Initial sanitized code sync

internal/db/crypto.go

@@ -0,0 +1,78 @@
+package db
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+)
+
+var encryptionKey []byte
+
+func SetEncryptionKey(hexKey string) error {
+	key, err := hex.DecodeString(hexKey)
+	if err != nil {
+		return fmt.Errorf("decode encryption key: %w", err)
+	}
+	if len(key) != 32 {
+		return fmt.Errorf("encryption key must be 32 bytes (64 hex chars), got %d bytes", len(key))
+	}
+	encryptionKey = key
+	return nil
+}
+
+func Encrypt(plaintext string) (string, error) {
+	if len(encryptionKey) == 0 {
+		return plaintext, nil
+	}
+	block, err := aes.NewCipher(encryptionKey)
+	if err != nil {
+		return "", err
+	}
+	aesGCM, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", err
+	}
+	nonce := make([]byte, aesGCM.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return "", err
+	}
+	ciphertext := aesGCM.Seal(nonce, nonce, []byte(plaintext), nil)
+	return hex.EncodeToString(ciphertext), nil
+}
+
+func Decrypt(ciphertextHex string) (string, error) {
+	if len(encryptionKey) == 0 {
+		return ciphertextHex, nil
+	}
+	ciphertext, err := hex.DecodeString(ciphertextHex)
+	if err != nil {
+		return "", err
+	}
+	block, err := aes.NewCipher(encryptionKey)
+	if err != nil {
+		return "", err
+	}
+	aesGCM, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", err
+	}
+	nonceSize := aesGCM.NonceSize()
+	if len(ciphertext) < nonceSize {
+		return "", fmt.Errorf("ciphertext too short")
+	}
+	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
+	plaintext, err := aesGCM.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return "", err
+	}
+	return string(plaintext), nil
+}
+
+func HashSHA256(data string) string {
+	h := sha256.Sum256([]byte(data))
+	return hex.EncodeToString(h[:])
+}