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NAME
crypto - Crypto Functions
DESCRIPTION
This module provides a set of cryptographic functions.
* Hash functions - Secure Hash Standard, The MD5 Message Digest Algorithm (RFC 1321)
and The MD4 Message Digest Algorithm (RFC 1320)
* Hmac functions - Keyed-Hashing for Message Authentication (RFC 2104)
* Block ciphers - DES and AES in Block Cipher Modes - ECB, CBC, CFB, OFB, CTR and GCM
*
RSA encryption RFC 1321
* Digital signatures Digital Signature Standard (DSS) and Elliptic Curve Digital
Signature Algorithm (ECDSA)
*
Secure Remote Password Protocol (SRP - RFC 2945)
* gcm: Dworkin, M., "Recommendation for Block Cipher Modes of Operation: Galois/Counter
Mode (GCM) and GMAC", National Institute of Standards and Technology SP 800- 38D,
November 2007.
DATA TYPES
key_value() = integer() | binary()
Always binary() when used as return value
rsa_public() = [key_value()] = [E, N]
Where E is the public exponent and N is public modulus.
rsa_private() = [key_value()] = [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_value()] = [P, Q, G, Y]
Where P, Q and G are the dss parameters and Y is the public key.
dss_private() = [key_value()] = [P, Q, G, X]
Where P, Q and G are the dss parameters and X is the private key.
srp_public() = key_value()
Where is A or B from SRP design
srp_private() = key_value()
Where is a or b from SRP design
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'
dh_public() = key_value()
dh_private() = key_value()
dh_params() = [key_value()] = [P, G]
ecdh_public() = key_value()
ecdh_private() = key_value()
ecdh_params() = ec_named_curve() | ec_explicit_curve()
ec_explicit_curve() =
{ec_field(), Prime :: key_value(), Point :: key_value(), Order :: integer(), CoFactor :: none | integer()}
ec_field() = {prime_field, Prime :: integer()} |
{characteristic_two_field, M :: integer(), Basis :: ec_basis()}
ec_basis() = {tpbasis, K :: non_neg_integer()} |
{ppbasis, K1 :: non_neg_integer(), K2 :: non_neg_integer(), K3 :: non_neg_integer()} |
onbasis
ec_named_curve() ->
sect571r1| sect571k1| sect409r1| sect409k1| secp521r1| secp384r1| secp224r1| secp224k1|
secp192k1| secp160r2| secp128r2| secp128r1| sect233r1| sect233k1| sect193r2| sect193r1|
sect131r2| sect131r1| sect283r1| sect283k1| sect163r2| secp256k1| secp160k1| secp160r1|
secp112r2| secp112r1| sect113r2| sect113r1| sect239k1| sect163r1| sect163k1| secp256r1|
secp192r1|
brainpoolP160r1| brainpoolP160t1| brainpoolP192r1| brainpoolP192t1| brainpoolP224r1|
brainpoolP224t1| brainpoolP256r1| brainpoolP256t1| brainpoolP320r1| brainpoolP320t1|
brainpoolP384r1| brainpoolP384t1| brainpoolP512r1| brainpoolP512t1
Note that the sect curves are GF2m (characteristic two) curves and are only supported if
the underlying OpenSSL has support for them. See also crypto:supports/0
stream_cipher() = rc4 | aes_ctr
block_cipher() = aes_cbc128 | aes_cfb8 | aes_cfb128 | aes_ige256 | blowfish_cbc |
blowfish_cfb64 | des_cbc | des_cfb | des3_cbc | des3_cbf
| des_ede3 | rc2_cbc
aead_cipher() = aes_gcm | chacha20_poly1305
stream_key() = aes_key() | rc4_key()
block_key() = aes_key() | blowfish_key() | des_key()| des3_key()
aes_key() = iodata()
Key length is 128, 192 or 256 bits
rc4_key() = iodata()
Variable key length from 8 bits up to 2048 bits (usually between 40 and 256)
blowfish_key() = iodata()
Variable key length from 32 bits up to 448 bits
des_key() = iodata()
Key length is 64 bits (in CBC mode only 8 bits are used)
des3_key() = [binary(), binary(), binary()]
Each key part is 64 bits (in CBC mode only 8 bits are used)
digest_type() = md5 | sha | sha224 | sha256 | sha384 | sha512
hash_algorithms() = md5 | ripemd160 | sha | sha224 | sha256 | sha384 | sha512
md4 is also supported for hash_init/1 and hash/2. Note that both md4 and md5 are
recommended only for compatibility with existing applications.
cipher_algorithms() = des_cbc | des_cfb | des3_cbc | des3_cbf | des_ede3 |
blowfish_cbc | blowfish_cfb64 | aes_cbc128 | aes_cfb8 | aes_cfb128| aes_cbc256 | aes_ige256 | aes_gcm | chacha20_poly1305 | rc2_cbc | aes_ctr| rc4
public_key_algorithms() = rsa |dss | ecdsa | dh | ecdh | ec_gf2m
Note that ec_gf2m is not strictly a public key algorithm, but a restriction on what curves
are supported with ecdsa and ecdh.
