Crypt::PK::DSA(3)     User Contributed Perl Documentation    Crypt::PK::DSA(3)


NAME
       Crypt::PK::DSA - Public key cryptography based on DSA

SYNOPSIS
        ### OO interface

        #Encryption: Alice
        my $pub = Crypt::PK::DSA->new('Bob_pub_dsa1.der');
        my $ct = $pub->encrypt("secret message");
        #
        #Encryption: Bob (received ciphertext $ct)
        my $priv = Crypt::PK::DSA->new('Bob_priv_dsa1.der');
        my $pt = $priv->decrypt($ct);

        #Signature: Alice
        my $priv = Crypt::PK::DSA->new('Alice_priv_dsa1.der');
        my $sig = $priv->sign_message($message);
        #
        #Signature: Bob (received $message + $sig)
        my $pub = Crypt::PK::DSA->new('Alice_pub_dsa1.der');
        $pub->verify_message($sig, $message) or die "ERROR";

        #Key generation
        my $pk = Crypt::PK::DSA->new();
        $pk->generate_key(30, 256);
        my $private_der = $pk->export_key_der('private');
        my $public_der = $pk->export_key_der('public');
        my $private_pem = $pk->export_key_pem('private');
        my $public_pem = $pk->export_key_pem('public');

        ### Functional interface

        #Encryption: Alice
        my $ct = dsa_encrypt('Bob_pub_dsa1.der', "secret message");
        #Encryption: Bob (received ciphertext $ct)
        my $pt = dsa_decrypt('Bob_priv_dsa1.der', $ct);

        #Signature: Alice
        my $sig = dsa_sign_message('Alice_priv_dsa1.der', $message);
        #Signature: Bob (received $message + $sig)
        dsa_verify_message('Alice_pub_dsa1.der', $sig, $message) or die "ERROR";

METHODS
   new
         my $pk = Crypt::PK::DSA->new();
         #or
         my $pk = Crypt::PK::DSA->new($priv_or_pub_key_filename);
         #or
         my $pk = Crypt::PK::DSA->new(\$buffer_containing_priv_or_pub_key);

       Support for password protected PEM keys

         my $pk = Crypt::PK::DSA->new($priv_pem_key_filename, $password);
         #or
         my $pk = Crypt::PK::DSA->new(\$buffer_containing_priv_pem_key, $password);

   generate_key
       Uses Yarrow-based cryptographically strong random number generator
       seeded with random data taken from "/dev/random" (UNIX) or
       "CryptGenRandom" (Win32).

        $pk->generate_key($group_size, $modulus_size);
        # $group_size  ... in bytes .. 15 < $group_size < 1024
        # $modulus_size .. in bytes .. ($modulus_size - $group_size) < 512

        ### Bits of Security according to libtomcrypt documentation
        # 80 bits   => generate_key(20, 128)
        # 120 bits  => generate_key(30, 256)
        # 140 bits  => generate_key(35, 384)
        # 160 bits  => generate_key(40, 512)

        ### Sizes according section 4.2 of FIPS 186-4
        # (L and N are the bit lengths of p and q respectively)
        # L = 1024, N = 160 => generate_key(20, 128)
        # L = 2048, N = 224 => generate_key(28, 256)
        # L = 2048, N = 256 => generate_key(32, 256)
        # L = 3072, N = 256 => generate_key(32, 384)

        $pk->generate_key($param_hash)
        # $param_hash is { d => $d, p => $p, q => $q }
        # where $d, $p, $q are hex strings

        $pk->generate_key(\$dsa_param)
        # $dsa_param is the content of DER or PEM file with DSA params
        # e.g. openssl dsaparam 2048

   import_key
       Loads private or public key in DER or PEM format.

