case there is no  engine  support  in  the
              underlying OpenSSL implementation.

       engine_remove(Engine) -> Result

              Types:

                 Engine = engine_ref()
                 Result = ok | {error, Reason :: term()}

              Remove the engine from OpenSSL's internal list.

              The  function  raises  a error:badarg if the parameters are in wrong format. It may
              also raise the exception error:notsup in case there is no  engine  support  in  the
              underlying OpenSSL implementation.

       engine_get_id(Engine) -> EngineId

              Types:

                 Engine = engine_ref()
                 EngineId = unicode:chardata()

              Return the ID for the engine, or an empty binary if there is no id set.

              The  function  raises  a error:badarg if the parameters are in wrong format. It may
              also raise the exception error:notsup in case there is no  engine  support  in  the
              underlying OpenSSL implementation.

       engine_get_name(Engine) -> EngineName

              Types:

                 Engine = engine_ref()
                 EngineName = unicode:chardata()

              Return  the  name (eg a description) for the engine, or an empty binary if there is
              no name set.

              The function raises a error:badarg if the parameters are in wrong  format.  It  may
              also  raise  the  exception  error:notsup in case there is no engine support in the
              underlying OpenSSL implementation.

       engine_list() -> Result

              Types:

                 Result = [EngineId :: unicode:chardata()]

              List the id's of all engines in OpenSSL's internal list.

              It may also raise the exception error:notsup in case there is no engine support  in
              the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

              May  raise  exception error:notsup in case engine functionality is not supported by
              the underlying OpenSSL implementation.

       ensure_engine_loaded(EngineId, LibPath) -> Result

              Types:

                 EngineId = LibPath = unicode:chardata()
                 Result =
                     {ok, Engine :: engine_ref()} | {error, Reason :: term()}

              Loads the OpenSSL engine given by EngineId and the  path  to  the  dynamic  library
              implementing    the    engine.    This    function   is   the   same   as   calling
              ensure_engine_loaded/3 with EngineMethods  set  to  a  list  of  all  the  possible
              methods. An error tuple is returned if the engine can't be loaded.

              The  function  raises  a error:badarg if the parameters are in wrong format. It may
              also raise the exception error:notsup in case there is no  engine  support  in  the
              underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

       ensure_engine_loaded(EngineId, LibPath, EngineMethods) -> Result

              Types:

                 EngineId = LibPath = unicode:chardata()
                 EngineMethods = [engine_method_type()]
                 Result =
                     {ok, Engine :: engine_ref()} | {error, Reason :: term()}

              Loads  the  OpenSSL  engine  given  by EngineId and the path to the dynamic library
              implementing the engine. This function differs from the normal engine_load in  that
              sense  it  also  add  the  engine  id  to the internal list in OpenSSL. Then in the
              following calls to the function it just fetch the reference to the  engine  instead
              of loading it again. An error tuple is returned if the engine can't be loaded.

              The  function  raises  a error:badarg if the parameters are in wrong format. It may
              also raise the exception error:notsup in case there is no  engine  support  in  the
              underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

       ensure_engine_unloaded(Engine) -> Result

              Types:

                 Engine = engine_ref()
                 Result = ok | {error, Reason :: term()}

              Unloads  an  engine  loaded with the ensure_engine_loaded function. It both removes
              the label from the OpenSSL internal  engine  list  and  unloads  the  engine.  This
              function  is the same as calling ensure_engine_unloaded/2 with EngineMethods set to
              a list of all the possible methods. An error tuple is returned if the engine  can't
              be unloaded.

              The  function  raises  a error:badarg if the parameters are in wrong format. It may
              also raise the exception error:notsup in case there is no  engine  support  in  the
              underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

       ensure_engine_unloaded(Engine, EngineMethods) -> Result

              Types:

                 Engine = engine_ref()
                 EngineMethods = [engine_method_type()]
                 Result = ok | {error, Reason :: term()}

              Unloads  an  engine  loaded with the ensure_engine_loaded function. It both removes
              the label from the OpenSSL internal engine list and unloads the  engine.  An  error
              tuple is returned if the engine can't be unloaded.

              The  function  raises  a error:badarg if the parameters are in wrong format. It may
              also raise the exception error:notsup in case there is no  engine  support  in  the
              underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

OLD API

EXPORTS

       block_encrypt(Type :: block_cipher_without_iv(),
                     Key :: key(),
                     PlainText :: iodata()) ->
                        binary() | run_time_error()

          Dont:
              Don't use this function for new programs! Use the-new-api.

              Encrypt PlainText according to Type block cipher.

              May  raise  exception  error:notsup in case the chosen Type is not supported by the
              underlying libcrypto implementation.

