MessageDigest (moe.ios.core API)

java.lang.Object
- java.security.MessageDigestSpi
- - java.security.MessageDigest

Direct Known Subclasses:

BCMessageDigest
```
public abstract class MessageDigest
extends MessageDigestSpi
```
Uses a one-way hash function to turn an arbitrary number of bytes into a fixed-length byte sequence. The original arbitrary-length sequence is the message, and the fixed-length byte sequence is the digest or message digest.
Sample Code

The basic pattern to digest an InputStream looks like this:
```
  MessageDigest digester = MessageDigest.getInstance("MD5");
  byte[] bytes = new byte[8192];
  int byteCount;
  while ((byteCount = in.read(bytes)) > 0) {
    digester.update(bytes, 0, byteCount);
  }
  byte[] digest = digester.digest();
 
```
That is, after creating or resetting a MessageDigest you should call update(byte[],int,int) for each block of input data, and then call digest() to get the final digest. Note that calling digest resets the MessageDigest. Advanced users who want partial digests should clone their MessageDigest before calling digest.
This class is not thread-safe.
See Also:

MessageDigestSpi

Constructor Summary

Constructors
Modifier Constructor and Description

protected MessageDigest(String algorithm)
Constructs a new instance of MessageDigest with the name of the algorithm to use.

Constructors
Modifier	Constructor and Description
`protected`	`MessageDigest(String algorithm)` Constructs a new instance of `MessageDigest` with the name of the algorithm to use.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`byte[]`	`digest()` Computes and returns the final hash value for this `MessageDigest`.
`byte[]`	`digest(byte[] input)` Performs the final update and then computes and returns the final hash value for this `MessageDigest`.
`int`	`digest(byte[] buf, int offset, int len)` Computes and stores the final hash value for this `MessageDigest`.
`String`	`getAlgorithm()` Returns the name of the algorithm of this `MessageDigest`.
`int`	`getDigestLength()` Returns the engine digest length in bytes.
`static MessageDigest`	`getInstance(String algorithm)` Returns a new instance of `MessageDigest` that utilizes the specified algorithm.
`static MessageDigest`	`getInstance(String algorithm, Provider provider)` Returns a new instance of `MessageDigest` that utilizes the specified algorithm from the specified provider.
`static MessageDigest`	`getInstance(String algorithm, String provider)` Returns a new instance of `MessageDigest` that utilizes the specified algorithm from the specified provider.
`Provider`	`getProvider()` Returns the provider associated with this `MessageDigest`.
`static boolean`	`isEqual(byte[] digesta, byte[] digestb)` Indicates whether to digest are equal by performing a simply byte-per-byte compare of the two digests.
`void`	`reset()` Puts this `MessageDigest` back in an initial state, such that it is ready to compute a one way hash value.
`String`	`toString()` Returns a string containing a concise, human-readable description of this `MessageDigest` including the name of its algorithm.
`void`	`update(byte arg0)` Updates this `MessageDigest` using the given `byte`.
`void`	`update(byte[] input)` Updates this `MessageDigest` using the given `byte[]`.
`void`	`update(byte[] input, int offset, int len)` Updates this `MessageDigest` using the given `byte[]`.
`void`	`update(ByteBuffer input)` Updates this `MessageDigest` using the given `input`.

Methods inherited from class java.security.MessageDigestSpi
clone, engineDigest, engineDigest, engineGetDigestLength, engineReset, engineUpdate, engineUpdate, engineUpdate

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

- Constructor Detail
  - MessageDigest
```
protected MessageDigest(String algorithm)
```
    Constructs a new instance of MessageDigest with the name of the algorithm to use.
    
    Parameters:
    
    algorithm - the name of algorithm to use
- Method Detail
  - getInstance
```
public static MessageDigest getInstance(String algorithm)
                                 throws NoSuchAlgorithmException
```
    Returns a new instance of MessageDigest that utilizes the specified algorithm.
    
    Parameters:
    
    algorithm - the name of the algorithm to use
    
    Returns:
    
    a new instance of MessageDigest that utilizes the specified algorithm
    
    Throws:
    
    NoSuchAlgorithmException - if the specified algorithm is not available
    
    NullPointerException - if algorithm is null
  - getInstance
```
public static MessageDigest getInstance(String algorithm,
                                        String provider)
                                 throws NoSuchAlgorithmException,
                                        NoSuchProviderException
```
    Returns a new instance of MessageDigest that utilizes the specified algorithm from the specified provider.
    
