Create S/MIME with Detached Signature

Python example to create a simple S/MIME message with a detached digital signature.

Download Chilkat Python Library

import sys
import chilkat

mime = chilkat.CkMime()

#  Any string argument automatically begins the 30-day trial.
success = mime.UnlockComponent("30-day trial")
if (success != True):
    print "MIME component unlock failed"
    sys.exit()

#  Find our digital certificate from the Current User certificate store.
ccs = chilkat.CkCreateCS()

certStore = ccs.OpenCurrentUserStore()

cert = certStore.FindCertBySubjectCN("Chilkat Software, Inc.")

if (cert == None ):
    print cert.lastErrorText()
    sys.exit()

#  Our MIME object is currently empty.  Add some header fields
#  and a body:
mime.AddHeaderField("subject","this is a test")
mime.AddHeaderField("test123","this is a test 123")
mime.put_ContentType("text/plain")
mime.put_Charset("iso-8859-1")
mime.SetBodyFromPlainText("This is the body")

print "Original MIME message:"
print mime.getMime()

#  The original MIME looks like this:
#  ----------------------------------
#  subject: this is a test
#  test123: this is a test 123
#  content-type: text/plain;
#  	 charset="iso-8859-1"
# 
#  This is the body
#  ----------------------------------

#  Add a detached signature.  Transfer the header fields
#  from our existing MIME to what will become the new outer
#  envelope.
transferHeaderFields = True
success = mime.AddDetachedSignature2(cert,transferHeaderFields)
if (success != True):
    print mime.lastErrorText()
    sys.exit()

print "----------------------------------"
print "S/MIME with detached signature:"
print mime.getMime()

print "Success!"

#  The signed MIME looks like this:
#  --------------------------------
#  content-type: multipart/signed;
#  	boundary="----=_NextPart_e7c_2b68_282042d9.6ba23d56";
#  	protocol="application/x-pkcs7-signature";
#  	micalg=SHA1
#  subject: this is a test
#  test123: this is a test 123
# 
#  This is a multi-part message in MIME format.
# 
#  ------=_NextPart_e7c_2b68_282042d9.6ba23d56
#  content-type: text/plain;
#  	 charset="iso-8859-1"
# 
#  This is the body
#  ------=_NextPart_e7c_2b68_282042d9.6ba23d56
#  content-transfer-encoding: base64
#  content-type: application/x-pkcs7-signature;
#  	name="smime.p7s"
#  content-disposition: attachment;
#  	 filename="smime.p7s"
# 
#  MIIGAAYJKoZIhvcNAQcCoIIF8TCCBe0CAQExCzAJBgUrDgMCGgUAMAsGCSqGSIb3DQEHAaCC
#  A9kwggPVMIIDPqADAgECAhB4ouTcAmLszrGi170k1deSMA0GCSqGSIb3DQEBBQUAMFUxCzAJ
#  BgNVBAYTAlpBMSUwIwYDVQQKExxUaGF3dGUgQ29uc3VsdGluZyAoUHR5KSBMdGQuMR8wHQYD
#  VQQDExZUaGF3dGUgQ29kZSBTaWduaW5nIENBMB4XDTA3MDExNTAwMDAwMFoXDTA4MDExNTIz
#  NTk1OVowgZ0xCzAJBgNVBAYTAlVTMREwDwYDVQQIEwhJbGxpbm9pczEQMA4GA1UEBxMHV2hl
#  YXRvbjEfMB0GA1UEChMWQ2hpbGthdCBTb2Z0d2FyZSwgSW5jLjEnMCUGA1UECxMeU2VjdXJl
#  IEFwcGxpY2F0aW9uIERldmVsb3BtZW50MR8wHQYDVQQDExZDaGlsa2F0IFNvZnR3YXJlLCBJ
#  bmMuMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwR2t6b/Kn4VzNCOlj1YGkHxD
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#  oWK88fkOo81pqHogTpGfy4nibWg72XkPk135leMw/Jme37q7OR/zm6HceFlyyO0WL1fYx09P
#  pYbj1lYNvVo8n38ohT8T/7h3N4GUlQIDAQABo4HYMIHVMAwGA1UdEwEB/wQCMAAwPgYDVR0f
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#  CSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMDcwNDA0MTkzMDUyWjAjBgkqhkiG9w0BCQQx
#  FgQUevptGkutc0lb6gI3NPHovx4Di34wDQYJKoZIhvcNAQEBBQAEggEAk4jqKMsn7D+MjGtY
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#  RunBBTJ+BxCbDXfjwJJTYVy1Uhsedv+o7Gfj9LlAVysNLjda5VcU7x/OOBVst034X+map3ds
#  85yBrfcJ/LyQs/lyZYmSPgOpFIBSy3oULPzYt45EUVsuk5qSZ1MA4HeIDW37b8OfQOW8pLEL
#  cBRducU19lpDOp5hBRZDR3zu+/9ddWKxKvcH04WitYRBi5TtqhQxpep+vRhJX8EPY6cgenJ+
#  lbDURg552YftF4EpDGALADR41j6sUMzb0QOz4A==
# 
#  ------=_NextPart_e7c_2b68_282042d9.6ba23d56--
# 
#