Unicode C++

Verify an RSA Signature Against the Signed Hash

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Demonstrates how to validate an RSA Signature against the hash that was signed. Unicode C++

#include <CkBinDataW.h>
#include <CkPublicKeyW.h>
#include <CkRsaW.h>

void ChilkatSample(void)
    {
    bool success = false;

    CkBinDataW bd;
    int i;
    for (i = 0; i <= 100; i++) {
        bd.AppendEncoded(L"000102030405060708090A0B0C0D0E0F",L"hex");
    }

    const wchar_t *sha256_base64 = bd.getHash(L"sha256",L"base64");
    wprintf(L"sha256 hash in base64 format: %s\n",sha256_base64);

    const wchar_t *base64_rsa_sig = L"AwF2BbOvL6jA5DwmMAc9n6J2Cc8PI6Rj5W079+aKJcIEtPWRzHor0Bvc3aftGM3Jbgj6SXlIC3M3RYS7UZOnfiHKFNZgbxaNT5WwsWooK42ZkC8DBZl0p7OunBUKd5SciUo+TKilioeUkriN3L1Zl9hwi3HVDVqgVo3XXskwIftSqLSFlepTLTmOWj9Y93dp8J4D9RyLtNgFQBc0WB22tyJTsuY56mLcWe1AMF3LizB9OrbwjynF2u16xWlrJdugccz795fJBUV9aQSD+8S3KeqwQhoi8RK1uhD68aGCyaSpBq0NZ8COAkn7MXaF4POxrAAt8udfHM+PRfSOptcH/w==";

    //  Get the public key to be used for signature verification.
    CkPublicKeyW pubKey;
    success = pubKey.LoadFromFile(L"rsaKeys/chilkat-rsa-2048.pem");
    if (success == false) {
        wprintf(L"%s\n",pubKey.lastErrorText());
        return;
    }

    CkRsaW rsa;
    success = rsa.UsePublicKey(pubKey);
    if (success == false) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    //  Verify the hash against the signature.
    rsa.put_EncodingMode(L"base64");
    success = rsa.VerifyHashENC(sha256_base64,L"sha256",base64_rsa_sig);

    if (success == false) {
        wprintf(L"%s\n",rsa.lastErrorText());
        wprintf(L"Signature invalid.\n");
    }
    else {
        wprintf(L"Signature valid.\n");
    }
    }