(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.

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#include <C_CkRsa.h>
#include <C_CkPublicKey.h>
#include <C_CkPrivateKey.h>

void ChilkatSample(void)
    {
    HCkRsa rsa;
    HCkPublicKey pubkey;
    BOOL success;
    const char *plainText;
    BOOL usePrivateKey;
    const char *encryptedStr;
    HCkRsa rsa2;
    HCkPrivateKey privKey;
    const char *originalStr;

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

    rsa = CkRsa_Create();

    // First load a public key object with a public key.
    // In this case, we'll load it from a file.
    pubkey = CkPublicKey_Create();
    success = CkPublicKey_LoadFromFile(pubkey,"qa_data/pem/rsa_public.pem");
    if (success != TRUE) {
        printf("%s\n",CkPublicKey_lastErrorText(pubkey));
        CkRsa_Dispose(rsa);
        CkPublicKey_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 = "Time is an illusion. Lunchtime doubly so.";

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

    // To get OAEP padding, set the OaepPadding property:
    CkRsa_putOaepPadding(rsa,TRUE);

    // To use SHA1 or SHA-256, set the OaepHash property
    CkRsa_putOaepHash(rsa,"sha256");
    // for SHA1 --
    CkRsa_putOaepHash(rsa,"sha1");

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

    // Encrypt..
    usePrivateKey = FALSE;
    encryptedStr = CkRsa_encryptStringENC(rsa,plainText,usePrivateKey);
    printf("%s\n",encryptedStr);

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

    privKey = CkPrivateKey_Create();
    success = CkPrivateKey_LoadEncryptedPem(privKey,"qa_data/pem/rsa_passwd.pem","passwd");
    if (success != TRUE) {
        printf("%s\n",CkPrivateKey_lastErrorText(privKey));
        CkRsa_Dispose(rsa);
        CkPublicKey_Dispose(pubkey);
        CkRsa_Dispose(rsa2);
        CkPrivateKey_Dispose(privKey);
        return;
    }

    success = CkRsa_ImportPrivateKeyObj(rsa2,privKey);

    // Make sure we have the same settings used for encryption.
    CkRsa_putOaepPadding(rsa2,TRUE);
    CkRsa_putEncodingMode(rsa2,"hex");
    CkRsa_putOaepHash(rsa2,"sha1");

    originalStr = CkRsa_decryptStringENC(rsa2,encryptedStr,TRUE);

    printf("%s\n",originalStr);


    CkRsa_Dispose(rsa);
    CkPublicKey_Dispose(pubkey);
    CkRsa_Dispose(rsa2);
    CkPrivateKey_Dispose(privKey);

    }