         $pk->import_key($filename);
         #or
         $pk->import_key(\$buffer_containing_key);

       Support for password protected PEM keys

         $pk->import_key($pem_filename, $password);
         #or
         $pk->import_key(\$buffer_containing_pem_key, $password);

       Loading private or public keys form perl hash:

        $pk->import_key($hashref);

        # where $hashref is a key exported via key2hash
        $pk->import_key({
          p => "AAF839A764E04D80824B79FA1F0496C093...", #prime modulus
          q => "D05C4CB45F29D353442F1FEC43A6BE2BE8...", #prime divisor
          g => "847E8896D12C9BF18FE283AE7AD58ED7F3...", #generator of a subgroup of order q in GF(p)
          x => "6C801901AC74E2DC714D75A9F6969483CF...", #private key, random  0 < x < q
          y => "8F7604D77FA62C7539562458A63C7611B7...", #public key, where y = g^x mod p
        });

       Supported key formats:

       o   DSA public keys

            -----BEGIN PUBLIC KEY-----
            MIIBtjCCASsGByqGSM44BAEwggEeAoGBAJKyu+puNMGLpGIhbD1IatnwlI79ePr4
            YHe2KBhRkheKxWUZRpN1Vd/+usS2IHSJ9op5cSWETiP05d7PMtJaitklw7jhudq3
            GxNvV/GRdCQm3H6d76FHP88dms4vcDYc6ry6wKERGfNEtZ+4BAKrMZK+gDYsF4Aw
            U6WVR969kYZhAhUA6w25FgSRmJ8W4XkvC60n8Wv3DpMCgYA4ZFE+3tLOM24PZj9Z
            rxuqUzZZdR+kIzrsIYpWN9ustbmdKLKwsqIaUIxc5zxHEhbAjAIf8toPD+VEQIpY
            7vgJgDhXuPq45BgN19iLTzOJwIhAFXPZvnAdIo9D/AnMw688gT6g6U8QCZwX2XYg
            ICiVcriYVNcjVKHSFY/X0Oi7CgOBhAACgYB4ZTn4OYT/pjUd6tNhGPtOS3CE1oaj
            5ScbetXg4ZDpceEyQi8VG+/ZTbs8var8X77JdEdeQA686cAxpOaVgW8V4odvcmfA
            BfueiGnPXjqGfppiHAyL1Ngyd+EsXKmKVXZYAVFVI0WuJKiZBSVURU7+ByxOfpGa
            fZhibr0SggWixQ==
            -----END PUBLIC KEY-----

       o   DSA private keys

            -----BEGIN DSA PRIVATE KEY-----
            MIIBuwIBAAKBgQCSsrvqbjTBi6RiIWw9SGrZ8JSO/Xj6+GB3tigYUZIXisVlGUaT
            dVXf/rrEtiB0ifaKeXElhE4j9OXezzLSWorZJcO44bnatxsTb1fxkXQkJtx+ne+h
            Rz/PHZrOL3A2HOq8usChERnzRLWfuAQCqzGSvoA2LBeAMFOllUfevZGGYQIVAOsN
            uRYEkZifFuF5LwutJ/Fr9w6TAoGAOGRRPt7SzjNuD2Y/Wa8bqlM2WXUfpCM67CGK
            VjfbrLW5nSiysLKiGlCMXOc8RxIWwIwCH/LaDw/lRECKWO74CYA4V7j6uOQYDdfY
            i08zicCIQBVz2b5wHSKPQ/wJzMOvPIE+oOlPEAmcF9l2ICAolXK4mFTXI1Sh0hWP
            19DouwoCgYB4ZTn4OYT/pjUd6tNhGPtOS3CE1oaj5ScbetXg4ZDpceEyQi8VG+/Z
            Tbs8var8X77JdEdeQA686cAxpOaVgW8V4odvcmfABfueiGnPXjqGfppiHAyL1Ngy
            d+EsXKmKVXZYAVFVI0WuJKiZBSVURU7+ByxOfpGafZhibr0SggWixQIVAL7Sia03
            8bvANjjL9Sitk8slrM6P
            -----END DSA PRIVATE KEY-----

       o   DSA private keys in password protected PEM format:

