83 lines
2.3 KiB
Go
83 lines
2.3 KiB
Go
// Keywarden - Centralized SSH Key Management and Deployment
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// Copyright (C) 2026 Patrick Asmus (scriptos)
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// SPDX-License-Identifier: AGPL-3.0-or-later
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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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"crypto/sha256"
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"encoding/base64"
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"fmt"
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"io"
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)
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// Service handles AES-256-GCM encryption/decryption
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type Service struct {
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key []byte // 32 bytes for AES-256
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}
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// NewService creates a new encryption service from a passphrase.
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//
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// NOTE: Key derivation currently uses SHA-256 for backward compatibility with
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// existing encrypted data. A migration to a proper KDF (e.g. Argon2id) would
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// require re-encrypting all stored secrets and is tracked as a future improvement.
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func NewService(passphrase string) *Service {
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hash := sha256.Sum256([]byte(passphrase))
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return &Service{key: hash[:]}
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}
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// Encrypt encrypts plaintext using AES-256-GCM and returns base64-encoded ciphertext
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func (s *Service) Encrypt(plaintext string) (string, error) {
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block, err := aes.NewCipher(s.key)
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if err != nil {
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return "", fmt.Errorf("failed to create cipher: %w", err)
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}
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gcm, err := cipher.NewGCM(block)
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if err != nil {
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return "", fmt.Errorf("failed to create GCM: %w", 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 "", fmt.Errorf("failed to generate nonce: %w", err)
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}
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ciphertext := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
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return base64.StdEncoding.EncodeToString(ciphertext), nil
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}
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// Decrypt decrypts base64-encoded AES-256-GCM ciphertext
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func (s *Service) Decrypt(encoded string) (string, error) {
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ciphertext, err := base64.StdEncoding.DecodeString(encoded)
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if err != nil {
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return "", fmt.Errorf("failed to decode base64: %w", err)
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}
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block, err := aes.NewCipher(s.key)
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if err != nil {
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return "", fmt.Errorf("failed to create cipher: %w", err)
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}
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gcm, err := cipher.NewGCM(block)
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if err != nil {
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return "", fmt.Errorf("failed to create GCM: %w", err)
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}
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nonceSize := gcm.NonceSize()
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if len(ciphertext) < nonceSize {
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return "", fmt.Errorf("ciphertext too short")
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}
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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 "", fmt.Errorf("failed to decrypt: %w", err)
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}
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return string(plaintext), nil
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}
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