forked from lightsparkdev/go-sdk
/
crypto.go
157 lines (131 loc) · 3.6 KB
/
crypto.go
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// Copyright ©, 2023-present, Lightspark Group, Inc. - All Rights Reserved
package utils
import (
"crypto"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/rsa"
"crypto/sha256"
"crypto/x509"
"encoding/base64"
"encoding/json"
"errors"
"golang.org/x/crypto/pbkdf2"
)
const KEY_LEN = 32
func SignPayload(payload []byte, signingKey []byte) (string, error) {
privateKey, err := x509.ParsePKCS8PrivateKey(signingKey)
if err != nil {
return "", err
}
rsaKey, ok := privateKey.(*rsa.PrivateKey)
if !ok {
return "", errors.New("private key is not an RSA key")
}
hashed := sha256.Sum256(payload)
signature, err := rsa.SignPSS(rand.Reader, rsaKey, crypto.SHA256, hashed[:], nil)
if err != nil {
return "", err
}
return base64.StdEncoding.EncodeToString(signature), nil
}
func DecryptPrivateKey(cipherVersion string, encryptedValue string,
password string) ([]byte, error) {
decoded, err := base64.StdEncoding.DecodeString(encryptedValue)
if err != nil {
return nil, err
}
var header map[string]interface{}
if cipherVersion == "AES_256_CBC_PBKDF2_5000_SHA256" {
header = map[string]interface{}{"v": 0, "i": 5000}
decoded = decoded[8:]
} else {
err = json.Unmarshal([]byte(cipherVersion), &header)
if err != nil {
return nil, err
}
if lvs, ok := header["lsv"]; ok {
if lvs.(int) == 2 {
header["v"] = 3
}
}
}
version := int(header["v"].(float64))
if version < 0 || version > 4 {
return nil, errors.New("unknown version ")
}
iteration := int(header["i"].(float64))
if version == 3 {
salt := decoded[len(decoded)-8:]
nonce := decoded[0:12]
ciphertext := decoded[12 : len(decoded)-8]
key := deriveKey([]byte(password), salt, iteration)
return decryptGcm(ciphertext, key, nonce)
}
var saltLen, ivLen int
if version < 4 {
saltLen = 8
ivLen = 16
} else {
saltLen = 16
ivLen = 12
}
salt := decoded[:saltLen]
ciphertext := decoded[saltLen:]
key, iv := deriveKeyIv([]byte(password), salt, iteration, KEY_LEN+ivLen)
if version < 2 {
return decryptCbc(ciphertext, key, iv)
} else {
return decryptGcm(ciphertext, key, iv)
}
}
func deriveKey(password []byte, salt []byte, iterations int) []byte {
return pbkdf2.Key(password, salt, iterations, 32, sha256.New)
}
func deriveKeyIv(password []byte, salt []byte, iterations int, length int) ([]byte, []byte) {
derived := pbkdf2.Key(password, salt, iterations, length, sha256.New)
return derived[:KEY_LEN], derived[KEY_LEN:]
}
func decryptGcm(ciphertext []byte, key []byte, nonce []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
}
return gcm.Open(nil, nonce, ciphertext, nil)
}
func decryptCbc(ciphertext []byte, key []byte, nonce []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
mode := cipher.NewCBCDecrypter(block, nonce)
decryptedData := make([]byte, len(ciphertext)-aes.BlockSize)
mode.CryptBlocks(decryptedData, ciphertext[aes.BlockSize:])
// Remove PKCS7 padding from the decrypted data
unpaddedData, err := pkcs7Unpad(decryptedData)
if err != nil {
return nil, err
}
return unpaddedData, nil
}
func pkcs7Unpad(data []byte) ([]byte, error) {
if len(data) == 0 {
return nil, errors.New("cannot unpad empty data")
}
paddingLength := int(data[len(data)-1])
if paddingLength > len(data) {
return nil, errors.New("invalid padding length")
}
padding := data[len(data)-paddingLength:]
for _, b := range padding {
if int(b) != paddingLength {
return nil, errors.New("invalid padding")
}
}
return data[:len(data)-paddingLength], nil
}