User's Guide
Reference Manual
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public_key
User's Guide
Version 1.1

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Chapters

- Introduction
  - Top of chapter
  - Purpose
  - Prerequisites
  - Performance Tips
- Public-Key Records
  - Top of chapter
  - Data Types
  - RSA
  - DSA
  - ECDSA
  - PKIX Certificates
  - Standard Certificate Extensions
  - Private Internet Extensions
  - CRL and CRL Extensions Profile
- Getting Started
  - Top of chapter
  - PEM Files
  - RSA Public-Key Cryptography
  - Digital Signatures
  - SSH Files

# 2 Public-Key Records

This chapter briefly describes Erlang records derived from ASN.1 specifications used to handle public key infrastructure. The scope is to describe the data types of each component, not the semantics. For information on the semantics, refer to the relevant standards and RFCs linked in the sections below.

Use the following include directive to get access to the records and constant macros described in the following sections:

     -include_lib("public_key/include/public_key.hrl").

### 2.1 Data Types

Common non-standard Erlang data types used to describe the record fields in the following sections and which are not defined in the Public Key Reference Manual follows here:

time() =

  uct_time() | general_time()

uct_time() =

  {utcTime, "YYMMDDHHMMSSZ"}

general_time() =

  {generalTime, "YYYYMMDDHHMMSSZ"}

general_name() =

  {rfc822Name, string()}

  | {dNSName, string()}

  | {x400Address, string()}

  | {directoryName, {rdnSequence, [#AttributeTypeAndValue'{}]}}

  | {eidPartyName, special_string()}

  | {eidPartyName, special_string(), special_string()}

  | {uniformResourceIdentifier, string()}

  | {ipAddress, string()}

  | {registeredId, oid()}

  | {otherName, term()}

special_string() =

  {teletexString, string()}

  | {printableString, string()}

  | {universalString, string()}

  | {utf8String, binary()}

  | {bmpString, string()}

dist_reason() =

  unused

  | keyCompromise

  | cACompromise

  | affiliationChanged

  | superseded

  | cessationOfOperation

  | certificateHold

  | privilegeWithdrawn

  | aACompromise

OID_macro() =

  ?OID_name()

OID_name() =

  atom()

### 2.2 RSA

Erlang representation of Rivest-Shamir-Adleman cryptosystem (RSA) keys follows:

    #'RSAPublicKey'{
    	  modulus,       % integer()
    	  publicExponent % integer()
    	  }.

    #'RSAPrivateKey'{
              version,         % two-prime | multi
    	  modulus,         % integer()
    	  publicExponent,  % integer()
    	  privateExponent, % integer()
    	  prime1,          % integer()
    	  prime2,          % integer()
    	  exponent1,       % integer()
    	  exponent2,       % integer()
    	  coefficient,     % integer()
    	  otherPrimeInfos  % [#OtherPrimeInfo{}] | asn1_NOVALUE
    	 }.

    #'OtherPrimeInfo'{
    	prime,           % integer()
    	exponent,        % integer()
    	coefficient      % integer()
     	 }.

### 2.3 DSA

Erlang representation of Digigital Signature Algorithm (DSA) keys

    #'DSAPrivateKey',{
    	  version,      % integer()
    	  p,            % integer()
    	  q,            % integer()
    	  g,            % integer()
    	  y,            % integer()
    	  x             % integer()
    	  }.

    #'Dss-Parms',{
             p,         % integer()
    	 q,         % integer()
    	 g          % integer()
    	 }.

### 2.4 ECDSA

Erlang representation of Elliptic Curve Digital Signature Algorithm (ECDSA) keys follows:

    #'ECPrivateKey'{
              version,       % integer()
    	  privateKey,    % binary()
    	  parameters,    % der_encoded() - {'EcpkParameters', #'ECParameters'{}} |
    	                                   {'EcpkParameters', {namedCurve, oid()}} |
    	                                   {'EcpkParameters', 'NULL'} % Inherited by CA
    	  publicKey      % bitstring()
    	  }.

    #'ECParameters'{
          version,    % integer()
          fieldID,    % #'FieldID'{}
          curve,      % #'Curve'{}
          base,       % binary()
          order,      % integer()
          cofactor    % integer()
          }.

    #'Curve'{
    	a,        % binary()
    	b,        % binary()
    	seed      % bitstring() - optional

    	}.

    #'FieldID'{
    	fieldType,    % oid()
    	parameters    % Depending on fieldType
    	}.

