Cryptographic Streams

This chapter discusses filter streams for cryptography. The Java core API contains two of these in the java.security package, DigestInputStream and DigestOutputStream. The javax.crypto package contains two more, CipherInputStream and CipherOutputStream. All four of these streams use an engine object to handle the filtering. DigestInputStream and DigestOutputStream use a MessageDigest object while CipherInputStream and CipherOutputStream use a Cipher object. The streams rely on the programmer to properly initialize andin the case of the digest streamsclean up after the engines. Therefore, we'll first look at the engine classes and then at the streams built around these engines.