From be3c356661507dc5d6dea152a8f8342e4ce0d387 Mon Sep 17 00:00:00 2001
From: Michael Rash <mbr@cipherdyne.org>
Date: Fri, 13 May 2016 09:25:06 -0700
Subject: [PATCH] [libfko] account for SHA3_256 and SHA3_512 digest lengths
 matching SHA256 and SHA512

---
 lib/fko_decode.c               | 43 +++++++++++++++++++++++++++++++++-
 test/tests/basic_operations.pl | 10 ++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/lib/fko_decode.c b/lib/fko_decode.c
index 1afdba65..b259e172 100644
--- a/lib/fko_decode.c
+++ b/lib/fko_decode.c
@@ -107,6 +107,13 @@ verify_digest(char *tbuf, int t_size, fko_ctx_t ctx)
             sha512_base64(tbuf, (unsigned char*)ctx->encoded_msg, ctx->encoded_msg_len);
             break;
 
+        /* Note that we check SHA3_256 and SHA3_512 below because the
+         * digest lengths for these are the same as SHA256 and SHA512
+         * respectively, and setting the digest type for an incoming
+         * decrypted SPA packet is done initially by looking at the
+         * length.
+         */
+
         default: /* Invalid or unsupported digest */
             return(FKO_ERROR_INVALID_DIGEST_TYPE);
     }
@@ -115,7 +122,39 @@ verify_digest(char *tbuf, int t_size, fko_ctx_t ctx)
      * digest in the message data.
     */
     if(constant_runtime_cmp(ctx->digest, tbuf, t_size) != 0)
-        return(FKO_ERROR_DIGEST_VERIFICATION_FAILED);
+    {
+        /* Could potentially also have been SHA3_256 or SHA3_512 */
+        if(ctx->digest_type == FKO_DIGEST_SHA256)
+        {
+            sha3_256_base64(tbuf, (unsigned char*)ctx->encoded_msg, ctx->encoded_msg_len);
+            if(constant_runtime_cmp(ctx->digest, tbuf, t_size) != 0)
+            {
+                return(FKO_ERROR_DIGEST_VERIFICATION_FAILED);
+            }
+            else
+            {
+                ctx->digest_type = FKO_DIGEST_SHA3_256;
+                ctx->digest_len  = SHA3_256_B64_LEN;
+            }
+
+        }
+        else if(ctx->digest_type == FKO_DIGEST_SHA512)
+        {
+            sha3_512_base64(tbuf, (unsigned char*)ctx->encoded_msg, ctx->encoded_msg_len);
+            if(constant_runtime_cmp(ctx->digest, tbuf, t_size) != 0)
+            {
+                return(FKO_ERROR_DIGEST_VERIFICATION_FAILED);
+            }
+            else
+            {
+                ctx->digest_type = FKO_DIGEST_SHA3_512;
+                ctx->digest_len  = SHA3_512_B64_LEN;
+            }
+
+        }
+        else
+            return(FKO_ERROR_DIGEST_VERIFICATION_FAILED);
+    }
 
     return FKO_SUCCESS;
 }
@@ -135,6 +174,7 @@ is_valid_digest_len(int t_size, fko_ctx_t ctx)
             ctx->digest_len  = SHA1_B64_LEN;
             break;
 
+        /* Could also match SHA3_256_B64_LEN, handled in verify_digest() */
         case SHA256_B64_LEN:
             ctx->digest_type = FKO_DIGEST_SHA256;
             ctx->digest_len  = SHA256_B64_LEN;
@@ -145,6 +185,7 @@ is_valid_digest_len(int t_size, fko_ctx_t ctx)
             ctx->digest_len  = SHA384_B64_LEN;
             break;
 
+        /* Could also match SHA3_512_B64_LEN, handled in verify_digest() */
         case SHA512_B64_LEN:
             ctx->digest_type = FKO_DIGEST_SHA512;
             ctx->digest_len  = SHA512_B64_LEN;
diff --git a/test/tests/basic_operations.pl b/test/tests/basic_operations.pl
index 455662c3..65a5bc7e 100644
--- a/test/tests/basic_operations.pl
+++ b/test/tests/basic_operations.pl
@@ -1176,6 +1176,16 @@
                 'vars' => {'KEY' => 'testtest', 'DIGEST_TYPE' => 'SHA512'}}],
         'positive_output_matches' => [qr/Digest\sType\:\s.*SHA512/],
     },
+    {
+        'category' => 'basic operations',
+        'subcategory' => 'client rc file',
+        'detail'   => 'digest SHA3_256',
+        'function' => \&client_rc_file,
+        'cmdline'  => $client_rewrite_rc_args,
+        'write_rc_file' => [{'name' => 'default',
+                'vars' => {'KEY' => 'testtest', 'DIGEST_TYPE' => 'SHA3_256'}}],
+        'positive_output_matches' => [qr/Digest\sType\:\s.*SHA3_256/],
+    },
     {
         'category' => 'basic operations',
         'subcategory' => 'client rc file',