http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.crypto;


Ciphers producing a key stream which can be reset to particular points in the stream implement this.

/**
 * Ciphers producing a key stream which can be reset to particular points in the stream implement this.
 */
public interface SkippingCipher
{
    
Skip numberOfBytes forwards, or backwards.

Params:
  • numberOfBytes – the number of bytes to skip (positive forward, negative backwards).
Throws:
Returns:the number of bytes actually skipped.
/**
     * Skip numberOfBytes forwards, or backwards.
     *
     * @param numberOfBytes the number of bytes to skip (positive forward, negative backwards).
     * @return the number of bytes actually skipped.
     * @throws java.lang.IllegalArgumentException if numberOfBytes is an invalid value.
     */
    long skip(long numberOfBytes);

    
Reset the cipher and then skip forward to a given position.

Params:
  • position – the number of bytes in to set the cipher state to.
Returns:the byte position moved to.
/**
     * Reset the cipher and then skip forward to a given position.
     *
     * @param position the number of bytes in to set the cipher state to.
     * @return the byte position moved to.
     */
    long seekTo(long position);

    
Return the current "position" of the cipher

Returns:the current byte position.
/**
     * Return the current "position" of the cipher
     *
     * @return the current byte position.
     */
    long getPosition();
}