(Unicode C++) Duplicate openssl dgst -sha256 -sign private.pem -out sha256.sig in.dat

Demonstrates how to duplicate this OpenSSL command:

openssl dgst -sha256 -sign private.pem -out sha256.sig in.dat

1. Creates a SHA256 digest of the contents of the input file
2. Signs the SHA256 digest using the private key.

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

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

    CkPrivateKeyW pkey;

    // Load the private key from an PEM file:
    success = pkey.LoadPemFile(L"private.pem");
    if (success == false) {
        wprintf(L"%s\n",pkey.lastErrorText());
        return;
    }

    CkRsaW rsa;

    // Import the private key into the RSA component:
    success = rsa.UsePrivateKey(pkey);
    if (success == false) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    // OpenSSL uses big-endian.
    rsa.put_LittleEndian(false);

    // Load the file to be signed.
    CkBinDataW bdFileData;
    success = bdFileData.LoadFile(L"in.dat");

    CkBinDataW bdSig;
    success = rsa.SignBd(bdFileData,L"sha256",bdSig);
    if (success == false) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    // Save the binary signature to a file.
    success = bdSig.WriteFile(L"signature.sig");
    if (success != true) {
        wprintf(L"Failed to write signature.sig.\n");
        return;
    }

    wprintf(L"Success.\n");
    }