#!/usr/bin/env python

from __future__ import print_function

"""S/MIME HOWTO demo program.

Copyright (c) 1999-2001 Ng Pheng Siong. All rights reserved."""

from M2Crypto import BIO, Rand, SMIME, X509


def makebuf(text):
    return BIO.MemoryBuffer(text)


# Make a MemoryBuffer of the message.
buf = makebuf("a sign of our times")

# Seed the PRNG.
Rand.load_file("randpool.dat", -1)

# Instantiate an SMIME object.
s = SMIME.SMIME()

# Load signer's key and cert. Sign the buffer.
s.load_key("signer_key.pem", "signer.pem")
p7 = s.sign(buf)

# Load target cert to encrypt the signed message to.
x509 = X509.load_cert("recipient.pem")
sk = X509.X509_Stack()
sk.push(x509)
s.set_x509_stack(sk)

# Set cipher: 3-key triple-DES in CBC mode.
s.set_cipher(SMIME.Cipher("des_ede3_cbc"))

# Create a temporary buffer.
tmp = BIO.MemoryBuffer()

# Write the signed message into the temporary buffer.
s.write(tmp, p7)

# Encrypt the temporary buffer.
p7 = s.encrypt(tmp)

# Output p7 in mail-friendly format.
out = BIO.MemoryBuffer()
out.write("From: sender@example.dom\n")
out.write("To: recipient@example.dom\n")
out.write("Subject: M2Crypto S/MIME testing\n")
s.write(out, p7)

print(out.read())

# Save the PRNG's state.
Rand.save_file("randpool.dat")
