utils

func Aes256Decrypt(ciphertext []byte, key []byte, iv []byte) ([]byte, error)

func Aes256Encrypt(plaintext []byte, key []byte, iv []byte) ([]byte, error)

func Hkdf(hash func() hash.Hash, secret []byte, salt []byte, info []byte, length int) []byte

func Pkcs7Pad(data []byte, blockSize int) ([]byte, error)

func Pkcs7Strip(data []byte, blockSize int) ([]byte, error)

func SecureRandomBytes(length int32) ([]byte, error)