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 (in PKCS1 format) is:\n",
$rsa->get_public_key_string();
print "public key (in X509 format) is:\n",
$rsa->get_public_key_x509_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 a string containing Base64/DER-encoding of either the PKCS1 or
X.509 representation of the key. 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 string containing the Base64/DER encoding of the PKCS1
representation of the key. 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 (mandatory) argument is the key
size, while the second optional argument specifies the public
exponent (the default public exponent is 65537). The padding is set
to PKCS1_OAEP, but can be changed with "use_xxx_padding" methods.
new_key_from_parameters
Given "Crypt::OpenSSL::Bignum" objects for "n", "e", and optionally
"d", "p", and "q", where "p" and "q" are the prime factors of "n",
"e" is the public exponent and "d" is the private exponent, create a
new "Crypt::OpenSSL::RSA" object using these values. If "p" and "q"
are provided and "d" is "undef", "d" is computed. Note that while
"p" and "q" are not necessary for a private key, their presence will
speed up computation.
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.
Instance Methods
DESTROY
Clean up after ourselves. In particular, erase and free the memory
occupied by the RSA key structure.
get_public_key_string
Return the Base64/DER-encoded PKCS1 representation of the public
key. This string has header and footer lines:
-----BEGIN RSA PUBLIC KEY------
-----END RSA PUBLIC KEY------
get_public_key_x509_string
Return the Base64/DER-encoded representation of the "subject public
key", suitable for use in X509 certificates. This string has header
and footer lines:
-----BEGIN PUBLIC KEY------
-----END PUBLIC KEY------
and is the format that is produced by running "openssl rsa -pubout".
get_private_key_string
Return the Base64/DER-encoded PKCS1 representation of the private
key. This string has header and footer lines:
-----BEGIN RSA PRIVATE KEY------
-----END RSA PRIVATE KEY------
encrypt
Encrypt a binary "string" using the public (portion of the) key.
decrypt
Decrypt a binary "string". Croaks if the key is public only.
private_encrypt
Encrypt a binary "string" using the private key. Croaks if the key
is public only.
public_decrypt
Decrypt a binary "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.
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.
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_sha224_hash, use_sha256_hash, use_sha384_hash, use_sha512_hash
These FIPS 180-2 hash algorithms, for use when signing and verifying
messages, are only available with newer openssl versions (>= 0.9.8).
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. Croaks if the key is
public only.
get_key_parameters
Return "Crypt::OpenSSL::Bignum" objects representing the values of
"n", "e", "d", "p", "q", "d mod (p-1)", "d mod (q-1)", and "1/q mod
p", where "p" and "q" are the prime factors of "n", "e" is the
public exponent and "d" is the private exponent. Some of these
values may return as "undef"; only "n" and "e" will be defined for a
public key. The "Crypt::OpenSSL::Bignum" module must be installed
for this to work.
is_private
Return true if this is a private key, and false if it is private
only.
BUGS
There is a small memory leak when generating new keys of more than 512
bits.
AUTHOR
Ian Robertson, "iroberts@cpan.org". For support, please email
"perl-openssl-users@lists.sourceforge.net".
ACKNOWLEDGEMENTS
LICENSE
Copyright (c) 2001-2011 Ian Robertson. Crypt::OpenSSL::RSA is free
software; you may redistribute it and/or modify it under the same terms
as Perl itself.
SEE ALSO
perl(1), Crypt::OpenSSL::Random(3), Crypt::OpenSSL::Bignum(3), rsa(3),
RSA_new(3), RSA_public_encrypt(3), RSA_size(3), RSA_generate_key(3),
RSA_check_key(3)