Crypt-X509::CRL version 0.1
===========================
    Crypt::X509::CRL is an object oriented X.509 certificate revocation list
    parser with numerous methods for directly extracting information from
    certificate revocation lists.

INSTALLATION
    To install this module type the following:

       perl Makefile.PL
       make
       make test
       make install

DEPENDENCIES
    This module requires:

      Convert::ASN1

NAME
    Crypt::X509::CRL - Parses an X.509 certificate revocation list

SYNOPSIS
     use Crypt::X509::CRL;

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

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

REQUIRES
    Convert::ASN1

DESCRIPTION
    Crypt::X509::CRL parses X.509 certificate revocation lists. Methods are
    provided for accessing most CRL 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. It is also based upon the
    works of Mike Jackson and Alexander Jung perl module Crypt::X509.

    The following RFC 3280 Extensions are available (noted are the ones I
    have implemented).

            Authority Key Identifier (implemented)
            CRL Number (implemented)
            Issuing Distribution Point (implemented)
            Issuer Alternative Name
            Delta CRL Indicator
            Freshest CRL (a.k.a. Delta CRL Distribution Point)

    The following RFC 3280 CRL Entry Extensions are available (noted are the
    ones I have implemented).

            Reason Code (implemented)
            Hold Instruction Code (implemented)
            Invalidity Date (implemented)
            Certificate Issuer

    NOTE: The use of 'utcTime' in determining the revocation date of a given
    certificate is based on RFC 3280 for dates through the year 2049.
    Starting with dates in 2050 and beyond the RFC calls for revocation
    dates to be listed as 'generalTime'.

CONSTRUCTOR
  new ( OPTIONS )
    Creates and returns a parsed X.509 CRL 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.

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

   Example:
      use Crypt::X509::CRL;
      use Data::Dumper;

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

      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.

   Example:
      $decoded= Crypt::X509::CRL->new(crl => $crl);
      if ( $decoded->error ) {
            warn "Error on parsing Certificate Revocation List: ", $decoded->error;
      }

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

  version
    Returns the certificate revocation list's version as an integer. Returns
    undef if the version is not specified, since it is an optional field in
    some cases.

   NOTE that version is defined as an Integer where:
            0 = v1
            1 = v2
            2 = v3

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

   NOTE that version is defined as an Integer where:
            0 = v1
            1 = v2
            2 = v3

  this_update
    Returns either the utcTime or generalTime of the certificate revocation
    list's date of publication. Returns undef if not defined.

   Example:
      $decoded = Crypt::X509::CRL->new(crl => $crl);
      print "CRL was published at ", gmtime( $decoded->this_update ), " GMT\n";

  next_update
    Returns either the utcTime or generalTime of the certificate revocation
    list's date of expiration. Returns undef if not defined.

   Example:
      $decoded = Crypt::X509::CRL->new(crl => $crl);
      if ( $decoded->next_update > time() ) {
            warn "CRL has expired!";
      }

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

  signature_length
    Return's the length of the certificate's signature.

  signature_algorithm
    Returns the certificate's signature algorithm as an OID string.

   Example:
      $decoded = Crypt::X509::CRL->new(crl => $crl);
      print "CRL signature is encrypted with:", $decoded->signature_algorithm, "\n";

      Example Output: CRL signature is encrypted with: 1.2.840.113549.1.1.5

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

   Example:
      $decoded = Crypt::X509::CRL->new(crl => $crl);
      print "CRL signature is encrypted with:", $decoded->SigEncAlg, "\n";

      Example Output: CRL signature is encrypted with: RSA

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

   Example:
      $decoded = Crypt::X509::CRL->new(crl => $crl);
      print "CRL signature is hashed with:", $decoded->SigHashAlg, "\n";

      Example Output: CRL signature is encrypted with: SHA1

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

   Example:
      $decoded = Crypt::X509::CRL->new( $crl );
      print "CRL 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.

  key_identifier
    Returns the authority key identifier as a bit string.

   Example:
            $decoded = Crypt::X509::CRL->new( $crl );
            my $s = unpack("H*" , $decoded->key_identifier);
            print "The Authority Key Identifier in HEX is: $s\n";

            Example output:
            The Authority Key Identifier in HEX is: 86595f93caf32da620a4f9595a4a935370e792c9

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

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

  authority_serial
    Returns the authority's certificate serial number.

  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.

  crl_number
    Returns the CRL Number as an integer.

  IDPs
    Returns the Issuing Distribution Points as a hash providing for the
    default values.

   Example:
            print "Issuing Distribution Points:\n";
            my $IDPs = $decoded->IDPs;
            for my $key ( sort keys %{ $IDPs } ) {
                    print "$key = ";
                    if ( defined $IDPs->{ $key } ) {
                            print $IDPs->{ $key }, "\n";
                    } else {
                            print "undef\n";
                    }
            }

   Example Output:
            Issuing Distribution Points:
            critical = 1
            directory_addr = CN=CRL2, O=U.S. Government, C=US
            indirectCRL = 0
            onlyAttribCerts = 0
            onlyCaCerts = 0
            onlyUserCerts = 1
            reasonFlags = undef
            url = undef

   Example of returned data structure:
            critical        = 0 or 1 # default is FALSE
            directory_addr  = CN=CR1,c=US # default is undef
            url             = ldap://ldap.gov/cn=CRL1,c=US # default is undef
            onlyUserCerts   = 0 or 1 # default is FALSE
            onlyCaCerts     = 0 or 1 # default is FALSE
            onlyAttribCerts = 0 or 1 # default is FALSE
            indirectCRL     = 0 or 1 # default is FALSE
            reasonFlags     = BIT STRING # default is undef

  revocation_list
    Returns an array of hashes for the revoked certificates listed on the
    given CRL. The keys to the hash are the certificate serial numbers in
    decimal format.

   Example:
            print "Revocation List:\n";
            my $rls = $decoded->revocation_list;
            my $count_of_rls = keys %{ $rls };
            print "Found $count_of_rls revoked certificate(s) on this CRL.\n";
            for my $key ( sort keys %{ $rls } ) {
                    print "Certificate: ", DecimalToHex( $key ), "\n";
                    for my $extn ( sort keys %{ $rls->{ $key } } ) {
                            if ( $extn =~ /date/i ) {
                                    print "\t$extn: ", ConvertTime( $rls->{ $key }{ $extn } ), "\n";
                            } else {
                                    print "\t$extn: ", $rls->{ $key }{ $extn }, "\n";
                            }
                    }
            }

   Example Output:
            Revocation List:
            Found 1 revoked certificate(s) on this CRL.
            Certificate: 44 53 a0 f3
                    crlReason: keyCompromise
                    invalidityDate: Wednesday, September 27, 2006 12:54:51 PM
                    revocationDate: Wednesday, September 27, 2006 1:29:36 PM

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-CRL.t.

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

    It is also based on the Crypt::X509 perl module, which was contributed
    by Mike Jackson and Alexander Jung.

AUTHOR
    Duncan Segrest <CPAN@GigaGeek.info> ,

COPYRIGHT AND LICENSE
    Copyright (c) 2007 by Duncan Segrest <CPAN@GigaGeek.info>.

    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself, either Perl version 5.8.8 or, at
    your option, any later version of Perl 5 you may have available.