feat: added NCEncryptionGetIvSize() function and helpers

2 files changed, 74 insertions, 44 deletions

diff --git a/src/noscrypt.c b/src/noscrypt.c
index deadca6..fededaf 100644
--- a/src/noscrypt.c
+++ b/src/noscrypt.c
@@ -310,7 +310,7 @@ static _nc_fn_inline NCResult _encryptNip44Ex(
 
 	result = NC_SUCCESS;
 
-	ncSpanInitC(&nonceSpan, args->nonceData, NC_ENCRYPTION_NONCE_SIZE);
+	ncSpanInitC(&nonceSpan, args->nonceData, NC_NIP44_IV_SIZE);
 	
 	/* Message key will be derrived on every encryption call */
 	if (_getMessageKey(ck, nonceSpan, &messageKey) != CSTATUS_OK)
@@ -344,13 +344,14 @@ static _nc_fn_inline NCResult _decryptNip44Ex(const NCContext* ctx, const struct
 	struct message_key messageKey;
 	const struct nc_expand_keys* cipherKeys;
 
-	DEBUG_ASSERT2(ctx != NULL, "Expected valid context")
-	DEBUG_ASSERT2(ck != NULL, "Expected valid conversation key")
-	DEBUG_ASSERT2(args != NULL, "Expected valid encryption args")
+	DEBUG_ASSERT2(ctx != NULL, "Expected valid context");
+	DEBUG_ASSERT2(ck != NULL, "Expected valid conversation key");
+	DEBUG_ASSERT2(args != NULL, "Expected valid encryption args");
+	DEBUG_ASSERT(args->version == NC_ENC_VERSION_NIP44);
 
 	result = NC_SUCCESS;
 
-	ncSpanInitC(&nonceSpan, args->nonceData, NC_ENCRYPTION_NONCE_SIZE);
+	ncSpanInitC(&nonceSpan, args->nonceData, NC_NIP44_IV_SIZE);
 	
 	if (_getMessageKey(ck, nonceSpan, &messageKey) != CSTATUS_OK)
 	{
@@ -401,7 +402,7 @@ static NCResult _verifyMacEx(
 	DEBUG_ASSERT2(conversationKey != NULL, "Expected valid conversation key")
 	DEBUG_ASSERT2(args != NULL, "Expected valid mac verification args")
 
-	ncSpanInitC(&nonceSpan, args->nonce32, NC_ENCRYPTION_NONCE_SIZE);
+	ncSpanInitC(&nonceSpan, args->nonce32, NC_NIP44_IV_SIZE);
 	ncSpanInitC(&payloadSpan, args->payload, args->payloadSize);
 
 	/*
@@ -979,7 +980,7 @@ Cleanup:
 	return result;
 }
 
-NC_EXPORT NCResult NCComputeMac(
+NC_EXPORT NCResult NC_CC NCComputeMac(
 	const NCContext* ctx,
 	const uint8_t hmacKey[NC_HMAC_KEY_SIZE],
 	const uint8_t* payload,
@@ -1069,13 +1070,14 @@ Cleanup:
 
 #define ENSURE_ENC_MODE(args, mode) if(args->version != mode) return E_VERSION_NOT_SUPPORTED;
 
-NC_EXPORT NCResult NCSetEncryptionPropertyEx(
+NC_EXPORT NCResult NC_CC NCEncryptionSetPropertyEx(
 	NCEncryptionArgs* args,
 	uint32_t property,
 	uint8_t* value,
 	uint32_t valueLen
 )
 {
+	uint32_t ivSize;
 
 	CHECK_NULL_ARG(args, 0)
 	CHECK_NULL_ARG(value, 2)
@@ -1091,22 +1093,6 @@ NC_EXPORT NCResult NCSetEncryptionPropertyEx(
 
 		return NC_SUCCESS;
 
-	case NC_ENC_SET_NIP04_IV:
-		/*
-		* The safest way to store the nip04 IV is in the nonce
-		* field. An IV is essentially a nonce. A secure random
-		* number used to encrypt the first block of a CBC chain.
-		*/
-
-		CHECK_ARG_RANGE(valueLen, AES_IV_SIZE, UINT32_MAX, 3)
-
-		ENSURE_ENC_MODE(args, NC_ENC_VERSION_NIP04)
-
-		args->nonceData = value;
-
-		return NC_SUCCESS;
-
-
 	case NC_ENC_SET_NIP04_KEY:
 		/*
 		* The AES key is stored in the hmac key field, since
@@ -1122,13 +1108,17 @@ NC_EXPORT NCResult NCSetEncryptionPropertyEx(
 
 		return NC_SUCCESS;
 
