Package: 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 theoscryptolibrary which provides access to the C-bindings of OpenSSL
and implements many high and low level functionality. Additionallyasn1cryptois used which is“A fast, pure
Python library for parsing and serializing ASN.1 structures.”.RequirementsPython 3.5+asn1cryptooscryptoExampleEncryptionThe 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'] = "AliceRSA@example.com"
message['To'] = "BobRSA@example.com"
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: AliceRSA@example.com
To: BobRSA@example.com
Subject: Plain Text Message

MIIBhwYJKoZIhvcNAQcDoIIBeDCCAXQCAQAxgb4wgbsCAQAwJjASMRAwDgYDVQQD
EwdDYXJsUlNBAhBGNGvHgABWvBHTbi7NXXHQMAsGCSqGSIb3DQEBAQSBgFmMsY5d
H446eMYRwzVUREH2+Nv9VyflrA9rJlU/4yKqGGEnzt+YRPQaU+KoZ8iURaMB/GLE
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hzVvf6SVWc4Aefv8xdQOMF1relsVahjvjFJrMIGtBgkqhkiG9w0BBwEwHQYJYIZI
AWUDBAEqBBArK3YkdLMydTK8DyyQvUj+gIGAaC/h3NVeGcVpdkDI9iP4OxqC4chk
BHeK+KpYJJYlelSt7D5LlRuRHjnRy3laU3bi1bxm0vxefx2ihf5rZRblpLWwnuft
duFKvXKUX0Es6Q78LpY8Ng3IxMGYNMWiCTMyqDGgC32JRI3H8twsG0/NIoZxKDXQ
1k7QedeP0a+JhVc=SigningThe 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'] = "AliceRSA@example.com"
message['To'] = "BobRSA@example.com"
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: AliceRSA@example.com
To: BobRSA@example.com
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
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------39D1127DF0061CD9BB50644B14CCEF86--Sign and EncryptThe 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'] = "AliceRSA@example.com"
message['To'] = "BobRSA@example.com"
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: AliceRSA@example.com
To: BobRSA@example.com
Subject: Text Message - Signed and Encrypted

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e3FI2iig5N6ytDwcN2MGTzr0SuhUe+JEQys2z2A=AcknowledgementsPython SMAILis heavily inspired bypython-smimeand is actually a fork of that code base. All credits go to
original Author(s).LicenseThis software is licensed under the Apache License 2.0. See the LICENSE file in
the top distribution directory for the full license text.VersioningThis software followsSemantic Versioning