man Net::DNS::RR::RRSIG (3): DNS RRSIG resource record

SYNOPSIS

use Net::DNS;
$rr = new Net::DNS::RR('name RRSIG typecovered algorithm labels
orgttl sigexpiration siginception
keytag signame signature');
use Net::DNS::SEC;
$sigrr = create Net::DNS::RR::RRSIG( \@rrset, $keypath,
sigex => 20161231010101
sigin => 20161201010101
);
$sigrr->verify( \@rrset, $keyrr ) || die $sigrr->vrfyerrstr;

DESCRIPTION

Class for DNS digital signature (RRSIG) resource records.

In addition to the regular methods inherited from Net::DNS::RR the class contains a method to sign RRsets using private keys (create) and a method for verifying signatures over RRsets (verify).

The RRSIG RR is an implementation of RFC4034. See Net::DNS::RR::SIG for an implementation of SIG0 (RFC2931).

METHODS

The available methods are those inherited from the base class augmented by the type-specific methods defined in this package.

Use of undocumented package features or direct access to internal data structures is discouraged and could result in program termination or other unpredictable behaviour.

typecovered

    $typecovered = $rr->typecovered;

The typecovered field identifies the type of the RRset that is covered by this RRSIG record.

algorithm

    $algorithm = $rr->algorithm;

The algorithm number field identifies the cryptographic algorithm used to create the signature.

algorithm() may also be invoked as a class method or simple function to perform mnemonic and numeric code translation.

labels

    $labels = $rr->labels;
    $rr->labels( $labels );

The labels field specifies the number of labels in the original RRSIG RR owner name.

orgttl

    $orgttl = $rr->orgttl;
    $rr->orgttl( $orgttl );

The original TTL field specifies the TTL of the covered RRset as it appears in the authoritative zone.

sigexpiration and siginception times

sigex sigin sigval

    $expiration = $rr->sigexpiration;
    $expiration = $rr->sigexpiration( $value );
    $inception = $rr->siginception;
    $inception = $rr->siginception( $value );

The signature expiration and inception fields specify a validity time interval for the signature.

The value may be specified by a string with format 'yyyymmddhhmmss' or a Perl time() value.

Return values are dual-valued, providing either a string value or numerical Perl time() value.

keytag

    $keytag = $rr->keytag;
    $rr->keytag( $keytag );

The keytag field contains the key tag value of the DNSKEY RR that validates this signature.

signame

    $signame = $rr->signame;
    $rr->signame( $signame );

The signer name field value identifies the owner name of the DNSKEY RR that a validator is supposed to use to validate this signature.

signature

sig

    $sig = $rr->sig;
    $rr->sig( $sig );

The Signature field contains the cryptographic signature that covers the RRSIG RDATA (excluding the Signature field) and the RRset specified by the RRSIG owner name, RRSIG class, and RRSIG type covered fields.

sigbin

    $sigbin = $rr->sigbin;
    $rr->sigbin( $sigbin );

Binary representation of the cryptographic signature.

create

Create a signature over a RR set.

    use Net::DNS::SEC;
    $keypath = '/home/olaf/keys/Kbla.foo.+001+60114.private';
    $sigrr = create Net::DNS::RR::RRSIG( \@rrsetref, $keypath );
    $sigrr = create Net::DNS::RR::RRSIG( \@rrsetref, $keypath,
                                        sigex => 20161231010101
                                        sigin => 20161201010101
                                        );
    $sigrr->print;
    # Alternatively use Net::DNS::SEC::Private 
    $private = Net::DNS::SEC::Private->new($keypath);
    $sigrr= create Net::DNS::RR::RRSIG( \@rrsetref, $private );

create() is an alternative constructor for a RRSIG RR object.

This method returns an RRSIG with the signature over the subject rrset (an array of RRs) made with the private key stored in the key file.

The first argument is a reference to an array that contains the RRset that needs to be signed.

The second argument is a string which specifies the path to a file containing the private key as generated by dnssec-keygen.

The optional remaining arguments consist of ( name => value ) pairs as follows:

        sigex  => 20161231010101,       # signature expiration
        sigin  => 20161201010101,       # signature inception
        sigval => 30,                   # validity window (days)
        ttl    => 3600                  # TTL

The sigin and sigex values may be specified as Perl time values or as a string with the format 'yyyymmddhhmmss'. The default for sigin is the time of signing.

The sigval argument specifies the signature validity window in days ( sigex = sigin + sigval ).

By default the signature is valid for 30 days.

By default the TTL matches the RRset that is presented for signing.

verify

    $verify = $sigrr->verify( $rrsetref, $keyrr );
    $verify = $sigrr->verify( $rrsetref, [$keyrr, $keyrr2, $keyrr3] );

$rrsetref contains a reference to an array of RR objects and the method verifies the RRset against the signature contained in the $sigrr object itself using the public key in $keyrr.

The second argument can either be a Net::DNS::RR::KEYRR object or a reference to an array of such objects. Verification will return successful as soon as one of the keys in the array leads to positive validation.

Returns 0 on error and sets $sig->vrfyerrstr

vrfyerrstr

    $verify = $sigrr->verify( $rrsetref, $keyrr );
    print $sigrr->vrfyerrstr unless $verify;
    $sigrr->verify( $rrsetref, $keyrr ) || die $sigrr->vrfyerrstr;

KEY GENERATION

Private key files and corresponding public DNSKEY records are most conveniently generated using dnssec-keygen, a program that comes with the ISC BIND distribution.

    dnssec-keygen -a 10 -b 2048 -f ksk  rsa.example.
    dnssec-keygen -a 10 -b 1024         rsa.example.
    dnssec-keygen -a 14 -f ksk  ecdsa.example.
    dnssec-keygen -a 14         ecdsa.example.

Do not change the name of the file generated by dnssec-keygen. The create method uses the filename to determine the keyowner, algorithm and the keyid (keytag).

REMARKS

The code is not optimised for speed. It is probably not suitable to be used for signing large zones.

If this code is still around in 2100 (not a leap year) you will need to check for proper handling of times ...

ACKNOWLEDGMENTS

Andy Vaskys (Network Associates Laboratories) supplied the code for handling RSA with SHA1 (Algorithm 5).

T.J. Mather, the Crypt::OpenSSL::DSA maintainer, for his quick responses to bug report and feature requests.

Dick Franks added support for elliptic curve signatures.

Mike McCauley created the Crypt::OpenSSL::ECDSA perl extension module specifically for this development.

COPYRIGHT

LICENSE

Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of the author not be used in advertising or publicity pertaining to distribution of the software without specific prior written permission.

THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.