-	case NC_ENC_SET_NIP44_NONCE:
+	case NC_ENC_SET_IV:
+		
+		ivSize = NCEncryptionGetIvSize(args->version);
 
-		/* Nonce buffer must be at least the size, max doesnt matter */
-		CHECK_ARG_RANGE(valueLen, NC_ENCRYPTION_NONCE_SIZE, UINT32_MAX, 3)
+		/* Gaurd invalid version */
+		if (ivSize == 0)
+		{
+			return E_VERSION_NOT_SUPPORTED;
+		}
 
-		/* Nonce is only used in nip44 mode */
-		ENSURE_ENC_MODE(args, NC_ENC_VERSION_NIP44)
+		CHECK_ARG_RANGE(valueLen, ivSize, ivSize, 3)
 
 		args->nonceData = value;
 
@@ -1155,13 +1145,13 @@ NC_EXPORT NCResult NCSetEncryptionPropertyEx(
 	return E_INVALID_ARG;
 }
 
-NC_EXPORT NCResult NCSetEncryptionProperty(
+NC_EXPORT NCResult NC_CC NCEncryptionSetProperty(
 	NCEncryptionArgs* args,
 	uint32_t property,
 	uint32_t value
 )
 {
-	return NCSetEncryptionPropertyEx(
+	return NCEncryptionSetPropertyEx(
 		args, 
 		property, 
 		(uint8_t*)&value, 
@@ -1169,7 +1159,7 @@ NC_EXPORT NCResult NCSetEncryptionProperty(
 	);
 }
 
-NC_EXPORT NCResult NCSetEncryptionData(
+NC_EXPORT NCResult NC_CC NCEncryptionSetData(
 	NCEncryptionArgs* args,
 	const uint8_t* input,
 	uint8_t* output,
@@ -1186,4 +1176,19 @@ NC_EXPORT NCResult NCSetEncryptionData(
 	args->dataSize = dataSize;
 
 	return NC_SUCCESS;	
-}
\ No newline at end of file
+}
+
+NC_EXPORT uint32_t NC_CC NCEncryptionGetIvSize(uint32_t version)
+{
+	switch (version)
+	{
+	case NC_ENC_VERSION_NIP04:
+		return NC_NIP04_IV_SIZE;
+
+	case NC_ENC_VERSION_NIP44:
+		return NC_NIP44_IV_SIZE;
+
+	default:
+		return 0;
+	}
+}
diff --git a/src/noscryptutil.c b/src/noscryptutil.c
index 4cee2c3..0d7a55c 100644
--- a/src/noscryptutil.c
+++ b/src/noscryptutil.c
@@ -37,6 +37,7 @@
 #define MIN_PADDING_SIZE		0x20u
 #define NIP44_VERSION_SIZE		0x01u
 #define NIP44_PT_LEN_SIZE		sizeof(uint16_t)
+#define NIP44_NONCE_SIZE		NC_NIP44_IV_SIZE
 
 /*
 * minimum size for a valid nip44 payload
@@ -200,7 +201,7 @@ static _nc_fn_inline uint32_t _calcNip44TotalOutSize(uint32_t inputSize)
 
 	bufferSize = NIP44_VERSION_SIZE;
 
-	bufferSize += NC_ENCRYPTION_NONCE_SIZE;
+	bufferSize += NIP44_NONCE_SIZE;
 
 	bufferSize += NIP44_PT_LEN_SIZE;
 
@@ -267,7 +268,7 @@ static _nc_fn_inline int _nip44ParseSegments(
 	*nonce = ncSpanSliceC(
 		payload,
 		NIP44_VERSION_SIZE,
-		NC_ENCRYPTION_NONCE_SIZE
+		NIP44_NONCE_SIZE
 	);
 
 	/*
@@ -293,8 +294,8 @@ static _nc_fn_inline int _nip44ParseSegments(
 	*/
 	*cipherText = ncSpanSliceC(
 		payload,
-		NIP44_VERSION_SIZE + NC_ENCRYPTION_NONCE_SIZE,
-		payload.size - (NIP44_VERSION_SIZE + NC_ENCRYPTION_NONCE_SIZE + NC_ENCRYPTION_MAC_SIZE)
+		NIP44_VERSION_SIZE + NIP44_NONCE_SIZE,
+		payload.size - (NIP44_VERSION_SIZE + NIP44_NONCE_SIZE + NC_ENCRYPTION_MAC_SIZE)
 	);
 
 	return 1;
@@ -357,12 +358,23 @@ static NCResult _nip44EncryptCompleteCore(
 
 	ZERO_FILL(hmacKeyOut, sizeof(hmacKeyOut));
 
