mirror of https://github.com/openssl/openssl.git
132 lines
4.8 KiB
Plaintext
132 lines
4.8 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
RSA_public_encrypt, RSA_private_decrypt - RSA public key cryptography
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/rsa.h>
|
|
|
|
The following functions have been deprecated since OpenSSL 3.0, and can be
|
|
hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
|
|
see L<openssl_user_macros(7)>:
|
|
|
|
int RSA_public_encrypt(int flen, const unsigned char *from,
|
|
unsigned char *to, RSA *rsa, int padding);
|
|
|
|
int RSA_private_decrypt(int flen, const unsigned char *from,
|
|
unsigned char *to, RSA *rsa, int padding);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
Both of the functions described on this page are deprecated.
|
|
Applications should instead use L<EVP_PKEY_encrypt_init_ex(3)>,
|
|
L<EVP_PKEY_encrypt(3)>, L<EVP_PKEY_decrypt_init_ex(3)> and
|
|
L<EVP_PKEY_decrypt(3)>.
|
|
|
|
RSA_public_encrypt() encrypts the B<flen> bytes at B<from> (usually a
|
|
session key) using the public key B<rsa> and stores the ciphertext in
|
|
B<to>. B<to> must point to RSA_size(B<rsa>) bytes of memory.
|
|
|
|
B<padding> denotes one of the following modes:
|
|
|
|
=over 4
|
|
|
|
=item RSA_PKCS1_PADDING
|
|
|
|
PKCS #1 v1.5 padding. This currently is the most widely used mode.
|
|
However, it is highly recommended to use RSA_PKCS1_OAEP_PADDING in
|
|
new applications. SEE WARNING BELOW.
|
|
|
|
=item RSA_PKCS1_OAEP_PADDING
|
|
|
|
EME-OAEP as defined in PKCS #1 v2.0 with SHA-1, MGF1 and an empty
|
|
encoding parameter. This mode is recommended for all new applications.
|
|
|
|
=item RSA_NO_PADDING
|
|
|
|
Raw RSA encryption. This mode should I<only> be used to implement
|
|
cryptographically sound padding modes in the application code.
|
|
Encrypting user data directly with RSA is insecure.
|
|
|
|
=back
|
|
|
|
When encrypting B<flen> must not be more than RSA_size(B<rsa>) - 11 for the
|
|
PKCS #1 v1.5 based padding modes, not more than RSA_size(B<rsa>) - 42 for
|
|
RSA_PKCS1_OAEP_PADDING and exactly RSA_size(B<rsa>) for RSA_NO_PADDING.
|
|
When a padding mode other than RSA_NO_PADDING is in use, then
|
|
RSA_public_encrypt() will include some random bytes into the ciphertext
|
|
and therefore the ciphertext will be different each time, even if the
|
|
plaintext and the public key are exactly identical.
|
|
The returned ciphertext in B<to> will always be zero padded to exactly
|
|
RSA_size(B<rsa>) bytes.
|
|
B<to> and B<from> may overlap.
|
|
|
|
RSA_private_decrypt() decrypts the B<flen> bytes at B<from> using the
|
|
private key B<rsa> and stores the plaintext in B<to>. B<flen> should
|
|
be equal to RSA_size(B<rsa>) but may be smaller, when leading zero
|
|
bytes are in the ciphertext. Those are not important and may be removed,
|
|
but RSA_public_encrypt() does not do that. B<to> must point
|
|
to a memory section large enough to hold the maximal possible decrypted
|
|
data (which is equal to RSA_size(B<rsa>) for RSA_NO_PADDING,
|
|
RSA_size(B<rsa>) - 11 for the PKCS #1 v1.5 based padding modes and
|
|
RSA_size(B<rsa>) - 42 for RSA_PKCS1_OAEP_PADDING).
|
|
B<padding> is the padding mode that was used to encrypt the data.
|
|
B<to> and B<from> may overlap.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
RSA_public_encrypt() returns the size of the encrypted data (i.e.,
|
|
RSA_size(B<rsa>)). RSA_private_decrypt() returns the size of the
|
|
recovered plaintext. A return value of 0 is not an error and
|
|
means only that the plaintext was empty.
|
|
|
|
On error, -1 is returned; the error codes can be
|
|
obtained by L<ERR_get_error(3)>.
|
|
|
|
=head1 WARNINGS
|
|
|
|
Decryption failures in the RSA_PKCS1_PADDING mode leak information
|
|
which can potentially be used to mount a Bleichenbacher padding oracle
|
|
attack. This is an inherent weakness in the PKCS #1 v1.5 padding
|
|
design. Prefer RSA_PKCS1_OAEP_PADDING.
|
|
|
|
In OpenSSL before version 3.2.0, both the return value and the length of
|
|
returned value could be used to mount the Bleichenbacher attack.
|
|
Since version 3.2.0, the default provider in OpenSSL does not return an
|
|
error when padding checks fail. Instead it generates a random
|
|
message based on used private
|
|
key and provided ciphertext so that application code doesn't have to implement
|
|
a side-channel secure error handling.
|
|
Applications that want to be secure against side-channel attacks with
|
|
providers that don't implement implicit rejection, still need to
|
|
handle the returned values using side-channel free code.
|
|
Side-channel free handling of the error stack can be performed using
|
|
either a pair of unconditional L<ERR_set_mark(3)> and L<ERR_pop_to_mark(3)>
|
|
calls or by using the L<ERR_clear_error(3)> call.
|
|
|
|
=head1 CONFORMING TO
|
|
|
|
SSL, PKCS #1 v2.0
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<ERR_get_error(3)>, L<RAND_bytes(3)>,
|
|
L<RSA_size(3)>, L<EVP_PKEY_decrypt(3)>, L<EVP_PKEY_encrypt(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
Both of these functions were deprecated in OpenSSL 3.0.
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved.
|
|
|
|
Licensed under the Apache License 2.0 (the "License"). You may not use
|
|
this file except in compliance with the License. You can obtain a copy
|
|
in the file LICENSE in the source distribution or at
|
|
L<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|