101 lines
2.4 KiB
Go
101 lines
2.4 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/hex"
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"fmt"
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"io"
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)
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// Service defines the interface for encryption and decryption operations.
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type Service interface {
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Encrypt(plaintext string) (string, error)
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Decrypt(ciphertextHex string) (string, error)
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}
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type serviceImpl struct {
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key []byte
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}
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// NewService creates a new encryption service.
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// The hexKey must be a 64-character hex-encoded string, representing a 32-byte key.
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func NewService(hexKey string) (Service, error) {
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if hexKey == "" {
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// Return a disabled service instead of an error
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return &disabledService{}, nil
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}
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key, err := hex.DecodeString(hexKey)
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if err != nil {
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return nil, fmt.Errorf("failed to decode encryption key: %w. It must be a hex-encoded string", err)
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}
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if len(key) != 32 {
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return nil, fmt.Errorf("encryption key must be 32 bytes long (64 hex characters)")
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}
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return &serviceImpl{key: key}, nil
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}
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// Encrypt encrypts a plaintext string using AES-256-GCM.
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func (s *serviceImpl) 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 "", 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 "", 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 "", err
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}
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ciphertext := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
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return hex.EncodeToString(ciphertext), nil
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}
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// Decrypt decrypts a hex-encoded ciphertext string.
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func (s *serviceImpl) Decrypt(ciphertextHex string) (string, error) {
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ciphertext, err := hex.DecodeString(ciphertextHex)
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if err != nil {
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return "", fmt.Errorf("failed to decode ciphertext: %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 "", 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 "", 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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// disabledService is a no-op implementation of the Service interface.
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type disabledService struct{}
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func (s *disabledService) Encrypt(plaintext string) (string, error) {
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return plaintext, nil
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}
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func (s *disabledService) Decrypt(ciphertext string) (string, error) {
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return ciphertext, nil
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}
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