            -----BEGIN DSA PRIVATE KEY-----
            Proc-Type: 4,ENCRYPTED
            DEK-Info: DES-CBC,227ADC3AA0299491

            UISxBYAxPQMl2eK9LMAeHsssF6IxO+4G2ta2Jn8VE+boJrrH3iSTKeMXGjGaXl0z
            DwcLGV+KMR70y+cxtTb34rFy+uSpBy10dOQJhxALDbe1XfCDQIUfaXRfMNA3um2I
            JdZixUD/zcxBOUzao+MCr0V9XlJDgqBhJ5EEr53XHH07Eo5fhiBfbbR9NzdUPFrQ
            p2ASyZtFh7RXoIBUCQgg21oeLddcNWV7gd/Y46kghO9s0JbJ8C+IsuWEPRSq502h
            tSoDN6B0sxbVvOUICLLbQaxt7yduTAhRxVIJZ1PWATTVD7CZBVz9uIDZ7LOv+er2
            1q3vkwb8E9spPsA240+BnfD571XEop4jrawxC0VKQZ+3cPVLc6jhIsxvzzFQUt67
            g66v8GUgt7KF3KhVV7qEtntybQWDWb+K/uTIH9Ra8nP820d3Rnl61pPXDPlluteT
            WSLOvEMN2zRmkaxQNv/tLdT0SYpQtdjw74G3A6T7+KnvinKrjtp1a/AXkCF9hNEx
            DGbxOYo1UOmk8qdxWCrab34nO+Q8oQc9wjXHG+ZtRYIMoGMKREK8DeL4H1RPNkMf
            rwXWk8scd8QFmJAb8De1VQ==
            -----END DSA PRIVATE KEY-----

       o   SSH public DSA keys

            ssh-dss AAAAB3NzaC1kc3MAAACBAKU8/avmk...4XOwuEssAVhmwA==

       o   SSH public DSA keys (RFC-4716 format)

            ---- BEGIN SSH2 PUBLIC KEY ----
            Comment: "1024-bit DSA, converted from OpenSSH"
            AAAAB3NzaC1kc3MAAACBAKU8/avmkFeGnSqwYG7dZnQlG+01QNaxu3F5v0NcL/SRUW7Idp
            Uq8t14siK0mA6yjphLhOf5t8gugTEVBllP86ANSbFigH7WN3v6ydJWqm60pNhNHN//50cn
            NtIsXbxeq3VtsI64pkH1OJqeZDHLmu73k4T0EKOzsylSfF/wtVBJAAAAFQChpubLHViwPB
            +jSvUb8e4THS7PBQAAAIAJD1PMCiTCQa1xyD/NCWOajCufTOIzKAhm6l+nlBVPiKI+262X
            pYt127Ke4mPL8XJBizoTjSQN08uHMg/8L6W/cdO2aZ+mhkBnS1xAm83DAwqLrDraR1w/4Q
            RFxr5Vbyy8qnejrPjTJobBN1BGsv84wHkjmoCn6pFIfkGYeATlJgAAAIAHYPU1zMVBTDWr
            u7SNC4G2UyWGWYYLjLytBVHfQmBa51CmqrSs2kCfGLGA1ynfYENsxcJq9nsXrb4i17H5BH
            JFkH0g7BUDpeBeLr8gsK3WgfqWwtZsDkltObw9chUD/siK6q/dk/fSIB2Ho0inev7k68Z5
            ZkNI4XOwuEssAVhmwA==
            ---- END SSH2 PUBLIC KEY ----

   export_key_der
        my $private_der = $pk->export_key_der('private');
        #or
        my $public_der = $pk->export_key_der('public');

   export_key_pem
        my $private_pem = $pk->export_key_pem('private');
        #or
        my $public_pem = $pk->export_key_pem('public');
        #or
        my $public_pem = $pk->export_key_pem('public_x509');

       With parameter 'public' uses header and footer lines:

         -----BEGIN DSA PUBLIC KEY------
         -----END DSA PUBLIC KEY------

       With parameter 'public_x509' uses header and footer lines:

         -----BEGIN PUBLIC KEY------
         -----END PUBLIC KEY------

       Support for password protected PEM keys

        my $private_pem = $pk->export_key_pem('private', $password);
        #or
        my $private_pem = $pk->export_key_pem('private', $password, $cipher);

        # supported ciphers: 'DES-CBC'
        #                    'DES-EDE3-CBC'
        #                    'SEED-CBC'
        #                    'CAMELLIA-128-CBC'
        #                    'CAMELLIA-192-CBC'
        #                    'CAMELLIA-256-CBC'
        #                    'AES-128-CBC'
        #                    'AES-192-CBC'
        #                    'AES-256-CBC' (DEFAULT)

   encrypt
        my $pk = Crypt::PK::DSA->new($pub_key_filename);
        my $ct = $pk->encrypt($message);
        #or
        my $ct = $pk->encrypt($message, $hash_name);

