Update documentation of RSA_padding_check_PKCS1_OAEP_mgf1

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

diff --git a/doc/man3/RSA_padding_add_PKCS1_type_1.pod b/doc/man3/RSA_padding_add_PKCS1_type_1.pod
index 49340f1399b80aa173c18b6b2a653ae238055ed5..685063b2e0b2f2af9be99477d4b83f6e5b184071 100644 (file)
--- a/doc/man3/RSA_padding_add_PKCS1_type_1.pod
+++ b/doc/man3/RSA_padding_add_PKCS1_type_1.pod
@@ -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 Apache License 2.0 (the "License").  You may not use
 this file except in compliance with the License.  You can obtain a copy