Fix libsha2_digest + minor improvements

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 39 insertions, 28 deletions

diff --git a/digest.c b/digest.c
index bcd318f..c15e2fa 100644
--- a/digest.c
+++ b/digest.c
@@ -13,8 +13,7 @@
 void
 libsha2_digest(struct libsha2_state *restrict state, const char *restrict message, size_t msglen, char *output)
 {
-	char *appendix;
-	size_t i, j, k, n;
+	size_t off, i, n;
 
 	if (msglen & ~(size_t)7) {
 		libsha2_update(state, message, msglen & ~(size_t)7);
@@ -22,40 +21,52 @@ libsha2_digest(struct libsha2_state *restrict state, const char *restrict messag
 		msglen &= (size_t)7;
 	}
 
-	k = 8 * state->chunk_size;
-	n = state->chunk_size + 8;
-	n = (k + (n % k)) % k;
-	n = n / 8 - 1;
-
-	appendix = state->appendix;
+	off = (state->message_size / 8) % state->chunk_size;
 	if (msglen) {
-		j = 7 - msglen;
-		*appendix = *message;
-		*appendix |= (char)(1 << j);
-		*appendix &= (char)~((1 << j) - 1);
+		state->chunk[off] = *message;
+		state->chunk[off] |= (char)(1 << (7 - msglen));
+		state->chunk[off] &= (char)~((1 << (7 - msglen)) - 1);
+		state->message_size += msglen;
 	} else {
-		*appendix = (char)128;
+		state->chunk[off] = 0x80;
 	}
+	off += 1;
 
-	k = state->message_size + msglen;
-	i = state->chunk_size / 8;
-	appendix += n + i - 1;
-	for (i = i < sizeof(size_t) ? i : sizeof(size_t); i--;)
-		*(appendix - i) = (char)((k >> (i * 8)) & 255);
+	if (off > state->chunk_size - 8 * (1 + (state->algorithm > LIBSHA2_256))) {
+		memset(state->chunk + off, 0, state->chunk_size - off);
+		off = 0;
+		libsha2_process(state, state->chunk);
+	}
 
-	n += state->chunk_size;
-	libsha2_update(state, state->appendix, n);
+	memset(state->chunk + off, 0, state->chunk_size - 8 - off);
+	state->chunk[state->chunk_size - 8] = (char)(state->message_size >> 56);
+	state->chunk[state->chunk_size - 7] = (char)(state->message_size >> 48);
+	state->chunk[state->chunk_size - 6] = (char)(state->message_size >> 40);
+	state->chunk[state->chunk_size - 5] = (char)(state->message_size >> 32);
+	state->chunk[state->chunk_size - 4] = (char)(state->message_size >> 24);
+	state->chunk[state->chunk_size - 3] = (char)(state->message_size >> 16);
+	state->chunk[state->chunk_size - 2] = (char)(state->message_size >>  8);
+	state->chunk[state->chunk_size - 1] = (char)(state->message_size >>  0);
+	libsha2_process(state, state->chunk);
 
 	n = libsha2_algorithm_output_size(state->algorithm);
 	if (state->algorithm <= LIBSHA2_256) {
-		for (i = 0; i < 8; i++)
-			for (j = 0; j < (state->chunk_size / 16); j++)
-				if (k = (i + 1) * (state->chunk_size / 16) - j - 1, k < n)
-					output[k] = (char)((state->h.b32[i] >> (8 * j)) & 255);
+		for (i = 0, n /= 4; i < n; i++) {
+			output[4 * i + 0] = (char)(state->h.b32[i] >> 24);
+			output[4 * i + 1] = (char)(state->h.b32[i] >> 16);
+			output[4 * i + 2] = (char)(state->h.b32[i] >>  8);
+			output[4 * i + 3] = (char)(state->h.b32[i] >>  0);
+		}
 	} else {
-		for (i = 0; i < 8; i++)
-			for (j = 0; j < (state->chunk_size / 16); j++)
-				if (k = (i + 1) * (state->chunk_size / 16) - j - 1, k < n)
-					output[k] = (char)((state->h.b64[i] >> (8 * j)) & 255);
+		for (i = 0, n = (n + 7) / 8; i < n; i++) {
+			output[8 * i + 0] = (char)(state->h.b64[i] >> 56);
+			output[8 * i + 1] = (char)(state->h.b64[i] >> 48);
+			output[8 * i + 2] = (char)(state->h.b64[i] >> 40);
+			output[8 * i + 3] = (char)(state->h.b64[i] >> 32);
+			output[8 * i + 4] = (char)(state->h.b64[i] >> 24);
+			output[8 * i + 5] = (char)(state->h.b64[i] >> 16);
+			output[8 * i + 6] = (char)(state->h.b64[i] >>  8);
+			output[8 * i + 7] = (char)(state->h.b64[i] >>  0);
+		}
 	}
 }