CkPython

Verify Opaque Signature and Retrieve Signing Certificates

See more Digital Signatures Examples

Demonstrates how to verify a PCKS7 opaque digital signature (signed data), extract the original file/data, and then extract the certificate(s) that were used to sign. CkPython

import sys
import chilkat

success = False

# This example assumes the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

crypt = chilkat.CkCrypt2()

# Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
success = crypt.VerifyP7M("qa_data/p7m/opaqueSig.p7","qa_output/originalData.dat")
if (success == False):
    print(crypt.lastErrorText())
    sys.exit()

# Alternatively, we can do it in memory...
binData = chilkat.CkBinData()
success = binData.LoadFile("qa_data/p7m/opaqueSig.p7")
# Your app should check for success, but we'll skip the check for brevity..

# If verified, the signature is unwrapped and binData is replaced with the original data that was signed.
success = crypt.OpaqueVerifyBd(binData)
if (success == False):
    print(crypt.lastErrorText())
    sys.exit()

# For our testing, we signed some text, so we can get it from the binData..
print("Original Data:")
print(binData.getString("utf-8"))

# After any method call that verifies a signature, the crypt object will contain the certificate(s)
# that were used for signing (assuming the X.509 certs were available in the signature, which is typically the case).

# Get each signing certificate, and build the certificate chain for each.
cert = chilkat.CkCert()
certChain = chilkat.CkCertChain()
numCerts = crypt.get_NumSignerCerts()
i = 0
while i < numCerts :
    crypt.LastSignerCert(i,cert)
    print(cert.subjectDN())

    success = cert.BuildCertChain(certChain)
    if (success == False):
        print(cert.lastErrorText())
        sys.exit()

    i = i + 1