5 RSA_padding_add_PKCS1_type_1, RSA_padding_check_PKCS1_type_1,
6 RSA_padding_add_PKCS1_type_2, RSA_padding_check_PKCS1_type_2,
7 RSA_padding_add_PKCS1_OAEP, RSA_padding_check_PKCS1_OAEP,
8 RSA_padding_add_PKCS1_OAEP_mgf1, RSA_padding_check_PKCS1_OAEP_mgf1,
9 RSA_padding_add_SSLv23, RSA_padding_check_SSLv23,
10 RSA_padding_add_none, RSA_padding_check_none - asymmetric encryption
15 #include <openssl/rsa.h>
17 int RSA_padding_add_PKCS1_type_1(unsigned char *to, int tlen,
18 const unsigned char *f, int fl);
20 int RSA_padding_check_PKCS1_type_1(unsigned char *to, int tlen,
21 const unsigned char *f, int fl, int rsa_len);
23 int RSA_padding_add_PKCS1_type_2(unsigned char *to, int tlen,
24 const unsigned char *f, int fl);
26 int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
27 const unsigned char *f, int fl, int rsa_len);
29 int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
30 const unsigned char *f, int fl,
31 const unsigned char *p, int pl);
33 int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
34 const unsigned char *f, int fl, int rsa_len,
35 const unsigned char *p, int pl);
37 int RSA_padding_add_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
38 const unsigned char *f, int fl,
39 const unsigned char *p, int pl,
40 const EVP_MD *md, const EVP_MD *mgf1md);
42 int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
43 const unsigned char *f, int fl, int rsa_len,
44 const unsigned char *p, int pl,
45 const EVP_MD *md, const EVP_MD *mgf1md);
47 int RSA_padding_add_SSLv23(unsigned char *to, int tlen,
48 const unsigned char *f, int fl);
50 int RSA_padding_check_SSLv23(unsigned char *to, int tlen,
51 const unsigned char *f, int fl, int rsa_len);
53 int RSA_padding_add_none(unsigned char *to, int tlen,
54 const unsigned char *f, int fl);
56 int RSA_padding_check_none(unsigned char *to, int tlen,
57 const unsigned char *f, int fl, int rsa_len);
61 The RSA_padding_xxx_xxx() functions are called from the RSA encrypt,
62 decrypt, sign and verify functions. Normally they should not be called
63 from application programs.
65 However, they can also be called directly to implement padding for other
66 asymmetric ciphers. RSA_padding_add_PKCS1_OAEP() and
67 RSA_padding_check_PKCS1_OAEP() may be used in an application combined
68 with B<RSA_NO_PADDING> in order to implement OAEP with an encoding
71 RSA_padding_add_xxx() encodes B<fl> bytes from B<f> so as to fit into
72 B<tlen> bytes and stores the result at B<to>. An error occurs if B<fl>
73 does not meet the size requirements of the encoding method.
75 The following encoding methods are implemented:
81 PKCS #1 v2.0 EMSA-PKCS1-v1_5 (PKCS #1 v1.5 block type 1); used for signatures
85 PKCS #1 v2.0 EME-PKCS1-v1_5 (PKCS #1 v1.5 block type 2)
93 PKCS #1 EME-PKCS1-v1_5 with SSL-specific modification
101 The random number generator must be seeded prior to calling
102 RSA_padding_add_xxx().
103 If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to
104 external circumstances (see L<RAND(7)>), the operation will fail.
106 RSA_padding_check_xxx() verifies that the B<fl> bytes at B<f> contain
107 a valid encoding for a B<rsa_len> byte RSA key in the respective
108 encoding method and stores the recovered data of at most B<tlen> bytes
109 (for B<RSA_NO_PADDING>: of size B<tlen>)
112 For RSA_padding_xxx_OAEP(), B<p> points to the encoding parameter
113 of length B<pl>. B<p> may be B<NULL> if B<pl> is 0.
115 For RSA_padding_xxx_OAEP_mgf1(), B<md> points to the md hash,
116 if B<md> is B<NULL> that means md=sha1, and B<mgf1md> points to
117 the mgf1 hash, if B<mgf1md> is B<NULL> that means mgf1md=md.
121 The RSA_padding_add_xxx() functions return 1 on success, 0 on error.
122 The RSA_padding_check_xxx() functions return the length of the
123 recovered data, -1 on error. Error codes can be obtained by calling
128 The result of RSA_padding_check_PKCS1_type_2() is a very sensitive
129 information which can potentially be used to mount a Bleichenbacher
130 padding oracle attack. This is an inherent weakness in the PKCS #1
131 v1.5 padding design. Prefer PKCS1_OAEP padding. If that is not
132 possible, the result of RSA_padding_check_PKCS1_type_2() should be
133 checked in constant time if it matches the expected length of the
134 plaintext and additionally some application specific consistency
135 checks on the plaintext need to be performed in constant time.
136 If the plaintext is rejected it must be kept secret which of the
137 checks caused the application to reject the message.
138 Do not remove the zero-padding from the decrypted raw RSA data
139 which was computed by RSA_private_decrypt() with B<RSA_NO_PADDING>,
140 as this would create a small timing side channel which could be
141 used to mount a Bleichenbacher attack against any padding mode
142 including PKCS1_OAEP.
146 L<RSA_public_encrypt(3)>,
147 L<RSA_private_decrypt(3)>,
148 L<RSA_sign(3)>, L<RSA_verify(3)>,
153 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
155 Licensed under the Apache License 2.0 (the "License"). You may not use
156 this file except in compliance with the License. You can obtain a copy
157 in the file LICENSE in the source distribution or at
158 L<https://www.openssl.org/source/license.html>.