PKCS7 SignedData Signature (embeds Signed Data)

How to create a PKCS7 signature. The resulting PKCS7 structure is encoded to a printable string using hex or base64 encoding. The data being signed is embedded within the PKCS#7 structure.

Demonstrates how to verify the signature and recover the original data.

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import sys
import chilkat

crypt = chilkat.CkCrypt2()

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

cert = chilkat.CkCert()
success = cert.LoadByCommonName("Chilkat Software")
if (success != True):
    print cert.lastErrorText()
    sys.exit()

#  Make sure this certificate has a private key available:

bHasPrivateKey = cert.HasPrivateKey()
if (bHasPrivateKey != True):
    print "No private key available for signing."
    sys.exit()

#  Tell the encryption component to use this cert.
crypt.SetSigningCert(cert)

strData = "This is the data to be signed."

#  Indicate that the PKCS7 signature should be returned
#  as a base64 encoded string:
crypt.put_EncodingMode("base64")

#  The EncodingMode may be set to other values such as
#  "hex", "url", "quoted-printable", etc.

strSignatureWithData = crypt.opaqueSignStringENC(strData)

print strSignatureWithData

#  Now verify the signature against the original data.

#  Tell the component what certificate to use for verification.
crypt.SetVerifyCert(cert)

originalData = crypt.opaqueVerifyStringENC(strSignatureWithData)
if (originalData == None ):
    #  The signature verification failed.
    print crypt.lastErrorText()
else:
    print originalData
    print "Signature verified!"