introducing RSA-OAEP (can encrypt one message correctly)

[arm-crypto-lib.git] / bigint / bigint.c

diff --git a/bigint/bigint.c b/bigint/bigint.c
index 22bad1b2b3d750f2a6ceef281228c9c7df4afeb1..c1a82ab496689b854541fda034ca1a268cfcb9d4 100644 (file)
--- a/bigint/bigint.c
+++ b/bigint/bigint.c
@@ -81,6 +81,21 @@ void bigint_adjust(bigint_t* a){
 
 /******************************************************************************/
 
+uint16_t bigint_length_b(bigint_t* a){
+       if(!a->length_B || a->length_B==0){
+               return 0;
+       }
+       return (a->length_B-1) * BIGINT_WORD_SIZE + GET_FBS(a);
+}
+
+/******************************************************************************/
+
+uint16_t bigint_length_B(bigint_t* a){
+       return (bigint_length_b(a)+7)/8;
+}
+
+/******************************************************************************/
+
 uint32_t bigint_get_first_set_bit(bigint_t* a){
        if(a->length_B==0){
                return (uint32_t)(-1);
@@ -671,6 +686,9 @@ void bigint_reduce(bigint_t* a, const bigint_t* r){
        uint16_t shift;
        while(a->length_B > r->length_B){
                shift = (a->length_B - r->length_B) * 8 * sizeof(bigint_word_t) + GET_FBS(a) - rfbs - 1;
+               if(a->wordv[a->length_B-1] > r->wordv[r->length_B-1]){
+                       shift += 1;
+               }
 //             cli_putstr("\r\nDBG: (p) shift = "); cli_hexdump_rev(&shift, 2);
 //             cli_putstr(" a_len = "); cli_hexdump_rev(&a->length_B, 2);
 //             cli_putstr(" r_len = "); cli_hexdump_rev(&r->length_B, 2);