first idea of RSA (PKCS#1 v1.5)

[arm-crypto-lib.git] / rsa / rsa_pkcs15.c

diff --git a/rsa/rsa_pkcs15.c b/rsa/rsa_pkcs15.c
new file mode 100644 (file)
index 0000000..781c9ba
--- /dev/null
+++ b/rsa/rsa_pkcs15.c
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+/* rsa_pkcs15.c */
+/*
+    This file is part of the ARM-Crypto-Lib.
+    Copyright (C) 2006-2011 Daniel Otte (daniel.otte@rub.de)
+
+    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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include "bigint.h"
+#include "rsa_basic.h"
+
+#include "bigint_io.h"
+#include "cli.h"
+
+#include "random_dummy.h"
+
+uint8_t rsa_encrypt_pkcs15(void* dest, uint16_t* out_length, const void* src,
+       uint16_t length_B, rsa_publickey_t* key, const void* pad){
+       int16_t pad_length;
+       bigint_t x;
+       pad_length = (bigint_get_first_set_bit(key->modulus) + 7) / 8 - length_B - 3;
+       if(pad_length<8){
+               cli_putstr("\r\nERROR: pad_length<8; pad_length: ");
+               cli_hexdump_rev(&pad_length, 2);
+               return 2; /* message to long */
+       }
+       if(!pad){
+               uint16_t i;
+               uint8_t c;
+               for(i=0; i<pad_length; ++i){
+                       do{
+                               c = prng_get_byte();
+                       }while(c==0);
+                       ((uint8_t*)dest)[i+2] = c;
+               }
+       }else{
+               memcpy((uint8_t*)dest + 2, pad, pad_length);
+       }
+       ((uint8_t*)dest)[0] = 0x00;
+       ((uint8_t*)dest)[1] = 0x02;
+       ((uint8_t*)dest)[2+pad_length] = 0x00;
+       memcpy((uint8_t*)dest+3+pad_length, src, length_B);
+       x.wordv = dest;
+       x.length_B = (length_B+pad_length+3+sizeof(bigint_word_t)-1)/sizeof(bigint_word_t);
+       bigint_adjust(&x);
+       rsa_os2ip(&x, NULL, length_B+pad_length+3);
+       rsa_enc(&x, key);
+       rsa_i2osp(NULL, &x, out_length);
+       return 0;
+}
+
+uint8_t rsa_decrypt_pkcs15(void* dest, uint16_t* out_length, const void* src,
+       uint16_t length_B, rsa_privatekey_t* key, void* pad){
+       bigint_t x;
+       uint16_t m_length, pad_length=0, idx=0;
+       x.wordv = dest;
+       rsa_os2ip(&x, src, length_B);
+       rsa_dec(&x, key);
+       rsa_i2osp(NULL, &x, &m_length);
+       while(((uint8_t*)x.wordv)[idx]==0 && idx<m_length){
+               ++idx;
+       }
+       if(((uint8_t*)x.wordv)[idx]!=2 || idx>=m_length){
+               return 1;
+       }
+       ++idx;
+       while(((uint8_t*)x.wordv)[idx+pad_length]!=0  && (idx+pad_length)<m_length){
+               ++pad_length;
+       }
+       if(pad_length<8 || (idx+pad_length)>=m_length){
+               return 2;
+       }
+       *out_length = m_length - idx - pad_length - 1;
+       memcpy(dest, ((uint8_t*)x.wordv) + idx + pad_length + 1, m_length - idx - pad_length - 1);
+       if(pad){
+               memcpy(pad, ((uint8_t*)x.wordv)+idx, pad_length);
+       }
+       return 0;
+}
+