mirror of
https://github.com/lordmathis/lemma.git
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136 lines
3.3 KiB
Go
136 lines
3.3 KiB
Go
// Package secrets provides an Encryptor interface for encrypting and decrypting strings using AES-256-GCM.
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package secrets
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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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"novamd/internal/logging"
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)
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// Service is an interface for encrypting and decrypting strings
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type Service interface {
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Encrypt(plaintext string) (string, error)
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Decrypt(ciphertext string) (string, error)
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}
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type encryptor struct {
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gcm cipher.AEAD
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}
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var logger logging.Logger
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func getLogger() logging.Logger {
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if logger == nil {
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logger = logging.WithGroup("secrets")
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}
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return logger
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}
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// ValidateKey checks if the provided base64-encoded key is suitable for AES-256
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func ValidateKey(key string) error {
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_, err := decodeAndValidateKey(key)
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return err
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}
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// decodeAndValidateKey validates and decodes the base64-encoded key
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// Returns the decoded key bytes if valid
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func decodeAndValidateKey(key string) ([]byte, error) {
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if key == "" {
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return nil, fmt.Errorf("encryption key is required")
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}
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keyBytes, err := base64.StdEncoding.DecodeString(key)
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if err != nil {
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return nil, fmt.Errorf("invalid base64 encoding: %w", err)
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}
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if len(keyBytes) != 32 {
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return nil, fmt.Errorf("encryption key must be 32 bytes (256 bits): got %d bytes", len(keyBytes))
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}
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// Verify the key can be used for AES
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_, err = aes.NewCipher(keyBytes)
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if err != nil {
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return nil, fmt.Errorf("invalid encryption key: %w", err)
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}
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return keyBytes, nil
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}
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// NewService creates a new Encryptor instance with the provided base64-encoded key
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func NewService(key string) (Service, error) {
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log := getLogger()
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keyBytes, err := decodeAndValidateKey(key)
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if err != nil {
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return nil, err
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}
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block, err := aes.NewCipher(keyBytes)
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if err != nil {
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return nil, 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 nil, fmt.Errorf("failed to create GCM: %w", err)
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}
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log.Info("encryption service created")
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return &encryptor{gcm: gcm}, nil
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}
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// Encrypt encrypts the plaintext using AES-256-GCM
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func (e *encryptor) Encrypt(plaintext string) (string, error) {
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log := getLogger()
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if plaintext == "" {
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log.Debug("empty plaintext provided, returning empty string")
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return "", nil
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}
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nonce := make([]byte, e.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 := e.gcm.Seal(nonce, nonce, []byte(plaintext), nil)
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encoded := base64.StdEncoding.EncodeToString(ciphertext)
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log.Debug("data encrypted", "inputLength", len(plaintext), "outputLength", len(encoded))
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return encoded, nil
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}
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// Decrypt decrypts the ciphertext using AES-256-GCM
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func (e *encryptor) Decrypt(ciphertext string) (string, error) {
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log := getLogger()
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if ciphertext == "" {
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log.Debug("empty ciphertext provided, returning empty string")
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return "", nil
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}
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data, err := base64.StdEncoding.DecodeString(ciphertext)
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if err != nil {
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return "", fmt.Errorf("invalid base64 encoding: %w", err)
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}
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nonceSize := e.gcm.NonceSize()
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if len(data) < nonceSize {
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return "", fmt.Errorf("invalid ciphertext: too short")
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}
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nonce, ciphertextBytes := data[:nonceSize], data[nonceSize:]
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plaintext, err := e.gcm.Open(nil, nonce, ciphertextBytes, nil)
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if err != nil {
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return "", err
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}
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log.Debug("data decrypted", "inputLength", len(ciphertext), "outputLength", len(plaintext))
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return string(plaintext), nil
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}
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