(Unicode C++) RSA Sign Binary Data and Verify (Recover the Original Data)

Demonstrates how to RSA sign binary data and then verify/recover the original data.

Note: This example uses methods introduced in Chilkat v9.5.0.77.

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

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#include <CkPrivateKeyW.h>
#include <CkRsaW.h>
#include <CkBinDataW.h>
#include <CkPublicKeyW.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    // Load an RSA private key for signing.
    CkPrivateKeyW privKey;
    success = privKey.LoadEncryptedPemFile(L"qa_data/pem/rsa_passwd.pem",L"passwd");
    if (success == false) {
        wprintf(L"%s\n",privKey.lastErrorText());
        return;
    }

    CkRsaW rsa;
    rsa.UsePrivateKey(privKey);

    // We have some binary data (in hex) to sign
    const wchar_t *originalData = L"0102030405060708090A";
    CkBinDataW bd;
    bd.AppendEncoded(originalData,L"hex");

    // If successful, the contents of bd are replaced with the RSA signature.
    success = rsa.SignRawBd(bd);
    if (success == false) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    // Show the RSA signature in base64
    wprintf(L"%s\n",bd.getEncoded(L"base64"));

    // ------------------------------------------
    // Get the public key from the private key
    CkPublicKeyW pubKey;
    privKey.ToPublicKey(pubKey);

    // Verify the signature and extract the original data.
    CkRsaW rsa2;
    rsa2.UsePublicKey(pubKey);

    bool bVerified = rsa2.VerifyRawBd(bd);
    wprintf(L"signature verified: %d\n",bVerified);

    // Show the original data:
    wprintf(L"original data: %s\n",bd.getEncoded(L"hex"));
    }