Class CipherInputStream

java.lang.Object
java.io.InputStream
java.io.FilterInputStream
javax.crypto.CipherInputStream
All Implemented Interfaces:
Closeable,AutoCloseable
public classCipherInputStreamextendsFilterInputStream
ACipherInputStream is composed of anInputStream and aCipher object so that read() methods return data that are read in from the underlyingInputStream but have been additionally processed by theCipher object. TheCipher object must be fully initialized before being used by aCipherInputStream.

For example, if theCipher object is initialized for decryption, theCipherInputStream will attempt to read in data and decrypt them, before returning the decrypted data.

This class adheres strictly to the semantics, especially the failure semantics, of its ancestor classesjava.io.FilterInputStream andjava.io.InputStream. This class has exactly those methods specified in its ancestor classes, and overrides them all. Moreover, this class catches all exceptions that are not thrown by its ancestor classes. In particular, theskip method skips, and theavailable method counts only data that have been processed by the encapsulatedCipher object. This class may catchBadPaddingException and other exceptions thrown by failed integrity checks during decryption. These exceptions are not re-thrown, so the client may not be informed that integrity checks failed. Because of this behavior, this class may not be suitable for use with decryption in an authenticated mode of operation (e.g. GCM). Applications that require authenticated encryption can use theCipher API directly as an alternative to using this class.

It is crucial for a programmer using this class not to use methods that are not defined or overridden in this class (such as a new method or constructor that is later added to one of the super classes), because the design and implementation of those methods are unlikely to have considered security impact with regard toCipherInputStream.

Since:
1.4
See Also:

  • Constructor Details

    • CipherInputStream

      public CipherInputStream(InputStream is,Cipher c)
      Constructs aCipherInputStream from anInputStream and aCipher object.
      Note: if the specified input stream or cipher isnull, aNullPointerException may be thrown later when they are used.
      Parameters:
      is - the to-be-processed input stream
      c - an initializedCipher object

    • CipherInputStream

      protected CipherInputStream(InputStream is)
      Constructs aCipherInputStream from anInputStream without specifying aCipher object. This has the effect of constructing aCipherInputStream using aNullCipher.
      Note: if the specified input stream isnull, aNullPointerException may be thrown later when it is used.
      Parameters:
      is - the to-be-processed input stream

  • Method Details

    • read

      public int read() throwsIOException
      Reads the next byte of data from this input stream. The value byte is returned as anint in the range0 to255. If no byte is available because the end of the stream has been reached, the value-1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.
      Overrides:
      read in class FilterInputStream
      Returns:
      the next byte of data, or-1 if the end of the stream is reached.
      Throws:
      IOException - if an I/O error occurs.
      See Also:

    • read

      public int read(byte[] b) throwsIOException
      Reads up tob.length bytes of data from this input stream into an array of bytes.

      Theread method ofInputStream calls theread method of three arguments with the argumentsb,0, andb.length.

      Overrides:
      read in class FilterInputStream
      Parameters:
      b - the buffer into which the data is read.
      Returns:
      the total number of bytes read into the buffer, or-1 is there is no more data because the end of the stream has been reached.
      Throws:
      IOException - if an I/O error occurs.
      See Also:

    • read

      public int read(byte[] b, int off, int len) throwsIOException
      Reads up tolen bytes of data from this input stream into an array of bytes. This method blocks until some input is available. If the first argument isnull, up tolen bytes are read and discarded.
      Overrides:
      read in class FilterInputStream
      Parameters:
      b - the buffer into which the data is read.
      off - the start offset in the destination arraybuf
      len - the maximum number of bytes read.
      Returns:
      the total number of bytes read into the buffer, or-1 if there is no more data because the end of the stream has been reached.
      Throws:
      IOException - if an I/O error occurs.
      See Also:

    • skip

      public long skip(long n) throwsIOException
      Skipsn bytes of input from the bytes that can be read from this input stream without blocking.

      Fewer bytes than requested might be skipped. The actual number of bytes skipped is equal ton or the result of a call toavailable, whichever is smaller. Ifn is less than zero, no bytes are skipped.

      The actual number of bytes skipped is returned.

      Overrides:
      skip in class FilterInputStream
      Parameters:
      n - the number of bytes to be skipped.
      Returns:
      the actual number of bytes skipped.
      Throws:
      IOException - if an I/O error occurs.
      See Also:

    • available

      public int available() throwsIOException
      Returns the number of bytes that can be read from this input stream without blocking. Theavailable method ofInputStream returns0. This methodshould be overridden by subclasses.
      Overrides:
      available in class FilterInputStream
      Returns:
      the number of bytes that can be read from this input stream without blocking.
      Throws:
      IOException - if an I/O error occurs.

    • close

      public void close() throwsIOException
      Closes this input stream and releases any system resources associated with the stream.

      Theclose method ofCipherInputStream calls theclose method of its underlying input stream.

      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Overrides:
      close in class FilterInputStream
      Throws:
      IOException - if an I/O error occurs.
      See Also:

    • markSupported

      public boolean markSupported()
      Tests if this input stream supports themark andreset methods, which it does not.
      Overrides:
      markSupported in class FilterInputStream
      Returns:
      false, since this class does not support themark andreset methods.
      See Also: