core: crypto add support for SHA-512/256 for RFCs 8760/7616

src/core/crypto/sha256.c

@@ -301,6 +301,18 @@ const static sha2_word64 sha512_initial_hash_value[8] = {
 	0x5be0cd19137e2179ULL
 };
 
+/* Initial hash value H for SHA-512/256 */
+const static sha2_word64 sha512_256_initial_hash_value[8] = {
+	0x22312194FC2BF72CULL,
+	0x9F555FA3C84C64C2ULL,
+	0x2393B86B6F53B151ULL,
+	0x963877195940EABDULL,
+	0x96283EE2A88EFFE3ULL,
+	0xBE5E1E2553863992ULL,
+	0x2B0199FC2C85B8AAULL,
+	0x0EB72DDC81C52CA2ULL
+};
+
 /*
  * Constant used by SHA256/384/512_End() functions for converting the
  * digest to a readable hexadecimal character string:
@@ -636,7 +648,7 @@ char* sr_SHA256_Data(const sha2_byte* data, size_t len, char digest[SHA256_DIGES
 }
 
 
-/*** SHA-512: *********************************************************/
+/*** SHA-512 SHA-512/256: *********************************************************/
 void sr_SHA512_Init(SHA512_CTX* context) {
 	if (context == (SHA512_CTX*)0) {
 		return;
@@ -646,6 +658,15 @@ void sr_SHA512_Init(SHA512_CTX* context) {
 	context->bitcount[0] = context->bitcount[1] =  0;
 }
 
+void sr_SHA512_256_Init(SHA512_CTX* context) {
+	if (context == (SHA512_CTX*)0) {
+		return;
+	}
+	MEMCPY_BCOPY(context->state, sha512_256_initial_hash_value, SHA512_DIGEST_LENGTH);
+	MEMSET_BZERO(context->buffer, SHA512_BLOCK_LENGTH);
+	context->bitcount[0] = context->bitcount[1] =  0;
+}
+
 #ifdef SHA2_UNROLL_TRANSFORM
 
 /* Unrolled SHA-512 round macros: */

src/core/crypto/sha256.h

@@ -97,6 +97,7 @@ char* sr_SHA384_End(SHA384_CTX*, char[SHA384_DIGEST_STRING_LENGTH]);
 char* sr_SHA384_Data(const uint8_t*, size_t, char[SHA384_DIGEST_STRING_LENGTH]);
 
 void sr_SHA512_Init(SHA512_CTX*);
+void sr_SHA512_256_Init(SHA512_CTX*);
 void sr_SHA512_Update(SHA512_CTX*, const uint8_t*, size_t);
 void sr_SHA512_Final(sha2_byte[SHA512_DIGEST_LENGTH], SHA512_CTX*);
 char* sr_SHA512_End(SHA512_CTX*, char[SHA512_DIGEST_STRING_LENGTH]);
@@ -117,6 +118,7 @@ char* sr_SHA384_End();
 char* sr_SHA384_Data();
 
 void sr_SHA512_Init();
+void sr_SHA512_256_Init();
 void sr_SHA512_Update();
 void sr_SHA512_Final();
 char* sr_SHA512_End();