com.chrylis.codec.base58

Class Base58Codec

java.lang.Object

com.chrylis.codec.base58.Base58Codec

public class Base58Codec
extends Object

The operations contained in this class are confined to their methods and are entirely thread-safe. In fact, all of the methods are implemented statically, and the instance-bound encode(byte[]) and decode(String) methods are non-static simply to accommodate possible future compatibility with Apache Commons-Codec.

Author:

Christopher Smith

Field Summary

Fields

Modifier and Type	Field and Description
static char[]	ALPHABET Unfortunately, the good folks at Flickr didn't think to make the alphabet ASCIIbetical, so we can't binary-search the byte[].
static BigInteger	BASE
static int	BLOCK_LENGTH_BYTES The number of whole unencoded bytes in a block of 128 Base58 digits.
static int	BLOCK_LENGTH_DIGITS The number of whole encoded Base58 digits resulting from a block of 29 bytes.
static Charset	CHARSET_ASCII

Constructor Summary

Constructors

Constructor and Description
Base58Codec()

Method Summary

Methods

Modifier and Type	Method and Description
byte[]	decode(String source)
byte[]	decode(String source, int numBytes)
static byte[]	doDecode(String source) Decode a Base58-encoded value into bytes.
static byte[]	doDecode(String source, int numBytes) Decode a Base58-encoded value into the specified number of bytes, MSB first (with zero-padding at the front).
static String	doEncode(byte[] source) Encode a stream of MSB-ordered bytes into Base58.
static String	doEncode(long value) Convenience method to encode a long value.
String	encode(byte[] source)
String	encode(long value)
static byte[]	padToSize(byte[] array, int size) Front-pad a byte array with zeroes or remove leading zero bytes.
static Iterator<Character>	stringIterator(String string) Provides an Iterator over the characters in a String.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

CHARSET_ASCII

public static final Charset CHARSET_ASCII

BASE

public static final BigInteger BASE

BLOCK_LENGTH_BYTES

public static final int BLOCK_LENGTH_BYTES

The number of whole unencoded bytes in a block of 128 Base58 digits.

See Also:

Constant Field Values

BLOCK_LENGTH_DIGITS

public static final int BLOCK_LENGTH_DIGITS

The number of whole encoded Base58 digits resulting from a block of 29 bytes.

See Also:

Constant Field Values

ALPHABET

public static final char[] ALPHABET

Unfortunately, the good folks at Flickr didn't think to make the alphabet ASCIIbetical, so we can't binary-search the byte[].

Constructor Detail

Base58Codec

public Base58Codec()

Method Detail

doEncode

public static String doEncode(byte[] source)

Encode a stream of MSB-ordered bytes into Base58. Automatically pads negative numbers with a leading zero byte.

Parameters:

source - the bytes to be encoded

Returns:

the encoded representation

encode

public String encode(byte[] source)

doEncode

public static String doEncode(long value)

Convenience method to encode a long value. Converts the value into a byte array and calls encode(byte[]).

Parameters:

value - the number to be encoded

Returns:

the encoded representation

encode

public String encode(long value)

doDecode

public static byte[] doDecode(String source)

Decode a Base58-encoded value into bytes. Note that this method will return the fewest number of bytes necessary to completely represent the value; if the value may be smaller than the size of the target type, use decode(String, int) to front-pad to a specific length. If the original value encoded was negative, this method will return a leading zero byte added as padding.

Parameters:

source - a Base58-encoded value

Returns:

the bytes represented by the value, unpadded

decode

public byte[] decode(String source)

doDecode

public static byte[] doDecode(String source,
              int numBytes)

Decode a Base58-encoded value into the specified number of bytes, MSB first (with zero-padding at the front).

Parameters:

source - a Base58-encoded value

numBytes - the size of the byte array to be returned

Returns:

the bytes represented by the value, zero-padded at the front

decode

public byte[] decode(String source,
            int numBytes)

stringIterator

public static Iterator<Character> stringIterator(String string)

Provides an Iterator over the characters in a String. Cribbed from this Stack Overflow answer.

Parameters:

string - the string to iterate over

Returns:

an Iterator over the string's characters

padToSize

public static byte[] padToSize(byte[] array,
               int size)

Front-pad a byte array with zeroes or remove leading zero bytes. Useful when trying to extract a type of a specific width (such as a long or 128-bit UUID) from an encoded string, since the decoder doesn't know how wide the original input was and only returns the number of bytes necessary to represent the decoded value, which might include a zero pad to force the value positive.

Parameters:

array - the array to be padded

size - the target size of the array

Returns:

a new array, zero-padded in front to the size requested