(C) 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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#include <C_CkPrivateKey.h>
#include <C_CkPublicKey.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkPrivateKey privKey;
    HCkPublicKey pubKey;
    BOOL bPreferPkcs1;

    success = FALSE;

    privKey = CkPrivateKey_Create();

    // 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.)
    success = CkPrivateKey_LoadPemFile(privKey,"qa_data/pem/VP_Private.pem");
    if (success == FALSE) {
        printf("%s\n",CkPrivateKey_lastErrorText(privKey));
        CkPrivateKey_Dispose(privKey);
        return;
    }

    // Step 2: Get the public key object from the private key object.
    pubKey = CkPublicKey_Create();
    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.
    bPreferPkcs1 = FALSE;
    success = CkPublicKey_SavePemFile(pubKey,bPreferPkcs1,"qa_data/pem/VP_Public.pem");
    if (CkPublicKey_getLastMethodSuccess(pubKey) == FALSE) {
        printf("%s\n",CkPublicKey_lastErrorText(pubKey));
        CkPrivateKey_Dispose(privKey);
        CkPublicKey_Dispose(pubKey);
        return;
    }

    printf("Extracted and saved public key from private key.\n");


    CkPrivateKey_Dispose(privKey);
    CkPublicKey_Dispose(pubKey);

    }