Crypt::X509(3p)

NAME
Crypt::X509 - Parse a X.509 certificate

SYNOPSIS
 use Crypt::X509;

 $decoded = Crypt::X509->new( cert => $cert );

 $subject_email = $decoded->subject_email;
 print "do not use after: ".gmtime($decoded->not_after)." GMT\n";

REQUIRES
Convert::ASN1

DESCRIPTION
Crypt::X509 parses X.509 certificates. Methods are provided for accessing most certificate elements.

It is based on the generic ASN.1 module by Graham Barr, on the x509decode example by Norbert Klasen and contributions on the perl-ldap-dev-Mailinglist by Chriss Ridd.

CONSTRUCTOR

  new ( OPTIONS )
Creates and returns a parsed X.509 certificate hash, containing the parsed contents. The data is organised as specified in RFC 2459. By default only the first ASN.1 Layer is decoded. Nested decoding is done automagically through the data access methods.

cert => $certificate
    A variable containing the DER formatted certificate to be parsed (eg. as stored in "usercertificate;binary" attribute in an LDAP-directory).

  use Crypt::X509;
  use Data::Dumper;

  $decoded= Crypt::X509->new(cert => $cert);

  print Dumper($decoded);

METHODS

  error
Returns the last error from parsing, "undef" when no error occured. This error is updated on deeper parsing with the data access methods.

  $decoded= Crypt::X509->new(cert => $cert);
  if ($decoded->error) {
    warn "Error on parsing Certificate:".$decoded->error;
  }

DATA ACCESS METHODS
You can access all parsed data directly from the returned hash. For convenience the following methods have been implemented to give quick access to the most-used certificate attributes.

  version
Returns the certificate's version as an integer. NOTE that version is defined as an Integer where 0 = v1, 1 = v2, and 2 = v3.

  version_string
Returns the certificate's version as a string value.

  serial
returns the serial number (integer or Math::BigInt Object, that gets automagic evaluated in scalar context) from the certificate

  $decoded= Crypt::X509->new(cert => $cert);
  print "Certificate has serial number:".$decoded->serial."\n";

  not_before
returns the GMT-timestamp of the certificate's beginning date of validity. If the Certificate holds this Entry in utcTime, it is guaranteed by the RFC to been correct.

As utcTime is limited to 32-bit values (like unix-timestamps) newer certificates hold the timesamps as "generalTime"-entries. The contents of "generalTime"-entries are not well defined in the RFC and are returned by this module unmodified, if no utcTime-entry is found.

  $decoded= Crypt::X509->new(cert => $cert);
  if ($decoded->notBefore < time()) {
    warn "Certificate: not yet valid!";
  }

  not_after
returns the GMT-timestamp of the certificate's ending date of validity. If the Certificate holds this Entry in utcTime, it is guaranteed by the RFC to been correct.

As utcTime is limited to 32-bit values (like unix-timestamps) newer certificates hold the timesamps as "generalTime"-entries. The contents of "generalTime"-entries are not well defined in the RFC and are returned by this module unmodified, if no utcTime-entry is found.

  $decoded= Crypt::X509->new(cert => $cert);
  print "Certificate expires on ".gmtime($decoded->not_after)." GMT\n";

  signature
Return's the certificate's signature in binary DER format.

  pubkey
Returns the certificate's public key in binary DER format.

  pubkey_size
Returns the certificate's public key size.

  pubkey_algorithm
Returns the algorithm as OID string which the public key was created with.

  PubKeyAlg
returns the subject public key encryption algorithm (e.g. 'RSA') as string.

  $decoded= Crypt::X509->new(cert => $cert);
  print "Certificate public key is encrypted with:".$decoded->PubKeyAlg."\n";

  Example Output: Certificate public key is encrypted with: RSA

  pubkey_components
If this certificate contains an RSA key, this function returns a hashref { modulus => $m, exponent => $e) from that key; each value in the hash will be an integer scalar or a Math::BigInt object.

For other pubkey types, it returns undef (implementations welcome!).

  sig_algorithm
Returns the certificate's signature algorithm as OID string

  $decoded= Crypt::X509->new(cert => $cert);
  print "Certificate signature is encrypted with:".$decoded->sig_algorithm."\n";>

  Example Output: Certificate signature is encrypted with: 1.2.840.113549.1.1.5

  SigEncAlg
returns the signature encryption algorithm (e.g. 'RSA') as string.

  $decoded= Crypt::X509->new(cert => $cert);
  print "Certificate signature is encrypted with:".$decoded->SigEncAlg."\n";

  Example Output: Certificate signature is encrypted with: RSA

  SigHashAlg
returns the signature hashing algorithm (e.g. 'SHA1') as string.

