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. C

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

void ChilkatSample(void)
    {
    BOOL success;
    HCkRsa rsa;
    HCkPrivateKey privKey;
    HCkPublicKey pubKey;
    const char *plainText;
    HCkRsa rsaEncryptor;
    BOOL usePrivateKey;
    const char *encryptedStr;
    HCkRsa rsaDecryptor;
    const char *decryptedStr;

    success = FALSE;

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

    rsa = CkRsa_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 = CkPrivateKey_Create();
    success = CkRsa_GenKey(rsa,2048,privKey);
    if (success == FALSE) {
        printf("%s\n",CkRsa_lastErrorText(rsa));
        CkRsa_Dispose(rsa);
        CkPrivateKey_Dispose(privKey);
        return;
    }

    pubKey = CkPublicKey_Create();
    CkPrivateKey_ToPublicKey(privKey,pubKey);

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

    //  Start with a new RSA object to demonstrate that all we
    //  need are the keys previously exported:
    rsaEncryptor = CkRsa_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".
    CkRsa_putEncodingMode(rsaEncryptor,"hex");

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

    usePrivateKey = FALSE;
    encryptedStr = CkRsa_encryptStringENC(rsaEncryptor,plainText,usePrivateKey);
    printf("%s\n",encryptedStr);

    //  Now decrypt:
    rsaDecryptor = CkRsa_Create();

    CkRsa_putEncodingMode(rsaDecryptor,"hex");
    success = CkRsa_UsePrivateKey(rsaDecryptor,privKey);

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

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


    CkRsa_Dispose(rsa);
    CkPrivateKey_Dispose(privKey);
    CkPublicKey_Dispose(pubKey);
    CkRsa_Dispose(rsaEncryptor);
    CkRsa_Dispose(rsaDecryptor);

    }