              For keylengths and blocksizes see the User's Guide.

       block_decrypt(Type :: block_cipher_without_iv(),
                     Key :: key(),
                     Data :: iodata()) ->
                        binary() | run_time_error()

          Dont:
              Don't use this function for new programs! Use the new api.

              Decrypt CipherText according to Type block cipher.

              May raise exception error:notsup in case the chosen Type is not  supported  by  the
              underlying libcrypto implementation.

              For keylengths and blocksizes see the User's Guide.

       block_encrypt(Type, Key, Ivec, PlainText) -> CipherText | Error
       block_encrypt(AeadType, Key, Ivec, {AAD, PlainText}) -> {CipherText, CipherTag} | Error
       block_encrypt(aes_gcm  |  aes_ccm, Key, Ivec, {AAD, PlainText, TagLength}) -> {CipherText,
       CipherTag} | Error

              Types:

                 Type = block_cipher_with_iv()
                 AeadType = aead_cipher()
                 Key = key() | des3_key()
                 PlainText = iodata()
                 AAD = IVec = CipherText = CipherTag = binary()
                 TagLength = 1..16
                 Error = run_time_error()

          Dont:
              Don't use this function for new programs! Use the new api.

              Encrypt PlainText according to Type block cipher. IVec is an arbitrary initializing
              vector.

              In   AEAD   (Authenticated   Encryption   with   Associated   Data)  mode,  encrypt
              PlainTextaccording  to  Type  block  cipher  and  calculate  CipherTag  that   also
              authenticates the AAD (Associated Authenticated Data).

              May  raise  exception  error:notsup in case the chosen Type is not supported by the
              underlying libcrypto implementation.

              For keylengths, iv-sizes and blocksizes see the User's Guide.

       block_decrypt(Type, Key, Ivec, CipherText) -> PlainText | Error
       block_decrypt(AeadType, Key, Ivec, {AAD, CipherText, CipherTag}) -> PlainText | Error

              Types:

                 Type = block_cipher_with_iv()
                 AeadType = aead_cipher()
                 Key = key() | des3_key()
                 PlainText = iodata()
                 AAD = IVec = CipherText = CipherTag = binary()
                 Error = BadTag | run_time_error()
                 BadTag = error

          Dont:
              Don't use this function for new programs! Use the new api.

              Decrypt  CipherText  according  to  Type  block  cipher.  IVec  is   an   arbitrary
              initializing vector.

              In   AEAD   (Authenticated   Encryption   with   Associated   Data)  mode,  decrypt
              CipherTextaccording to Type block cipher and check the authenticity  the  PlainText
              and  AAD  (Associated  Authenticated Data) using the CipherTag. May return error if
              the decryption or validation fail's

              May raise exception error:notsup in case the chosen Type is not  supported  by  the
              underlying libcrypto implementation.

              For keylengths, iv-sizes and blocksizes see the User's Guide.

       stream_init(Type, Key) -> State | run_time_error()

              Types:

                 Type = rc4
                 Key = iodata()
                 State = stream_state()

          Dont:
              Don't use this function for new programs! Use the new api.

              Initializes  the  state  for  use  in  RC4  stream  encryption  stream_encrypt  and
              stream_decrypt

              For keylengths see the User's Guide.

       stream_init(Type, Key, IVec) -> State | run_time_error()

              Types:

                 Type = stream_cipher()
                 Key = iodata()
                 IVec = binary()
                 State = stream_state()

          Dont:
              Don't use this function for new programs! Use the new api.

              Initializes the state for use in streaming AES encryption using Counter mode (CTR).
              Key  is  the  AES  key  and  must  be either 128, 192, or 256 bits long. IVec is an
              arbitrary initializing vector of 128 bits (16 bytes). This state is  for  use  with
              stream_encrypt and stream_decrypt.

              For keylengths and iv-sizes see the User's Guide.

       stream_encrypt(State, PlainText) ->
                         {NewState, CipherText} | run_time_error()

              Types:

                 State = stream_state()
                 PlainText = iodata()
                 NewState = stream_state()
                 CipherText = iodata()

          Dont:
              Don't use this function for new programs! Use the new api.

              Encrypts  PlainText according to the stream cipher Type specified in stream_init/3.
              Text can be any number of bytes. The initial State is  created  using  stream_init.
              NewState must be passed into the next call to stream_encrypt.

       stream_decrypt(State, CipherText) ->
                         {NewState, PlainText} | run_time_error()

              Types:

                 State = stream_state()
                 CipherText = iodata()
                 NewState = stream_state()
                 PlainText = iodata()

          Dont:
              Don't use this function for new programs! Use the new api.

