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

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

diff --git a/rsa/rsa_basic.c b/rsa/rsa_basic.c
new file mode 100644 (file)
index 0000000..3e536b8
--- /dev/null
+++ b/rsa/rsa_basic.c
@@ -0,0 +1,77 @@
+/* rsa_basic.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 "cli.h"
+
+void rsa_enc(bigint_t* data, rsa_publickey_t* key){
+       bigint_expmod_u(data, data, key->exponent, key->modulus);
+}
+
+void rsa_dec(bigint_t* data, rsa_privatekey_t* key){
+       bigint_expmod_u(data, data, key->exponent, key->modulus);
+}
+
+void rsa_os2ip(bigint_t* dest, const void* data, uint32_t length_B){
+       uint8_t off;
+       off = length_B % sizeof(bigint_word_t);
+       if(!data){
+               if(off){
+                       dest->wordv = realloc(dest->wordv, length_B + sizeof(bigint_word_t) - off);
+                       memmove((uint8_t*)dest->wordv+off, dest->wordv, length_B);
+                       memset(dest->wordv, 0, off);
+               }
+       }else{
+               if(off){
+                       memcpy((uint8_t*)dest->wordv + off, data, length_B);
+                       memset(dest, 0, off);
+               }else{
+                       memcpy(dest->wordv, data, length_B);
+               }
+       }
+       dest->length_B = (length_B + sizeof(bigint_word_t) - 1) / sizeof(bigint_word_t);
+       bigint_changeendianess(dest);
+       bigint_adjust(dest);
+}
+
+void rsa_i2osp(void* dest, bigint_t* src, uint16_t* out_length_B){
+       *out_length_B = bigint_get_first_set_bit(src) / 8 + 1;
+       if(dest){
+               uint16_t i;
+               for(i=*out_length_B; i>0; --i){
+                       *((uint8_t*)dest) = ((uint8_t*)src->wordv)[i-1];
+                       dest = (uint8_t*)dest + 1;
+               }
+       }else{
+               uint8_t off;
+               bigint_changeendianess(src);
+               bigint_adjust(src);
+
+               off = bigint_get_last_set_bit(src)/8;
+               if(off){
+                       memmove(src->wordv, (uint8_t*)src->wordv+off, *out_length_B);
+               }
+       }
+}
+