230 lines
6.3 KiB
C
230 lines
6.3 KiB
C
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/* rsa_oaep.c */
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/*
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This file is part of the ARM-Crypto-Lib.
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Copyright (C) 2006-2012 Daniel Otte (daniel.otte@rub.de)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include "memxor.h"
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#include "mgf1.h"
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#include "bigint.h"
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#include "rsa_basic.h"
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#include "rsa_oaep.h"
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#include "random_dummy.h"
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#include "hfal/hfal_sha1.h"
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#include "cli.h"
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#include "uart_lowlevel.h"
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mgf1_parameter_t mgf1_default_parameter = {
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&sha1_desc
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};
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rsa_oaep_parameter_t rsa_oaep_default_parameter = {
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mgf1,
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&sha1_desc,
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&mgf1_default_parameter
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};
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rsa_label_t rsa_oaep_default_label = {
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0, NULL
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};
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uint8_t rsa_encrypt_oaep(void* dest, uint16_t* out_length,
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const void* src, uint16_t length_B,
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rsa_publickey_t* key, const rsa_oaep_parameter_t *p,
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const rsa_label_t* label, const void* seed){
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if(!p){
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p = &rsa_oaep_default_parameter;
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}
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if(!label){
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label = &rsa_oaep_default_label;
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}
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uint16_t hv_len = (hfal_hash_getHashsize(p->hf)+7)/8;
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if(length_B > bigint_length_B(key->modulus) - 2*hv_len - 2){
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/* message too long */
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return 1;
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}
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uint16_t buffer_len = bigint_length_B(key->modulus);
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/*
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cli_putstr("\r\n buffer_len = ");
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cli_hexdump_rev(&buffer_len, 2);
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cli_putstr("\r\n modulus_len = ");
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cli_hexdump_rev(&key->modulus->length_B, 2);
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*/
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uint8_t* buffer = (uint8_t*)dest;
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uint8_t off;
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/* the following needs some explanation:
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* off is the offset which is used for compensating the effect of
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* changeendian() when it operates on multi-byte words.
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* */
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off = (sizeof(bigint_word_t) -(bigint_get_first_set_bit(key->modulus)/8+1)%(sizeof(bigint_word_t)*8))
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% (sizeof(bigint_word_t));
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buffer += off;
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buffer_len -= off;
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// cli_putstr("\r\n off = ");
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// cli_hexdump_byte(off);
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uint8_t* seed_buffer = buffer + 1;
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uint16_t db_len = buffer_len - hv_len - 1;
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uint8_t* db = seed_buffer + hv_len;
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uint16_t maskbuffer_len = db_len>hv_len?db_len:hv_len;
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uint8_t maskbuffer[maskbuffer_len];
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bigint_t x;
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memset(dest, 0, seed_buffer - buffer + off);
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memset(db + hv_len, 0, db_len - hv_len - length_B -1);
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hfal_hash_mem(p->hf, db, label->label, label->length_b);
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db[db_len - length_B - 1] = 0x01;
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memcpy(db+db_len - length_B, src, length_B);
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if(seed){
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memcpy(seed_buffer, seed, hv_len);
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}else{
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/* generate random seed */
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if(!prng_get_byte){
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return 2; /* ERROR: no random generator specified */
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}
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uint16_t i;
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for(i=0; i<hv_len; ++i){
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seed_buffer[i] = prng_get_byte();
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}
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}
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// cli_putstr("\r\n msg (raw, pre-feistel):\r\n");
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// cli_hexdump_block(dest, bigint_length_B(key->modulus), 4, 16);
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p->mgf(maskbuffer, seed_buffer, hv_len, db_len, p->mgf_parameter);
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memxor(db, maskbuffer, db_len);
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p->mgf(maskbuffer, db, db_len, hv_len, p->mgf_parameter);
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memxor(seed_buffer, maskbuffer, hv_len);
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// cli_putstr("\r\n msg (raw, post-feistel):\r\n");
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// cli_hexdump_block(dest, bigint_length_B(key->modulus), 4, 16);
