gnupg decrypt command with php with passphrase - php

Question

Im using Gnupg to decrypt a file:
gpg --decrypt -o file.xml file.gpg
You need a passphrase to unlock the secret key for
user: "TEST-COMPANY (DAM Key) <test#test.de>"
4096-bit RSA key, ID 257C2D21, created 2018-04-23
Enter passphrase:
Then I write this passphrase and then works.
And now I want to make it automatic using this command on PHP:
$command = 'gpg --decrypt -o file.xml file.gpg'
exec($command);
The problem came when system ask for phassphrase.
I tried this:
$command = 'gpg --decrypt -o file.xml file.gpg | [Passphrase]'
but doesn't work.
Any idea about this?
Thank you

Answer 1

Just adding the answer that the OP and #CD001 figured out in the comments, because it helped me immensely (thanks!), and seems like a common issue (secret key was generated with passphrase, and generating new keys isn't an option). I was pulling my hair out trying to decrypt with the GnuPG functions, before learning that as of GnuPG 2.1, it can't decrypt a file with passphrase-generated key (as noted in comment here). Configuring gpg-agent with a preset passphrase may work fine, but I much prefer what the OP here did.
$encrypted_file = "file.csv.pgp";
$path_to_file = $_SERVER["DOCUMENT_ROOT"]."/dir1/dir2";
$passphrase = "passphrase";
$command = "echo {$passphrase} | gpg --passphrase-fd 0 --batch --yes {$path_to_file}/{$encrypted_file}";
exec($command);
If successful, the decrypted file will be in the same directory, without the .pgp extension. So make sure it was successful...
$decrypted_file = str_replace(".pgp", "", $encrypted_file );
if (file_exists("{$path_to_file}/{$decrypted_file}")) {
echo "Successfully decrypted $encrypted_file to $decrypted_file";
}