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NAME
public_key - API module for public key infrastructure.
DESCRIPTION
This module provides functions to handle public key infrastructure. It can encode/decode different file
formats (PEM, openssh), sign and verify digital signatures and validate certificate paths and certificate
revocation lists.
PUBLIC_KEY
* public_key requires the crypto and asn1 applications, the latter since R16 (hopefully the runtime
dependency on asn1 will be removed again in the future).
* Supports RFC 5280 - Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation
List (CRL) Profile
* Supports PKCS-1 - RSA Cryptography Standard
* Supports DSS- Digital Signature Standard (DSA - Digital Signature Algorithm)
* Supports PKCS-3 - Diffie-Hellman Key Agreement Standard
* Supports PKCS-5 - Password-Based Cryptography Standard
* Supports PKCS-8 - Private-Key Information Syntax Standard
* Supports PKCS-10 - Certification Request Syntax Standard
COMMON DATA TYPES
Note:
All records used in this manual are generated from ASN.1 specifications and are documented in the User's
Guide. See Public key records and X.509 Certificate records.
Use the following include directive to get access to the records and constant macros described here and
in the User's Guide.
-include_lib("public_key/include/public_key.hrl").
Data Types
oid() - a tuple of integers as generated by the ASN1 compiler.
boolean() = true | false
string() = [bytes()]
der_encoded() = binary()
pki_asn1_type() = 'Certificate' | 'RSAPrivateKey'| 'RSAPublicKey' |
'DSAPrivateKey' | 'DSAPublicKey' | 'DHParameter' | 'SubjectPublicKeyInfo' |
'PrivateKeyInfo' | 'CertificationRequest' | 'ECPrivateKey'|
'EcpkParameters'
pem_entry () = {pki_asn1_type(), binary(), %% DER or encrypted DER
not_encrypted | cipher_info()}
cipher_info() = {"RC2-CBC | "DES-CBC" | "DES-EDE3-CBC", crypto:rand_bytes(8)} |
'PBES2-params'}
rsa_public_key() = #'RSAPublicKey'{}
rsa_private_key() = #'RSAPrivateKey'{}
dsa_public_key() = {integer(), #'Dss-Parms'{}}
dsa_private_key() = #'DSAPrivateKey'{}
ec_public_key() = {#'ECPoint'{}, #'EcpkParameters'{} | {namedCurve, oid()}}
ec_private_key() = #'ECPrivateKey'{}
public_crypt_options() = [{rsa_pad, rsa_padding()}].
rsa_padding() = 'rsa_pkcs1_padding' | 'rsa_pkcs1_oaep_padding'
| 'rsa_no_padding'
rsa_digest_type() = 'md5' | 'sha' | 'sha224' | 'sha256' | 'sha384' | 'sha512'
dss_digest_type() = 'sha'
ecdsa_digest_type() = 'sha'| 'sha224' | 'sha256' | 'sha384' | 'sha512'
crl_reason() = unspecified | keyCompromise | cACompromise | affiliationChanged | superseded | cessationOfOperation | certificateHold | privilegeWithdrawn | aACompromise
ssh_file() = openssh_public_key | rfc4716_public_key |
known_hosts | auth_keys
EXPORTS
compute_key(OthersKey, MyKey)->
compute_key(OthersKey, MyKey, Params)->
Types:
OthersKey = #'ECPoint'{} | binary(), MyKey = #'ECPrivateKey'{} | binary()
Params = #'DHParameter'{}
Compute shared secret
decrypt_private(CipherText, Key) -> binary()
decrypt_private(CipherText, Key, Options) -> binary()
Types:
CipherText = binary()
Key = rsa_private_key()
Options = public_crypt_options()
Public key decryption using the private key. See also crypto:private_decrypt/4
decrypt_public(CipherText, Key) - > binary()
decrypt_public(CipherText, Key, Options) - > binary()
Types:
CipherText = binary()
Key = rsa_public_key()
Options = public_crypt_options()
Public key decryption using the public key. See also crypto:public_decrypt/4
der_decode(Asn1type, Der) -> term()
Types:
Asn1Type = atom()
ASN.1 type present in the public_key applications asn1 specifications.
Der = der_encoded()
Decodes a public key ASN.1 DER encoded entity.
der_encode(Asn1Type, Entity) -> der_encoded()
Types:
Asn1Type = atom()
Asn1 type present in the public_key applications ASN.1 specifications.
Entity = term()
The erlang representation of Asn1Type
Encodes a public key entity with ASN.1 DER encoding.
generate_key(Params) -> {Public::binary(), Private::binary()} | #'ECPrivateKey'{}
Types:
Params = #'DHParameter'{} | {namedCurve, oid()} | #'ECParameters'{}
Generates a new keypair
pem_decode(PemBin) -> [pem_entry()]
Types:
PemBin = binary()
Example {ok, PemBin} = file:read_file("cert.pem").
