(Unicode C++) RSA Sign utf-8 Bytes of String to get Base64 RSA Signature

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Demonstrates how RSA sign the utf-8 byte representation of a string to get the signature in base64 format.

Chilkat C/C++ Library Downloads
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#include <CkCertW.h>
#include <CkStringBuilderW.h>
#include <CkRsaW.h>

void ChilkatSample(void)
    {
    // Assuming the smartcard/USB token is installed with the correct drivers from the manufacturer,
    // this code can work on multiple platforms including Windows, MacOS, Linux, and iOS.

    // Chilkat automatically detects and determines the way in which the HSM is used,
    // which can be by PKCS11, Apple Keychain, Microsoft CNG / Crypto API, or ScMinidriver.

    CkCertW cert;

    // Set the token/smartcard PIN prior to loading.
    cert.put_SmartCardPin(L"123456");

    // Specify the certificate by its common name.
    bool success = cert.LoadFromSmartcard(L"cn=chilkat-rsa-2048");
    if (success == false) {
        wprintf(L"%s\n",cert.lastErrorText());
        return;
    }

    wprintf(L"Signing with cert: %s\n",cert.subjectCN());

    // Create a string to be hashed and signed.
    CkStringBuilderW sb;
    bool crlfLineEnding = true;
    int i;
    for (i = 0; i <= 10; i++) {
        sb.AppendLine(L"This is a test.",crlfLineEnding);
    }

    CkRsaW rsa;

    // Use the certificate's private key for signing.
    success = rsa.SetX509Cert(cert,true);
    if (success == false) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    // Sign the SHA-256 hash of the utf-8 byte representation of the contents of sb
    // Return the signature in base64 format.
    rsa.put_EncodingMode(L"base64");
    rsa.put_Charset(L"utf-8");
    const wchar_t *stringToSign = sb.getAsString();
    const wchar_t *sigBase64 = rsa.signStringENC(stringToSign,L"sha256");
    if (rsa.get_LastMethodSuccess() == false) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    wprintf(L"RSA signature as base64: %s\n",sigBase64);
    }