Release: v0.1.0-alpha

internal/encryption/encryption.go

@@ -0,0 +1,79 @@
+// Keywarden - Centralized SSH Key Management and Deployment
+// Copyright (C) 2026 Patrick Asmus (scriptos)
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+package encryption
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"fmt"
+	"io"
+)
+
+// Service handles AES-256-GCM encryption/decryption
+type Service struct {
+	key []byte // 32 bytes for AES-256
+}
+
+// NewService creates a new encryption service from a passphrase
+func NewService(passphrase string) *Service {
+	// Derive a 32-byte key from the passphrase using SHA-256
+	hash := sha256.Sum256([]byte(passphrase))
+	return &Service{key: hash[:]}
+}
+
+// Encrypt encrypts plaintext using AES-256-GCM and returns base64-encoded ciphertext
+func (s *Service) Encrypt(plaintext string) (string, error) {
+	block, err := aes.NewCipher(s.key)
+	if err != nil {
+		return "", fmt.Errorf("failed to create cipher: %w", err)
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", fmt.Errorf("failed to create GCM: %w", err)
+	}
+
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return "", fmt.Errorf("failed to generate nonce: %w", err)
+	}
+
+	ciphertext := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
+	return base64.StdEncoding.EncodeToString(ciphertext), nil
+}
+
+// Decrypt decrypts base64-encoded AES-256-GCM ciphertext
+func (s *Service) Decrypt(encoded string) (string, error) {
+	ciphertext, err := base64.StdEncoding.DecodeString(encoded)
+	if err != nil {
+		return "", fmt.Errorf("failed to decode base64: %w", err)
+	}
+
+	block, err := aes.NewCipher(s.key)
+	if err != nil {
+		return "", fmt.Errorf("failed to create cipher: %w", err)
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", fmt.Errorf("failed to create GCM: %w", err)
+	}
+
+	nonceSize := gcm.NonceSize()
+	if len(ciphertext) < nonceSize {
+		return "", fmt.Errorf("ciphertext too short")
+	}
+
+	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
+	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return "", fmt.Errorf("failed to decrypt: %w", err)
+	}
+
+	return string(plaintext), nil
+}