    #'ECPoint'{
          point %  binary() - the public key
          }.

### 2.5 PKIX Certificates

Erlang representation of PKIX certificates derived from ASN.1 specifications see also X509 certificates (RFC 5280), also referred to as plain type, are as follows:

    #'Certificate'{
    		tbsCertificate,        % #'TBSCertificate'{}
    		signatureAlgorithm,    % #'AlgorithmIdentifier'{}
    		signature              % bitstring()
    	       }.

    #'TBSCertificate'{
    	  version,              % v1 | v2 | v3
    	  serialNumber,         % integer()
    	  signature,            % #'AlgorithmIdentifier'{}
    	  issuer,               % {rdnSequence, [#AttributeTypeAndValue'{}]}
    	  validity,             % #'Validity'{}
    	  subject,              % {rdnSequence, [#AttributeTypeAndValue'{}]}
    	  subjectPublicKeyInfo, % #'SubjectPublicKeyInfo'{}
    	  issuerUniqueID,       % binary() | asn1_novalue
    	  subjectUniqueID,      % binary() | asn1_novalue
    	  extensions            % [#'Extension'{}]
    	 }.

    #'AlgorithmIdentifier'{
    	  algorithm,  % oid()
    	  parameters  % der_encoded()
    	 }.

Erlang alternate representation of PKIX certificate, also referred to as otp type

    #'OTPCertificate'{
    		tbsCertificate,        % #'OTPTBSCertificate'{}
    		signatureAlgorithm,    % #'SignatureAlgorithm'
    		signature              % bitstring()
    	       }.

    #'OTPTBSCertificate'{
    	  version,              % v1 | v2 | v3
    	  serialNumber,         % integer()
    	  signature,            % #'SignatureAlgorithm'
    	  issuer,               % {rdnSequence, [#AttributeTypeAndValue'{}]}
    	  validity,             % #'Validity'{}
    	  subject,              % {rdnSequence, [#AttributeTypeAndValue'{}]}
    	  subjectPublicKeyInfo, % #'OTPSubjectPublicKeyInfo'{}
    	  issuerUniqueID,       % binary() | asn1_novalue
    	  subjectUniqueID,      % binary() | asn1_novalue
    	  extensions            % [#'Extension'{}]
    	 }.

    #'SignatureAlgorithm'{
    	  algorithm,  % id_signature_algorithm()
    	  parameters  % asn1_novalue | #'Dss-Parms'{}
    	 }.

id_signature_algorithm() = OID_macro()

The available OID names are as follows:

OID Name
id-dsa-with-sha1
id-dsaWithSHA1 (ISO or OID to above)
md2WithRSAEncryption
md5WithRSAEncryption
sha1WithRSAEncryption
sha-1WithRSAEncryption (ISO or OID to above)
sha224WithRSAEncryption
sha256WithRSAEncryption
sha512WithRSAEncryption
ecdsa-with-SHA1

Table 2.1: Signature Algorithm OIDs

The data type 'AttributeTypeAndValue', is represented as the following erlang record:

    #'AttributeTypeAndValue'{
    	  type,   % id_attributes()
    	  value   % term()
    	 }.

The attribute OID name atoms and their corresponding value types are as follows:

OID Name | Value Type
id-at-name | special_string()
id-at-surname | special_string()
id-at-givenName | special_string()
id-at-initials | special_string()
id-at-generationQualifier | special_string()
id-at-commonName | special_string()
id-at-localityName | special_string()
id-at-stateOrProvinceName | special_string()
id-at-organizationName | special_string()
id-at-title | special_string()
id-at-dnQualifier | {printableString, string()}
id-at-countryName | {printableString, string()}
id-at-serialNumber | {printableString, string()}
id-at-pseudonym | special_string()

Table 2.2: Attribute OIDs

The data types 'Validity', 'SubjectPublicKeyInfo', and 'SubjectPublicKeyInfoAlgorithm' are represented as the following Erlang records:

    #'Validity'{
    	  notBefore, % time()
    	  notAfter   % time()
    	 }.

    #'SubjectPublicKeyInfo'{
    	  algorithm,       % #AlgorithmIdentifier{}
    	  subjectPublicKey % binary()
    	 }.

    #'SubjectPublicKeyInfoAlgorithm'{
    	  algorithm,  % id_public_key_algorithm()
    	  parameters  % public_key_params()
    	 }.

