package auth import ( "bytes" "crypto/aes" "crypto/cipher" "crypto/rand" "golang.org/x/crypto/argon2" ) // Len of salt for passwords in bytes const saltLen = 32 func generateSalt(length int) ([]byte, error) { salt := make([]byte, length) if _, err := rand.Read(salt); err != nil { return nil, err } return salt, nil } func hashPassword(password string) ([]byte, error) { salt, err := generateSalt(saltLen) if err != nil { return nil, err } hash := argon2.IDKey([]byte(password), salt, 1, 64*1024, 4, 32) hash = append(hash, salt...) // return bcrypt.GenerateFromPassword([]byte(password), 14) return hash, nil } // Compare a raw password against a hash + salt func comparePassword(password string, hash []byte) bool { // Hash is actually hash(password)+salt salt := hash[len(hash)-saltLen:] return bytes.Equal(argon2.IDKey([]byte(password), salt, 1, 64*1024, 4, 32), hash) } // Copied and adjusted from: https://bruinsslot.jp/post/golang-crypto/ func Encrypt(key, data []byte) ([]byte, error) { key, salt, err := deriveKey(key, nil) if err != nil { return nil, err } blockCipher, err := aes.NewCipher(key) if err != nil { return nil, err } gcm, err := cipher.NewGCM(blockCipher) if err != nil { return nil, err } nonce := make([]byte, gcm.NonceSize()) if _, err = rand.Read(nonce); err != nil { return nil, err } ciphertext := gcm.Seal(nonce, nonce, data, nil) ciphertext = append(ciphertext, salt...) return ciphertext, nil } func Decrypt(key, data []byte) ([]byte, error) { salt, data := data[len(data)-32:], data[:len(data)-32] key, _, err := deriveKey(key, salt) if err != nil { return nil, err } blockCipher, err := aes.NewCipher(key) if err != nil { return nil, err } gcm, err := cipher.NewGCM(blockCipher) if err != nil { return nil, err } nonce, ciphertext := data[:gcm.NonceSize()], data[gcm.NonceSize():] plaintext, err := gcm.Open(nil, nonce, ciphertext, nil) if err != nil { return nil, err } return plaintext, nil } func deriveKey(password, salt []byte) ([]byte, []byte, error) { if salt == nil { salt = make([]byte, 32) if _, err := rand.Read(salt); err != nil { return nil, nil, err } } key := argon2.IDKey(password, salt, 1, 64*1024, 4, 32) return key, salt, nil }