From b2fe2f26ba2d8a2800bcaa3de979aa04bc43cb4a Mon Sep 17 00:00:00 2001
From: Alexandre Paillier <alexandre.paillier@ledger.fr>
Date: Mon, 2 May 2022 15:32:45 +0200
Subject: [PATCH] Implements the hashing part of typeHash

---
 src_features/signMessageEIP712/type_hash.c | 28 +++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/src_features/signMessageEIP712/type_hash.c b/src_features/signMessageEIP712/type_hash.c
index e3069ce..ee471fc 100644
--- a/src_features/signMessageEIP712/type_hash.c
+++ b/src_features/signMessageEIP712/type_hash.c
@@ -4,6 +4,7 @@
 #include "mem.h"
 #include "encode_type.h"
 #include "type_hash.h"
+#include "sha3.h"
 
 const uint8_t *type_hash(const void *const structs_array,
                          const char *const struct_name,
@@ -12,12 +13,19 @@ const uint8_t *type_hash(const void *const structs_array,
     const void *const mem_loc_bak = mem_alloc(0); // backup the memory location
     const char  *typestr;
     uint16_t    length;
+    sha3_context ctx;
+    const uint8_t *hash;
+    uint8_t *hash_ptr;
 
     typestr = encode_type(structs_array, struct_name, struct_name_length, &length);
     if (typestr == NULL)
     {
         return NULL;
     }
+    sha3_Init256(&ctx);
+    sha3_SetFlags(&ctx, SHA3_FLAGS_KECCAK);
+    sha3_Update(&ctx, typestr, length);
+    hash = sha3_Finalize(&ctx);
 
 #ifdef DEBUG
     fwrite(typestr, sizeof(char), length, stdout);
@@ -27,5 +35,23 @@ const uint8_t *type_hash(const void *const structs_array,
     // restore the memory location
     mem_dealloc(mem_alloc(0) - mem_loc_bak);
 
-    return NULL;
+    // copy hash into memory
+    if ((hash_ptr = mem_alloc(KECCAK256_HASH_LENGTH)) == NULL)
+    {
+        return NULL;
+    }
+#ifdef DEBUG
+    printf("-> 0x");
+#endif
+    for (int idx = 0; idx < KECCAK256_HASH_LENGTH; ++idx)
+    {
+        hash_ptr[idx] = hash[idx];
+#ifdef DEBUG
+        printf("%.02x", hash[idx]);
+#endif
+    }
+#ifdef DEBUG
+    printf("\n");
+#endif
+    return hash_ptr;
 }