Converting PHP openssl script to openssl command

Question

I'm using the following method to decrypt the data,

$clear = openssl_decrypt($data, 'aes-256-cbc', $pass, 0, $iv);

$iv is always null, but it works

But when I use openssl to decrypt the same file (the data is base64 encoded),

openssl aes-256-cbc -d -a -in encrypted

After inputing the password, it says error reading input file, totally weird error

Any ideas?

Artjom B. · Accepted Answer · 2017-02-28 07:17:56Z

1

In PHP $pass is actually the full binary key. The openssl utility expects the actual password. You might want to use

openssl aes-256-cbc -d -a -in encrypted -K <hex-encoded key> -nosalt -iv 00000000000000000000000000000000

answered Feb 28, 2017 at 6:35

Artjom B.

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3 Comments

I've tried openssl 1.1, openssl 1.0.2 and 0.9.8, none of them have the -noiv command line option

The $pass is a user input, e.g abcdefg, so PHP transformed it to binary key?

It probably silently pads it with 0x00 bytes until the key has 256 bit. In your case abcdefg\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0.