[NFR] The Cookie encrypted, I want to get the value of the original

[iwai]

In this case, I want to get the value set.
I want you to return, the value that you trim the "\ 0".

And I have confirmed for this issue. #749

$key  = 'passowrd';
$text = 'a';

$di = new Phalcon\DI\FactoryDefault();
$di->set('crypt', function() use ($key) {
    $crypt = new Phalcon\Crypt();
    $crypt->setKey($key);
    return $crypt;
});

$_COOKIE['test-key'] = $di->get('crypt')->encryptBase64($text, $key);

$cookie = new Phalcon\Http\Response\Cookies();
$cookie->useEncryption(true);
$cookie->setDI($di);

var_dump($cookie->get('test-key')->getValue());

Output:

string(32) "a\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"

[ghost]

@phalcon

This patch implements encryption/decryption with PKCS7 padding (this will make sure that the decrypted string will be exactly the same as the original one — the length will be preserved) and this will allow one to use encrypt/decrypt with cookies just like @iwai wants:

diff --git a/ext/crypt.c b/ext/crypt.c
index 7b447aa..bd0db33 100644
--- a/ext/crypt.c
+++ b/ext/crypt.c
@@ -168,7 +168,9 @@ PHP_METHOD(Phalcon_Crypt, getKey){
 PHP_METHOD(Phalcon_Crypt, encrypt){

        zval *text, *key = NULL, *encrypt_key = NULL, *cipher, *mode, *iv_size;
-       zval *key_size, *rand, *iv, *encrypt, *final_encrypt;
+       zval *key_size, *rand, *iv, *encrypt, *block_size, *padded;
+       unsigned char pad;
+       char *padding;

        PHALCON_MM_GROW();

@@ -216,13 +218,30 @@ PHP_METHOD(Phalcon_Crypt, encrypt){
        PHALCON_INIT_VAR(iv);
        phalcon_call_func_p2(iv, "mcrypt_create_iv", iv_size, rand);

+       PHALCON_INIT_VAR(block_size);
+       phalcon_call_func_p2(block_size, "mcrypt_get_block_size", cipher, mode);
+       convert_to_long_ex(&block_size);
+       pad = (unsigned char)(Z_LVAL_P(block_size) - (Z_STRLEN_P(text) % Z_LVAL_P(block_size)));
+
+#ifdef HAVE_ALLOCA
+       padding = alloca(pad);
+#else
+       padding = emalloc(pad);
+#endif
+       memset(padding, pad, pad);
+
+       PHALCON_INIT_VAR(padded);
+       phalcon_concat_vs(&padded, text, padding, pad, 0 TSRMLS_CC);
+
+#ifndef HAVE_ALLOCA
+       efree(padding);
+#endif
+
        PHALCON_INIT_VAR(encrypt);
-       phalcon_call_func_p5(encrypt, "mcrypt_encrypt", cipher, encrypt_key, text, mode, iv);
-       
-       PHALCON_INIT_VAR(final_encrypt);
-       PHALCON_CONCAT_VV(final_encrypt, iv, encrypt);
+       phalcon_call_func_p5(encrypt, "mcrypt_encrypt", cipher, encrypt_key, padded, mode, iv);

-       RETURN_CTOR(final_encrypt);
+       PHALCON_CONCAT_VV(return_value, iv, encrypt);
+       RETURN_MM();
 }

 /**
@@ -239,7 +258,8 @@ PHP_METHOD(Phalcon_Crypt, encrypt){
 PHP_METHOD(Phalcon_Crypt, decrypt){

        zval *text, *key = NULL, *decrypt_key = NULL, *cipher, *mode, *iv_size;
-       zval *key_size, *text_size, *zero, *iv, *text_to_decipher;
+       zval *key_size, *text_size, *iv, *text_to_decipher, *decrypted;
+       unsigned char pad;

        PHALCON_MM_GROW();

@@ -273,6 +293,7 @@ PHP_METHOD(Phalcon_Crypt, decrypt){

        PHALCON_INIT_VAR(iv_size);
        phalcon_call_func_p2(iv_size, "mcrypt_get_iv_size", cipher, mode);
+       convert_to_long_ex(&iv_size);

        PHALCON_INIT_VAR(key_size);
        phalcon_fast_strlen(key_size, decrypt_key);
@@ -288,15 +309,32 @@ PHP_METHOD(Phalcon_Crypt, decrypt){
                return;
        }

-       PHALCON_INIT_VAR(zero);
-       ZVAL_LONG(zero, 0);
-       
        PHALCON_INIT_VAR(iv);
-       phalcon_call_func_p3(iv, "substr", text, zero, iv_size);
+       phalcon_substr(iv, text, 0, Z_LVAL_P(iv_size));

        PHALCON_INIT_VAR(text_to_decipher);
-       phalcon_call_func_p2(text_to_decipher, "substr", text, iv_size);
-       phalcon_call_func_p5(return_value, "mcrypt_decrypt", cipher, decrypt_key, text_to_decipher, mode, iv);
+       phalcon_substr(text_to_decipher, text, Z_LVAL_P(iv_size), 0);
+
+       PHALCON_INIT_VAR(decrypted);
+       phalcon_call_func_p5(decrypted, "mcrypt_decrypt", cipher, decrypt_key, text_to_decipher, mode, iv);
+       convert_to_string_ex(&decrypted);
+
+       if (Z_STRLEN_P(decrypted)) {
+               pad = (unsigned char)(Z_STRVAL_P(decrypted)[Z_STRLEN_P(decrypted) - 1]);
+               if (pad < Z_STRLEN_P(decrypted)) {
+                       phalcon_substr(return_value, decrypted, 0, Z_STRLEN_P(decrypted) - pad);
+               }
+               else if (pad == Z_STRLEN_P(decrypted)) {
+                       RETVAL_EMPTY_STRING();
+               }
+               else {
+                       RETVAL_FALSE;
+               }
+       }
+       else {
+               RETVAL_FALSE;
+       }
+
        RETURN_MM();
 }

However, there is one major drawback: this is not compatible with the original encrypt() implementation: this decrypt() implementation won't be able to decrypt the text encrypted with the original encrypt().

What would you suggest?

[phalcon]

Can we add a method to Phalcon\Encrypt to specify that PKCS7 padding must be used?

[ghost]

Yes, we can but does it mean that we will have to update CryptInterface as well?

[phalcon]

@yES,

something like:

$crypt = new Phalcon\Crypt();
$crypt->usePadding(false);

[ghost]

OK, makes sense.

[ghost]

OK, I am going to implement

• PKCS#7 padding
• ANSI X.923 padding
• ISO 10126 padding
• ISO/IEC 7816-4 padding
• partially reversible zero padding

[iwai]

Sorry for reply late.
Everyone, Thank you for fast answer.
Thank you very much @sjinks !!

[ghost]

Fixed in #887