MIME S/MIME Signing Algorithm Properties

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Demonstrates the properties that control S/MIME signing: SigningAlg (the RSA signature scheme, PKCS1-V1_5 or RSASSA-PSS), SigningHashAlg (the message-digest algorithm), Micalg and Protocol (the micalg and protocol parameters of a multipart/signed Content-Type), and UseXPkcs7 (whether historical x-pkcs7 media-type names are used). The properties are configured before creating a detached signature.

import sys
import chilkat

success = False

mime = chilkat.CkMime()
success = mime.SetBodyFromPlainText("This message will be signed.")
if (success == False):
    print(mime.lastErrorText())
    sys.exit()

#  SigningAlg is the RSA signature scheme.  The default is PKCS1-V1_5; set RSASSA-PSS (or pss) for
#  RSASSA-PSS.
mime.put_SigningAlg("PKCS1-V1_5")

#  SigningHashAlg is the message-digest algorithm.  The default is sha256.
mime.put_SigningHashAlg("sha256")

#  Micalg and Protocol are the micalg and protocol parameters written into a multipart/signed
#  Content-Type header field.  They are normally set automatically, but can be controlled here.
mime.put_Micalg("sha-256")
mime.put_Protocol("application/pkcs7-signature")

#  UseXPkcs7 controls whether newly created S/MIME media types use the historical x-pkcs7 names.
mime.put_UseXPkcs7(False)

#  Load a signing certificate (with private key access) from a PFX.  The PFX password should come
#  from a secure source rather than being hard-coded.
pfxPassword = "myPfxPassword"
cert = chilkat.CkCert()
success = cert.LoadPfxFile("qa_data/signer.pfx",pfxPassword)
if (success == False):
    print(cert.lastErrorText())
    sys.exit()

#  Create the detached signature using the algorithms configured above.
success = mime.AddDetachedSignature(cert)
if (success == False):
    print(mime.lastErrorText())
    sys.exit()

print("Signed with SigningAlg=" + mime.signingAlg() + " SigningHashAlg=" + mime.signingHashAlg())