net.eduvax.util

Class Crypto

java.lang.Object

net.eduvax.util.Crypto

public class Crypto
extends java.lang.Object

Simple crypto utility.

Field Summary

Fields

Modifier and Type	Field and Description
private static java.lang.String	_base64 base 64 code set.
private byte[]	_key Cypher key.
private static java.security.MessageDigest	_md5 Hash code provider.
private static java.util.Random	_rnd Random generator.

Constructor Summary

Constructors

Constructor and Description
Crypto(java.lang.String key) Create new Crypto tool.

Method Summary

Methods

Modifier and Type	Method and Description
static byte[]	base64Decode(java.lang.String str) Simple base 64 decoding.
static java.lang.String	base64Encode(byte[] data) Simple base 64 encoding.
private java.lang.String	cypher(java.lang.String str, boolean determinist) Simple crypto implementation.
static java.lang.String	getMD5HashString(java.lang.String str) Compute MD5 hash string.
java.lang.String	nonReversCrypt(java.lang.String str) Non reversible encryption.
java.lang.String	reversibleCrypt(java.lang.String str) Reversible crypt of a string.
java.lang.String	uncrypt(java.lang.String str) Decrypt a string encrypted in a revesible way.

Methods inherited from class java.lang.Object

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

Field Detail

_key

private byte[] _key

Cypher key.

_base64

private static java.lang.String _base64

base 64 code set.

_rnd

private static java.util.Random _rnd

Random generator.

_md5

private static java.security.MessageDigest _md5

Hash code provider.

Constructor Detail

Crypto

public Crypto(java.lang.String key)

Create new Crypto tool.

Parameters:

key - cipher key.

Method Detail

reversibleCrypt

public java.lang.String reversibleCrypt(java.lang.String str)

Reversible crypt of a string. The ciphered string can e deciphered using the uncrypt() method. The encryption is non determinist, even when using the same encryption key, a random seed will produce a different encryption at each use.

Parameters:

str - string to crypt.

Returns:

cyphered string.

nonReversCrypt

public java.lang.String nonReversCrypt(java.lang.String str)

Non reversible encryption. This encryption is base on hash code. This encryption method is determinist. Using the same key, a string will always produce the same encrypted string. Then to check validity of a candidate password, just encrypt the candidate to compare with the stored encrypted string.

Parameters:

str - string to be encrypted.

Returns:

encrypted string.

getMD5HashString

public static java.lang.String getMD5HashString(java.lang.String str)

Compute MD5 hash string.

Parameters:

str - string to hash

Returns:

string representation of the hash code.

uncrypt

public java.lang.String uncrypt(java.lang.String str)

Decrypt a string encrypted in a revesible way. This method is dedicated to decrypt string encrypted using the reversibleCrypt() method.

Parameters:

str - cyphered string.

Returns:

decyphered string.

cypher

private java.lang.String cypher(java.lang.String str,
                      boolean determinist)

Simple crypto implementation. input string XOR (cypher key + optional random seed). The cyhered bytes are base 64 encoded to keep encryption compatible with ASCII streams.

Parameters:

str - string to crypt

determinist - crypt methode : with random seed (true), without random seed (false)

Returns:

crypted string.

base64Encode

public static java.lang.String base64Encode(byte[] data)

Simple base 64 encoding. Not real full base 64 encoding, produce string without any CR char. Regular 72 char line split is not produced.

Parameters:

data - data to be encoded.

Returns:

base 64 encoded string.

base64Decode

public static byte[] base64Decode(java.lang.String str)

Simple base 64 decoding. Dedicated to base 64 string created by this class's base64Encoding method. Does not handle some regular base 64 encoding such as multiline encoding.

Parameters:

str - string to decode.

Returns:

decoded data as byte array.