              Decrypts CipherText according to the stream cipher Type specified in stream_init/3.
              PlainText can  be  any  number  of  bytes.  The  initial  State  is  created  using
              stream_init. NewState must be passed into the next call to stream_decrypt.

       supports() -> [Support]

              Types:

                 Support =
                     {hashs, Hashs} |
                     {ciphers, Ciphers} |
                     {public_keys, PKs} |
                     {macs, Macs} |
                     {curves, Curves} |
                     {rsa_opts, RSAopts}
                 Hashs =
                     [sha1() |
                      sha2() |
                      sha3() |
                      blake2() |
                      ripemd160 |
                      compatibility_only_hash()]
                 Ciphers = [cipher()]
                 PKs = [rsa | dss | ecdsa | dh | ecdh | ec_gf2m]
                 Macs = [hmac | cmac | poly1305]
                 Curves =
                     [ec_named_curve() | edwards_curve_dh() | edwards_curve_ed()]
                 RSAopts = [rsa_sign_verify_opt() | rsa_opt()]

          Dont:
              Don't use this function for new programs! Use supports/1 in the new api.

              Can  be  used  to  determine  which  crypto  algorithms  that  are supported by the
              underlying libcrypto library

              See hash_info/1 and  cipher_info/1  for  information  about  the  hash  and  cipher
              algorithms.

       hmac(Type, Key, Data) -> Mac

       hmac(Type, Key, Data, MacLength) -> Mac

              Types:

                 Type = hmac_hash_algorithm()
                 Key = Data = iodata()
                 MacLength = integer()
                 Mac = binary()

          Dont:
              Don't use this function for new programs! Use mac/4 or macN/5 in the new api.

              Computes a HMAC of type Type from Data using Key as the authentication key.

              MacLength will limit the size of the resultant Mac.

       hmac_init(Type, Key) -> State

              Types:

                 Type = hmac_hash_algorithm()
                 Key = iodata()
                 State = hmac_state()

          Dont:
              Don't use this function for new programs! Use mac_init/3 in the new api.

              Initializes  the  context for streaming HMAC operations. Type determines which hash
              function to use in the HMAC operation. Key is the authentication key. The  key  can
              be any length.

       hmac_update(State, Data) -> NewState

              Types:

                 Data = iodata()
                 State = NewState = hmac_state()

          Dont:
              Don't use this function for new programs! Use mac_update/2 in the new api.

              Updates  the  HMAC  represented  by Context using the given Data. Context must have
              been generated using an HMAC init function (such as hmac_init).  Data  can  be  any
              length.  NewContext  must  be passed into the next call to hmac_update or to one of
              the functions hmac_final and hmac_final_n

          Warning:
              Do not use a  Context  as  argument  in  more  than  one  call  to  hmac_update  or
              hmac_final. The semantics of reusing old contexts in any way is undefined and could
              even crash the VM in earlier releases. The reason for this limitation is a lack  of
              support in the underlying libcrypto API.

       hmac_final(State) -> Mac

              Types:

                 State = hmac_state()
                 Mac = binary()

          Dont:
              Don't use this function for new programs! Use mac_final/1 in the new api.

              Finalizes  the  HMAC operation referenced by Context. The size of the resultant MAC
              is determined by the type of hash function used to generate it.

       hmac_final_n(State, HashLen) -> Mac

              Types:

                 State = hmac_state()
                 HashLen = integer()
                 Mac = binary()

          Dont:
              Don't use this function for new programs! Use mac_finalN/2 in the new api.

              Finalizes the HMAC operation referenced by Context. HashLen must  be  greater  than
              zero.  Mac  will  be  a  binary with at most HashLen bytes. Note that if HashLen is
              greater than the actual number of bytes returned  from  the  underlying  hash,  the
              returned hash will have fewer than HashLen bytes.

       cmac(Type, Key, Data) -> Mac

       cmac(Type, Key, Data, MacLength) -> Mac

              Types:

                 Type =
                     cbc_cipher() |
                     cfb_cipher() |
                     blowfish_cbc | des_ede3 | rc2_cbc
                 Key = Data = iodata()
                 MacLength = integer()
                 Mac = binary()

          Dont:
              Don't use this function for new programs! Use mac/4 or macN/5 in the new api.

              Computes a CMAC of type Type from Data using Key as the authentication key.

              MacLength will limit the size of the resultant Mac.

       poly1305(Key :: iodata(), Data :: iodata()) -> Mac

              Types:

                 Mac = binary()

          Dont:
              Don't use this function for new programs! Use mac/3 or macN/4 in the new api.

              Computes  a  POLY1305  message authentication code (Mac) from Data using Key as the
              authentication key.