openssl/crypto/rsa/rsa_x931.c
Tomas Mraz 7ed6de997f Copyright year updates
Reviewed-by: Neil Horman <nhorman@openssl.org>
Release: yes
2024-09-05 09:35:49 +02:00

149 lines
3.7 KiB
C

/*
* Copyright 2005-2024 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
*/
/*
* RSA low level APIs are deprecated for public use, but still ok for
* internal use.
*/
#include "internal/deprecated.h"
#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/objects.h>
/*
* X9.31 Embeds the hash inside the following data structure
*
* header (4 bits = 0x6)
* padding (consisting of zero or more 4 bit values of a sequence of 0xB,
* ending with the terminator 0xA)
* hash(Msg) hash of a message (the output size is related to the hash function)
* trailer (consists of 2 bytes)
* The 1st byte is related to a part number for a hash algorithm
* (See RSA_X931_hash_id()), followed by the fixed value 0xCC
*
* The RSA modulus size n (which for X9.31 is 1024 + 256*s) is the size of the data
* structure, which determines the padding size.
* i.e. len(padding) = n - len(header) - len(hash) - len(trailer)
*
* Params:
* to The output buffer to write the data structure to.
* tolen The size of 'to' in bytes (it is the size of the n)
* from The input hash followed by the 1st byte of the trailer.
* flen The size of the input hash + 1 (trailer byte)
*/
int RSA_padding_add_X931(unsigned char *to, int tlen,
const unsigned char *from, int flen)
{
int j;
unsigned char *p;
/*
* We need at least 1 byte for header + padding (0x6A)
* And 2 trailer bytes (but we subtract 1 since flen includes 1 trailer byte)
*/
j = tlen - flen - 2;
if (j < 0) {
ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
return -1;
}
p = (unsigned char *)to;
/* If no padding start and end nibbles are in one byte */
if (j == 0) {
*p++ = 0x6A;
} else {
*p++ = 0x6B;
if (j > 1) {
memset(p, 0xBB, j - 1);
p += j - 1;
}
*p++ = 0xBA;
}
memcpy(p, from, (unsigned int)flen);
p += flen;
*p = 0xCC;
return 1;
}
int RSA_padding_check_X931(unsigned char *to, int tlen,
const unsigned char *from, int flen, int num)
{
int i = 0, j;
const unsigned char *p;
p = from;
if ((num != flen) || ((*p != 0x6A) && (*p != 0x6B))) {
ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_HEADER);
return -1;
}
if (*p++ == 0x6B) {
j = flen - 3;
for (i = 0; i < j; i++) {
unsigned char c = *p++;
if (c == 0xBA)
break;
if (c != 0xBB) {
ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_PADDING);
return -1;
}
}
j -= i;
if (i == 0) {
ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_PADDING);
return -1;
}
} else {
j = flen - 2;
}
if (p[j] != 0xCC) {
ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_TRAILER);
return -1;
}
memcpy(to, p, (unsigned int)j);
return j;
}
/*
* Translate between X9.31 hash ids and NIDs
* The returned values relate to ISO/IEC 10118 part numbers which consist of
* a hash algorithm and hash number. The returned values are used as the
* first byte of the 'trailer'.
*/
int RSA_X931_hash_id(int nid)
{
switch (nid) {
case NID_sha1:
return 0x33;
case NID_sha256:
return 0x34;
case NID_sha384:
return 0x36;
case NID_sha512:
return 0x35;
}
return -1;
}