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## org.apache.poi.poifs.crypt.binaryrc4
Class BinaryRC4Decryptor

    java.lang.Object
      org.apache.poi.poifs.crypt.Decryptor
          org.apache.poi.poifs.crypt.binaryrc4.BinaryRC4Decryptor

All Implemented Interfaces:
  java.lang.Cloneable

    public class BinaryRC4Decryptor

extends Decryptor
implements java.lang.Cloneable

Field Summary

Fields inherited from class org.apache.poi.poifs.crypt.Decryptor
`DEFAULT_PASSWORD, DEFAULT_POIFS_ENTRY, encryptionInfo`

Constructor Summary
`protected` | `BinaryRC4Decryptor()`

Method Summary
`BinaryRC4Decryptor` | `clone()`
`protected static javax.crypto.SecretKey` | `generateSecretKey(java.lang.String password, EncryptionVerifier ver)`
`ChunkedCipherInputStream` | `getDataStream(DirectoryNode dir)` Return a stream with decrypted data.
`java.io.InputStream` | `getDataStream(java.io.InputStream stream, int size, int initialPos)` Wraps a stream for decryption
`long` | `getLength()` Returns the length of the encrypted data that can be safely read with `Decryptor.getDataStream(org.apache.poi.poifs.filesystem.DirectoryNode)`.
`javax.crypto.Cipher` | `initCipherForBlock(javax.crypto.Cipher cipher, int block)` Initializes a cipher object for a given block index for encryption
`protected static javax.crypto.Cipher` | `initCipherForBlock(javax.crypto.Cipher cipher, int block, EncryptionInfo encryptionInfo, javax.crypto.SecretKey skey, int encryptMode)`
`void` | `setChunkSize(int chunkSize)` Sets the chunk size of the data stream.
`boolean` | `verifyPassword(java.lang.String password)`

Methods inherited from class org.apache.poi.poifs.crypt.Decryptor
`getBlockSizeInBytes, getDataStream, getDataStream, getDataStream, getEncryptionInfo, getInstance, getIntegrityHmacKey, getIntegrityHmacValue, getKeySizeInBytes, getSecretKey, getVerifier, setEncryptionInfo, setIntegrityHmacKey, setIntegrityHmacValue, setSecretKey, setVerifier`

Methods inherited from class java.lang.Object
`equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### BinaryRC4Decryptor

    protected BinaryRC4Decryptor()

Method Detail

### verifyPassword

    public boolean verifyPassword(java.lang.String password)

  Specified by:
    `verifyPassword` in class `Decryptor`

### initCipherForBlock

    public javax.crypto.Cipher initCipherForBlock(javax.crypto.Cipher cipher,
                                                  int block)
                                           throws java.security.GeneralSecurityException

  Description copied from class: `Decryptor`
  Initializes a cipher object for a given block index for encryption

  Overrides:
    `initCipherForBlock` in class `Decryptor`
  Parameters:
    `cipher` - may be null, otherwise the given instance is reset to the new block index
    `block` - the block index, e.g. the persist/slide id (hslf)
  Returns:
    a new cipher object, if cipher was null, otherwise the reinitialized cipher
  Throws:
    `java.security.GeneralSecurityException`

### initCipherForBlock

    protected static javax.crypto.Cipher initCipherForBlock(javax.crypto.Cipher cipher,
                                                            int block,
                                                            EncryptionInfo encryptionInfo,
                                                            javax.crypto.SecretKey skey,
                                                            int encryptMode)
                                                     throws java.security.GeneralSecurityException

  Throws:
    `java.security.GeneralSecurityException`

### generateSecretKey

    protected static javax.crypto.SecretKey generateSecretKey(java.lang.String password,
                                                              EncryptionVerifier ver)

### getDataStream

    public ChunkedCipherInputStream getDataStream(DirectoryNode dir)
                                           throws java.io.IOException,
                                                  java.security.GeneralSecurityException

  Description copied from class: `Decryptor`
  Return a stream with decrypted data.

  Use `Decryptor.getLength()` to get the size of that data that can be safely read from the stream. Just reading to the end of the input stream is not sufficient because there are normally padding bytes that must be discarded

  Specified by:
    `getDataStream` in class `Decryptor`
  Parameters:
    `dir` - the node to read from
  Returns:
    decrypted stream
  Throws:
    `java.io.IOException`
    `java.security.GeneralSecurityException`

### getDataStream

    public java.io.InputStream getDataStream(java.io.InputStream stream,
                                             int size,
                                             int initialPos)
                                      throws java.io.IOException,
                                             java.security.GeneralSecurityException

  Description copied from class: `Decryptor`
  Wraps a stream for decryption

  As we are handling streams and don't know the total length beforehand, it's the callers duty to care for the length of the entries.

  Overrides:
    `getDataStream` in class `Decryptor`
  Parameters:
    `stream` - the stream to be wrapped
    `initialPos` - initial/current byte position within the stream
  Returns:
    decrypted stream
  Throws:
    `java.io.IOException`
    `java.security.GeneralSecurityException`

### getLength

    public long getLength()

  Description copied from class: `Decryptor`
  Returns the length of the encrypted data that can be safely read with `Decryptor.getDataStream(org.apache.poi.poifs.filesystem.DirectoryNode)`. Just reading to the end of the input stream is not sufficient because there are normally padding bytes that must be discarded

  The length variable is initialized in `Decryptor.getDataStream(org.apache.poi.poifs.filesystem.DirectoryNode)`, an attempt to call getLength() prior to getDataStream() will result in IllegalStateException.

  Specified by:
    `getLength` in class `Decryptor`
  Returns:
    length of the encrypted data

### setChunkSize

    public void setChunkSize(int chunkSize)

  Description copied from class: `Decryptor`
  Sets the chunk size of the data stream. Needs to be set before the data stream is requested. When not set, the implementation uses method specific default values

  Overrides:
    `setChunkSize` in class `Decryptor`
  Parameters:
    `chunkSize` - the chunk size, i.e. the block size with the same encryption key

### clone

    public BinaryRC4Decryptor clone()
                             throws java.lang.CloneNotSupportedException

  Overrides:
    `clone` in class `Decryptor`
  Throws:
    `java.lang.CloneNotSupportedException`

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Copyright 2017 The Apache Software Foundation or its licensors, as applicable.