/ 
CryptX-0.013
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/ Crypt::PK::DSA

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

FUNCTIONS

dsa_encrypt

DSA based encryption.

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

dsa_decrypt

DSA based decryption.

dsa_sign

Generate DSA signature.

dsa_verify

Verify DSA signature.

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);

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  ... 15 < $group_size < 1024
# $modulus_size .. ($modulus_size - $group_size) < 512

# Bits of Security  $group_size  $modulus_size
# 80                20           128
# 120               30           256
# 140               35           384
# 160               40           512

import_key

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

encrypt

decrypt

sign

verify

is_private

size