import gpgme
import StringIO
import sys
import getpass
import os

def passphrase_cb(uid_hint, pass_info, prev_was_bad, fd):
    print uid_hint
    print pass_info
    print prev_was_bad
    print 'please provide the password for: %s' % uid_hint
    res = getpass.getpass()
    os.write(fd, '%s\n' % res)


ctx = gpgme.Context()
ctx.armor = True
ctx.passphrase_cb = passphrase_cb
key = ctx.get_key(sys.argv[1])
ctx.signers = [key]
plaintext = open(sys.argv[2], 'r')
signature = StringIO.StringIO()
new_sigs = ctx.sign(plaintext, signature, gpgme.SIG_MODE_DETACH)
signature.seek(0)
print signature.read()