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/*
* Pidgin-Encryption OAEP padding routines, from PKCS#1 v2.1
*
* Copyright (C) 2003 William Tompkins
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <pk11func.h>
#include <keyhi.h>
/* for g_assert; PORT_Assert seems disabled... */
#include <glib.h>
#include "nss_mgf1.h"
#include "nss_oaep.h"
static const unsigned char SHA1_NullHash[20] = {0xda, 0x39, 0xa3, 0xee,
0x5e, 0x6b, 0x4b, 0x0d,
0x32, 0x55, 0xbf, 0xef,
0x95, 0x60, 0x18, 0x90,
0xaf, 0xd8, 0x07, 0x09};
static const unsigned int hlen = 20; /* SHA1 hash length */
int oaep_pad_block(unsigned char* padded_data, unsigned int padded_len,
const unsigned char* data, unsigned int data_len) {
unsigned char* seed_pos = padded_data + 1;
unsigned char* db_pos = seed_pos + hlen;
unsigned char* lhash_pos = db_pos;
unsigned char* ps_pos = lhash_pos + hlen;
unsigned char* msg_pos = padded_data + padded_len - data_len;
unsigned char* padded_end = padded_data + padded_len; /* one AFTER end */
int ps_len = msg_pos - ps_pos;
SECStatus rv;
*padded_data = 0;
/* fill seed_pos with hlen random bytes */
rv = PK11_GenerateRandom(seed_pos, hlen);
g_assert(rv == SECSuccess);
/* fill lhash_pos with sha-1 constant => empty label*/
PORT_Memcpy(lhash_pos, SHA1_NullHash, hlen);
/* fill ps with 00 00 00 ... 00 01 */
if (ps_len < 1) return 0;
PORT_Memset(ps_pos, 0, ps_len - 1);
ps_pos[ps_len - 1] = 1;
/* fill msg_pos with data */
PORT_Memcpy(msg_pos, data, data_len);
/* Do the masking */
mgf1(db_pos, padded_end - db_pos, seed_pos, hlen);
mgf1(seed_pos, hlen, db_pos, padded_end - db_pos);
return 1;
}
int oaep_unpad_block(unsigned char* unpadded_data, unsigned int * unpadded_len,
unsigned char* orig_padded_data, unsigned padded_len) {
unsigned char* padded_data = PORT_Alloc(padded_len);
unsigned char* seed_pos = padded_data + 1;
unsigned char* db_pos = seed_pos + hlen;
unsigned char* lhash_pos = db_pos;
unsigned char* ps_pos = lhash_pos + hlen;
unsigned char* padded_end = padded_data + padded_len;
unsigned char* msg_pos;
PORT_Memcpy(padded_data, orig_padded_data, padded_len);
*unpadded_len = 0;
mgf1(seed_pos, hlen, db_pos, padded_len - (db_pos - padded_data));
mgf1(db_pos, padded_len - (db_pos - padded_data),
seed_pos, hlen);
if ((PORT_Memcmp(lhash_pos, SHA1_NullHash, hlen) != 0) ||
(*padded_data != 0)) {
PORT_ZFree(padded_data, padded_len);
return 0;
}
msg_pos = ps_pos;
while ((msg_pos < padded_end) && (*msg_pos == 0)) {
++msg_pos;
}
if ((msg_pos == padded_end) || (*msg_pos != 1)) {
PORT_ZFree(padded_data, padded_len);
return 0;
}
msg_pos++;
*unpadded_len = padded_len + padded_data - msg_pos;
PORT_Memcpy(unpadded_data, msg_pos, *unpadded_len);
PORT_ZFree(padded_data, padded_len);
return 1;
}
unsigned int oaep_max_unpadded_len(unsigned int padded_len) {
int extrastuff = 2 *hlen + 2;
if (padded_len < extrastuff) return 0;
return padded_len - extrastuff;
}
void oaep_test() {
int mod_size = 512/8;
unsigned char data[4096/8];
unsigned char pad_data[4096/8];
int data_size;
unsigned char data_out[4096/8];
unsigned int data_out_len;
SECStatus rv;
/* overkill, but what the hey. */
while (mod_size <= 4096/8) {
rv = PK11_GenerateRandom(data, oaep_max_unpadded_len(mod_size));
g_assert(rv == SECSuccess);
for (data_size = 0; data_size <= oaep_max_unpadded_len(mod_size); ++data_size) {
g_assert( oaep_pad_block(pad_data, mod_size, data, data_size) );
g_assert( oaep_unpad_block(data_out, &data_out_len, pad_data, mod_size) );
g_assert( memcmp(data_out, data, data_size) == 0);
g_assert( data_size == data_out_len);
}
mod_size *= 2;
}
}
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