The public-key algorithm OID name atoms are as follows:

OID Name
rsaEncryption
id-dsa
dhpublicnumber
id-keyExchangeAlgorithm
id-ecPublicKey

Table 2.3: Public-Key Algorithm OIDs

    #'Extension'{
    	  extnID,    % id_extensions() | oid()
    	  critical,  % boolean()
    	  extnValue  % der_encoded()
    	 }.

id_extensions() Standard Certificate Extensions, Private Internet Extensions, CRL Extensions and CRL Entry Extensions.

### 2.6 Standard Certificate Extensions

The standard certificate extensions OID name atoms and their corresponding value types are as follows:

OID Name | Value Type
id-ce-authorityKeyIdentifier | #'AuthorityKeyIdentifier'{}
id-ce-subjectKeyIdentifier | oid()
id-ce-keyUsage | [key_usage()]
id-ce-privateKeyUsagePeriod | #'PrivateKeyUsagePeriod'{}
id-ce-certificatePolicies | #'PolicyInformation'{}
id-ce-policyMappings | #'PolicyMappings_SEQOF'{}
id-ce-subjectAltName | general_name()
id-ce-issuerAltName | general_name()
id-ce-subjectDirectoryAttributes | [#'Attribute'{}]
id-ce-basicConstraints | #'BasicConstraints'{}
id-ce-nameConstraints | #'NameConstraints'{}
id-ce-policyConstraints | #'PolicyConstraints'{}
id-ce-extKeyUsage | [id_key_purpose()]
id-ce-cRLDistributionPoints | [#'DistributionPoint'{}]
id-ce-inhibitAnyPolicy | integer()
id-ce-freshestCRL | [#'DistributionPoint'{}]

Table 2.4: Standard Certificate Extensions

Here:

key_usage()
  =

  digitalSignature

  | nonRepudiation

  | keyEncipherment

  | dataEncipherment

  | keyAgreement

  | keyCertSign

  | cRLSign

  | encipherOnly

  | decipherOnly

And for id_key_purpose():

OID Name
id-kp-serverAuth
id-kp-clientAuth
id-kp-codeSigning
id-kp-emailProtection
id-kp-timeStamping
id-kp-OCSPSigning

Table 2.5: Key Purpose OIDs

    #'AuthorityKeyIdentifier'{
    	  keyIdentifier,	    % oid()
    	  authorityCertIssuer,      % general_name()
    	  authorityCertSerialNumber % integer()
    	 }.

    #'PrivateKeyUsagePeriod'{
    	  notBefore,   % general_time()
    	  notAfter     % general_time()
    	 }.

    #'PolicyInformation'{
    	  policyIdentifier,  % oid()
    	  policyQualifiers   % [#PolicyQualifierInfo{}]
    	 }.

    #'PolicyQualifierInfo'{
    	  policyQualifierId,   % oid()
    	  qualifier            % string() | #'UserNotice'{}
    	 }.

    #'UserNotice'{
             noticeRef,   % #'NoticeReference'{}
    	 explicitText % string()
    	 }.

    #'NoticeReference'{
             organization,    % string()
    	 noticeNumbers    % [integer()]
    	 }.

    #'PolicyMappings_SEQOF'{
    	  issuerDomainPolicy,  % oid()
    	  subjectDomainPolicy  % oid()
    	 }.

    #'Attribute'{
              type,  % oid()
    	  values % [der_encoded()]
    	  }).

    #'BasicConstraints'{
    	  cA,		    % boolean()
    	  pathLenConstraint % integer()
    	 }).

    #'NameConstraints'{
    	  permittedSubtrees, % [#'GeneralSubtree'{}]
    	  excludedSubtrees   % [#'GeneralSubtree'{}]
    	 }).

    #'GeneralSubtree'{
    	  base,    % general_name()
    	  minimum, % integer()
    	  maximum  % integer()
    	 }).

    #'PolicyConstraints'{
    	  requireExplicitPolicy, % integer()
    	  inhibitPolicyMapping   % integer()
    	 }).

    #'DistributionPoint'{
    	  distributionPoint, % {fullName, [general_name()]} | {nameRelativeToCRLIssuer,
    	  [#AttributeTypeAndValue{}]}
    	  reasons,           % [dist_reason()]
    	  cRLIssuer          % [general_name()]
    	 }).

