133 lines
3.5 KiB
Go
133 lines
3.5 KiB
Go
package encryption
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"encoding/base64"
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"fmt"
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"io"
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)
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// Cipher provides methods to encrypt and decrypt
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type Cipher interface {
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Encrypt(value []byte) ([]byte, error)
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Decrypt(ciphertext []byte) ([]byte, error)
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}
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type base64Cipher struct {
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Cipher Cipher
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}
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// NewBase64Cipher returns a new AES Cipher for encrypting cookie values
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// and wrapping them in Base64 -- Supports Legacy encryption scheme
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func NewBase64Cipher(c Cipher) Cipher {
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return &base64Cipher{Cipher: c}
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}
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// Encrypt encrypts a value with the embedded Cipher & Base64 encodes it
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func (c *base64Cipher) Encrypt(value []byte) ([]byte, error) {
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encrypted, err := c.Cipher.Encrypt(value)
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if err != nil {
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return nil, err
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}
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return []byte(base64.StdEncoding.EncodeToString(encrypted)), nil
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}
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// Decrypt Base64 decodes a value & decrypts it with the embedded Cipher
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func (c *base64Cipher) Decrypt(ciphertext []byte) ([]byte, error) {
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encrypted, err := base64.StdEncoding.DecodeString(string(ciphertext))
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if err != nil {
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return nil, fmt.Errorf("failed to base64 decode value %s", err)
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}
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return c.Cipher.Decrypt(encrypted)
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}
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type cfbCipher struct {
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cipher.Block
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}
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// NewCFBCipher returns a new AES CFB Cipher
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func NewCFBCipher(secret []byte) (Cipher, error) {
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c, err := aes.NewCipher(secret)
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if err != nil {
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return nil, err
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}
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return &cfbCipher{Block: c}, err
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}
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// Encrypt with AES CFB
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func (c *cfbCipher) Encrypt(value []byte) ([]byte, error) {
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ciphertext := make([]byte, aes.BlockSize+len(value))
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iv := ciphertext[:aes.BlockSize]
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if _, err := io.ReadFull(rand.Reader, iv); err != nil {
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return nil, fmt.Errorf("failed to create initialization vector %s", err)
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}
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stream := cipher.NewCFBEncrypter(c.Block, iv) //nolint:staticcheck
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stream.XORKeyStream(ciphertext[aes.BlockSize:], value)
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return ciphertext, nil
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}
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// Decrypt an AES CFB ciphertext
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func (c *cfbCipher) Decrypt(ciphertext []byte) ([]byte, error) {
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if len(ciphertext) < aes.BlockSize {
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return nil, fmt.Errorf("encrypted value should be at least %d bytes, but is only %d bytes", aes.BlockSize, len(ciphertext))
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}
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iv, ciphertext := ciphertext[:aes.BlockSize], ciphertext[aes.BlockSize:]
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plaintext := make([]byte, len(ciphertext))
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stream := cipher.NewCFBDecrypter(c.Block, iv) //nolint:staticcheck
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stream.XORKeyStream(plaintext, ciphertext)
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return plaintext, nil
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}
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type gcmCipher struct {
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cipher.Block
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}
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// NewGCMCipher returns a new AES GCM Cipher
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func NewGCMCipher(secret []byte) (Cipher, error) {
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c, err := aes.NewCipher(secret)
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if err != nil {
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return nil, err
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}
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return &gcmCipher{Block: c}, err
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}
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// Encrypt with AES GCM on raw bytes
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func (c *gcmCipher) Encrypt(value []byte) ([]byte, error) {
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gcm, err := cipher.NewGCM(c.Block)
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if err != nil {
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return nil, err
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}
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nonce := make([]byte, gcm.NonceSize())
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if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
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return nil, err
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}
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// Using nonce as Seal's dst argument results in it being the first
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// chunk of bytes in the ciphertext. Decrypt retrieves the nonce/IV from this.
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ciphertext := gcm.Seal(nonce, nonce, value, nil)
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return ciphertext, nil
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}
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// Decrypt an AES GCM ciphertext
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func (c *gcmCipher) Decrypt(ciphertext []byte) ([]byte, error) {
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gcm, err := cipher.NewGCM(c.Block)
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if err != nil {
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return nil, err
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}
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nonceSize := gcm.NonceSize()
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nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
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plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
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if err != nil {
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return nil, err
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}
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return plaintext, nil
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}
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