Improved input service. New Manager web app. Directory and small readme for output service.

manager/crypto.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"errors"
+	"io"
+
+	"golang.org/x/crypto/pbkdf2"
+)
+
+type Crypto struct {
+	serverKey []byte
+}
+
+func NewCrypto(serverKeyStr string) (*Crypto, error) {
+	// Decode the base64 server key
+	serverKey, err := base64.StdEncoding.DecodeString(serverKeyStr)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(serverKey) != 32 {
+		return nil, errors.New("invalid server key length")
+	}
+
+	logger.Info("Crypto initialized with server key")
+	return &Crypto{serverKey: serverKey}, nil
+}
+
+func GenerateServerKey() (string, error) {
+	key := make([]byte, 32)
+	if _, err := rand.Read(key); err != nil {
+		return "", err
+	}
+	return base64.StdEncoding.EncodeToString(key), nil
+}
+
+func (c *Crypto) deriveUserKey(userID string) []byte {
+	// Derive a 32-byte key from user ID using PBKDF2
+	// Using server key as salt for additional security
+	return pbkdf2.Key([]byte(userID), c.serverKey, 100000, 32, sha256.New)
+}
+
+func (c *Crypto) encrypt(data []byte, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, err
+	}
+
+	ciphertext := gcm.Seal(nonce, nonce, data, nil)
+	return ciphertext, nil
+}
+
+func (c *Crypto) decrypt(data []byte, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	nonceSize := gcm.NonceSize()
+	if len(data) < nonceSize {
+		return nil, errors.New("ciphertext too short")
+	}
+
+	nonce, ciphertext := data[:nonceSize], data[nonceSize:]
+	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	return plaintext, nil
+}
+
+func (c *Crypto) EncryptWithServerKey(data []byte) ([]byte, error) {
+	return c.encrypt(data, c.serverKey)
+}
+
+func (c *Crypto) DecryptWithServerKey(data []byte) ([]byte, error) {
+	return c.decrypt(data, c.serverKey)
+}
+
+func (c *Crypto) EncryptWithUserKey(data []byte, userID string) ([]byte, error) {
+	userKey := c.deriveUserKey(userID)
+	return c.encrypt(data, userKey)
+}
+
+func (c *Crypto) DecryptWithUserKey(data []byte, userID string) ([]byte, error) {
+	userKey := c.deriveUserKey(userID)
+	return c.decrypt(data, userKey)
+}