    Parameters:
    
    algorithm - the name of the algorithm to use
    
    provider - the name of the provider
    
    Returns:
    
    a new instance of MessageDigest that utilizes the specified algorithm from the specified provider
    
    Throws:
    
    NoSuchAlgorithmException - if the specified algorithm is not available
    
    NoSuchProviderException - if the specified provider is not available
    
    NullPointerException - if algorithm is null
    
    IllegalArgumentException - if provider == null || provider.isEmpty()
  - getInstance
```
public static MessageDigest getInstance(String algorithm,
                                        Provider provider)
                                 throws NoSuchAlgorithmException
```
    Returns a new instance of MessageDigest that utilizes the specified algorithm from the specified provider. The provider supplied does not have to be registered.
    
    Parameters:
    
    algorithm - the name of the algorithm to use
    
    provider - the provider
    
    Returns:
    
    a new instance of MessageDigest that utilizes the specified algorithm from the specified provider
    
    Throws:
    
    NoSuchAlgorithmException - if the specified algorithm is not available
    
    NullPointerException - if algorithm is null
    
    IllegalArgumentException - if provider == null
  - reset
```
public void reset()
```
    Puts this MessageDigest back in an initial state, such that it is ready to compute a one way hash value.
  - update
```
public void update(byte arg0)
```
    Updates this MessageDigest using the given byte.
    
    Parameters:
    
    arg0 - the byte to update this MessageDigest with
    
    See Also:
    
    reset()
  - update
```
public void update(byte[] input,
                   int offset,
                   int len)
```
    Updates this MessageDigest using the given byte[].
    
    Parameters:
    
    input - the byte array
    
    offset - the index of the first byte in input to update from
    
    len - the number of bytes in input to update from
    
    Throws:
    
    IllegalArgumentException - if offset or len are not valid in respect to input
  - update
```
public void update(byte[] input)
```
    Updates this MessageDigest using the given byte[].
    
    Parameters:
    
    input - the byte array
    
    Throws:
    
    NullPointerException - if input is null
  - digest
```
public byte[] digest()
```
    Computes and returns the final hash value for this MessageDigest. After the digest is computed the receiver is reset.
    
    Returns:
    
    the computed one way hash value
    
    See Also:
    
    reset()
  - digest
```
public int digest(byte[] buf,
                  int offset,
                  int len)
           throws DigestException
```
    Computes and stores the final hash value for this MessageDigest. After the digest is computed the receiver is reset.
    
    Parameters:
    
    buf - the buffer to store the result
    
    offset - the index of the first byte in buf to store
    
    len - the number of bytes allocated for the digest
    
    Returns:
    
    the number of bytes written to buf
    
    Throws:
    
    DigestException - if an error occurs
    
    IllegalArgumentException - if offset or len are not valid in respect to buf
    
    See Also:
    
    reset()
  - digest
```
public byte[] digest(byte[] input)
```
    Performs the final update and then computes and returns the final hash value for this MessageDigest. After the digest is computed the receiver is reset.
    
    Parameters:
    
    input - the byte array
    
    Returns:
    
    the computed one way hash value
    
    See Also:
    
    reset()
  - toString
```
public String toString()
```
    Returns a string containing a concise, human-readable description of this MessageDigest including the name of its algorithm.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    a printable representation for this MessageDigest
  - isEqual
```
public static boolean isEqual(byte[] digesta,
                              byte[] digestb)
```
    Indicates whether to digest are equal by performing a simply byte-per-byte compare of the two digests.
    
    Parameters:
    
    digesta - the first digest to be compared
    
    digestb - the second digest to be compared
    
    Returns:
    
    true if the two hashes are equal, false otherwise
  - getAlgorithm
```
public final String getAlgorithm()
```
    Returns the name of the algorithm of this MessageDigest.
    
    Returns:
    
    the name of the algorithm of this MessageDigest
  - getProvider
```
public final Provider getProvider()
```
    Returns the provider associated with this MessageDigest.
    
    Returns:
    
    the provider associated with this MessageDigest
  - getDigestLength
```
public final int getDigestLength()
```
    Returns the engine digest length in bytes. If the implementation does not implement this function or is not an instance of Cloneable, 0 is returned.
    
    Returns:
    
    the digest length in bytes, or 0
  - update
```
public final void update(ByteBuffer input)
```
    Updates this MessageDigest using the given input.
    
    Parameters:
    
    input - the ByteBuffer

Class MessageDigest

Sample Code

Constructor Summary

Method Summary

Methods inherited from class java.security.MessageDigestSpi

Methods inherited from class java.lang.Object

Constructor Detail

MessageDigest

Method Detail

getInstance

getInstance

getInstance

reset

update

update

update

digest

digest

digest

toString

isEqual

getAlgorithm

getProvider

getDigestLength

update