(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.

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 <CkPrivateKey.h>
#include <CkRsa.h>
#include <CkBinData.h>

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

    CkPrivateKey pkey;

    // Load the private key from an PEM file:
    bool success = pkey.LoadPemFile("private.pem");
    if (success != true) {
        std::cout << pkey.lastErrorText() << "\r\n";
        return;
    }

    CkRsa rsa;

    // Import the private key into the RSA component:
    success = rsa.ImportPrivateKeyObj(pkey);
    if (success != true) {
        std::cout << rsa.lastErrorText() << "\r\n";
        return;
    }

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

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

    CkBinData bdSig;
    success = rsa.SignBd(bdFileData,"sha256",bdSig);
    if (success != true) {
        std::cout << rsa.lastErrorText() << "\r\n";
        return;
    }

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

    std::cout << "Success." << "\r\n";
    }