        #NOTE: $hash_name can be 'SHA1' (DEFAULT), 'SHA256' or any other hash supported by Crypt::Digest

   decrypt
        my $pk = Crypt::PK::DSA->new($priv_key_filename);
        my $pt = $pk->decrypt($ciphertext);

   sign_message
        my $pk = Crypt::PK::DSA->new($priv_key_filename);
        my $signature = $priv->sign_message($message);
        #or
        my $signature = $priv->sign_message($message, $hash_name);

        #NOTE: $hash_name can be 'SHA1' (DEFAULT), 'SHA256' or any other hash supported by Crypt::Digest

   verify_message
        my $pk = Crypt::PK::DSA->new($pub_key_filename);
        my $valid = $pub->verify_message($signature, $message)
        #or
        my $valid = $pub->verify_message($signature, $message, $hash_name);

        #NOTE: $hash_name can be 'SHA1' (DEFAULT), 'SHA256' or any other hash supported by Crypt::Digest

   sign_hash
        my $pk = Crypt::PK::DSA->new($priv_key_filename);
        my $signature = $priv->sign_hash($message_hash);

   verify_hash
        my $pk = Crypt::PK::DSA->new($pub_key_filename);
        my $valid = $pub->verify_hash($signature, $message_hash);

   is_private
        my $rv = $pk->is_private;
        # 1 .. private key loaded
        # 0 .. public key loaded
        # undef .. no key loaded

   size
        my $size = $pk->size;
        # returns key size (length of the prime p) in bytes or undef if key not loaded

   size_q
        my $size = $pk->size_q;
        # returns length of the prime q in bytes or undef if key not loaded

   key2hash
        my $hash = $pk->key2hash;

        # returns hash like this (or undef if no key loaded):
        {
          type => 1,   # integer: 1 .. private, 0 .. public
          size => 256, # integer: key size in bytes
          # all the rest are hex strings
          p => "AAF839A764E04D80824B79FA1F0496C093...", #prime modulus
          q => "D05C4CB45F29D353442F1FEC43A6BE2BE8...", #prime divisor
          g => "847E8896D12C9BF18FE283AE7AD58ED7F3...", #generator of a subgroup of order q in GF(p)
          x => "6C801901AC74E2DC714D75A9F6969483CF...", #private key, random  0 < x < q
          y => "8F7604D77FA62C7539562458A63C7611B7...", #public key, where y = g^x mod p
        }

FUNCTIONS
   dsa_encrypt
       DSA based encryption as implemented by libtomcrypt. See method
       "encrypt" below.

        my $ct = dsa_encrypt($pub_key_filename, $message);
        #or
        my $ct = dsa_encrypt(\$buffer_containing_pub_key, $message);
        #or
        my $ct = dsa_encrypt($pub_key_filename, $message, $hash_name);

        #NOTE: $hash_name can be 'SHA1' (DEFAULT), 'SHA256' or any other hash supported by Crypt::Digest

       Encryption works similar to the Crypt::PK::ECC encryption whereas
       shared DSA key is computed, and the hash of the shared key XOR'ed
       against the plaintext forms the ciphertext.

   dsa_decrypt
       DSA based decryption as implemented by libtomcrypt. See method
       "decrypt" below.

        my $pt = dsa_decrypt($priv_key_filename, $ciphertext);
        #or
        my $pt = dsa_decrypt(\$buffer_containing_priv_key, $ciphertext);

   dsa_sign_message
       Generate DSA signature. See method "sign_message" below.

        my $sig = dsa_sign_message($priv_key_filename, $message);
        #or
        my $sig = dsa_sign_message(\$buffer_containing_priv_key, $message);
        #or
        my $sig = dsa_sign_message($priv_key, $message, $hash_name);

   dsa_verify_message
       Verify DSA signature. See method "verify_message" below.

        dsa_verify_message($pub_key_filename, $signature, $message) or die "ERROR";
        #or
        dsa_verify_message(\$buffer_containing_pub_key, $signature, $message) or die "ERROR";
        #or
        dsa_verify_message($pub_key, $signature, $message, $hash_name) or die "ERROR";

   dsa_sign_hash
       Generate DSA signature. See method "sign_hash" below.

