package includes cryptography-based classes, but it does not contain
classes for actual encryption and
decryption. That is the job of the
package. This package supports symmetric-key cryptography, in which
the same key is used for both encryption and decryption and must be
known by both the sender and the receiver of encrypted data.
interface represents an encryption key; the first step of any
cryptographic operation is to obtain an appropriate
SecretKey. Unfortunately, the
supplied with the JDK cannot generate and store secret keys, so a
program must handle these tasks itself. Here is some code that shows
various ways to work with
import javax.crypto.*; import javax.crypto.spec.*; // Generate encryption keys with a KeyGenerator object KeyGenerator desGen = KeyGenerator.getInstance("DES"); // DES algorithm SecretKey desKey = desGen.generateKey(); // Generate a key KeyGenerator desEdeGen = KeyGenerator.getInstance("DESede"); // Triple DES SecretKey desEdeKey = desEdeGen.generateKey(); // Generate a key // SecretKey is an opaque representation of a key. Use SecretKeyFactory to // convert to a transparent representation that can be manipulated: saved // to a file, securely transmitted to a receiving party, etc. SecretKeyFactory desFactory = SecretKeyFactory.getInstance("DES"); DESKeySpec desSpec = (DESKeySpec) desFactory.getKeySpec(desKey, javax.crypto.spec.DESKeySpec.class); ...
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