Tcl

RSA Signature/Verify with .key and .cer

See more RSA Examples

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature. Tcl

load ./chilkat.dll

set success 0

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

set privKey [new_CkPrivateKey]

# Load the private key from an RSA .key file:
set success [CkPrivateKey_LoadPemFile $privKey "privateKey.key"]
if {$success == 0} then {
    puts [CkPrivateKey_lastErrorText $privKey]
    delete_CkPrivateKey $privKey
    exit
}

set rsa [new_CkRsa]

# Import the private key into the RSA component:
set success [CkRsa_UsePrivateKey $rsa $privKey]
if {$success == 0} then {
    puts [CkRsa_lastErrorText $rsa]
    delete_CkPrivateKey $privKey
    delete_CkRsa $rsa
    exit
}

# Create the signature as a hex string:
CkRsa_put_EncodingMode $rsa "hex"

set strData "This is the string to be signed."

# Sign the string using the sha256 hash algorithm.
# Other valid choices are "md2", "sha1", "sha384",
# "sha512", and "md5".
set hexSig [CkRsa_signStringENC $rsa $strData "sha256"]

puts "$hexSig"

# Load a digital certificate from a .cer file:
set cert [new_CkCert]

set success [CkCert_LoadFromFile $cert "myCert.cer"]
if {$success == 0} then {
    puts [CkCert_lastErrorText $cert]
    delete_CkPrivateKey $privKey
    delete_CkRsa $rsa
    delete_CkCert $cert
    exit
}

set pubKey [new_CkPublicKey]

CkCert_GetPublicKey $cert $pubKey

# Now verify using a new instance of the RSA object:
set rsa2 [new_CkRsa]

# Import the public key into the RSA object:
set success [CkRsa_UsePublicKey $rsa2 $pubKey]
if {$success == 0} then {
    puts [CkRsa_lastErrorText $rsa2]
    delete_CkPrivateKey $privKey
    delete_CkRsa $rsa
    delete_CkCert $cert
    delete_CkPublicKey $pubKey
    delete_CkRsa $rsa2
    exit
}

# The signature is a hex string, so make sure the EncodingMode is correct:
CkRsa_put_EncodingMode $rsa2 "hex"

# Verify the signature:
set success [CkRsa_VerifyStringENC $rsa2 $strData "sha256" $hexSig]
if {$success == 0} then {
    puts [CkRsa_lastErrorText $rsa2]
    delete_CkPrivateKey $privKey
    delete_CkRsa $rsa
    delete_CkCert $cert
    delete_CkPublicKey $pubKey
    delete_CkRsa $rsa2
    exit
}

puts "Success."

delete_CkPrivateKey $privKey
delete_CkRsa $rsa
delete_CkCert $cert
delete_CkPublicKey $pubKey
delete_CkRsa $rsa2