=================
Tester for S/MIME
=================

main.py is a tester for S/MIME mail. 
Edit the config.ini with your mail server credentials and preferences and just run main.py to generate some fancy S/MIME messages. For example a mixed message with encrypted and non-encrypted content.
Note: Certificates should be PEM format with separate private key file. The private key file shall have NO password.

Example Run:
============

 S/MIME tester
-----------------

> loading config from: config.ini

> configuration: 

SMTP host: smtp.XXXX.XXXX.XXX
SMTP port: 587
From: [email protected]
To: ['[email protected]']
Use SSL: False
Use STARTTLS: True
S/MIME cipher: aes256_cbc
S/MIME hash digest algorithm: sha512
S/MIME signature algorithm: rsa
Signer certificate file: ./certs/XXXX_16384_512.crt
Signer key file: ./private/[email protected]_16384_512.key

Recipient cert files: ['./certs/[email protected]_16384_512.crt']

> sending mail


with attachments

Type 1: sending mixed smime email
message size: 6556858
...
<and other types as configured in main.py>
...

Configuration:
--------------
Edit the magic values in the starting section of the source code of main.py, it is easier to change small details in the source code than to configure each and every item in a config file. So the config file 
only has more or less static data such as account information.

Also configure account and mail server data in the config.ini file.
Here refer to the example config.ini file included.
The config.ini data is printed optionally when the program runs for documentation reasons.

Purpose:
--------
This S/MIME tester was written as part of a research project into S/MIME. It is intended to send different types of S/MIME messages which could also be nested in order to test email servers (not influenced) and email clients (very different behavior observed). A research paper on this topic will be published soon.

Credits:
--------
The Tester is based on the included library Python SMAIL written by Robert Habermann, which was a bit improved where needed:

====================
Library Python SMAIL
====================

This library makes it simple to create S/MIME messages in Python. It supports signing (using RSA keys),
encryption (using a public RSA key, in AES128-CBC, AES192-CBC or AES256-CBC modes) and the combination of both -
where the message is first signed and the result is then encrypted (*"enveloped"*).

The foundation of python-smail is the `oscrypto`_ library which provides access to the C-bindings of OpenSSL
and implements many high and low level functionality. Additionally `asn1crypto`_ is used which is *"A fast, pure
Python library for parsing and serializing ASN.1 structures."*.


Requirements
------------

* Python 3.5+
* asn1crypto
* oscrypto



Example
-------


Encryption
##########

The code below loads Bob's public key in PEM format and uses it to encrypt
the e-mail in S/MIME format::

    import os
    from email.mime.text import MIMEText
    from email.utils import formatdate
    from smail import encrypt_message

    message = MIMEText("This a plain text body!")
    message['Date'] = formatdate(localtime=True)
    message['From'] = "[email protected]"
    message['To'] = "[email protected]"
    message['Subject'] = "Text Message - Encrypted"

    cert = os.path.join('tests', 'testdata', 'BobRSASignByCarl.pem')

    encrypted_message = encrypt_message(message, [cert])
    print(encrypted_message.as_string())

Output::

    MIME-Version: 1.0
    Content-Type: application/pkcs7-mime; smime-type=enveloped-data; name=smime.p7m
    Content-Transfer-Encoding: base64
    Content-Disposition: attachment; filename=smime.p7m
    Date: Tue, 17 Mar 2020 19:58:17 +0100
    From: [email protected]
    To: [email protected]
    Subject: Plain Text Message

    MIIBhwYJKoZIhvcNAQcDoIIBeDCCAXQCAQAxgb4wgbsCAQAwJjASMRAwDgYDVQQD
    EwdDYXJsUlNBAhBGNGvHgABWvBHTbi7NXXHQMAsGCSqGSIb3DQEBAQSBgFmMsY5d
    H446eMYRwzVUREH2+Nv9VyflrA9rJlU/4yKqGGEnzt+YRPQaU+KoZ8iURaMB/GLE
    ZupCnJ79VAjs+RX6kyMtKMXvcsRkzR8GGGPLHNEbqqFmDY5VQrC/jA66w6/xPjdb
    hzVvf6SVWc4Aefv8xdQOMF1relsVahjvjFJrMIGtBgkqhkiG9w0BBwEwHQYJYIZI
    AWUDBAEqBBArK3YkdLMydTK8DyyQvUj+gIGAaC/h3NVeGcVpdkDI9iP4OxqC4chk
    BHeK+KpYJJYlelSt7D5LlRuRHjnRy3laU3bi1bxm0vxefx2ihf5rZRblpLWwnuft
    duFKvXKUX0Es6Q78LpY8Ng3IxMGYNMWiCTMyqDGgC32JRI3H8twsG0/NIoZxKDXQ
    1k7QedeP0a+JhVc=


