commit 03c9ad07815ba065b3dc0440d5e8b66a68c4a442
author Roland Mikhel <roland.mikhel@arm.com> Wed Mar 08 15:56:43 2023 +0100
committer Dávid Vincze <david.vincze@arm.com> Tue Sep 12 16:29:11 2023 +0200
tree 1f97cdbd5eb8f5f08a2be549a7d588fbd15417f8
parent 5899face4d9132004b2d3487c9a62fddefd017cf

bootutil: Replace hash with SHA384 when P384 is used

Currently all the hashing functionality is done with SHA256
but if we would like to use ECDSA-P384 that requires SHA384
as the hashing algorithm, but MCUboot is using SHA256
for image hashing and public key hashing. This commit modifies
the hashing operations to use SHA384 thus SHA256 can be omitted
which is beneficial from a code size standpoint.

Signed-off-by: Roland Mikhel <roland.mikhel@arm.com>
Change-Id: I59230f76f88e0b42ad6383b2c9b71b73f33d7dd7

boot/bootutil/src/image_rsa.c

diff --git a/boot/bootutil/src/image_rsa.c b/boot/bootutil/src/image_rsa.c
index 34ee85b..37c35e0 100644
--- a/boot/bootutil/src/image_rsa.c
+++ b/boot/bootutil/src/image_rsa.c
@@ -43,7 +43,7 @@
  */
 #if !defined(MCUBOOT_USE_PSA_CRYPTO)
 
-#include "bootutil/crypto/sha256.h"
+#include "bootutil/crypto/sha.h"
 
 /*
  * Constants for this particular constrained implementation of
@@ -86,17 +86,17 @@
 static void
 pss_mgf1(uint8_t *mask, const uint8_t *hash)
 {
-    bootutil_sha256_context ctx;
+    bootutil_sha_context ctx;
     uint8_t counter[4] = { 0, 0, 0, 0 };
     uint8_t htmp[PSS_HLEN];
     int count = PSS_MASK_LEN;
     int bytes;
 
     while (count > 0) {
-        bootutil_sha256_init(&ctx);
-        bootutil_sha256_update(&ctx, hash, PSS_HLEN);
-        bootutil_sha256_update(&ctx, counter, 4);
-        bootutil_sha256_finish(&ctx, htmp);
+        bootutil_sha_init(&ctx);
+        bootutil_sha_update(&ctx, hash, PSS_HLEN);
+        bootutil_sha_update(&ctx, counter, 4);
+        bootutil_sha_finish(&ctx, htmp);
 
         counter[3]++;
 
@@ -109,7 +109,7 @@
         count -= bytes;
     }
 
-    bootutil_sha256_drop(&ctx);
+    bootutil_sha_drop(&ctx);
 }
 
 /*
@@ -121,7 +121,7 @@
 bootutil_cmp_rsasig(bootutil_rsa_context *ctx, uint8_t *hash, uint32_t hlen,
   uint8_t *sig, size_t slen)
 {
-    bootutil_sha256_context shactx;
+    bootutil_sha_context shactx;
     uint8_t em[MBEDTLS_MPI_MAX_SIZE];
     uint8_t db_mask[PSS_MASK_LEN];
     uint8_t h2[PSS_HLEN];
@@ -221,12 +221,12 @@
     /* Step 12.  Let M' = 0x00 00 00 00 00 00 00 00 || mHash || salt; */
 
     /* Step 13.  Let H' = Hash(M') */
-    bootutil_sha256_init(&shactx);
-    bootutil_sha256_update(&shactx, pss_zeros, 8);
-    bootutil_sha256_update(&shactx, hash, PSS_HLEN);
-    bootutil_sha256_update(&shactx, &db_mask[PSS_MASK_SALT_POS], PSS_SLEN);
-    bootutil_sha256_finish(&shactx, h2);
-    bootutil_sha256_drop(&shactx);
+    bootutil_sha_init(&shactx);
+    bootutil_sha_update(&shactx, pss_zeros, 8);
+    bootutil_sha_update(&shactx, hash, PSS_HLEN);
+    bootutil_sha_update(&shactx, &db_mask[PSS_MASK_SALT_POS], PSS_SLEN);
+    bootutil_sha_finish(&shactx, h2);
+    bootutil_sha_drop(&shactx);
 
     /* Step 14.  If H = H', output "consistent".  Otherwise, output
      * "inconsistent". */