org.tranche.hash
Class BigHash

java.lang.Object
  org.tranche.hash.BigHash

All Implemented Interfaces:

java.lang.Comparable<BigHash>

public final class BigHash
extends java.lang.Object
implements java.lang.Comparable<BigHash>

A utility class for making and representing all of the hash information required for files on Tranche.

Author:

Jayson Falkner - jfalkner@umich.edu, James "Augie" Hill - augman85@gmail.com, Bryan Smith - bryanesmith@gmail.com

Field Summary

static int	HASH_LENGTH The exact size of the hash.
static int	HASH_STRING_LENGTH_BASE16 BigHash length in Base16.
static int	HASH_STRING_LENGTH_BASE64 BigHash length in Base64.
static int	LENGTH_LENGTH Length of bytes represented by BigHash.
static int	LENGTH_OFFSET Offset of the beggingin of the Length portion of the BigHash.
static int	MD5_LENGTH MD5 hash length in bytes.
static int	MD5_OFFSET Offset of the beginning of the MD5 portion of the BigHash.
static int	SHA1_LENGTH SHA-1 hash length in bytes.
static int	SHA1_OFFSET Offset of the beginning of the SHA-1 portion of the BigHash.
static int	SHA256_LENGTH SHA-256 hash length in bytes.
static int	SHA256_OFFSET Offset of the beginning of the SHA-256 portion of the BigHash.

Constructor Summary

BigHash(byte[] bytes)
Construct a BigHash object from an array of bytes.

BigHash(byte[] bytes, byte[] padding)
Construct a BigHash object from an array of bytes and padding.

BigHash(byte[] bytes, int length)
Construct a BigHash object from an array of bytes using a length that starts from the begnning of the array.

BigHash(byte[] bytes, int length, byte[] padding)
Construct a BigHash object from an array of bytes using a length and and additional padding.

BigHash(java.io.File f)
Construct a BigHash object from a file.

BigHash(java.io.File f, byte[] padding)
Construct a BigHash object from a file with some additional padding.

BigHash(java.io.InputStream is, long length)
Construct a BigHash object from a stream of a specified length.

BigHash(java.io.InputStream is, long length, byte[] padding)
Construct a BigHash object from a stream of specified length with some additional padding.

Method Summary

void	add(BigHash hash)
BigHash	clone()
int	compareTo(BigHash bh) Similar to standard compareTo() methods, this compares to determine the equality of two BigHash objects.
static BigHash	createFromBytes(byte[] bytes) Create a BigHash object from a set of bytes.
static BigHash	createFromBytes(byte[] bytes, int offset) Create a BigHash object from a set of bytes with a given offset where to begin calculation of the hash.
static BigHash	createHashFromString(java.lang.String hash) Create the hash from either a Base16 or Base64 encoded string.
boolean	equals(java.lang.Object obj) A customization of the equals() method to check BigHash objects.
long	getLength() Another method for getting BigHash length used for hashes prior to 5/1/2008.
java.nio.ByteBuffer	getMD5() Return MD5 portion of BigHash.
BigHash	getNext() Gets the next BigHash in the BigHash universe (this+1).
BigHash	getPrevious() Gets the previous BigHash in the BigHash universe (this - 1).
java.nio.ByteBuffer	getSHA1() Return SHA-1 portion of BigHash.
java.nio.ByteBuffer	getSHA256() Return SHA-256 portion of BigHash.
int	hashCode() A customization of the hashCode() method to check BigHash objects.
java.lang.String	toBase16String() Return a Base16 encoded representation of the BigHash as a string.
java.lang.String	toBase64String() Return a Base64 encoded representation of the BigHash as a string.
byte[]	toByteArray() Return a byte array representation of the BigHash.
java.lang.String	toString() Return a Base64 encoded representation of the BigHash as a string.
java.lang.String	toWebSafeString()

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

MD5_LENGTH

public static final int MD5_LENGTH

MD5 hash length in bytes.

See Also:

Constant Field Values

SHA1_LENGTH

public static final int SHA1_LENGTH

SHA-1 hash length in bytes.

See Also:

Constant Field Values

SHA256_LENGTH

public static final int SHA256_LENGTH

SHA-256 hash length in bytes.

See Also:

Constant Field Values

LENGTH_LENGTH

public static final int LENGTH_LENGTH

Length of bytes represented by BigHash.

See Also:

Constant Field Values

MD5_OFFSET

public static final int MD5_OFFSET

Offset of the beginning of the MD5 portion of the BigHash.

See Also:

Constant Field Values

SHA1_OFFSET

public static final int SHA1_OFFSET

Offset of the beginning of the SHA-1 portion of the BigHash.

See Also:

Constant Field Values

SHA256_OFFSET

public static final int SHA256_OFFSET

Offset of the beginning of the SHA-256 portion of the BigHash.

See Also:

Constant Field Values

LENGTH_OFFSET

public static final int LENGTH_OFFSET

Offset of the beggingin of the Length portion of the BigHash.

