Commit f1006f18 authored by Bernd Edlinger's avatar Bernd Edlinger
Browse files

Update documentation of RSA_padding_check_PKCS1_OAEP_mgf1 



Reviewed-by: default avatarKurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/8365)

(cherry picked from commit f0e4a860)
parent 930e0310

doc/man3/RSA_padding_add_PKCS1_type_1.pod

+41 −19
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
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_SSLv23, RSA_padding_check_SSLv23,

RSA_padding_add_none, RSA_padding_check_none - asymmetric encryption

padding
@@ -14,35 +15,46 @@ padding 
 #include <openssl/rsa.h>



 int RSA_padding_add_PKCS1_type_1(unsigned char *to, int tlen,

                                  unsigned char *f, int fl);

                                  const 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);

                                    const 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);

                                  const 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);

                                    const 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);

                                const unsigned char *f, int fl,

                                const 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);

                                  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_SSLv23(unsigned char *to, int tlen,

                            unsigned char *f, int fl);

                            const unsigned char *f, int fl);



 int RSA_padding_check_SSLv23(unsigned char *to, int tlen,

                              unsigned char *f, int fl, int rsa_len);

                              const unsigned char *f, int fl, int rsa_len);



 int RSA_padding_add_none(unsigned char *to, int tlen,

                          unsigned char *f, int fl);

                          const unsigned char *f, int fl);



 int RSA_padding_check_none(unsigned char *to, int tlen,

                            unsigned char *f, int fl, int rsa_len);

                            const unsigned char *f, int fl, int rsa_len);



=head1 DESCRIPTION
@@ -98,6 +110,10 @@ at B<to>. 
For RSA_padding_xxx_OAEP(), B<p> points to the encoding parameter

of length B<pl>. B<p> may be B<NULL> if B<pl> is 0.



For RSA_padding_xxx_OAEP_mgf1(), B<md> points to the md hash,

if B<md> is B<NULL> that means md=sha1, and B<mgf1md> points to

the mgf1 hash, if B<mgf1md> is B<NULL> that means mgf1md=md.



=head1 RETURN VALUES



The RSA_padding_add_xxx() functions return 1 on success, 0 on error.
@@ -107,15 +123,21 @@ L<ERR_get_error(3)>. 


=head1 WARNING



The RSA_padding_check_PKCS1_type_2() padding check leaks timing

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. Otherwise it can

be recommended to pass zero-padded B<f>, so that B<fl> equals to

B<rsa_len>, and if fixed by protocol, B<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

granilarity as it occurs, post-factum timing analysis won't do.

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 B<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.



=head1 SEE ALSO
@@ -125,7 +147,7 @@ L<RSA_sign(3)>, L<RSA_verify(3)> 


=head1 COPYRIGHT



Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.



Licensed under the OpenSSL license (the "License").  You may not use

this file except in compliance with the License.  You can obtain a copy