(CkPython) Get a Certificate's Key Size

Demonstrates how to get the RSA key size of a certificate (for example, 1024-bit, 2048-bit, etc.)

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat Python Downloads install with pip pip3 install chilkat or download... Python Module for Windows, MacOS, Linux, Alpine Linux

import sys
import chilkat

success = False

# For this example, I have a certificate in raw base64 format (not PEM),
# that looks like this:  "MIIGkDCCBHigAwIBAgIUMDA ... s/iqLsLA=="
sbCertBase64 = chilkat.CkStringBuilder()
success = sbCertBase64.LoadFile("qa_data/certs/base64Cert.txt","utf-8")

cert = chilkat.CkCert()
success = cert.LoadFromBase64(sbCertBase64.getAsString())
if (success == False):
    print(cert.lastErrorText())
    sys.exit()

# Get the public key.
pubKey = chilkat.CkPublicKey()
cert.GetPublicKey(pubKey)

numBits = pubKey.get_KeySize()
print("Number of bits = " + str(numBits))

# If using an older version of Chilkat, the key size can be obtained like this:
xml = chilkat.CkXml()
xml.LoadXml(pubKey.getXml())

binDat = chilkat.CkBinData()
binDat.AppendEncoded(xml.getChildContent("Modulus"),"base64")

numBits = 8 * binDat.get_NumBytes()
print("Number of bits = " + str(numBits))