Unicode C

RSA Encrypt and Decrypt Strings

See more RSA Examples

_LANGUAGE_ sample code to RSA public-key encrypt and decrypt strings using public and private keys. Unicode C

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

void ChilkatSample(void)
    {
    BOOL success;
    HCkRsaW rsa;
    HCkPrivateKeyW privKey;
    HCkPublicKeyW pubKey;
    const wchar_t *plainText;
    HCkRsaW rsaEncryptor;
    BOOL usePrivateKey;
    const wchar_t *encryptedStr;
    HCkRsaW rsaDecryptor;
    const wchar_t *decryptedStr;

    success = FALSE;

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

    rsa = CkRsaW_Create();

    // This example also generates the public and private
    // keys to be used in the RSA encryption.
    // Normally, you would generate a key pair once,
    // and distribute the public key to your partner.
    // Anything encrypted with the public key can be
    // decrypted with the private key.  The reverse is 
    // also true: anything encrypted using the private
    // key can be decrypted using the public key.

    // Generate a 2048-bit key.  Chilkat RSA supports
    // key sizes ranging from 512 bits to 4096 bits.
    privKey = CkPrivateKeyW_Create();
    success = CkRsaW_GenKey(rsa,2048,privKey);
    if (success == FALSE) {
        wprintf(L"%s\n",CkRsaW_lastErrorText(rsa));
        CkRsaW_Dispose(rsa);
        CkPrivateKeyW_Dispose(privKey);
        return;
    }

    pubKey = CkPublicKeyW_Create();
    CkPrivateKeyW_ToPublicKey(privKey,pubKey);

    plainText = L"Encrypting and decrypting should be easy!";

    // Start with a new RSA object to demonstrate that all we
    // need are the keys previously exported:
    rsaEncryptor = CkRsaW_Create();

    // Encrypted output is always binary.  In this case, we want
    // to encode the encrypted bytes in a printable string.
    // Our choices are "hex", "base64", "url", "quoted-printable".
    CkRsaW_putEncodingMode(rsaEncryptor,L"hex");

    // We'll encrypt with the public key and decrypt with the private
    // key.
    success = CkRsaW_UsePublicKey(rsaEncryptor,pubKey);

    usePrivateKey = FALSE;
    encryptedStr = CkRsaW_encryptStringENC(rsaEncryptor,plainText,usePrivateKey);
    wprintf(L"%s\n",encryptedStr);

    // Now decrypt:
    rsaDecryptor = CkRsaW_Create();

    CkRsaW_putEncodingMode(rsaDecryptor,L"hex");
    success = CkRsaW_UsePrivateKey(rsaDecryptor,privKey);

    usePrivateKey = TRUE;
    decryptedStr = CkRsaW_decryptStringENC(rsaDecryptor,encryptedStr,usePrivateKey);

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


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

    }