.\" -*- mode: troff; coding: utf-8 -*- .\" Automatically generated by Pod::Man 5.01 (Pod::Simple 3.43) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>. .ie n \{\ . ds C` "" . ds C' "" 'br\} .el\{\ . ds C` . ds C' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is >0, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" ======================================================================== .\" .IX Title "Crypt::OpenSSL::DSA 3pm" .TH Crypt::OpenSSL::DSA 3pm 2024-03-07 "perl v5.38.2" "User Contributed Perl Documentation" .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH NAME Crypt::OpenSSL::DSA \- Digital Signature Algorithm using OpenSSL .SH SYNOPSIS .IX Header "SYNOPSIS" .Vb 1 \& use Crypt::OpenSSL::DSA; \& \& # generate keys and write out to PEM files \& my $dsa = Crypt::OpenSSL::DSA\->generate_parameters( 512 ); \& $dsa\->generate_key; \& $dsa\->write_pub_key( $filename ); \& $dsa\->write_priv_key( $filename ); \& \& # using keys from PEM files \& my $dsa_priv = Crypt::OpenSSL::DSA\->read_priv_key( $filename ); \& my $sig = $dsa_priv\->sign($message); \& my $dsa_pub = Crypt::OpenSSL::DSA\->read_pub_key( $filename ); \& my $valid = $dsa_pub\->verify($message, $sig); \& \& # using keys from PEM strings \& my $dsa_priv = Crypt::OpenSSL::DSA\->read_priv_key_str( $key_string ); \& my $sig = $dsa_priv\->sign($message); \& my $dsa_pub = Crypt::OpenSSL::DSA\->read_pub_key_str( $key_string ); \& my $valid = $dsa_pub\->verify($message, $sig); .Ve .SH DESCRIPTION .IX Header "DESCRIPTION" Crypt::OpenSSL::DSA implements the DSA (Digital Signature Algorithm) signature verification system. .PP It is a thin XS wrapper to the DSA functions contained in the OpenSSL crypto library, located at http://www.openssl.org .SH "CLASS METHODS" .IX Header "CLASS METHODS" .ie n .IP "$dsa = Crypt::OpenSSL::DSA\->generate_parameters( $bits, $seed );" 4 .el .IP "\f(CW$dsa\fR = Crypt::OpenSSL::DSA\->generate_parameters( \f(CW$bits\fR, \f(CW$seed\fR );" 4 .IX Item "$dsa = Crypt::OpenSSL::DSA->generate_parameters( $bits, $seed );" Returns a new DSA object and generates the p, q and g parameters necessary to generate keys. .Sp bits is the length of the prime to be generated; the DSS allows a maximum of 1024 bits. .ie n .IP "$dsa = Crypt::OpenSSL::DSA\->read_params( $filename );" 4 .el .IP "\f(CW$dsa\fR = Crypt::OpenSSL::DSA\->read_params( \f(CW$filename\fR );" 4 .IX Item "$dsa = Crypt::OpenSSL::DSA->read_params( $filename );" Reads in a parameter PEM file and returns a new DSA object with the p, q and g parameters necessary to generate keys. .ie n .IP "$dsa = Crypt::OpenSSL::DSA\->read_pub_key( $filename );" 4 .el .IP "\f(CW$dsa\fR = Crypt::OpenSSL::DSA\->read_pub_key( \f(CW$filename\fR );" 4 .IX Item "$dsa = Crypt::OpenSSL::DSA->read_pub_key( $filename );" Reads in a public key PEM file and returns a new DSA object that can be used to verify DSA signatures. .ie n .IP "$dsa = Crypt::OpenSSL::DSA\->read_priv_key( $filename );" 4 .el .IP "\f(CW$dsa\fR = Crypt::OpenSSL::DSA\->read_priv_key( \f(CW$filename\fR );" 4 .IX Item "$dsa = Crypt::OpenSSL::DSA->read_priv_key( $filename );" Reads in a private key PEM file and returns a new DSA object that can be used to sign messages. .ie n .IP "$dsa = Crypt::OpenSSL::DSA\->read_pub_key_str( $key_string );" 4 .el .IP "\f(CW$dsa\fR = Crypt::OpenSSL::DSA\->read_pub_key_str( \f(CW$key_string\fR );" 4 .IX Item "$dsa = Crypt::OpenSSL::DSA->read_pub_key_str( $key_string );" Reads in a public key PEM string and returns a new DSA object that can be used to verify DSA signatures. The string should include the \-\-\-\-\-BEGIN...\-\-\-\-\- and \-\-\-\-\-END...\-\-\-\-\- lines. .ie n .IP "$dsa = Crypt::OpenSSL::DSA\->read_priv_key_str( $key_string );" 4 .el .IP "\f(CW$dsa\fR = Crypt::OpenSSL::DSA\->read_priv_key_str( \f(CW$key_string\fR );" 4 .IX Item "$dsa = Crypt::OpenSSL::DSA->read_priv_key_str( $key_string );" Reads in a private key PEM string and returns a new DSA object that can be used to sign messages. The string should include the \-\-\-\-\-BEGIN...\-\-\-\-\- and \-\-\-\-\-END...\-\-\-\-\- lines. .SH "OBJECT METHODS" .IX Header "OBJECT METHODS" .ie n .IP $dsa\->generate_key; 4 .el .IP \f(CW$dsa\fR\->generate_key; 4 .IX Item "$dsa->generate_key;" Generates private and public keys, assuming that \f(CW$dsa\fR is the return value of generate_parameters. .ie n .IP "$sig_size = $dsa\->get_sig_size( );" 4 .el .IP "\f(CW$sig_size\fR = \f(CW$dsa\fR\->get_sig_size( );" 4 .IX Item "$sig_size = $dsa->get_sig_size( );" Returns the maximum size of an ASN.1 encoded DSA signature for key dsa in bytes. .Sp .Vb 4 \& 512\-bit keys = 48 \&1024\-bit keys = 48 \&2024\-bit keys = 72 \&3072\-bit keys = 72 .Ve .Sp ASN.1 dsa signatures consist of: .Sp Sequence 1\-byte (0x30) Length 1\-byte Integer 1\-byte (0x02) Length 1\-byte (0x14) = 20 r 20\-bytes or 21\-bytes Integer 1\-byte (0x02) Length 1\-byte (0x14) = 20 s 20\-bytes or 21\-bytes .Sp 30 2C 02 14 6C.70.50.7C.93.A8.B5.EC.1E.A1.5E.C5.73.AA.0F.EA.4D.BE.42.7A 02 14 4E.AD.E6.BB.72.54.92.30.2B.03.AB.53.5D.3D.6E.88.B8.AA.D6.30 .Sp Note that the above signature is 46 bytes long \- the extra two bytes are used only when r and/or s are larger than or equal to 2^159. The extra bytes are used to distinguish positive from negative values. .Sp All that to say if you are using \fBget_sig_size()\fR to determine the size of r + s depending on the size of the key you can subtract 8 bytes for the ASN.1 overhead. .ie n .IP "$sig = $dsa\->sign( $message );" 4 .el .IP "\f(CW$sig\fR = \f(CW$dsa\fR\->sign( \f(CW$message\fR );" 4 .IX Item "$sig = $dsa->sign( $message );" Signs \f(CW$message\fR, returning the signature. Note that \f(CW$meesage\fR cannot exceed 20 characters in length. .Sp \&\f(CW$dsa\fR is the signer's private key. .ie n .IP "$sig_obj = $dsa\->do_sign( $message );" 4 .el .IP "\f(CW$sig_obj\fR = \f(CW$dsa\fR\->do_sign( \f(CW$message\fR );" 4 .IX Item "$sig_obj = $dsa->do_sign( $message );" Similar to \f(CW\*(C`sign\*(C'\fR, but returns a Crypt::OpenSSL::DSA::Signature object. .ie n .IP "$valid = $dsa\->verify( $message, $sig );" 4 .el .IP "\f(CW$valid\fR = \f(CW$dsa\fR\->verify( \f(CW$message\fR, \f(CW$sig\fR );" 4 .IX Item "$valid = $dsa->verify( $message, $sig );" Verifies that the \f(CW$sig\fR signature for \f(CW$message\fR is valid. .Sp \&\f(CW$dsa\fR is the signer's public key. .Sp Note: it croaks if the underlying library call returns error (\-1). .ie n .IP "$valid = $dsa\->do_verify( $message, $sig_obj );" 4 .el .IP "\f(CW$valid\fR = \f(CW$dsa\fR\->do_verify( \f(CW$message\fR, \f(CW$sig_obj\fR );" 4 .IX Item "$valid = $dsa->do_verify( $message, $sig_obj );" Similar to \f(CW\*(C`verify\*(C'\fR, but uses a Crypt::OpenSSL::DSA::Signature object. .Sp Note: it croaks if the underlying library call returns error (\-1). .ie n .IP "$dsa\->write_params( $filename );" 4 .el .IP "\f(CW$dsa\fR\->write_params( \f(CW$filename\fR );" 4 .IX Item "$dsa->write_params( $filename );" Writes the parameters into a PEM file. .ie n .IP "$dsa\->write_pub_key( $filename );" 4 .el .IP "\f(CW$dsa\fR\->write_pub_key( \f(CW$filename\fR );" 4 .IX Item "$dsa->write_pub_key( $filename );" Writes the public key into a PEM file. .ie n .IP "$dsa\->write_priv_key( $filename );" 4 .el .IP "\f(CW$dsa\fR\->write_priv_key( \f(CW$filename\fR );" 4 .IX Item "$dsa->write_priv_key( $filename );" Writes the private key into a PEM file. .ie n .IP "$p = $dsa\->get_p, $dsa\->set_p($p)" 4 .el .IP "\f(CW$p\fR = \f(CW$dsa\fR\->get_p, \f(CW$dsa\fR\->set_p($p)" 4 .IX Item "$p = $dsa->get_p, $dsa->set_p($p)" Gets/sets the prime number in binary format. .ie n .IP "$q = $dsa\->get_q, $dsa\->set_q($q)" 4 .el .IP "\f(CW$q\fR = \f(CW$dsa\fR\->get_q, \f(CW$dsa\fR\->set_q($q)" 4 .IX Item "$q = $dsa->get_q, $dsa->set_q($q)" Gets/sets the subprime number (q | p\-1) in binary format. .ie n .IP "$g = $dsa\->get_g, $dsa\->set_g($g)" 4 .el .IP "\f(CW$g\fR = \f(CW$dsa\fR\->get_g, \f(CW$dsa\fR\->set_g($g)" 4 .IX Item "$g = $dsa->get_g, $dsa->set_g($g)" Gets/sets the generator of subgroup in binary format. .ie n .IP "$pub_key = $dsa\->get_pub_key, $dsa\->set_pub_key($pub_key)" 4 .el .IP "\f(CW$pub_key\fR = \f(CW$dsa\fR\->get_pub_key, \f(CW$dsa\fR\->set_pub_key($pub_key)" 4 .IX Item "$pub_key = $dsa->get_pub_key, $dsa->set_pub_key($pub_key)" Gets/sets the public key (y = g^x) in binary format. .ie n .IP "$priv_key = $dsa\->get_priv_key, $dsa\->set_priv_key($priv_key)" 4 .el .IP "\f(CW$priv_key\fR = \f(CW$dsa\fR\->get_priv_key, \f(CW$dsa\fR\->set_priv_key($priv_key)" 4 .IX Item "$priv_key = $dsa->get_priv_key, $dsa->set_priv_key($priv_key)" Gets/sets the private key in binary format. .SH NOTES .IX Header "NOTES" Crpyt::DSA is a more mature Perl DSA module, but can be difficult to install, because of the Math::Pari requirement. .PP Comments, suggestions, and patches welcome. .SH AUTHOR .IX Header "AUTHOR" T.J. Mather, .SH COPYRIGHT .IX Header "COPYRIGHT" Copyright (c) 2002 T.J. Mather. Crypt::OpenSSL::DSA is free software; you may redistribute it and/or modify it under the same terms as Perl itself. .PP Paid support is available directly from the author of this package. Please see for more details. .SH "SEE ALSO" .IX Header "SEE ALSO" Crypt::OpenSSL::DSA::Signature .PP Crypt::DSA, Crypt::OpenSSL::RSA .PP Net::DNS::SEC