Updated: 2022/Sep/29
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RSA_padding_add_PKCS1_type_1(3) OpenSSL RSA_padding_add_PKCS1_type_1(3)
NAME
RSA_padding_add_PKCS1_type_1, RSA_padding_check_PKCS1_type_1,
RSA_padding_add_PKCS1_type_2, RSA_padding_check_PKCS1_type_2,
RSA_padding_add_PKCS1_OAEP, RSA_padding_check_PKCS1_OAEP,
RSA_padding_add_PKCS1_OAEP_mgf1, RSA_padding_check_PKCS1_OAEP_mgf1,
RSA_padding_add_none, RSA_padding_check_none - asymmetric encryption
padding
LIBRARY
libcrypto, -lcrypto
SYNOPSIS
#include <openssl/rsa.h>
The following functions have been deprecated since OpenSSL 3.0, and can
be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
version value, see openssl_user_macros(7):
int RSA_padding_add_PKCS1_type_1(unsigned char *to, int tlen,
const unsigned char *f, int fl);
int RSA_padding_check_PKCS1_type_1(unsigned char *to, int tlen,
const unsigned char *f, int fl, int rsa_len);
int RSA_padding_add_PKCS1_type_2(unsigned char *to, int tlen,
const unsigned char *f, int fl);
int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
const unsigned char *f, int fl, int rsa_len);
int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
const unsigned char *f, int fl,
const unsigned char *p, int pl);
int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
const unsigned char *f, int fl, int rsa_len,
const unsigned char *p, int pl);
int RSA_padding_add_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
const unsigned char *f, int fl,
const unsigned char *p, int pl,
const EVP_MD *md, const EVP_MD *mgf1md);
int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
const unsigned char *f, int fl, int rsa_len,
const unsigned char *p, int pl,
const EVP_MD *md, const EVP_MD *mgf1md);
int RSA_padding_add_none(unsigned char *to, int tlen,
const unsigned char *f, int fl);
int RSA_padding_check_none(unsigned char *to, int tlen,
const unsigned char *f, int fl, int rsa_len);
DESCRIPTION
All of the functions described on this page are deprecated.
Applications should instead use the EVP PKEY APIs.
The RSA_padding_xxx_xxx() functions are called from the RSA encrypt,
decrypt, sign and verify functions. Normally they should not be called
from application programs.
However, they can also be called directly to implement padding for
other asymmetric ciphers. RSA_padding_add_PKCS1_OAEP() and
RSA_padding_check_PKCS1_OAEP() may be used in an application combined
with RSA_NO_PADDING in order to implement OAEP with an encoding
parameter.
RSA_padding_add_xxx() encodes fl bytes from f so as to fit into tlen
bytes and stores the result at to. An error occurs if fl does not meet
the size requirements of the encoding method.
The following encoding methods are implemented:
PKCS1_type_1
PKCS #1 v2.0 EMSA-PKCS1-v1_5 (PKCS #1 v1.5 block type 1); used for
signatures
PKCS1_type_2
PKCS #1 v2.0 EME-PKCS1-v1_5 (PKCS #1 v1.5 block type 2)
PKCS1_OAEP
PKCS #1 v2.0 EME-OAEP
none
simply copy the data
The random number generator must be seeded prior to calling
RSA_padding_add_xxx(). If the automatic seeding or reseeding of the
OpenSSL CSPRNG fails due to external circumstances (see RAND(7)), the
operation will fail.
RSA_padding_check_xxx() verifies that the fl bytes at f contain a valid
encoding for a rsa_len byte RSA key in the respective encoding method
and stores the recovered data of at most tlen bytes (for
RSA_NO_PADDING: of size tlen) at to.
For RSA_padding_xxx_OAEP(), p points to the encoding parameter of
length pl. p may be NULL if pl is 0.
For RSA_padding_xxx_OAEP_mgf1(), md points to the md hash, if md is
NULL that means md=sha1, and mgf1md points to the mgf1 hash, if mgf1md
is NULL that means mgf1md=md.
RETURN VALUES
The RSA_padding_add_xxx() functions return 1 on success, 0 on error.
The RSA_padding_check_xxx() functions return the length of the
recovered data, -1 on error. Error codes can be obtained by calling
ERR_get_error(3).
WARNINGS
The result of RSA_padding_check_PKCS1_type_2() is a very sensitive
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 PKCS1_OAEP padding. If that is not possible, the
result of RSA_padding_check_PKCS1_type_2() should be checked in
constant time if it matches the expected length of the plaintext and
additionally some application specific consistency checks on the
plaintext need to be performed in constant time. If the plaintext is
rejected it must be kept secret which of the checks caused the
application to reject the message. Do not remove the zero-padding from
the decrypted raw RSA data which was computed by RSA_private_decrypt()
with RSA_NO_PADDING, as this would create a small timing side channel
which could be used to mount a Bleichenbacher attack against any
padding mode including PKCS1_OAEP.
SEE ALSO
RSA_public_encrypt(3), RSA_private_decrypt(3), RSA_sign(3),
RSA_verify(3), RAND(7)
HISTORY
All of these functions were deprecated in OpenSSL 3.0.
COPYRIGHT
Copyright 2000-2021 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
<https://www.openssl.org/source/license.html>.
3.0.12 2023-05-07 RSA_padding_add_PKCS1_type_1(3)