Signing
#######

The code below loads Alice's private and public key in PEM format and uses it to
sign the e-mail in S/MIME format::

    import os
    from email.mime.text import MIMEText
    from email.utils import formatdate
    from smail import sign_message

    message = MIMEText("This a plain text body!")
    message['Date'] = formatdate(localtime=True)
    message['From'] = "[email protected]"
    message['To'] = "[email protected]"
    message['Subject'] = "Text Message - Signed"

    key_signer = os.path.join('tests', 'testdata', 'AlicePrivRSASign.pem')
    cert_signer = os.path.join('tests', 'testdata', 'AliceRSASignByCarl.pem')

    signed_message = sign_message(message, key_signer, cert_signer)
    print(signed_message.as_string())

Output::

    MIME-Version: 1.0
    Content-Type: multipart/signed; protocol="application/x-pkcs7-signature"; micalg="sha-256"; boundary="----39D1127DF0061CD9BB50644B14CCEF86"
    Date: Tue, 17 Mar 2020 20:02:11 +0100
    From: [email protected]
    To: [email protected]
    Subject: Plain Text Message

    This is an S/MIME signed message

    ------39D1127DF0061CD9BB50644B14CCEF86
    Content-Type: text/plain; charset="us-ascii"
    MIME-Version: 1.0
    Content-Transfer-Encoding: 7bit

    This a plain text body!
    ------39D1127DF0061CD9BB50644B14CCEF86
    Content-Type: application/x-pkcs7-signature; name="smime.p7s"
    Content-Transfer-Encoding: base64
    Content-Disposition: attachment; filename="smime.p7s"

    MIIEIwYJKoZIhvcNAQcCoIIEFDCCBBACAQExDzANBglghkgBZQMEAgEFADALBgkq
    hkiG9w0BBwGgggIwMIICLDCCAZWgAwIBAgIQRjRrx4AAVrwR024uxBCzsDANBgkq
    hkiG9w0BAQUFADASMRAwDgYDVQQDEwdDYXJsUlNBMB4XDTk5MDkxOTAxMDg0N1oX
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    V1VLPuFuL9+BDcXarthOSnn4wbdRBhceRu7w8OnyoTtrwP58c0MiQVtyBQq1FuPZ
    WBKduWYjIg==

    ------39D1127DF0061CD9BB50644B14CCEF86--

Sign and Encrypt
################

The code below loads Alice's private and public key and also Bob's public key in PEM format and uses
it to sign and encrypt the e-mail (from Alice to Bob) in S/MIME format::


    import os
    from email.mime.text import MIMEText
    from email.utils import formatdate
    from smail import sign_and_encrypt_message

    message = MIMEText("This a plain text body!")
    message['Date'] = formatdate(localtime=True)
    message['From'] = "[email protected]"
    message['To'] = "[email protected]"
    message['Subject'] = "Text Message - Signed and Encrypted"

    key_signer = os.path.join('tests', 'testdata', 'AlicePrivRSASign.pem')
    cert_signer = os.path.join('tests', 'testdata', 'AliceRSASignByCarl.pem')

    cert = os.path.join('tests', 'testdata', 'BobRSASignByCarl.pem')

    signed_encrypted_message = sign_and_encrypt_message(message, key_signer, cert_signer, [cert])
    print(signed_encrypted_message.as_string())

Output::

    MIME-Version: 1.0
    Content-Type: application/pkcs7-mime; smime-type=enveloped-data; name=smime.p7m
    Content-Transfer-Encoding: base64
    Content-Disposition: attachment; filename=smime.p7m
    Date: Tue, 17 Mar 2020 20:05:34 +0100
    From: [email protected]
    To: [email protected]
    Subject: Text Message - Signed and Encrypted

    MIIIuQYJKoZIhvcNAQcDoIIIqjCCCKYCAQAxgb4wgbsCAQAwJjASMRAwDgYDVQQD
    EwdDYXJsUlNBAhBGNGvHgABWvBHTbi7NXXHQMAsGCSqGSIb3DQEBAQSBgH5C7eTN
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Acknowledgements
================

**Python SMAIL** is heavily inspired by `python-smime`_ and is actually a fork of that code base. All credits go to
original Author(s).


License
=======

This software is licensed under the Apache License 2.0. See the LICENSE file in
the top distribution directory for the full license text.


Versioning
==========

This software follows `Semantic Versioning`_


IMPORTED FROM:
https://gitlab.com/rhab/python-smail


.. _asn1crypto: https://github.com/wbond/asn1crypto
.. _oscrypto: https://github.com/wbond/oscrypto
.. _python-smime: https://github.com/balena/python-smime
.. _Semantic Versioning: http://semver.org/