EXPORTS
block_encrypt(Type, Key, PlainText) -> CipherText
Types:
Type = des_ecb | blowfish_ecb | aes_ecb
Key = block_key()
PlainText = iodata()
Encrypt PlainText according to Type block cipher.
May throw exception notsup in case the chosen Type is not supported by the
underlying OpenSSL implementation.
block_decrypt(Type, Key, CipherText) -> PlainText
Types:
Type = des_ecb | blowfish_ecb | aes_ecb
Key = block_key()
PlainText = iodata()
Decrypt CipherText according to Type block cipher.
May throw exception notsup in case the chosen Type is not supported by the
underlying OpenSSL implementation.
block_encrypt(Type, Key, Ivec, PlainText) -> CipherText
block_encrypt(AeadType, Key, Ivec, {AAD, PlainText}) -> {CipherText, CipherTag}
Types:
Type = block_cipher()
AeadType = aead_cipher()
Key = block_key()
PlainText = iodata()
AAD = IVec = CipherText = CipherTag = binary()
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 throw exception notsup in case the chosen Type is not supported by the
underlying OpenSSL implementation.
block_decrypt(Type, Key, Ivec, CipherText) -> PlainText
block_decrypt(AeadType, Key, Ivec, {AAD, CipherText, CipherTag}) -> PlainText | error
Types:
Type = block_cipher()
AeadType = aead_cipher()
Key = block_key()
PlainText = iodata()
AAD = IVec = CipherText = CipherTag = binary()
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 throw exception notsup in case the chosen Type is not supported by the
underlying OpenSSL implementation.
bytes_to_integer(Bin) -> Integer
Types:
Bin = binary() - as returned by crypto functions
Integer = integer()
Convert binary representation, of an integer, to an Erlang integer.
compute_key(Type, OthersPublicKey, MyKey, Params) -> SharedSecret
Types:
Type = dh | ecdh | srp
OthersPublicKey = dh_public() | ecdh_public() | srp_public()
MyKey = dh_private() | ecdh_private() | {srp_public(),srp_private()}
Params = dh_params() | ecdh_params() | SrpUserParams | SrpHostParams
SrpUserParams = {user, [DerivedKey::binary(), Prime::binary(),
Generator::binary(), Version::atom() | [Scrambler:binary()]]}
SrpHostParams = {host, [Verifier::binary(), Prime::binary(), Version::atom() |
[Scrambler::binary]]}
SharedSecret = binary()
Computes the shared secret from the private key and the other party's public key.
See also public_key:compute_key/2
exor(Data1, Data2) -> Result
Types:
Data1, Data2 = iodata()
Result = 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 | srp
Params = dh_params() | ecdh_params() | SrpUserParams | SrpHostParams
SrpUserParams = {user, [Generator::binary(), Prime::binary(), Version::atom()]}
SrpHostParams = {host, [Verifier::binary(), Generator::binary(),
Prime::binary(), Version::atom()]}
PublicKey = dh_public() | ecdh_public() | srp_public()
PrivKeyIn = undefined | dh_private() | ecdh_private() | srp_private()
PrivKeyOut = dh_private() | ecdh_private() | srp_private()
Generates public keys of type Type. See also public_key:generate_key/1
hash(Type, Data) -> Digest
Types:
Type = md4 | hash_algorithms()
Data = iodata()
Digest = binary()
Computes a message digest of type Type from Data.
May throw exception notsup in case the chosen Type is not supported by the
underlying OpenSSL implementation.
hash_init(Type) -> Context
Types:
Type = md4 | hash_algorithms()
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 throw exception notsup in case the chosen Type is not supported by the
underlying OpenSSL implementation.
hash_update(Context, Data) -> NewContext
Types:
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(Context) -> Digest
Types:
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.
hmac(Type, Key, Data) -> Mac
hmac(Type, Key, Data, MacLength) -> Mac
Types:
Type = hash_algorithms() - except ripemd160
Key = iodata()
Data = iodata()
MacLength = integer()
Mac = binary()
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) -> Context
Types:
Type = hash_algorithms() - except ripemd160
Key = iodata()
Context = binary()
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(Context, Data) -> NewContext
Types:
Context = NewContext = binary()
Data = iodata()
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 OpenSSL API.
hmac_final(Context) -> Mac
Types:
Context = Mac = binary()
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(Context, HashLen) -> Mac
Types:
Context = Mac = binary()
HashLen = non_neg_integer()
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.
