Function Decrypt

cryption/authcrypt.go:53–85

Decrypt decrypts the given base64 encoded ciphertext using AES-GCM with the provided base64 encoded key and returns the plaintext

(base64Ciphertext, base64Key string)

// Decrypt decrypts the given base64 encoded ciphertext using AES-GCM with the provided base64 encoded key and returns the plaintext
func Decrypt(base64Ciphertext, base64Key string) (string, error) {
	key, err := base64.StdEncoding.DecodeString(base64Key)
	if err != nil {
		return "", err
	}

	ciphertext, err := base64.StdEncoding.DecodeString(base64Ciphertext)
	if err != nil {
		return "", err
	}

	block, err := aes.NewCipher(key)
	if err != nil {
		return "", err
	}

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

	if len(ciphertext) < gcm.NonceSize() {
		return "", errors.New("ciphertext too short")
	}

	nonce, ciphertext := ciphertext[:gcm.NonceSize()], ciphertext[gcm.NonceSize():]
	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
	if err != nil {
		return "", err
	}

	return string(plaintext), nil
}

// it took me an embarrising long time to learn that the jwt tokens encode the expiration time inside of them
func GetJWTTokenExpirationUnix(token string) (*float64, error) {