website/pkg/encryption/encryption.go
2023-09-18 17:22:50 -07:00

109 lines
2.8 KiB
Go

// Package encryption provides functions to encode/decode AES encrypted secrets.
//
// Encryption is used to store sensitive information in the database, such as 2FA TOTP secrets
// for users who have 2FA authentication enabled.
//
// For new key generation, see pkg/config/variable.go#NewAESKey.
package encryption
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/sha256"
"errors"
"fmt"
"io"
"code.nonshy.com/nonshy/website/pkg/config"
)
// Encrypt a byte stream using the site's AES passphrase.
func Encrypt(input []byte) ([]byte, error) {
if len(config.Current.Encryption.AESKey) == 0 {
return nil, errors.New("AES key not configured")
}
// Generate a new AES cipher.
c, err := aes.NewCipher(config.Current.Encryption.AESKey)
if err != nil {
return nil, err
}
// gcm or Galois/Counter Mode
gcm, err := cipher.NewGCM(c)
if err != nil {
return nil, err
}
// Create a new byte array the size of the GCM nonce
// which must be passed to Seal.
nonce := make([]byte, gcm.NonceSize())
if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
return nil, fmt.Errorf("populating the nonce: %s", err)
}
// Encrypt the text using the Seal function.
// Seal encrypts and authenticates plaintext, authenticates the
// additional data and appends the result to dst, returning the
// updated slice. The nonce must be NonceSize() bytes long and
// unique for all time, for a given key.
result := gcm.Seal(nonce, nonce, input, nil)
return result, nil
}
// EncryptString encrypts a string value and returns the cipher text.
func EncryptString(input string) ([]byte, error) {
return Encrypt([]byte(input))
}
// Decrypt a byte stream using the site's AES passphrase.
func Decrypt(data []byte) ([]byte, error) {
if len(config.Current.Encryption.AESKey) == 0 {
return nil, errors.New("AES key not configured")
}
c, err := aes.NewCipher(config.Current.Encryption.AESKey)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(c)
if err != nil {
return nil, err
}
nonceSize := gcm.NonceSize()
if len(data) < nonceSize {
return nil, errors.New("ciphertext data less than nonceSize")
}
nonce, ciphertext := data[:nonceSize], data[nonceSize:]
plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
return nil, err
}
return plaintext, nil
}
// DecryptString decrypts a string value from ciphertext.
func DecryptString(data []byte) (string, error) {
decoded, err := Decrypt(data)
if err != nil {
return "", err
}
return string(decoded), nil
}
// Hash a byte array as SHA256 and returns the hex string.
func Hash(input []byte) string {
h := sha256.New()
h.Write(input)
return fmt.Sprintf("%x", h.Sum(nil))
}
// VerifyHash hashes a byte array and checks the result.
func VerifyHash(input []byte, expect string) bool {
return Hash(input) == expect
}