        my $sig = dsa_sign_hash($priv_key_filename, $message_hash);
        #or
        my $sig = dsa_sign_hash(\$buffer_containing_priv_key, $message_hash);

   dsa_verify_hash
       Verify DSA signature. See method "verify_hash" below.

        dsa_verify_hash($pub_key_filename, $signature, $message_hash) or die "ERROR";
        #or
        dsa_verify_hash(\$buffer_containing_pub_key, $signature, $message_hash) or die "ERROR";

OpenSSL interoperability
        ### let's have:
        # DSA private key in PEM format - dsakey.priv.pem
        # DSA public key in PEM format  - dsakey.pub.pem
        # data file to be signed - input.data

   Sign by OpenSSL, verify by Crypt::PK::DSA
       Create signature (from commandline):

        openssl dgst -sha1 -sign dsakey.priv.pem -out input.sha1-dsa.sig input.data

       Verify signature (Perl code):

        use Crypt::PK::DSA;
        use Crypt::Digest 'digest_file';
        use Crypt::Misc 'read_rawfile';

        my $pkdsa = Crypt::PK::DSA->new("dsakey.pub.pem");
        my $signature = read_rawfile("input.sha1-dsa.sig");
        my $valid = $pkdsa->verify_hash($signature, digest_file("SHA1", "input.data"), "SHA1", "v1.5");
        print $valid ? "SUCCESS" : "FAILURE";

   Sign by Crypt::PK::DSA, verify by OpenSSL
       Create signature (Perl code):

        use Crypt::PK::DSA;
        use Crypt::Digest 'digest_file';
        use Crypt::Misc 'write_rawfile';

        my $pkdsa = Crypt::PK::DSA->new("dsakey.priv.pem");
        my $signature = $pkdsa->sign_hash(digest_file("SHA1", "input.data"), "SHA1", "v1.5");
        write_rawfile("input.sha1-dsa.sig", $signature);

       Verify signature (from commandline):

        openssl dgst -sha1 -verify dsakey.pub.pem -signature input.sha1-dsa.sig input.data

   Keys generated by Crypt::PK::DSA
       Generate keys (Perl code):

        use Crypt::PK::DSA;
        use Crypt::Misc 'write_rawfile';

        my $pkdsa = Crypt::PK::DSA->new;
        $pkdsa->generate_key(20, 128);
        write_rawfile("dsakey.pub.der",  $pkdsa->export_key_der('public'));
        write_rawfile("dsakey.priv.der", $pkdsa->export_key_der('private'));
        write_rawfile("dsakey.pub.pem",  $pkdsa->export_key_pem('public_x509'));
        write_rawfile("dsakey.priv.pem", $pkdsa->export_key_pem('private'));
        write_rawfile("dsakey-passwd.priv.pem", $pkdsa->export_key_pem('private', 'secret'));

       Use keys by OpenSSL:

        openssl dsa -in dsakey.priv.der -text -inform der
        openssl dsa -in dsakey.priv.pem -text
        openssl dsa -in dsakey-passwd.priv.pem -text -inform pem -passin pass:secret
        openssl dsa -in dsakey.pub.der -pubin -text -inform der
        openssl dsa -in dsakey.pub.pem -pubin -text

   Keys generated by OpenSSL
       Generate keys:

        openssl dsaparam -genkey -out dsakey.priv.pem 1024
        openssl dsa -in dsakey.priv.pem -out dsakey.priv.der -outform der
        openssl dsa -in dsakey.priv.pem -out dsakey.pub.pem -pubout
        openssl dsa -in dsakey.priv.pem -out dsakey.pub.der -outform der -pubout
        openssl dsa -in dsakey.priv.pem -passout pass:secret -des3 -out dsakey-passwd.priv.pem

       Load keys (Perl code):

        use Crypt::PK::DSA;

        my $pkdsa = Crypt::PK::DSA->new;
        $pkdsa->import_key("dsakey.pub.der");
        $pkdsa->import_key("dsakey.priv.der");
        $pkdsa->import_key("dsakey.pub.pem");
        $pkdsa->import_key("dsakey.priv.pem");
        $pkdsa->import_key("dsakey-passwd.priv.pem", "secret");

SEE ALSO
       o   <https://en.wikipedia.org/wiki/Digital_Signature_Algorithm>

perl v5.40.0                      2024-10-20                 Crypt::PK::DSA(3)