Adding upstream version 2.52.6.

Signed-off-by: Daniel Baumann <daniel@debian.org>

middleware/encryptcookie/utils.go

@@ -0,0 +1,98 @@
+package encryptcookie
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+)
+
+// EncryptCookie Encrypts a cookie value with specific encryption key
+func EncryptCookie(value, key string) (string, error) {
+	keyDecoded, err := base64.StdEncoding.DecodeString(key)
+	if err != nil {
+		return "", fmt.Errorf("failed to base64-decode key: %w", err)
+	}
+
+	block, err := aes.NewCipher(keyDecoded)
+	if err != nil {
+		return "", fmt.Errorf("failed to create AES cipher: %w", err)
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", fmt.Errorf("failed to create GCM mode: %w", err)
+	}
+
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
+		return "", fmt.Errorf("failed to read: %w", err)
+	}
+
+	ciphertext := gcm.Seal(nonce, nonce, []byte(value), nil)
+
+	return base64.StdEncoding.EncodeToString(ciphertext), nil
+}
+
+// DecryptCookie Decrypts a cookie value with specific encryption key
+func DecryptCookie(value, key string) (string, error) {
+	keyDecoded, err := base64.StdEncoding.DecodeString(key)
+	if err != nil {
+		return "", fmt.Errorf("failed to base64-decode key: %w", err)
+	}
+	enc, err := base64.StdEncoding.DecodeString(value)
+	if err != nil {
+		return "", fmt.Errorf("failed to base64-decode value: %w", err)
+	}
+
+	block, err := aes.NewCipher(keyDecoded)
+	if err != nil {
+		return "", fmt.Errorf("failed to create AES cipher: %w", err)
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", fmt.Errorf("failed to create GCM mode: %w", err)
+	}
+
+	nonceSize := gcm.NonceSize()
+
+	if len(enc) < nonceSize {
+		return "", errors.New("encrypted value is not valid")
+	}
+
+	nonce, ciphertext := enc[:nonceSize], enc[nonceSize:]
+
+	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return "", fmt.Errorf("failed to decrypt ciphertext: %w", err)
+	}
+
+	return string(plaintext), nil
+}
+
+// GenerateKey Generates an encryption key
+func GenerateKey() string {
+	const keyLen = 32
+	ret := make([]byte, keyLen)
+
+	if _, err := rand.Read(ret); err != nil {
+		panic(err)
+	}
+
+	return base64.StdEncoding.EncodeToString(ret)
+}
+
+// Check given cookie key is disabled for encryption or not
+func isDisabled(key string, except []string) bool {
+	for _, k := range except {
+		if key == k {
+			return true
+		}
+	}
+
+	return false
+}