RSA_padding_check_PKCS1_type_2(3)
RSA_padding_add_PKCS1_type_1(3OpenSSRSA_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_SSLv23,
RSA_padding_check_SSLv23, RSA_padding_add_none,
RSA_padding_check_none - asymmetric encryption padding
SYNOPSIS
#include <openssl/rsa.h>
int RSA_padding_add_PKCS1_type_1(unsigned char *to, int tlen,
unsigned char *f, int fl);
int RSA_padding_check_PKCS1_type_1(unsigned char *to, int tlen,
unsigned char *f, int fl, int rsa_len);
int RSA_padding_add_PKCS1_type_2(unsigned char *to, int tlen,
unsigned char *f, int fl);
int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
unsigned char *f, int fl, int rsa_len);
int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
unsigned char *f, int fl, unsigned char *p, int pl);
int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
unsigned char *f, int fl, int rsa_len, unsigned char *p, int pl);
int RSA_padding_add_SSLv23(unsigned char *to, int tlen,
unsigned char *f, int fl);
int RSA_padding_check_SSLv23(unsigned char *to, int tlen,
unsigned char *f, int fl, int rsa_len);
int RSA_padding_add_none(unsigned char *to, int tlen,
unsigned char *f, int fl);
int RSA_padding_check_none(unsigned char *to, int tlen,
unsigned char *f, int fl, int rsa_len);
DESCRIPTION
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
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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
SSLv23
PKCS #1 EME-PKCS1-v1_5 with SSL-specific modification
none
simply copy the data
The random number generator must be seeded prior to calling
RSA_padding_add_xxx().
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.
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).
WARNING
The RSA_padding_check_PKCS1_type_2() padding check leaks
timing 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. Otherwise it can be recommended to pass
zero-padded f, so that fl equals to rsa_len, and if fixed by
protocol, tlen being set to the expected length. In such
case leakage would be minimal, it would take attacker's
ability to observe memory access pattern with byte
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RSA_padding_add_PKCS1_type_1(3OpenSSRSA_padding_add_PKCS1_type_1(3)
granilarity as it occurs, post-factum timing analysis won't
do.
SEE ALSO
RSA_public_encrypt(3), RSA_private_decrypt(3), RSA_sign(3),
RSA_verify(3)
HISTORY
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_SSLv23(),
RSA_padding_check_SSLv23(), RSA_padding_add_none() and
RSA_padding_check_none() appeared in SSLeay 0.9.0.
RSA_padding_add_PKCS1_OAEP() and
RSA_padding_check_PKCS1_OAEP() were added in OpenSSL 0.9.2b.
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