110 lines
2.4 KiB
Go
110 lines
2.4 KiB
Go
package main
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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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"errors"
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"io"
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"golang.org/x/crypto/pbkdf2"
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)
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type Crypto struct {
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serverKey []byte
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}
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func NewCrypto(serverKeyStr string) (*Crypto, error) {
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// Decode the base64 server key
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serverKey, err := base64.StdEncoding.DecodeString(serverKeyStr)
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if err != nil {
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return nil, err
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}
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if len(serverKey) != 32 {
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return nil, errors.New("invalid server key length")
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}
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logger.Info("Crypto initialized with server key")
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return &Crypto{serverKey: serverKey}, nil
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}
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func GenerateServerKey() (string, error) {
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key := make([]byte, 32)
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if _, err := rand.Read(key); err != nil {
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return "", err
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}
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return base64.StdEncoding.EncodeToString(key), nil
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}
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func (c *Crypto) deriveUserKey(userID string) []byte {
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// Derive a 32-byte key from user ID using PBKDF2
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// Using server key as salt for additional security
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return pbkdf2.Key([]byte(userID), c.serverKey, 100000, 32, sha256.New)
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}
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func (c *Crypto) encrypt(data []byte, key []byte) ([]byte, error) {
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, 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, 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 nil, err
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}
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ciphertext := gcm.Seal(nonce, nonce, data, nil)
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return ciphertext, nil
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}
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func (c *Crypto) decrypt(data []byte, key []byte) ([]byte, error) {
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, 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, err
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}
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nonceSize := gcm.NonceSize()
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if len(data) < nonceSize {
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return nil, errors.New("ciphertext too short")
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}
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nonce, ciphertext := data[:nonceSize], data[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 nil, err
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}
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return plaintext, nil
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}
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func (c *Crypto) EncryptWithServerKey(data []byte) ([]byte, error) {
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return c.encrypt(data, c.serverKey)
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}
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func (c *Crypto) DecryptWithServerKey(data []byte) ([]byte, error) {
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return c.decrypt(data, c.serverKey)
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}
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func (c *Crypto) EncryptWithUserKey(data []byte, userID string) ([]byte, error) {
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userKey := c.deriveUserKey(userID)
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return c.encrypt(data, userKey)
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}
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func (c *Crypto) DecryptWithUserKey(data []byte, userID string) ([]byte, error) {
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userKey := c.deriveUserKey(userID)
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return c.decrypt(data, userKey)
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}
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