+	/* Get the nonce/iv size so we know how much nonce data to write */
+	result = NCUtilCipherGetIvSize(state);
+	DEBUG_ASSERT(result > 0);
+
 	/* Start by appending the version number */
 	ncSpanAppend(message, &outPos, Nip44VersionValue, sizeof(Nip44VersionValue));
 
 	/* next is nonce data */
-	ncSpanAppend(message, &outPos, encArgs.nonceData, NC_ENCRYPTION_NONCE_SIZE);
-	DEBUG_ASSERT(outPos == 1 + NC_ENCRYPTION_NONCE_SIZE);
+	ncSpanAppend(message, &outPos, encArgs.nonceData, (uint32_t)result);
+
+	/* 
+	* Assert the output points to the end of the nonce segment 
+	* for nip44 this is exactly 33 bytes. This assert also doubles
+	* to check the output of NCUtilCipherGetIvSize() to ensure
+	* it's returning the correct size for nip44
+	*/
+	DEBUG_ASSERT(outPos == 1 + NIP44_NONCE_SIZE);
 
 	/*
 	* Assign the hmac key from the stack buffer. Since the args structure
@@ -372,7 +384,7 @@ static NCResult _nip44EncryptCompleteCore(
 	* addresses.
 	*/
 
-	result = NCSetEncryptionPropertyEx(
+	result = NCEncryptionSetPropertyEx(
 		&encArgs,
 		NC_ENC_SET_NIP44_MAC_KEY,
 		hmacKeyOut,
@@ -397,7 +409,7 @@ static NCResult _nip44EncryptCompleteCore(
 	* plainText size field.
 	*/
 
-	result = NCSetEncryptionData(
+	result = NCEncryptionSetData(
 		&encArgs,
 		ncSpanGetOffset(message, outPos),	/* in place encryption */
 		ncSpanGetOffset(message, outPos),
@@ -517,7 +529,7 @@ static NCResult _nip44DecryptCompleteCore(
 	if ((state->_flags & NC_UTIL_CIPHER_MAC_NO_VERIFY) == 0)
 	{
 		DEBUG_ASSERT(ncSpanGetSizeC(macValue) == NC_ENCRYPTION_MAC_SIZE);
-		DEBUG_ASSERT(ncSpanGetSizeC(macData) > NC_ENCRYPTION_NONCE_SIZE + MIN_PADDING_SIZE);
+		DEBUG_ASSERT(ncSpanGetSizeC(macData) > NIP44_NONCE_SIZE + MIN_PADDING_SIZE);
 
 		/* Assign the mac data to the mac verify args */
 		macArgs.mac32 = ncSpanGetOffsetC(macValue, 0);
@@ -550,7 +562,7 @@ static NCResult _nip44DecryptCompleteCore(
 
 	DEBUG_ASSERT2(cipherText.size >= MIN_PADDING_SIZE, "Cipertext segment was parsed incorrectly. Too small");
 	
-	result = NCSetEncryptionData(
+	result = NCEncryptionSetData(
 		&encArgs,
 		ncSpanGetOffsetC(cipherText, 0),
 		ncSpanGetOffset(output, 0),			/*decrypt ciphertext and write directly to the output buffer */
@@ -852,7 +864,7 @@ NC_EXPORT NCResult NCUtilCipherSetProperty(
 	CHECK_NULL_ARG(ctx, 0)
 
 	/* All other arguments are verified */
-	return NCSetEncryptionPropertyEx(
+	return NCEncryptionSetPropertyEx(
 		&ctx->encArgs, 
 		property, 
 		value, 
@@ -908,3 +920,16 @@ NC_EXPORT NCResult NC_CC NCUtilCipherUpdate(
 		return E_VERSION_NOT_SUPPORTED;
 	}
 }
+
+NC_EXPORT NCResult NC_CC NCUtilCipherGetIvSize(const NCUtilCipherContext* encCtx)
+{
+	uint32_t ivSize;
+
+	CHECK_NULL_ARG(encCtx, 0);
+
+	ivSize = NCEncryptionGetIvSize(encCtx->encArgs.version);
+
+	return ivSize == 0
+		? E_VERSION_NOT_SUPPORTED
+		: (NCResult)ivSize;
+}