How can I decrypt a PGP Self Decrypting Archive programatically? [closed]

Question

Everyday I receive SDA files for whom I have the passphrase. The decryption is done by running the file and manually entering a passphrase in the program window that pops up. I'd like to avoid this manual step, and turn it into a step of an automated process.

The way this would work is the following: As soon as my daemon detects that a new file has arrived to my inbox, my program would download, decrypt and save it. I know how to do all these with code, except the decryption part.

Instead of running the .exe file, and manually entering the passphrase, I want to read it's contents, and with the passphrase, decrypt the data contained within it, which looks like this:

4d5a 9000 0300 0000 0400 0000 ffff 0000
b800 0000 0000 0000 4000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 f000 0000
0e1f ba0e 00b4 09cd 21b8 014c cd21 5468
...etc

The language I'm currently using is PHP, but taking a look at an implementation in any language will help.

Any ideas?

Answer 1

PGP self-decrypting archives is just EXE stub + PGP message inside of this file. You should parse EXE headers, and found where this data is stored, extract it, and decrypt using GnuPG or any other PGP library.