  $decoded= Crypt::X509->new(cert => $cert);
  print "Certificate signature is hashed with:".$decoded->SigHashAlg."\n";

  Example Output: Certificate signature is encrypted with: SHA1

  Subject
returns a pointer to an array of strings containing subject nameparts of the certificate. Attributenames for the most common Attributes are translated from the OID-Numbers, unknown numbers are output verbatim.

  $decoded= Convert::ASN1::X509->new($cert);
  print "DN for this Certificate is:".join(',',@{$decoded->Subject})."\n";

  SubjectRaw
Returns the RDNs as list of hashes, values are stringified but OIDs are not translated.

If a component contains a SET, the component will become an array of hashes on the second level.

  SubjectSequence
Returns the subject as returned from the ASN1 parser.

  subject_country
Returns the string value for subject's country (= the value with the
 OID 2.5.4.6 or in DN Syntax everything after "C="). Only the first entry is returned. "undef" if subject contains no country attribute.

  subject_locality
Returns the string value for subject's locality (= the value with the OID 2.5.4.7 or in DN Syntax everything after "l="). Only the first entry is returned. "undef" if subject contains no locality attribute.

  subject_state
Returns the string value for subject's state or province (= the value with the OID 2.5.4.8 or in DN Syntax everything after "S="). Only the first entry is returned. "undef" if subject contains no state attribute.

  subject_org
Returns the string value for subject's organization (= the value with the OID 2.5.4.10 or in DN Syntax everything after "O="). Only the first entry is returned. "undef" if subject contains no organization attribute.

  subject_ou
Returns the string value for subject's organizational unit (= the value with the OID 2.5.4.11 or in DN Syntax everything after "OU="). Only the first entry is returned. "undef" if subject contains no organization attribute.

  subject_cn
Returns the string value for subject's common name (= the value with the OID 2.5.4.3 or in DN Syntax everything after "CN="). Only the first entry is returned. "undef" if subject contains no common name attribute.

  subject_email
Returns the string value for subject's email address (= the value with the OID 1.2.840.113549.1.9.1 or in DN Syntax everything after "emailAddress="). Only the first entry is returned. "undef" if subject contains no email attribute.

  Issuer
returns a pointer to an array of strings building the DN of the certificate issuer (= the DN of the CA). Attributenames for the most common Attributes are translated from the OID-Numbers, unknown numbers are output verbatim.

  $decoded= Crypt::X509->new($cert);
  print "Certificate was issued by:".join(',',@{$decoded->Issuer})."\n";

  issuer_cn
Returns the string value for issuer's common name (= the value with the OID 2.5.4.3 or in DN Syntax everything after "CN="). Only the first entry is returned. "undef" if issuer contains no common name attribute.

  issuer_country
Returns the string value for issuer's country (= the value with the
 OID 2.5.4.6 or in DN Syntax everything after "C="). Only the first entry is returned. "undef" if issuer contains no country attribute.

  issuer_state
Returns the string value for issuer's state or province (= the value with the OID 2.5.4.8 or in DN Syntax everything after "S="). Only the first entry is returned. "undef" if issuer contains no state attribute.

  issuer_locality
Returns the string value for issuer's locality (= the value with the OID 2.5.4.7 or in DN Syntax everything after "L="). Only the first entry is returned. "undef" if issuer contains no locality attribute.

  issuer_org
Returns the string value for issuer's organization (= the value with the OID 2.5.4.10 or in DN Syntax everything after "O="). Only the first entry is returned. "undef" if issuer contains no organization attribute.

  issuer_email
Returns the string value for issuer's email address (= the value with the OID 1.2.840.113549.1.9.1 or in DN Syntax everything after "E="). Only the first entry is returned. "undef" if issuer contains no email attribute.

  KeyUsage
returns a pointer to an array of strings describing the valid Usages for this certificate. "undef" is returned, when the extension is not set in the certificate.

If the extension is marked critical, this is also reported.

  $decoded= Crypt::X509->new(cert => $cert);
  print "Allowed usages for this Certificate are:\n".join("\n",@{$decoded->KeyUsage})."\n";

  Example Output:
  Allowed usages for this Certificate are:
  critical
  digitalSignature
  keyEncipherment
  dataEncipherment

  ExtKeyUsage
returns a pointer to an array of ExtKeyUsage strings (or OIDs for unknown OIDs) or "undef" if the extension is not filled. OIDs of the following ExtKeyUsages are known: serverAuth, clientAuth, codeSigning, emailProtection, timeStamping, OCSPSigning

If the extension is marked critical, this is also reported.

  $decoded= Crypt::X509->new($cert);
  print "ExtKeyUsage extension of this Certificates is: ", join(", ", @{$decoded->ExtKeyUsage}), "\n";

  Example Output: ExtKeyUsage extension of this Certificates is: critical, serverAuth

  SubjectAltName
returns a pointer to an array of strings containing alternative Subjectnames or "undef" if the extension is not filled. Usually this Extension holds the e-Mail address for person-certificates or DNS-Names for server certificates.