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">>,9469983,<<"OpenSSL 0.9.8a 11 Oct 2005">>}]
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
OpenSSL library used at runtime. In earlier OTP versions both numeric and text was
taken from the library.
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, Data) -> NextIVec
next_iv(Type, Data, IVec) -> NextIVec
Types:
Type = des_cbc | des3_cbc | aes_cbc | des_cfb
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(Type, CipherText, PrivateKey, Padding) -> PlainText
Types:
Type = rsa
CipherText = binary()
PrivateKey = rsa_private()
Padding = rsa_pkcs1_padding | rsa_pkcs1_oaep_padding | rsa_no_padding
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(Type, PlainText, PrivateKey, Padding) -> CipherText
Types:
Type = rsa
PlainText = binary()
The size of the PlainText must be less than byte_size(N)-11 if
rsa_pkcs1_padding is used, and byte_size(N) if rsa_no_padding is used, where N
is public modulus of the RSA key.
PrivateKey = rsa_private()
Padding = rsa_pkcs1_padding | rsa_no_padding
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(Type, CipherText, PublicKey, Padding) -> PlainText
Types:
Type = rsa
CipherText = binary()
PublicKey = rsa_public()
Padding = rsa_pkcs1_padding | rsa_no_padding
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(Type, PlainText, PublicKey, Padding) -> CipherText
Types:
Type = rsa
PlainText = binary()
The size of the PlainText must be less than byte_size(N)-11 if
rsa_pkcs1_padding is used, and byte_size(N) if rsa_no_padding is used, where N
is public modulus of the RSA key.
PublicKey = rsa_public()
Padding = rsa_pkcs1_padding | rsa_pkcs1_oaep_padding | rsa_no_padding
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_bytes(N) -> binary()
Types:
N = integer()
Generates N bytes randomly uniform 0..255, and returns the result in a binary. Uses
the crypto library pseudo-random number generator.
This function is not recommended for cryptographic purposes. Please use
strong_rand_bytes/1 instead.
rand_seed(Seed) -> ok
Types:
Seed = binary()
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 returns
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.
sign(Algorithm, DigestType, Msg, Key) -> binary()
Types:
Algorithm = rsa | dss | ecdsa
Msg = binary() | {digest,binary()}
The msg is either the binary "cleartext" data to be signed or it is the hashed
value of "cleartext" i.e. the digest (plaintext).
DigestType = digest_type()
Key = rsa_private() | dss_private() | [ecdh_private(),ecdh_params()]
Creates a digital signature.
Algorithm dss can only be used together with digest type sha.
See also public_key:sign/3.
start() -> ok
Equivalent to application:start(crypto).
stop() -> ok
Equivalent to application:stop(crypto).
strong_rand_bytes(N) -> binary()
Types:
N = integer()
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 throw exception low_entropy in case the random generator failed due to lack of
secure "randomness".
stream_init(Type, Key) -> State
Types:
Type = rc4
State = opaque()
Key = iodata()
Initializes the state for use in RC4 stream encryption stream_encrypt and
stream_decrypt
stream_init(Type, Key, IVec) -> State
Types:
Type = aes_ctr
State = opaque()
Key = iodata()
IVec = binary()
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.
stream_encrypt(State, PlainText) -> { NewState, CipherText}
Types:
Text = iodata()
CipherText = binary()
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 }
Types:
CipherText = iodata()
PlainText = binary()
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() -> AlgorithmList
Types:
AlgorithmList = [{hashs, [hash_algorithms()]}, {ciphers,
[cipher_algorithms()]}, {public_keys, [public_key_algorithms()]}
Can be used to determine which crypto algorithms that are supported by the
underlying OpenSSL library
ec_curves() -> EllipticCurveList
Types:
EllipticCurveList = [ec_named_curve()]
Can be used to determine which named elliptic curves are supported.
ec_curve(NamedCurve) -> EllipticCurve
Types:
NamedCurve = ec_named_curve()
EllipticCurve = ec_explicit_curve()
Return the defining parameters of a elliptic curve.
verify(Algorithm, DigestType, Msg, Signature, Key) -> boolean()
Types:
Algorithm = rsa | dss | ecdsa
Msg = binary() | {digest,binary()}
The msg is either the binary "cleartext" data or it is the hashed value of
"cleartext" i.e. the digest (plaintext).
DigestType = digest_type()
Signature = binary()
Key = rsa_public() | dss_public() | [ecdh_public(),ecdh_params()]
Verifies a digital signature
Algorithm dss can only be used together with digest type sha.
See also public_key:verify/4.