#! /usr/bin/python

from sys import argv
import os as OS
import catacomb as C

MAGIC = 'SSH PRIVATE KEY FILE FORMAT 1.1\n\0'
keyring, tag, outfile = argv[1:]
kf = C.KeyFile(keyring)
k = kf[tag]
kd = k.data

n, e = [kd[label].mp for label in ['n', 'e']]
priv = kd['private']
d, p, q, dp, dq, q_inv = \
  [priv[label].mp for label in ['d', 'p', 'q', 'd-mod-p', 'd-mod-q', 'q-inv']]

buf = C.WriteBuffer()
buf.put(MAGIC)
buf.putu8(0) # symmetric cipher type
buf.putu32(0) # `reserved data'
buf.putu32(n.nbits) # `not sure what this is'
buf.putu16(n.nbits).put(n.storeb())
buf.putu16(e.nbits).put(e.storeb())
buf.putblk32(k.fulltag) # comment
buf.putu16(1234).putu16(1234)# `next two pairs of characters are identical'
buf.putu16(d.nbits).put(d.storeb())
buf.putu16(q_inv.nbits).put(q_inv.storeb())
buf.putu16(q.nbits).put(q.storeb())
buf.putu16(p.nbits).put(p.storeb())
outtmp = outfile + '.new'
with open(outtmp, 'wb') as f: f.write(buf)
OS.rename(outtmp, outfile)