NAME

Crypt::OpenSSL::RSA - RSA encoding and decoding, using the openSSL libraries

SYNOPSIS

use Crypt::OpenSSL::Random;
use Crypt::OpenSSL::RSA;

# not necessary if we have /dev/random:
Crypt::OpenSSL::Random::random_seed($good_entropy);
Crypt::OpenSSL::RSA->import_random_seed();
$rsa_pub = Crypt::OpenSSL::RSA->new_public_key($key_string);
$rsa_pub->use_sslv23_padding(); # use_pkcs1_oaep_padding is the default
$ciphertext = $rsa->encrypt($plaintext);

$rsa_priv = Crypt::OpenSSL::RSA->new_private_key($key_string);
$plaintext = $rsa->encrypt($ciphertext);

$rsa = Crypt::OpenSSL::RSA->generate_key( 1024 ); # or
$rsa = Crypt::OpenSSL::RSA->generate_key( 1024, $prime );

print "private key is:\n", $rsa->get_private_key_string();
print "public key is:\n", $rsa->get_public_key_string();

$rsa_priv->use_md5_hash(); # use_sha1_hash is the default
$signature = $rsa_priv->sign($plaintext);
print "Signed correctly\n" if ( $rsa->verify($plaintext, $signature) );

DESCRIPTION

Crypt::OpenSSL::RSA provides the ability to RSA encrypt strings which are somewhat shorter than the block size of a key. It also allows for decryption, signatures and signature verification.

NOTE: Many of the methods in this package can croak, so use eval, or Error.pm's try/catch mechanism to capture errors. Also, while some methods from earlier versions of this package return true on success, this (never documented) behavior is no longer the case.

Class Methods

new_public_key

Create a new Crypt::OpenSSL::RSA object by loading a public key in from an X509 encoded string. The string should include the -----BEGIN...----- and -----END...----- lines. The padding is set to PKCS1_OAEP, but can be changed with the use_xxx_padding methods

new_private_key

Create a new Crypt::OpenSSL::RSA object by loading a private key in from an X509 encoded string. The string should include the -----BEGIN...----- and -----END...----- lines. The padding is set to PKCS1_OAEP, but can be changed with use_xxx_padding.

generate_key

Create a new Crypt::OpenSSL::RSA object by constructing a private/public key pair. The first (mandetory) argument is the key size, while the second optional argument specifies the public exponent (the default public exponent is 65535). The padding is set to PKCS1_OAEP, but can be changed with use_xxx_padding methods.

NOTE - using generate_key as an instance method on an rsa object created by the deprecated new method is itself deprecated.

import_random_seed

Import a random seed from Crypt::OpenSSL::Random, since the OpenSSL libraries won't allow sharing of random structures across perl XS modules.

new

The no-arg new constructor is DEPRECATED - use generate_key, new_public_key or new_private_key instead.

Instance Methods

DESTROY

Clean up after ourselves. In particular, erase and free the memory occupied by the RSA key structure.

load_public_key

DEPRECATED - use new_public_key instead

load_private_key

DEPRECATED - use new_public_key instead

get_public_key_string

Return the public portion of the key as an X509 encoded string.

get_private_key_string

Return the X509 encoding of the private key.

encrypt

Encrypt a string using the public (portion of the) key

sign

Sign a string using the secret (portion of the) key

verify

Check the signature on a text.

decrypt

Decrypt a binary "string". Croaks if the key is public only.

set_padding_mode

DEPRECATED Use the use_xxx_padding methods instead

use_no_padding

Use raw RSA encryption. This mode should only be used to implement cryptographically sound padding modes in the application code. Encrypting user data directly with RSA is insecure.

use_pkcs1_padding

Use PKCS #1 v1.5 padding. This currently is the most widely used mode of padding.

use_pkcs1_oaep_padding

Use EME-OAEP padding as defined in PKCS #1 v2.0 with SHA-1, MGF1 and an empty encoding parameter. This mode of padding is recommended for all new applications. It is the default mode used by Crypt::OpenSSL::RSA.

use_sslv23_padding

Use PKCS #1 v1.5 padding with an SSL-specific modification that denotes that the server is SSL3 capable.

get_padding_mode

DEPRECATED

use_md5_hash

Use the RFC 1321 MD5 hashing algorithm by Ron Rivest when signing and verifying messages.

use_sha1_hash

Use the RFC 3174 Secure Hashing Algorithm (FIPS 180-1) when signing and verifying messages. This is the default.

use_ripemd160_hash

Dobbertin, Bosselaers and Preneel's RIPEMD hashing algorithm when signing and verifying messages.

size

Returns the size, in bytes, of the key. All encrypted text will be of this size, and depending on the padding mode used, the length of the text to be encrypted should be:

pkcs1_oaep_padding

at most 42 bytes less than this size.

pkcs1_padding or sslv23_padding

at most 11 bytes less than this size.

no_padding

exactly this size.

check_key

This function validates the RSA key, returning a true value if the key is valid, and a false value otherwise.

BUGS

There is a small memory leak when generating new keys of more than 512 bits.

AUTHOR

Ian Robertson, iroberts@cpan.org

SEE ALSO

perl(1), Crypt::OpenSSL::Random(3), rsa(3), RSA_new(3), RSA_public_encrypt(3), RSA_size(3), RSA_generate_key(3), RSA_check_key(3)