(Tcl) Convert RSA Private Key to Public Key

Demonstrates how to get a public RSA key from a private RSA key.

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

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load ./chilkat.dll

set success 0

set privKey [new_CkPrivateKey]

# Step 1: Load the private key from a source.
# (Chilkat can load private keys from all types of formats, and from in-memory bytes or encoded strings.
# see the online reference documentation for more options.)
set success [CkPrivateKey_LoadPemFile $privKey "qa_data/pem/VP_Private.pem"]
if {$success == 0} then {
    puts [CkPrivateKey_lastErrorText $privKey]
    delete_CkPrivateKey $privKey
    exit
}

# Step 2: Get the public key object from the private key object.
set pubKey [new_CkPublicKey]

CkPrivateKey_ToPublicKey $privKey $pubKey

# Step 3: Save the public key in a desired format. 
# (Chilkat can load or save public and private keys in many different formats.  See
# the online reference documentation for more options.)

# Saves to a PKCS8 PEM file.
set bPreferPkcs1 0
set success [CkPublicKey_SavePemFile $pubKey $bPreferPkcs1 "qa_data/pem/VP_Public.pem"]
if {[CkPublicKey_get_LastMethodSuccess $pubKey] == 0} then {
    puts [CkPublicKey_lastErrorText $pubKey]
    delete_CkPrivateKey $privKey
    delete_CkPublicKey $pubKey
    exit
}

puts "Extracted and saved public key from private key."

delete_CkPrivateKey $privKey
delete_CkPublicKey $pubKey