Invoke OpenSSL command via shell_exec() in PHP [duplicate]

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Run Bash Command from PHP (3 answers)

Closed 9 years ago.

When I execute:

openssl_decrypt(
 base64_decode(file_get_contents('/path/to/file')),
 'aes-256-cbc',
 $key,
 OPENSSL_RAW_DATA,
 $iv
);

OpenSSL decrypts my file perfectly. However, when I execute:

shell_exec('openssl enc -aes-256-cbc -base64 -d -A -p -K ' . $key . ' -iv ' . $iv . ' -in /path/to/file -out /path/to/dest');

The destination file is not created.

Does anyone know what could be wrong? My client wants to be able to upload large files up to 2GB, and loading that much data into a PHP variable seems like an exceedingly bad idea.

Edit:

With bin2hex i get a seemingly sane command of:

openssl enc -aes-256-cbc -base64 -d -A -p -K 64343438343165333635663434663262633036636235656462383238356239303763373365353633 -iv abdd099c7bac8b514089d8c901c8395c -in /usr/www/vault/new/d71fd708181573c5f92c8f500ddcb399/787 -out /tmp/decrypted/57574484b684c

But with pack I get:

openssl enc -aes-256-cbc -base64 -d -A -p -K M�>VO���[ދ�� �7^6 -iv ⬧⬧⬧⬧⬧⬧⬧ -in /usr/www/vault/new/d71fd708181573c5f92c8f500ddcb399/787 -out /tmp/decrypted57574484b684c

• Machavity: Does your web user have permissions to run that file?
• user1119648: Yes, permissions are correct because the php openssl_decrypt command will decrypt the file perfectly with the same input parameters.
• Artjom B.: $key and $iv must be hex encoded for the command.
• user1119648: This question is not about how to execute shell commands in php, it's about openssl no decrypting files properly.

Answer 1

Maybe you need to encode your parameters so the shell can actually execute the command:

shell_exec('openssl enc -aes-256-cbc -base64 -d -A -p -K '
 . escapeshellarg($key) . ' -iv ' . escapeshellarg($iv)
 . ' -in /path/to/file -out /path/to/dest');

The same can be true for your file names if they contain e.g. spaces.

Edit: Actually Artjom B. is right: openssl says: -K/-iv key/iv in hex is the next argument. So you need to hex-encode it:

shell_exec('openssl enc -aes-256-cbc -base64 -d -A -p -K '
 . bin2hex($key) . ' -iv ' . bin2hex($iv)
 . ' -in /path/to/file -out /path/to/dest');

• user1119648: Yeah, I've tried hex encoding my key and iv to hex and it still doesn't output anything. I'm going to keep looking at it.
• Dennis B.: bin2hex encodes with "highest nibble first" which is network byte order. You can try to encode it with "lowest nibble first"/little endian, which is the byte order of a normal intel based PC, using pack: pack("h*", $key)