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. Unicode C

#include <C_CkRsaW.h>
#include <C_CkPrivateKeyW.h>
#include <C_CkPublicKeyW.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkRsaW rsa;
    HCkPrivateKeyW privKey;
    const wchar_t *strData;
    const wchar_t *hexSig;
    HCkPublicKeyW pubKey;

    success = FALSE;

    // 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.
    privKey = CkPrivateKeyW_Create();
    success = CkRsaW_GenKey(rsa,2048,privKey);

    CkRsaW_UsePrivateKey(rsa,privKey);

    // 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);

    // Now verify the signature:
    pubKey = CkPublicKeyW_Create();
    CkPrivateKeyW_ToPublicKey(privKey,pubKey);
    CkRsaW_UsePublicKey(rsa,pubKey);

    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"Signature validation failed!\n");
    }

    // 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"Signature validation failed!\n");
    }



    CkRsaW_Dispose(rsa);
    CkPrivateKeyW_Dispose(privKey);
    CkPublicKeyW_Dispose(pubKey);

    }