[keccak-asm] improving last block handling (reducing stack space)

diff --git a/keccak/keccak-stub.c b/keccak/keccak-stub.c
index 886e2d199716cf391cae2aa2aab209270493c481..8447703dd18a7c61a6ef7e05773b83b191489bc3 100644 (file)
--- a/keccak/keccak-stub.c
+++ b/keccak/keccak-stub.c
@@ -93,9 +93,6 @@ void keccak_lastBlock(keccak_ctx_t* ctx, const void* block, uint16_t length_b){
                block = (uint8_t*)block + ctx->bs;
                length_b -=  ctx->r;
        }
-//     uint8_t tmp[ctx->bs];
-       uint8_t pad[3];
-//     memset(tmp, 0x00, ctx->bs);
        memxor(ctx->a, block, (length_b)/8);
        /* appand 1 */
        if(length_b & 7){
@@ -107,19 +104,19 @@ void keccak_lastBlock(keccak_ctx_t* ctx, const void* block, uint16_t length_b){
        }else{
            ((uint8_t*)ctx->a)[length_b / 8] ^= 0x01;
        }
-       pad[0] = ctx->d;
-       pad[1] = ctx->bs;
-       pad[2] = 0x01;
        if(length_b / 8 + 1 + 3 <= ctx->bs){
-               memxor((uint8_t*)ctx->a + length_b / 8 + 1, pad, 3);
+        *((uint8_t*)ctx->a + length_b / 8 + 1) ^= ctx->d;
+        *((uint8_t*)ctx->a + length_b / 8 + 2) ^= ctx->bs;
+        *((uint8_t*)ctx->a + length_b / 8 + 3) ^= 1;
        }else{
                if(length_b / 8 + 1 + 2 <= ctx->bs){
-                       memxor((uint8_t*)ctx->a + length_b / 8 + 1, pad, 2);
+            *((uint8_t*)ctx->a + length_b / 8 + 1) ^= ctx->d;
+            *((uint8_t*)ctx->a + length_b / 8 + 2) ^= ctx->bs;
                        keccak_f1600(ctx->a);
                        ((uint8_t*)ctx->a)[0] ^= 0x01;
                }else{
                        if(length_b/8+1+1 <= ctx->bs){
-                               memxor((uint8_t*)ctx->a + length_b / 8 + 1, pad, 1);
+                               *((uint8_t*)ctx->a + length_b / 8 + 1) ^= ctx->d;
                                keccak_f1600(ctx->a);
                                ((uint8_t*)ctx->a)[0] ^= ctx->bs;
                                ((uint8_t*)ctx->a)[1] ^= 0x01;