It also pre-pends the field type (ie rfc822Name) to the returned value.

  $decoded= Crypt::X509->new($cert);
  print "E-Mail or Hostnames in this Certificates is/are:", join(", ", @{$decoded->SubjectAltName}), "\n";

  Example Output: E-Mail or Hostnames in this Certificates is/are: rfc822Name=user@server.com

  DecodedSubjectAltNames
Returns a pointer to an array of strings containing all the alternative subject name extensions.

Each such extension is represented as a decoded ASN.1 value, i.e. a pointer to a list of pointers to objects, each object having a single key with the type of the alternative name and a value specific to that type.

Example return value:

  [
    [
      {
        'directoryName' => {
          'rdnSequence' => [
            [
              {
                'value' => { 'utf8String' => 'example' },
                'type' => '2.5.4.3'
              }
            ]
          ]
        }
      },
      {
        'dNSName' => 'example.com'
      }
    ]
  ]

  authorityCertIssuer
returns a pointer to an array of strings building the DN of the Authority Cert Issuer. Attributenames for the most common Attributes are translated from the OID-Numbers, unknown numbers are output verbatim. undef if the extension is not set in the certificate.

  $decoded= Crypt::X509->new($cert);
  print "Certificate was authorised by:".join(',',@{$decoded->authorityCertIssuer})."\n";

  authority_serial
Returns the authority's certificate serial number.

  key_identifier
Returns the authority key identifier or undef if it is a rooted cert

  authority_cn
Returns the authority's ca.

  authority_country
Returns the authority's country.

  authority_state
Returns the authority's state.

  authority_locality
Returns the authority's locality.

  authority_org
Returns the authority's organization.

  authority_email
Returns the authority's email.

  CRLDistributionPoints
Returns the CRL distribution points as an array of strings (with one value usually)

  CRLDistributionPoints2
Returns the CRL distribution points as an array of hashes (allowing for some variations)

  CertificatePolicies
Returns the CertificatePolicies as an array of strings

  EntrustVersionInfo
Returns the EntrustVersion as a string

    print "Entrust Version: ", $decoded->EntrustVersion, "\n";

    Example Output: Entrust Version: V7.0

  SubjectDirectoryAttributes
Returns the SubjectDirectoryAttributes as an array of key = value pairs, to include a data type

    print "Subject Directory Attributes: ", join( ', ' , @{ $decoded->SubjectDirectoryAttributes } ), "\n";

    Example Output: Subject Directory Attributes: 1.2.840.113533.7.68.29 = 7 (integer)

  BasicConstraints
Returns the BasicConstraints as an array and the criticallity pre-pended.

  subject_keyidentifier
Returns the subject key identifier from the extensions.

  SubjectInfoAccess
Returns the SubjectInfoAccess as an array of hashes with key=value pairs.

        print "Subject Info Access: ";
        if ( defined $decoded->SubjectInfoAccess ) {
            my %SIA = $decoded->SubjectInfoAccess;
            for my $key ( keys %SIA ) {
                print "\n\t$key: \n\t";
                print join( "\n\t" , @{ $SIA{$key} } ), "\n";
            }
        } else { print "\n" }

    Example Output:
        Subject Info Access:
            1.3.6.1.5.5.7.48.5:
            uniformResourceIdentifier = http://pki.treas.gov/root_sia.p7c
            uniformResourceIdentifier = ldap://ldap.treas.gov/ou=US%20Treasury%20Root%20CA,ou=Certification%20Authorities,ou=Department%20of%20the%20Treasury,o=U.S.%20Government,c=US?cACertificate;binary,crossCertificatePair;binary

  PGPExtension
Returns the creation timestamp of the corresponding OpenPGP key. (see http://www.imc.org/ietf-openpgp/mail-archive/msg05320.html)

        print "PGPExtension: ";
        if ( defined $decoded->PGPExtension ) {
            my $creationtime = $decoded->PGPExtension;
            printf "\n\tcorresponding OpenPGP Creation Time: ", $creationtime, "\n";
                }

    Example Output:
        PGPExtension:
                    whatever

SEE ALSO
See the examples of "Convert::ASN1" and the <perl-ldap@perl.org> Mailing List. An example on how to load certificates can be found in t\Crypt-X509.t.

ACKNOWLEDGEMENTS
This module is based on the x509decode script, which was contributed to Convert::ASN1 in 2002 by Norbert Klasen.

AUTHORS
Mike Jackson <mj@sci.fi>, Alexander Jung <alexander.w.jung@gmail.com>, Duncan Segrest <duncan@gigageek.info> Oliver Welter <owelter@whiterabbitsecurity.com>

COPYRIGHT
Copyright (c) 2005 Mike Jackson <mj@sci.fi>. Copyright (c) 2001-2002 Norbert Klasen, DAASI International GmbH.

All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.