143 lines
3.8 KiB
C
143 lines
3.8 KiB
C
/* rsa_pkcs1v15.c */
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/*
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This file is part of the ARM-Crypto-Lib.
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Copyright (C) 2006-2011 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 "bigint.h"
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#include "rsa_basic.h"
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#define DEBUG 0
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#if DEBUG
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#include "bigint_io.h"
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#include "cli.h"
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#endif
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#include "random_dummy.h"
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uint16_t rsa_pkcs1v15_compute_padlength_B(const bigint_t* modulus, uint16_t msg_length_B){
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return bigint_get_first_set_bit(modulus) / 8 + 1 - msg_length_B - 3;
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}
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uint8_t rsa_encrypt_pkcs1v15(void* dest, uint16_t* out_length, const void* src,
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uint16_t length_B, const rsa_publickey_t* key, const void* pad){
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int16_t pad_length;
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bigint_t x;
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pad_length = rsa_pkcs1v15_compute_padlength_B(&key->modulus, length_B);
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if(pad_length<8){
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#if DEBUG
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cli_putstr("\r\nERROR: pad_length<8; pad_length: ");
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cli_hexdump_rev(&pad_length, 2);
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#endif
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return 2; /* message to long */
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}
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if(!pad){
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#if DEBUG
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cli_putstr("\r\nauto-generating pad ...");
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#endif
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uint16_t i;
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uint8_t c;
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for(i=0; i<pad_length; ++i){
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do{
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c = prng_get_byte();
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}while(c==0);
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((uint8_t*)dest)[i+2] = c;
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}
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}else{
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#if DEBUG
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cli_putstr("\r\nsupplied pad: ");
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cli_hexdump_block(pad, pad_length, 4, 16);
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#endif
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memcpy((uint8_t*)dest + 2, pad, pad_length);
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}
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((uint8_t*)dest)[0] = 0x00;
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((uint8_t*)dest)[1] = 0x02;
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((uint8_t*)dest)[2+pad_length] = 0x00;
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memcpy((uint8_t*)dest+3+pad_length, src, length_B);
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x.wordv = dest;
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x.length_W = (length_B+pad_length+3+sizeof(bigint_word_t)-1)/sizeof(bigint_word_t);
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#if DEBUG
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cli_putstr("\r\nx-data: ");
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cli_hexdump_block(x.wordv, x.length_W * sizeof(bigint_word_t), 4, 16);
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#endif
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bigint_adjust(&x);
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rsa_os2ip(&x, NULL, length_B+pad_length+3);
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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_pkcs1v15(void* dest, uint16_t* out_length, const void* src,
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uint16_t length_B, const rsa_privatekey_t* key, void* pad){
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bigint_t x;
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uint16_t m_length, pad_length=0, idx=0;
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x.wordv = dest;
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rsa_os2ip(&x, src, length_B);
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#if DEBUG
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cli_putstr("\r\ncalling rsa_dec() ...");
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cli_putstr("\r\nencoded block (src.len = 0x");
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cli_hexdump_rev(&length_B, 2);
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cli_putstr("):");
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cli_hexdump_block(x.wordv, x.length_W * sizeof(bigint_word_t), 4, 16);
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#endif
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rsa_dec(&x, key);
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#if DEBUG
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cli_putstr("\r\nfinished rsa_dec() ...");
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#endif
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rsa_i2osp(NULL, &x, &m_length);
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#if DEBUG
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cli_putstr("\r\ndecoded block:");
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cli_hexdump_block(x.wordv, m_length, 4, 16);
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#endif
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while(((uint8_t*)x.wordv)[idx]==0 && idx<m_length){
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++idx;
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}
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if(idx>=m_length){
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return 1;
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}
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if(((uint8_t*)x.wordv)[idx]!=2){
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return 3;
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}
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++idx;
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while(((uint8_t*)x.wordv)[idx+pad_length]!=0 && (idx+pad_length)<m_length){
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++pad_length;
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}
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if(pad_length<8 || (idx+pad_length)>=m_length){
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return 2;
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}
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*out_length = m_length - idx - pad_length - 1;
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if(pad){
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#if DEBUG
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cli_putstr("\r\npadding block:");
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cli_hexdump_block(((uint8_t*)x.wordv)+idx, pad_length, 4, 16);
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cli_putstr("\r\npad @ 0x");
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cli_hexdump_rev(&pad, 2);
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cli_putstr("\r\ndst @ 0x");
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cli_hexdump_rev(&dest, 2);
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#endif
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memcpy(pad, ((uint8_t*)x.wordv)+idx, pad_length);
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}
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memmove(dest, ((uint8_t*)x.wordv) + idx + pad_length + 1, m_length - idx - pad_length - 1);
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return 0;
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}
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