Single pass cape encrypt and decrypt

CapeAltDecrypt.h

void decrypt(char *source, char *destination, uint16_t length)
{
	length = length - 1;

	auto saltedKey = (salt ^ _reduced_key);

	auto b = length ^ saltedKey;
	uint8_t iv = source[length] ^ length ^ _key[b % _key_length];

	auto ivSaltedKey = iv ^ saltedKey;

	for (uint16_t i = 0; i < length; ++i)
	{
		auto a = saltedKey ^ i;
		destination[i] = source[i] ^ iv ^ i ^ _key[a % _key_length];
	}
}

CapeAltEncrypt.h

void encrypt(char *source, char *destination, uint16_t length, uint8_t iv)
{
	auto saltedKey = (salt ^ _reduced_key);
	auto ivSaltedKey = iv ^ saltedKey;

	for (uint16_t i = 0; i < length; ++i)
	{
		auto a = saltedKey ^ i;
		destination[i] = source[i] ^ iv ^ i ^ _key[a % _key_length];
	}

	auto b = length ^ saltedKey;
	destination[length] = iv ^ length ^ _key[b % _key_length];
}