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x.wordv = dest;
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x.length_B = key->modulus->length_B;
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bigint_adjust(&x);
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rsa_os2ip(&x, NULL, bigint_length_B(key->modulus));
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rsa_enc(&x, key);
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rsa_i2osp(NULL, &x, out_length);
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return 0;
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}
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uint8_t rsa_decrypt_oaep(void* dest, uint16_t* out_length,
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const void* src, uint16_t length_B,
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rsa_privatekey_t* key, const rsa_oaep_parameter_t *p,
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const rsa_label_t* label, void* seed){
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// cli_putstr("\r\n -->rsa_decrypt_oaep()"); uart_flush(0);
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if(!label){
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label = &rsa_oaep_default_label;
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}
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if(!p){
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p = &rsa_oaep_default_parameter;
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}
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uint16_t x_len, data_len;
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bigint_t x;
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uint16_t hv_len = hfal_hash_getHashsize(p->hf)/8;
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uint8_t label_hv[hv_len];
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uint16_t msg_len = bigint_get_first_set_bit(key->modulus) / 8 + 1;
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uint16_t db_len = msg_len - hv_len - 1;
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uint8_t maskbuffer[db_len>hv_len?db_len:hv_len];
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uint8_t *seed_buffer = dest;
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uint8_t *db_buffer = seed_buffer + hv_len;
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x_len = bigint_get_first_set_bit(key->modulus)/8;
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memset(dest, 0, bigint_length_B(key->modulus) - length_B);
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memcpy((uint8_t*)dest + bigint_length_B(key->modulus) - length_B, src, length_B);
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// cli_putc('a'); uart_flush(0);
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x.wordv = dest;
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x.length_B = key->modulus->length_B;
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x.info = 0;
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bigint_adjust(&x);
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// cli_putc('b'); uart_flush(0);
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rsa_os2ip(&x, NULL, bigint_length_B(key->modulus));
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// cli_putc('c'); uart_flush(0);
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rsa_dec(&x, key);
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// cli_putc('d'); uart_flush(0);
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rsa_i2osp(NULL, &x, &data_len);
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// cli_putstr("\r\n msg (raw, pre-move):\r\n");
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// cli_hexdump_block(dest, bigint_length_B(key->modulus), 4, 16);
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if(data_len > x_len){
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return 7;
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}
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/*
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cli_putstr("\r\n moving some bytes; x_len = ");
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cli_hexdump_rev(&x_len, 2);
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cli_putstr(" data_len = ");
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cli_hexdump_rev(&data_len, 2);
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uart_flush(0);
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*/
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if(x_len != data_len){
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memmove((uint8_t*)dest + x_len - data_len, dest, data_len);
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// cli_putstr(" (oh, not dead yet?!)");
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// uart_flush(0);
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memset(dest, 0, x_len - data_len);
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}
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hfal_hash_mem(p->hf, label_hv, label->label, label->length_b);
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/*
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cli_putstr("\r\n msg (raw, pre-feistel):\r\n");
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cli_hexdump_block(seed_buffer, bigint_length_B(key->modulus), 4, 16);
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uart_flush(0);
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*/
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p->mgf(maskbuffer, db_buffer, db_len, hv_len, p->mgf_parameter);
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memxor(seed_buffer, maskbuffer, hv_len);
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p->mgf(maskbuffer, seed_buffer, hv_len, db_len, p->mgf_parameter);
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memxor(db_buffer, maskbuffer, db_len);
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if(memcmp(label_hv, db_buffer, hv_len)){
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// cli_putstr("\r\nDBG: DB:\r\n");
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// cli_hexdump_block(db_buffer, db_len, 4, 16);
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return 2;
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}
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uint16_t ps_len=0;
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while(db_buffer[hv_len + ps_len++] == 0)
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;
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--ps_len;
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if(db_buffer[hv_len + ps_len] != 1){
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return 3;
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}
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if(seed){
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memcpy(seed, seed_buffer, hv_len);
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}
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msg_len = db_len - hv_len - 1 - ps_len;
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memmove(dest, db_buffer + hv_len + ps_len + 1, msg_len);
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*out_length = msg_len;
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return 0;
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}
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