java.security.DigestInputStream Maven / Gradle / Ivy
/*
This is not an official specification document, and usage is restricted.
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documentation, such as a unified set of documents of API signatures for
a platform that includes technologies expressed as Java APIs. The file
may also be used to produce "compilation stubs," which allow
applications to be compiled and validated for such platforms.
Any work generated from this file, such as unified javadocs or compiled
stub files, must be accompanied by this notice in its entirety.
This work corresponds to the API signatures of JSR 219: Foundation
Profile 1.1. In the event of a discrepency between this work and the
JSR 219 specification, which is available at
http://www.jcp.org/en/jsr/detail?id=219, the latter takes precedence.
*/
package java.security;
import java.io.IOException;
import java.io.EOFException;
import java.io.InputStream;
import java.io.FilterInputStream;
import java.io.PrintStream;
import java.io.ByteArrayInputStream;
/**
* A transparent stream that updates the associated message digest using
* the bits going through the stream.
*
*
To complete the message digest computation, call one of the
* digest methods on the associated message
* digest after your calls to one of this digest input stream's
* {@link #read() read} methods.
*
*
It is possible to turn this stream on or off (see
* {@link #on(boolean) on}). When it is on, a call to one of the
* read methods
* results in an update on the message digest. But when it is off,
* the message digest is not updated. The default is for the stream
* to be on.
*
*
Note that digest objects can compute only one digest (see
* {@link MessageDigest}),
* so that in order to compute intermediate digests, a caller should
* retain a handle onto the digest object, and clone it for each
* digest to be computed, leaving the orginal digest untouched.
*
* @see MessageDigest
*
* @see DigestOutputStream
*
* @version 1.34 00/02/02
* @author Benjamin Renaud
*/
public class DigestInputStream extends FilterInputStream
{
/**
* The message digest associated with this stream.
*/
protected MessageDigest digest;
/**
* Creates a digest input stream, using the specified input stream
* and message digest.
*
* @param stream the input stream.
*
* @param digest the message digest to associate with this stream.
*/
public DigestInputStream(InputStream stream, MessageDigest digest) {
super(stream);
}
/**
* Returns the message digest associated with this stream.
*
* @return the message digest associated with this stream.
* @see #setMessageDigest(java.security.MessageDigest)
*/
public MessageDigest getMessageDigest() {
return null;
}
/**
* Associates the specified message digest with this stream.
*
* @param digest the message digest to be associated with this stream.
* @see #getMessageDigest()
*/
public void setMessageDigest(MessageDigest digest) { }
/**
* Reads a byte, and updates the message digest (if the digest
* function is on). That is, this method reads a byte from the
* input stream, blocking until the byte is actually read. If the
* digest function is on (see {@link #on(boolean) on}), this method
* will then call update on the message digest associated
* with this stream, passing it the byte read.
*
* @return the byte read.
*
* @exception IOException if an I/O error occurs.
*
* @see MessageDigest#update(byte)
*/
public int read() throws IOException {
return 0;
}
/**
* Reads into a byte array, and updates the message digest (if the
* digest function is on). That is, this method reads up to
* len bytes from the input stream into the array
* b, starting at offset off. This method
* blocks until the data is actually
* read. If the digest function is on (see
* {@link #on(boolean) on}), this method will then call update
* on the message digest associated with this stream, passing it
* the data.
*
* @param b the array into which the data is read.
*
* @param off the starting offset into b of where the
* data should be placed.
*
* @param len the maximum number of bytes to be read from the input
* stream into b, starting at offset off.
*
* @return the actual number of bytes read. This is less than
* len if the end of the stream is reached prior to
* reading len bytes. -1 is returned if no bytes were
* read because the end of the stream had already been reached when
* the call was made.
*
* @exception IOException if an I/O error occurs.
*
* @see MessageDigest#update(byte[], int, int)
*/
public int read(byte[] b, int off, int len) throws IOException {
return 0;
}
/**
* Turns the digest function on or off. The default is on. When
* it is on, a call to one of the read methods results in an
* update on the message digest. But when it is off, the message
* digest is not updated.
*
* @param on true to turn the digest function on, false to turn
* it off.
*/
public void on(boolean on) { }
/**
* Prints a string representation of this digest input stream and
* its associated message digest object.
*/
public String toString() {
return null;
}
}