See Also:

Constant Field Values

HASH_LENGTH

public static final int HASH_LENGTH

The exact size of the hash. Made up of:

• MD5 length: 16 bytes
• SHA1 length: 20 bytes
• SHA256 length: 32 bytes
• Length of file length: 8 bytes

Hence this constant's value is 76 bytes, the sum of its components.

See Also:

Constant Field Values

HASH_STRING_LENGTH_BASE16

public static final int HASH_STRING_LENGTH_BASE16

BigHash length in Base16.

See Also:

Constant Field Values

HASH_STRING_LENGTH_BASE64

public static final int HASH_STRING_LENGTH_BASE64

BigHash length in Base64.

See Also:

Constant Field Values

Constructor Detail

BigHash

public BigHash(byte[] bytes)

Construct a BigHash object from an array of bytes.

Parameters:

bytes -

BigHash

public BigHash(byte[] bytes,
               int length)

Construct a BigHash object from an array of bytes using a length that starts from the begnning of the array.

Parameters:

bytes -

length -

BigHash

public BigHash(byte[] bytes,
               byte[] padding)

Construct a BigHash object from an array of bytes and padding.

Parameters:

bytes -

padding -

BigHash

public BigHash(byte[] bytes,
               int length,
               byte[] padding)

Construct a BigHash object from an array of bytes using a length and and additional padding.

Parameters:

bytes -

length -

padding -

BigHash

public BigHash(java.io.File f)
        throws java.io.FileNotFoundException

Construct a BigHash object from a file.

Parameters:

f -

Throws:

java.io.FileNotFoundException

BigHash

public BigHash(java.io.File f,
               byte[] padding)
        throws java.io.FileNotFoundException

Construct a BigHash object from a file with some additional padding.

Parameters:

f -

padding -

Throws:

java.io.FileNotFoundException

BigHash

public BigHash(java.io.InputStream is,
               long length)

Construct a BigHash object from a stream of a specified length.

Parameters:

is -

length -

BigHash

public BigHash(java.io.InputStream is,
               long length,
               byte[] padding)

Construct a BigHash object from a stream of specified length with some additional padding.

Parameters:

is -

length -

padding -

Method Detail

getMD5

public final java.nio.ByteBuffer getMD5()

Return MD5 portion of BigHash.

Returns:

getSHA1

public final java.nio.ByteBuffer getSHA1()

Return SHA-1 portion of BigHash.

Returns:

getSHA256

public final java.nio.ByteBuffer getSHA256()

Return SHA-256 portion of BigHash.

Returns:

getLength

public final long getLength()

Another method for getting BigHash length used for hashes prior to 5/1/2008.

Returns:

toByteArray

public final byte[] toByteArray()

Return a byte array representation of the BigHash.

Returns:

getNext

public final BigHash getNext()

Gets the next BigHash in the BigHash universe (this+1).

Returns:

getPrevious

public final BigHash getPrevious()

Gets the previous BigHash in the BigHash universe (this - 1).

Returns:

add

public final void add(BigHash hash)

Parameters:

hash -

clone

public BigHash clone()

Overrides:

clone in class java.lang.Object

Returns:

compareTo

public int compareTo(BigHash bh)

Similar to standard compareTo() methods, this compares to determine the equality of two BigHash objects.

Specified by:

compareTo in interface java.lang.Comparable<BigHash>

Parameters:

bh -

Returns:

createFromBytes

public static final BigHash createFromBytes(byte[] bytes)

Create a BigHash object from a set of bytes.

Parameters:

bytes -

Returns:

createFromBytes

public static final BigHash createFromBytes(byte[] bytes,
                                            int offset)

Create a BigHash object from a set of bytes with a given offset where to begin calculation of the hash.

Parameters:

bytes -

offset -

Returns:

toString

public final java.lang.String toString()

Return a Base64 encoded representation of the BigHash as a string.

Overrides:

toString in class java.lang.Object

Returns:

toBase64String

public final java.lang.String toBase64String()

Return a Base64 encoded representation of the BigHash as a string.

Returns:

toBase16String

public final java.lang.String toBase16String()

Return a Base16 encoded representation of the BigHash as a string.

Returns:

toWebSafeString

public final java.lang.String toWebSafeString()

Returns:

equals

public final boolean equals(java.lang.Object obj)

A customization of the equals() method to check BigHash objects. This method gets invoked alot because BigHash objects are the primary identifier of data on Tranche.

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

A customization of the hashCode() method to check BigHash objects. This method gets invoked alot because BigHash objects are the primary identifier of data on Tranche.

Overrides:

hashCode in class java.lang.Object

createHashFromString

public static final BigHash createHashFromString(java.lang.String hash)
                                          throws java.lang.RuntimeException

Create the hash from either a Base16 or Base64 encoded string.

Throws:

java.lang.RuntimeException