(Java) RSA Encrypt and Decrypt Strings

See more RSA Examples

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

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

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

    CkRsa rsa = new CkRsa();

    // 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.
    CkPrivateKey privKey = new CkPrivateKey();
    success = rsa.GenKey(2048,privKey);
    if (success == false) {
        System.out.println(rsa.lastErrorText());
        return;
        }

    CkPublicKey pubKey = new CkPublicKey();
    privKey.ToPublicKey(pubKey);

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

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

    // 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".
    rsaEncryptor.put_EncodingMode("hex");

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

    boolean usePrivateKey = false;
    String encryptedStr = rsaEncryptor.encryptStringENC(plainText,usePrivateKey);
    System.out.println(encryptedStr);

    // Now decrypt:
    CkRsa rsaDecryptor = new CkRsa();

    rsaDecryptor.put_EncodingMode("hex");
    success = rsaDecryptor.UsePrivateKey(privKey);

    usePrivateKey = true;
    String decryptedStr = rsaDecryptor.decryptStringENC(encryptedStr,usePrivateKey);

    System.out.println(decryptedStr);
  }
}