How to programmatically calculate Chrome extension ID?

Question

I\'m building an automated process to produce extensions. Is there a code example of calculating the extension-ID directly and entirely bypassing interaction with the browse

Answer 1

A nice and simple way to get the public key from the .crx file using python, since chrome only generates the private .pem key for you. The public key is actually stored in the .crx file.

This is based on the format of the .crx file found here http://developer.chrome.com/extensions/crx.html

import struct
import hashlib
import string

def get_pub_key_from_crx(crx_file):
    with open(crx_file, 'rb') as f:
        data = f.read()
    header = struct.unpack('<4sIII', data[:16])
    pubkey = struct.unpack('<%ds' % header[2], data[16:16+header[2]])[0]
    return pubkey

def get_extension_id(crx_file):
    pubkey = get_pub_key_from_crx(crx_file)
    digest = hashlib.sha256(pubkey).hexdigest()

    trans = string.maketrans('0123456789abcdef', string.ascii_lowercase[:16])
    return string.translate(digest[:32], trans)

if __name__ == '__main__':
    import sys
    if len(sys.argv) != 2:
        print 'usage: %s crx_file' % sys.argv[0]

    print get_extension_id(sys.argv[1])

Although this isn't possible to do "bypassing interaction with the browser", because you still need to generate the .crx file with a command like

chrome.exe --pack-extension=my_extension --pack-extension-key=my_extension.pem