update response

docs/lz-string.go

@@ -1,6 +1,10 @@
 package docs
 
 import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/sha256"
+	"encoding/base64"
 	"errors"
 	"math"
 	"unicode/utf8"
@@ -109,3 +113,71 @@ func DecompressFromEncodedUriComponent(input string) (string, error) {
 
 	return "", errors.New("Unexpected end of buffer reached.")
 }
+
+func StringDecrypt(key string, str string) string {
+	// hash
+	keyHash := sha256.Sum256([]byte(key))
+
+	// iv - encrypt method AES-256-CBC expects 16 bytes - else you will get a warning
+	iv := keyHash[:16]
+
+	// create a new aes cipher using the key and iv
+	block, err := aes.NewCipher(keyHash[:32])
+	if err != nil {
+		panic(err)
+	}
+
+	// decode the base64 string to a []byte
+	ciphertext, _ := base64.StdEncoding.DecodeString(str)
+
+	// create the decrypter
+	decrypter := cipher.NewCBCDecrypter(block, iv)
+
+	// decrypt
+	decrypted := make([]byte, len(ciphertext))
+	decrypter.CryptBlocks(decrypted, ciphertext)
+
+	// remove padding
+	padLen := int(decrypted[len(decrypted)-1])
+	decrypted = decrypted[:len(decrypted)-padLen]
+
+	return string(decrypted)
+}
+
+func ResponseVclaim(encrypted string, key string) (string, error) {
+
+	cipherText, err := base64.StdEncoding.DecodeString(encrypted)
+	if err != nil {
+		return "", err
+	}
+
+	hash := sha256.Sum256([]byte(key))
+
+	block, err := aes.NewCipher(hash[:])
+	if err != nil {
+		return "", err
+	}
+
+	if len(cipherText) < aes.BlockSize {
+		return "", errors.New("cipherText too short")
+	}
+
+	iv := hash[:aes.BlockSize]
+
+	if len(cipherText)%aes.BlockSize != 0 {
+		return "", errors.New("cipherText is not a multiple of the block size")
+	}
+
+	mode := cipher.NewCBCDecrypter(block, iv)
+	mode.CryptBlocks(cipherText, cipherText)
+
+	// cipherText, _ = pkcs7.Unpad(cipherText, aes.BlockSize)
+	cipherText, _ = Unpad(cipherText, aes.BlockSize)
+	// data, err := lzstring.DecompressFromEncodedURIComponent(string(cipherText))
+	data, err := DecompressFromEncodedUriComponent(string(cipherText))
+	if err != nil {
+		return "", err
+	}
+
+	return data, nil
+}