(Python) RSA Sign using Private Key of Certificate Type A3 (smart card / token)

Demonstrates RSA signing data using the private key of a certificate type A3 (smart card, token).

Note: This is a Windows-only example.

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

import sys
import chilkat

#  First get the A3 certificate that was installed on the Windows system.
certStore = chilkat.CkCertStore()

thumbprint = "12c1dd8015f3f03f7b1fa619dc24e2493ca8b4b2"

#  This is specific to Windows because it is opening the Windows Current-User certificate store.
bReadOnly = True
success = certStore.OpenCurrentUserStore(bReadOnly)
if (success != True):
    print(certStore.lastErrorText())
    sys.exit()

#  Find the certificate with the desired thumbprint
#  (There are many ways to locate a certificate.  This example chooses to find by thumbprint.)
# cert is a CkCert
cert = certStore.FindCertBySha1Thumbprint(thumbprint)
if (certStore.get_LastMethodSuccess() != True):
    print("Failed to find the certificate.")
    sys.exit()

print("Found: " + cert.subjectCN())

rsa = chilkat.CkRsa()

#  Provide the cert's private key
bUsePrivateKey = True
success = rsa.SetX509Cert(cert,bUsePrivateKey)

if (success != True):
    print(rsa.lastErrorText())
    sys.exit()

#  Now we're ready to sign..
dataToSign = chilkat.CkByteData()
sigData = chilkat.CkByteData()

#  Get bytes to be signed..
fac = chilkat.CkFileAccess()
success = fac.ReadEntireFile("in.dat",dataToSign)

success = rsa.SignBytes(dataToSign,"SHA-256",sigData)
if (success != True):
    print(rsa.lastErrorText())
    sys.exit()

print("Signature created.")