(Unicode C) RSA Encrypt RSA/ECB/OAEPWithSHA1AndMGF1Padding

Demonstrates how to RSA encrypt using RSA/ECB/OAEPWithSHA1AndMGF1Padding. Also demonstrates RSA/ECB/OAEPWithSHA-256AndMGF1Padding. Both of these terms are from Java's JCE. Note: In this context, "ECB" doesn't actually mean anything. It's a symmetric cipher mode that doesn't apply (or make sense) in this context.

Note: This example requires Chilkat v11.0.0 or greater.

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

void ChilkatSample(void)
    {
    BOOL success;
    HCkRsaW rsa;
    HCkPublicKeyW pubkey;
    const wchar_t *plainText;
    BOOL usePrivateKey;
    const wchar_t *encryptedStr;
    HCkRsaW rsa2;
    HCkPrivateKeyW privKey;
    const wchar_t *originalStr;

    success = FALSE;

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

    rsa = CkRsaW_Create();

    // First load a public key object with a public key.
    // In this case, we'll load it from a file.
    pubkey = CkPublicKeyW_Create();
    success = CkPublicKeyW_LoadFromFile(pubkey,L"qa_data/pem/rsa_public.pem");
    if (success == FALSE) {
        wprintf(L"%s\n",CkPublicKeyW_lastErrorText(pubkey));
        CkRsaW_Dispose(rsa);
        CkPublicKeyW_Dispose(pubkey);
        return;
    }

    // RSA encryption is limited to small amounts of data. The limit
    // is typically a few hundred bytes and is based on the key size and
    // padding (OAEP vs. PKCS1_5).  RSA encryption is typically used for
    // encrypting hashes or symmetric (bulk encryption algorithm) secret keys.
    plainText = L"Time is an illusion. Lunchtime doubly so.";

    // Import the public key to be used for encrypting.
    success = CkRsaW_UsePublicKey(rsa,pubkey);

    // To get OAEP padding, set the PkcsPadding property equal to FALSE
    CkRsaW_putPkcsPadding(rsa,FALSE);
    CkRsaW_putOaepHash(rsa,L"sha256");

    // Indicate we'll want hex output
    CkRsaW_putEncodingMode(rsa,L"hex");

    // Encrypt..
    usePrivateKey = FALSE;
    encryptedStr = CkRsaW_encryptStringENC(rsa,plainText,usePrivateKey);
    wprintf(L"%s\n",encryptedStr);

    // -------------------------------------------------
    // Now decrypt with the matching private key.
    rsa2 = CkRsaW_Create();

    privKey = CkPrivateKeyW_Create();
    success = CkPrivateKeyW_LoadEncryptedPem(privKey,L"qa_data/pem/rsa_passwd.pem",L"passwd");
    if (success == FALSE) {
        wprintf(L"%s\n",CkPrivateKeyW_lastErrorText(privKey));
        CkRsaW_Dispose(rsa);
        CkPublicKeyW_Dispose(pubkey);
        CkRsaW_Dispose(rsa2);
        CkPrivateKeyW_Dispose(privKey);
        return;
    }

    success = CkRsaW_UsePrivateKey(rsa2,privKey);

    // Make sure we have the same settings used for encryption.
    CkRsaW_putPkcsPadding(rsa2,FALSE);
    CkRsaW_putEncodingMode(rsa2,L"hex");
    CkRsaW_putOaepHash(rsa2,L"sha256");

    originalStr = CkRsaW_decryptStringENC(rsa2,encryptedStr,TRUE);

    wprintf(L"%s\n",originalStr);


    CkRsaW_Dispose(rsa);
    CkPublicKeyW_Dispose(pubkey);
    CkRsaW_Dispose(rsa2);
    CkPrivateKeyW_Dispose(privKey);

    }