Decode PEM binary data and return entries as ASN.1 DER encoded entities.
pem_encode(PemEntries) -> binary()
Types:
PemEntries = [pem_entry()]
Creates a PEM binary
pem_entry_decode(PemEntry) -> term()
pem_entry_decode(PemEntry, Password) -> term()
Types:
PemEntry = pem_entry()
Password = string()
Decodes a PEM entry. pem_decode/1 returns a list of PEM entries. Note that if the PEM entry is of
type 'SubjectPublickeyInfo' it will be further decoded to an rsa_public_key() or dsa_public_key().
pem_entry_encode(Asn1Type, Entity) -> pem_entry()
pem_entry_encode(Asn1Type, Entity, {CipherInfo, Password}) -> pem_entry()
Types:
Asn1Type = pki_asn1_type()
Entity = term()
The Erlang representation of Asn1Type. If Asn1Type is 'SubjectPublicKeyInfo' then Entity must
be either an rsa_public_key() or a dsa_public_key() and this function will create the
appropriate 'SubjectPublicKeyInfo' entry.
CipherInfo = cipher_info()
Password = string()
Creates a PEM entry that can be feed to pem_encode/1.
encrypt_private(PlainText, Key) -> binary()
Types:
PlainText = binary()
Key = rsa_private_key()
Public key encryption using the private key. See also crypto:private_encrypt/4
encrypt_public(PlainText, Key) -> binary()
Types:
PlainText = binary()
Key = rsa_public_key()
Public key encryption using the public key. See also crypto:public_encrypt/4
pkix_decode_cert(Cert, otp|plain) -> #'Certificate'{} | #'OTPCertificate'{}
Types:
Cert = der_encoded()
Decodes an ASN.1 DER encoded PKIX certificate. The otp option will use the customized ASN.1
specification OTP-PKIX.asn1 for decoding and also recursively decode most of the standard parts.
pkix_encode(Asn1Type, Entity, otp | plain) -> der_encoded()
Types:
Asn1Type = atom()
The ASN.1 type can be 'Certificate', 'OTPCertificate' or a subtype of either .
Entity = #'Certificate'{} | #'OTPCertificate'{} | a valid subtype
DER encodes a PKIX x509 certificate or part of such a certificate. This function must be used for
encoding certificates or parts of certificates that are decoded/created in the otp format, whereas
for the plain format this function will directly call der_encode/2.
pkix_is_issuer(Cert, IssuerCert) -> boolean()
Types:
Cert = der_encode() | #'OTPCertificate'{}
IssuerCert = der_encode() | #'OTPCertificate'{}
Checks if IssuerCert issued Cert
pkix_is_fixed_dh_cert(Cert) -> boolean()
Types:
Cert = der_encode() | #'OTPCertificate'{}
Checks if a Certificate is a fixed Diffie-Hellman Cert.
pkix_is_self_signed(Cert) -> boolean()
Types:
Cert = der_encode() | #'OTPCertificate'{}
Checks if a Certificate is self signed.
pkix_issuer_id(Cert, IssuedBy) -> {ok, IssuerID} | {error, Reason}
Types:
Cert = der_encode() | #'OTPCertificate'{}
IssuedBy = self | other
IssuerID = {integer(), {rdnSequence, [#'AttributeTypeAndValue'{}]}}
The issuer id consists of the serial number and the issuers name.
Reason = term()
Returns the issuer id.
pkix_normalize_name(Issuer) -> Normalized
Types:
Issuer = {rdnSequence,[#'AttributeTypeAndValue'{}]}
Normalized = {rdnSequence, [#'AttributeTypeAndValue'{}]}
Normalizes a issuer name so that it can be easily compared to another issuer name.
pkix_path_validation(TrustedCert, CertChain, Options) -> {ok, {PublicKeyInfo, PolicyTree}} | {error,
{bad_cert, Reason}}
Types:
TrustedCert = #'OTPCertificate'{} | der_encode() | unknown_ca | selfsigned_peer
Normally a trusted certificate but it can also be one of the path validation errors
unknown_ca or selfsigned_peer that can be discovered while constructing the input to this
function and that should be run through the verify_fun.
CertChain = [der_encode()]
A list of DER encoded certificates in trust order ending with the peer certificate.
