(Unicode C) Generate RSA Key and Sign a String

See more RSA Examples

Demonstrates how to generate a new RSA public/private key pair and use it to generate a signature for a string. The (binary) digital signature is returned as a hexidecimalized string.

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#include <C_CkRsaW.h>

void ChilkatSample(void)
    {
    HCkRsaW rsa;
    BOOL success;
    const wchar_t *strData;
    const wchar_t *hexSig;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    rsa = CkRsaW_Create();

    // Generate a 2048-bit RSA key.
    success = CkRsaW_GenerateKey(rsa,2048);

    // To return the signature in hex.
    CkRsaW_putEncodingMode(rsa,L"hex");

    strData = L"This is the string to be signed.";

    // Sign the SHA256 hash of the string.
    hexSig = CkRsaW_signStringENC(rsa,strData,L"sha256");

    wprintf(L"%s\n",hexSig);
    wprintf(L"%s\n",CkRsaW_lastErrorText(rsa));

    // Now verify the signature:
    success = CkRsaW_VerifyStringENC(rsa,strData,L"sha256",hexSig);
    if (success == TRUE) {
        wprintf(L"Signature verified!\n");
    }
    else {
        wprintf(L"%s\n",CkRsaW_lastErrorText(rsa));
    }

    // Try it with an invalid signature:
    success = CkRsaW_VerifyStringENC(rsa,strData,L"sha256",L"not a valid sig");
    if (success == TRUE) {
        wprintf(L"Signature verified!\n");
    }
    else {
        wprintf(L"%s\n",CkRsaW_lastErrorText(rsa));
    }

    // Try it with invalid data:
    success = CkRsaW_VerifyStringENC(rsa,L"Not the original data",L"sha256",hexSig);
    if (success == TRUE) {
        wprintf(L"Signature verified!\n");
    }
    else {
        wprintf(L"%s\n",CkRsaW_lastErrorText(rsa));
    }

    // Try it with the wrong hash algorithm:
    success = CkRsaW_VerifyStringENC(rsa,strData,L"sha-1",hexSig);
    if (success == TRUE) {
        wprintf(L"Signature verified!\n");
    }
    else {
        wprintf(L"%s\n",CkRsaW_lastErrorText(rsa));
    }



    CkRsaW_Dispose(rsa);

    }