package db
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"encoding/base64"
"errors"
"fmt"
"os"
"strings"
)
var encryptionKey []byte
// InitEncryptionKey loads CREDENTIAL_ENCRYPTION_KEY from env.
// Must be called at startup. Panics if the key is not set or invalid.
func InitEncryptionKey() {
raw := os.Getenv("CREDENTIAL_ENCRYPTION_KEY")
if raw == "" {
panic("CREDENTIAL_ENCRYPTION_KEY is required")
}
key, err := base64.StdEncoding.DecodeString(raw)
if err != nil || len(key) != 32 {
panic(fmt.Sprintf("CREDENTIAL_ENCRYPTION_KEY must be 32 bytes base64-encoded (got %d bytes)", len(key)))
}
encryptionKey = key
}
const encryptionVersion = "v1"
// encrypt encrypts plaintext with AES-256-GCM.
// Returns "v1:" + base64-encoded nonce+ciphertext.
func encrypt(plaintext []byte) (string, error) {
block, err := aes.NewCipher(encryptionKey)
if err != nil {
return "", err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return "", err
}
nonce := make([]byte, gcm.NonceSize())
if _, err := rand.Read(nonce); err != nil {
return "", err
}
sealed := gcm.Seal(nonce, nonce, plaintext, nil) // nonce || ciphertext || tag
return encryptionVersion + ":" + base64.StdEncoding.EncodeToString(sealed), nil
}
// decrypt decrypts a versioned ciphertext string.
// Supports "v1:base64data" format.
func decrypt(ciphertext string) ([]byte, error) {
data := ciphertext
if strings.HasPrefix(ciphertext, "v1:") {
data = ciphertext[3:]
}
raw, err := base64.StdEncoding.DecodeString(data)
if err != nil {
return nil, err
}
block, err := aes.NewCipher(encryptionKey)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
nonceSize := gcm.NonceSize()
if len(raw) < nonceSize {
return nil, errors.New("ciphertext too short")
}
return gcm.Open(nil, raw[:nonceSize], raw[nonceSize:], nil)
}