### 2.7 Private Internet Extensions

The private internet extensions OID name atoms and their corresponding value types are as follows:

OID Name | Value Type
id-pe-authorityInfoAccess | [#'AccessDescription'{}]
id-pe-subjectInfoAccess | [#'AccessDescription'{}]

Table 2.6: Private Internet Extensions

    #'AccessDescription'{
               accessMethod,    % oid()
    	   accessLocation   % general_name()
    	 }).

### 2.8 CRL and CRL Extensions Profile

Erlang representation of CRL and CRL extensions profile derived from ASN.1 specifications and RFC 5280 are as follows:

    #'CertificateList'{
              tbsCertList,        % #'TBSCertList{}
              signatureAlgorithm, % #'AlgorithmIdentifier'{}
              signature           % bitstring()
    	  }).

    #'TBSCertList'{
          version,             % v2 (if defined)
          signature,           % #AlgorithmIdentifier{}
          issuer,              % {rdnSequence, [#AttributeTypeAndValue'{}]}
          thisUpdate,          % time()
          nextUpdate,          % time()
          revokedCertificates, % [#'TBSCertList_revokedCertificates_SEQOF'{}]
          crlExtensions        % [#'Extension'{}]
          }).

    #'TBSCertList_revokedCertificates_SEQOF'{
             userCertificate,      % integer()
     	 revocationDate,       % timer()
    	 crlEntryExtensions    % [#'Extension'{}]
    	 }).

#### CRL Extensions

The CRL extensions OID name atoms and their corresponding value types are as follows:

OID Name | Value Type
id-ce-authorityKeyIdentifier | #'AuthorityKeyIdentifier{}
id-ce-issuerAltName | {rdnSequence, [#AttributeTypeAndValue'{}]}
id-ce-cRLNumber | integer()
id-ce-deltaCRLIndicator | integer()
id-ce-issuingDistributionPoint | #'IssuingDistributionPoint'{}
id-ce-freshestCRL | [#'Distributionpoint'{}]

Table 2.7: CRL Extensions

Here, the data type 'IssuingDistributionPoint' is represented as the following Erlang record:

    #'IssuingDistributionPoint'{
              distributionPoint,         % {fullName, [general_name()]} | {nameRelativeToCRLIssuer,
    	  [#AttributeTypeAndValue'{}]}
    	  onlyContainsUserCerts,     % boolean()
    	  onlyContainsCACerts,       % boolean()
    	  onlySomeReasons,           % [dist_reason()]
    	  indirectCRL,               % boolean()
    	  onlyContainsAttributeCerts % boolean()
    	  }).

#### CRL Entry Extensions

The CRL entry extensions OID name atoms and their corresponding value types are as follows:

OID Name | Value Type
id-ce-cRLReason | crl_reason()
id-ce-holdInstructionCode | oid()
id-ce-invalidityDate | general_time()
id-ce-certificateIssuer | general_name()

Table 2.8: CRL Entry Extensions

Here:

crl_reason()
  =

  unspecified

  | keyCompromise

  | cACompromise

  | affiliationChanged

  | superseded

  | cessationOfOperation

  | certificateHold

  | removeFromCRL

  | privilegeWithdrawn

  | aACompromise

#### PKCS#10 Certification Request

Erlang representation of a PKCS#10 certification request derived from ASN.1 specifications and RFC 5280 are as follows:

    #'CertificationRequest'{
              certificationRequestInfo #'CertificationRequestInfo'{},
    	  signatureAlgorithm	   #'CertificationRequest_signatureAlgorithm'{}}.
    	  signature                bitstring()
    	  }

    #'CertificationRequestInfo'{
    	  version       atom(),
    	  subject       {rdnSequence, [#AttributeTypeAndValue'{}]} ,
    	  subjectPKInfo #'CertificationRequestInfo_subjectPKInfo'{},
    	  attributes    [#'AttributePKCS-10' {}]
    	  }

    #'CertificationRequestInfo_subjectPKInfo'{
              algorithm		#'CertificationRequestInfo_subjectPKInfo_algorithm'{}
    	  subjectPublicKey 	  bitstring()
    	  }

    #'CertificationRequestInfo_subjectPKInfo_algorithm'{
         algorithm = oid(),
         parameters = der_encoded()
    }

    #'CertificationRequest_signatureAlgorithm'{
         algorithm = oid(),
         parameters = der_encoded()
         }

    #'AttributePKCS-10'{
        type = oid(),
        values = [der_encoded()]
    }