(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 <C_CkCertW.h>
#include <C_CkStringBuilderW.h>
#include <C_CkRsaW.h>

void ChilkatSample(void)
    {
    HCkCertW cert;
    BOOL success;
    HCkStringBuilderW sb;
    BOOL crlfLineEnding;
    int i;
    HCkRsaW rsa;
    const wchar_t *stringToSign;
    const wchar_t *sigBase64;

    // 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.

    cert = CkCertW_Create();

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

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

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

    // Create a string to be hashed and signed.
    sb = CkStringBuilderW_Create();
    crlfLineEnding = TRUE;

    for (i = 0; i <= 10; i++) {
        CkStringBuilderW_AppendLine(sb,L"This is a test.",crlfLineEnding);
    }

    rsa = CkRsaW_Create();

    // Use the certificate's private key for signing.
    success = CkRsaW_SetX509Cert(rsa,cert,TRUE);
    if (success == FALSE) {
        wprintf(L"%s\n",CkRsaW_lastErrorText(rsa));
        CkCertW_Dispose(cert);
        CkStringBuilderW_Dispose(sb);
        CkRsaW_Dispose(rsa);
        return;
    }

    // Sign the SHA-256 hash of the utf-8 byte representation of the contents of sb
    // Return the signature in base64 format.
    CkRsaW_putEncodingMode(rsa,L"base64");
    CkRsaW_putCharset(rsa,L"utf-8");
    stringToSign = CkStringBuilderW_getAsString(sb);
    sigBase64 = CkRsaW_signStringENC(rsa,stringToSign,L"sha256");
    if (CkRsaW_getLastMethodSuccess(rsa) == FALSE) {
        wprintf(L"%s\n",CkRsaW_lastErrorText(rsa));
        CkCertW_Dispose(cert);
        CkStringBuilderW_Dispose(sb);
        CkRsaW_Dispose(rsa);
        return;
    }

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


    CkCertW_Dispose(cert);
    CkStringBuilderW_Dispose(sb);
    CkRsaW_Dispose(rsa);

    }