(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.

Chilkat C/C++ Library Downloads
MS Visual C/C++ Linux/CentOS C/C++ Alpine Linux C/C++ MAC OS X C/C++	armhf/aarch64 C/C++ C++ Builder iOS C/C++ Android C/C++	Solaris C/C++ MinGW C/C++

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

void ChilkatSample(void)
    {
    // 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;
    bool success = privKey.LoadEncryptedPemFile(L"qa_data/pem/rsa_passwd.pem",L"passwd");
    if (success != true) {
        wprintf(L"%s\n",privKey.lastErrorText());
        return;
    }

    CkRsaW rsa;
    rsa.ImportPrivateKeyObj(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.OpenSslSignBd(bd);
    if (success != true) {
        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.GetPublicKey();

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

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

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

    delete pubKey;
    }