vb2_sha: Add sha256 extend

This patch adds vb2_sha256_extend, which extends a hash using a given block.

BUG=chrome-os-partner:51907
BRANCH=tot
TEST=make runtests

Change-Id: I512674f18dffc55692907c85b19ff19df88a5eeb
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/346234
Commit-Ready: Daisuke Nojiri <dnojiri@google.com>
Tested-by: Daisuke Nojiri <dnojiri@google.com>
Reviewed-by: Randall Spangler <rspangler@google.com>

3 files changed, 40 insertions, 4 deletions

diff --git a/firmware/2lib/2sha256.c b/firmware/2lib/2sha256.c
index fd41258c..d2cf6726 100644
--- a/firmware/2lib/2sha256.c
+++ b/firmware/2lib/2sha256.c
@@ -314,3 +314,21 @@ void vb2_sha256_finalize(struct vb2_sha256_context *ctx, uint8_t *digest)
 	UNPACK32(ctx->h[7], &digest[28]);
 #endif /* !UNROLL_LOOPS */
 }
+
+void vb2_sha256_extend(const uint8_t *from, const uint8_t *by, uint8_t *to)
+{
+	struct vb2_sha256_context dc;
+	int i;
+
+	for (i = 0; i < 8; i++) {
+		 PACK32(from, &dc.h[i]);
+		 from += 4;
+	}
+
+	vb2_sha256_transform(&dc, by, 1);
+
+	for (i = 0; i < 8; i++) {
+		 UNPACK32(dc.h[i], to);
+		 to += 4;
+	}
+}
diff --git a/firmware/2lib/include/2sha.h b/firmware/2lib/include/2sha.h
index 0077f379..38b8a816 100644
--- a/firmware/2lib/include/2sha.h
+++ b/firmware/2lib/include/2sha.h
@@ -133,6 +133,15 @@ void vb2_sha256_finalize(struct vb2_sha256_context *ctx, uint8_t *digest);
 void vb2_sha512_finalize(struct vb2_sha512_context *ctx, uint8_t *digest);
 
 /**
+ * Hash-extend data
+ *
+ * @param from	Hash to be extended. It has to be the hash size.
+ * @param by	Block to be extended by. It has to be the hash block size.
+ * @param to	Destination for extended data
+ */
+void vb2_sha256_extend(const uint8_t *from, const uint8_t *by, uint8_t *to);
+
+/**
  * Convert vb2_crypto_algorithm to vb2_hash_algorithm.
  *
  * @param algorithm	Crypto algorithm (vb2_crypto_algorithm)
diff --git a/tests/vb2_sha_tests.c b/tests/vb2_sha_tests.c
index c3185cac..94236355 100644
--- a/tests/vb2_sha_tests.c
+++ b/tests/vb2_sha_tests.c
@@ -50,13 +50,18 @@ void sha256_tests(void)
 	uint8_t digest[VB2_SHA256_DIGEST_SIZE];
 	uint8_t *test_inputs[3];
 	struct vb2_sha256_context ctx;
-	uint8_t expect_multiple[VB2_SHA256_DIGEST_SIZE] =
-		{
+	const uint8_t expect_multiple[VB2_SHA256_DIGEST_SIZE] = {
 			0x07, 0x08, 0xb4, 0xca, 0x46, 0x4c, 0x40, 0x39,
 			0x07, 0x06, 0x88, 0x80, 0x30, 0x55, 0x5d, 0x86,
 			0x0e, 0x4a, 0x0d, 0x2b, 0xc6, 0xc4, 0x87, 0x39,
-			0x2c, 0x16, 0x55, 0xb0, 0x82, 0x13, 0x16, 0x29
-		};
+			0x2c, 0x16, 0x55, 0xb0, 0x82, 0x13, 0x16, 0x29 };
+	const uint8_t extend_from[VB2_SHA256_DIGEST_SIZE] = { 0x00, };
+	const uint8_t extend_by[VB2_SHA256_BLOCK_SIZE] = { 0x00, };
+	const uint8_t expected_extend[VB2_SHA256_DIGEST_SIZE] = {
+		0x7c, 0xa5, 0x16, 0x14, 0x42, 0x5c, 0x3b, 0xa8, 0xce, 0x54,
+		0xdd, 0x2f, 0xc2, 0x02, 0x0a, 0xe7, 0xb6, 0xe5, 0x74, 0xd1,
+		0x98, 0x13, 0x6d, 0x0f, 0xae, 0x7e, 0x26, 0xcc, 0xbf, 0x0b,
+		0xe7, 0xa6 };
 	int i;
 
 	test_inputs[0] = (uint8_t *) oneblock_msg;
@@ -90,6 +95,10 @@ void sha256_tests(void)
 
 	TEST_EQ(vb2_hash_block_size(VB2_HASH_SHA256), VB2_SHA256_BLOCK_SIZE,
 		"vb2_hash_block_size(VB2_HASH_SHA256)");
+
+	/* Test SHA256 hash extend */
+	vb2_sha256_extend(extend_from, extend_by, digest);
+	TEST_SUCC(memcmp(digest, expected_extend, sizeof(digest)), NULL);
 }
 
 void sha512_tests(void)