(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.

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#include <C_CkCert.h>
#include <C_CkStringBuilder.h>
#include <C_CkRsa.h>

void ChilkatSample(void)
    {
    HCkCert cert;
    BOOL success;
    HCkStringBuilder sb;
    BOOL crlfLineEnding;
    int i;
    HCkRsa rsa;
    const char *stringToSign;
    const char *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 = CkCert_Create();

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

    // Specify the certificate by its common name.
    success = CkCert_LoadFromSmartcard(cert,"cn=chilkat-rsa-2048");
    if (success == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkCert_Dispose(cert);
        return;
    }

    printf("Signing with cert: %s\n",CkCert_subjectCN(cert));

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

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

    rsa = CkRsa_Create();

    // Use the certificate's private key for signing.
    success = CkRsa_SetX509Cert(rsa,cert,TRUE);
    if (success == FALSE) {
        printf("%s\n",CkRsa_lastErrorText(rsa));
        CkCert_Dispose(cert);
        CkStringBuilder_Dispose(sb);
        CkRsa_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.
    CkRsa_putEncodingMode(rsa,"base64");
    CkRsa_putCharset(rsa,"utf-8");
    stringToSign = CkStringBuilder_getAsString(sb);
    sigBase64 = CkRsa_signStringENC(rsa,stringToSign,"sha256");
    if (CkRsa_getLastMethodSuccess(rsa) == FALSE) {
        printf("%s\n",CkRsa_lastErrorText(rsa));
        CkCert_Dispose(cert);
        CkStringBuilder_Dispose(sb);
        CkRsa_Dispose(rsa);
        return;
    }

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


    CkCert_Dispose(cert);
    CkStringBuilder_Dispose(sb);
    CkRsa_Dispose(rsa);

    }