Options = proplists:proplists()
PublicKeyInfo = {?'rsaEncryption' | ?'id-dsa', rsa_public_key() | integer(), 'NULL' | 'Dss-
Parms'{}}
PolicyTree = term()
At the moment this will always be an empty list as Policies are not currently supported
Reason = cert_expired | invalid_issuer | invalid_signature | unknown_ca | selfsigned_peer |
name_not_permitted | missing_basic_constraint | invalid_key_usage | crl_reason()
Performs a basic path validation according to RFC 5280. However CRL validation is done separately
by pkix_crls_validate/3 and should be called from the supplied verify_fun
{verify_fun, fun()}:
The fun should be defined as:
fun(OtpCert :: #'OTPCertificate'{}, Event :: {bad_cert, Reason :: atom()} |
{extension, #'Extension'{}},
InitialUserState :: term()) ->
{valid, UserState :: term()} | {valid_peer, UserState :: term()} |
{fail, Reason :: term()} | {unknown, UserState :: term()}.
If the verify callback fun returns {fail, Reason}, the verification process is immediately
stopped. If the verify callback fun returns {valid, UserState}, the verification process is
continued, this can be used to accept specific path validation errors such as selfsigned_peer
as well as verifying application specific extensions. If called with an extension unknown to
the user application the return value {unknown, UserState} should be used.
{max_path_length, integer()}:
The max_path_length is the maximum number of non-self-issued intermediate certificates that
may follow the peer certificate in a valid certification path. So if max_path_length is 0 the
PEER must be signed by the trusted ROOT-CA directly, if 1 the path can be PEER, CA, ROOT-CA,
if it is 2 PEER, CA, CA, ROOT-CA and so on.
pkix_crls_validate(OTPCertificate, DPAndCRLs, Options) -> CRLStatus()
Types:
OTPCertificate = #'OTPCertificate'{}
DPAndCRLs = [{DP::#'DistributionPoint'{} ,CRL::#'CertificateList'{}}]
Options = proplists:proplists()
CRLStatus() = valid | {bad_cert, revocation_status_undetermined} | {bad_cert, {revoked,
crl_reason()}}
Performs CRL validation. It is intended to be called from the verify fun of
pkix_path_validation/3
{update_crl, fun()}:
The fun has the following type spec:
fun(#'DistributionPoint'{}, #'CertificateList'{}) -> #'CertificateList'{}
The fun should use the information in the distribution point to acesses the lates possible
version of the CRL. If this fun is not specified public_key will use the default
implementation:
fun(_DP, CRL) -> CRL end
pkix_sign(#'OTPTBSCertificate'{}, Key) -> der_encode()
Types:
Key = rsa_public_key() | dsa_public_key()
Signs a 'OTPTBSCertificate'. Returns the corresponding der encoded certificate.
pkix_sign_types(AlgorithmId) -> {DigestType, SignatureType}
Types:
AlgorithmId = oid()
Signature oid from a certificate or a certificate revocation list
DigestType = rsa_digest_type() | dss_digest_type()
SignatureType = rsa | dsa
Translates signature algorithm oid to erlang digest and signature types.
pkix_verify(Cert, Key) -> boolean()
Types:
Cert = der_encode()
Key = rsa_public_key() | dsa_public_key()
Verify PKIX x.509 certificate signature.
sign(Msg, DigestType, Key) -> binary()
Types:
Msg = binary() | {digest,binary()}
The msg is either the binary "plain text" data to be signed or it is the hashed value of
"plain text" i.e. the digest.
DigestType = rsa_digest_type() | dss_digest_type() | ecdsa_digest_type()
Key = rsa_private_key() | dsa_private_key() | ec_private_key()
Creates a digital signature.
ssh_decode(SshBin, Type) -> [{public_key(), Attributes::list()}]
Types:
SshBin = binary()
Example {ok, SshBin} = file:read_file("known_hosts").
Type = public_key | ssh_file()
If Type is public_key the binary may be either a rfc4716 public key or a openssh public key.
Decodes a ssh file-binary. In the case of know_hosts or auth_keys the binary may include one or
more lines of the file. Returns a list of public keys and their attributes, possible attribute
values depends on the file type represented by the binary.
rfc4716 attributes - see RFC 4716:
{headers, [{string(), utf8_string()}]}
auth_key attributes - see man sshd :
{comment, string()}{options, [string()]}{bits, integer()} - In ssh version 1 files
known_host attributes - see man sshd:
{hostnames, [string()]}{comment, string()}{bits, integer()} - In ssh version 1 files
ssh_encode([{Key, Attributes}], Type) -> binary()
Types:
Key = public_key()
Attributes = list()
Type = ssh_file()
Encodes a list of ssh file entries (public keys and attributes) to a binary. Possible attributes
depends on the file type, see ssh_decode/2
verify(Msg, DigestType, Signature, Key) -> boolean()
Types:
Msg = binary() | {digest,binary()}
The msg is either the binary "plain text" data or it is the hashed value of "plain text" i.e.
the digest.
DigestType = rsa_digest_type() | dss_digest_type() | ecdsa_digest_type()
Signature = binary()
Key = rsa_public_key() | dsa_public_key() | ec_public_key()
Verifies a digital signature