PHP OpenSSL Encrypt vs Command Line Encypt

Question

I've been having some issues with the builtin methods for PHP OpenSSL. I'm attempting to narrow down the issue by trying different methods. I'm trying the following:

$input = "this is a test string";
$opensslCommand = "echo \"{$input}\" | openssl enc -AES-128-CBC -a -nosalt -K " . bin2hex($hashing_secret) . " -iv ". bin2hex($iv);

$first = openssl_encrypt($input, "AES-128-CBC", $hashing_secret, 0, $iv);
$second = exec($opensslCommand);

print(urlencode($first) . "<br/>");
print(urlencode($second) . "<br/>");

however, the output of the above is:

hn%2FZkGKl9EQ7XgFFytcPkTPxJST2jCKEVDoojmkz8xs%3D
hn%2FZkGKl9EQ7XgFFytcPkdQESeAPqlFNwJivth28m9o%3D

As you can see, they start to diverge in the middle of the output. Do I have the configuration wrong for either the builtin or the command line?

3rd party edit:
Making more sense of the output:

Base64 encoded:
hn/ZkGKl9EQ7XgFFytcPkTPxJST2jCKEVDoojmkz8xs=
hn/ZkGKl9EQ7XgFFytcPkdQESeAPqlFNwJivth28m9o=

In hex:
867FD990 62A5F444 3B5E0145 CAD70F91 33F12524 F68C2284 543A288E 6933F31B
867FD990 62A5F444 3B5E0145 CAD70F91 D40449E0 0FAA514D C098AFB6 1DBC9BDA

Examining the binary it is clear that the first 16-bytes are the first block and identical, the second 16-bytes are the second block and differ. So this may be an encryption mode issue of that the end portion of the data to be encrypted is different. — zaph, Jun 08 '16 at 17:19
An easy online way to check encryption is [AES Calculator](http://extranet.cryptomathic.com/aescalc) by Cryptomathic. There are other calculators for other algorithms. — zaph, Jun 08 '16 at 17:22

score 2 · Accepted Answer · answered Jun 08 '16 at 16:39

echo is the culprit here. There's a certain parameter you can use with echo to suppress the newline it appends to its input string: -n. Turns out that was getting piped along with my input into openssl.

$opensslCommand = "echo -n \"{$input}\" | openssl enc -AES-128-CBC -a -nosalt -K " . bin2hex($hashing_secret) . " -iv ". bin2hex($iv);

is the correct command

PHP OpenSSL Encrypt vs Command Line Encypt

1 Answers1