http://www.bouncycastle.org/java.html: The Bouncy Castle Java APIs for CMS, PKCS, EAC, TSP, CMP, CRMF, OCSP, and certificate generation. This jar contains APIs for JDK 1.5 to JDK 1.8. The APIs can be used in conjunction with a JCE/JCA provider such as the one provided with the Bouncy Castle Cryptography APIs.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.operator;

import java.io.InputStream;

import org.bouncycastle.asn1.x509.AlgorithmIdentifier;


General interface for an operator that is able to produce
an InputStream that will decrypt a stream of encrypted data.

/**
 * General interface for an operator that is able to produce
 * an InputStream that will decrypt a stream of encrypted data.
 */
public interface InputDecryptor
{
    
Return the algorithm identifier describing the encryption
algorithm and parameters this decryptor can process.

Returns:algorithm oid and parameters.
/**
     * Return the algorithm identifier describing the encryption
     * algorithm and parameters this decryptor can process.
     *
     * @return algorithm oid and parameters.
     */
    AlgorithmIdentifier getAlgorithmIdentifier();

    
Wrap the passed in input stream encIn, returning an input stream
that decrypts what it reads from encIn before returning it.

Params:
  • encIn – InputStream containing encrypted input.
Returns:an decrypting InputStream
/**
     * Wrap the passed in input stream encIn, returning an input stream
     * that decrypts what it reads from encIn before returning it.
     *
     * @param encIn InputStream containing encrypted input.
     * @return an decrypting InputStream
     */
    InputStream getInputStream(InputStream encIn);
}