137 lines
3.2 KiB
Go
137 lines
3.2 KiB
Go
package lib
|
|
|
|
import (
|
|
"crypto/aes"
|
|
"crypto/cipher"
|
|
"crypto/hmac"
|
|
"crypto/rand"
|
|
"crypto/sha256"
|
|
"errors"
|
|
"io"
|
|
|
|
"github.com/klauspost/compress/zstd"
|
|
"golang.org/x/crypto/hkdf"
|
|
)
|
|
|
|
var (
|
|
ErrDecryptionFailed = errors.New("decryption failed")
|
|
ErrInvalidCiphertext = errors.New("invalid ciphertext")
|
|
)
|
|
|
|
// DeriveEntryKey derives a per-entry AES-256 key from the vault key using HKDF-SHA256.
|
|
func DeriveEntryKey(vaultKey []byte, entryID string) ([]byte, error) {
|
|
info := []byte("clawvault-entry-" + entryID)
|
|
reader := hkdf.New(sha256.New, vaultKey, nil, info)
|
|
key := make([]byte, 32) // AES-256
|
|
if _, err := io.ReadFull(reader, key); err != nil {
|
|
return nil, err
|
|
}
|
|
return key, nil
|
|
}
|
|
|
|
// DeriveHMACKey derives a separate HMAC key for blind indexes.
|
|
func DeriveHMACKey(vaultKey []byte) ([]byte, error) {
|
|
info := []byte("clawvault-hmac-index")
|
|
reader := hkdf.New(sha256.New, vaultKey, nil, info)
|
|
key := make([]byte, 32)
|
|
if _, err := io.ReadFull(reader, key); err != nil {
|
|
return nil, err
|
|
}
|
|
return key, nil
|
|
}
|
|
|
|
// BlindIndex computes an HMAC-SHA256 blind index for searchable encrypted fields.
|
|
// Returns truncated hash (16 bytes) for storage efficiency.
|
|
func BlindIndex(hmacKey []byte, plaintext string) []byte {
|
|
h := hmac.New(sha256.New, hmacKey)
|
|
h.Write([]byte(plaintext))
|
|
return h.Sum(nil)[:16] // truncate to 16 bytes
|
|
}
|
|
|
|
// Pack compresses with zstd then encrypts with AES-256-GCM (random nonce).
|
|
func Pack(key []byte, plaintext string) ([]byte, error) {
|
|
compressed, err := zstdCompress([]byte(plaintext))
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
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
|
|
}
|
|
|
|
return gcm.Seal(nonce, nonce, compressed, nil), nil
|
|
}
|
|
|
|
// Unpack decrypts AES-256-GCM then decompresses zstd.
|
|
func Unpack(key []byte, ciphertext []byte) (string, error) {
|
|
if len(ciphertext) == 0 {
|
|
return "", nil
|
|
}
|
|
|
|
block, err := aes.NewCipher(key)
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
|
|
gcm, err := cipher.NewGCM(block)
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
|
|
nonceSize := gcm.NonceSize()
|
|
if len(ciphertext) < nonceSize {
|
|
return "", ErrInvalidCiphertext
|
|
}
|
|
|
|
nonce, ct := ciphertext[:nonceSize], ciphertext[nonceSize:]
|
|
compressed, err := gcm.Open(nil, nonce, ct, nil)
|
|
if err != nil {
|
|
return "", ErrDecryptionFailed
|
|
}
|
|
|
|
decompressed, err := zstdDecompress(compressed)
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
|
|
return string(decompressed), nil
|
|
}
|
|
|
|
// zstd encoder/decoder (reusable, goroutine-safe)
|
|
var (
|
|
zstdEncoder, _ = zstd.NewWriter(nil, zstd.WithEncoderLevel(zstd.SpeedDefault))
|
|
zstdDecoder, _ = zstd.NewReader(nil)
|
|
)
|
|
|
|
func zstdCompress(data []byte) ([]byte, error) {
|
|
return zstdEncoder.EncodeAll(data, nil), nil
|
|
}
|
|
|
|
func zstdDecompress(data []byte) ([]byte, error) {
|
|
return zstdDecoder.DecodeAll(data, nil)
|
|
}
|
|
|
|
// GenerateToken generates a random hex token (32 bytes = 64 hex chars).
|
|
func GenerateToken() string {
|
|
b := make([]byte, 32)
|
|
rand.Read(b)
|
|
const hex = "0123456789abcdef"
|
|
result := make([]byte, 64)
|
|
for i, v := range b {
|
|
result[i*2] = hex[v>>4]
|
|
result[i*2+1] = hex[v&0x0f]
|
|
}
|
|
return string(result)
|
|
}
|