org.htmlparser.scanners

Class ScriptDecoder

public class ScriptDecoder extends Object

Decode script. Script obfuscated by the Windows Script Encoder provided by Microsoft, is converted to plaintext. This code is based loosely on example code provided by MrBrownstone with changes by Joe Steele, see scrdec14.c.
Field Summary
static intLAST_STATE
The state to enter when decrypting is complete.
protected static int[]mDigits
The base 64 decoding table.
protected static byte[]mEncodingIndex
Table of lookup choice.
protected static char[]mEscaped
The escaped characters corresponding to the each escape sequence.
protected static char[]mEscapes
Escape sequence characters.
protected static char[]mLeader
The leader.
protected static char[][]mLookupTable
Two dimensional lookup table.
protected static char[]mPrefix
The prefix.
protected static char[]mTrailer
The trailer.
protected static intSTATE_CHECKSUM
State when reading the checksum.
protected static intSTATE_DECODE
State while decoding.
static intSTATE_DONE
Termination state.
protected static intSTATE_ESCAPE
State when reading an escape sequence.
protected static intSTATE_FINAL
State while exiting.
static intSTATE_INITIAL
State on entry.
protected static intSTATE_LENGTH
State while reading the encoded length.
protected static intSTATE_PREFIX
State when reading up to decoded text.
Method Summary
protected static longdecodeBase64(char[] p)
Extract the base 64 encoded number.
static StringDecode(Page page, Cursor cursor)
Decode script encoded by the Microsoft obfuscator.

Field Detail

LAST_STATE

public static int LAST_STATE
The state to enter when decrypting is complete. If this is STATE_DONE, the decryption will return with any characters following the encoded text still unconsumed. Otherwise, if this is STATE_INITIAL, the input will be exhausted and all following characters will be contained in the return value of the Decode() method.

mDigits

protected static int[] mDigits
The base 64 decoding table. This array determines the value of decoded base 64 elements.

mEncodingIndex

protected static byte[] mEncodingIndex
Table of lookup choice. The decoding cycles between three flavours determined by this sequence of 64 choices, corresponding to the first dimension of the lookup table.

mEscaped

protected static char[] mEscaped
The escaped characters corresponding to the each escape sequence.

mEscapes

protected static char[] mEscapes
Escape sequence characters.

mLeader

protected static char[] mLeader
The leader. The prefix to the encoded script is #@~^nnnnnn== where the n are the length digits in base64.

mLookupTable

protected static char[][] mLookupTable
Two dimensional lookup table. The decoding uses this table to determine the plaintext for characters that aren't mEscaped.

mPrefix

protected static char[] mPrefix
The prefix. The prfix separates the encoded text from the length.

mTrailer

protected static char[] mTrailer
The trailer. The suffix to the encoded script is nnnnnn==^#~@ where the n are the checksum digits in base64. These characters are the part after the checksum.

STATE_CHECKSUM

protected static final int STATE_CHECKSUM
State when reading the checksum.

STATE_DECODE

protected static final int STATE_DECODE
State while decoding.

STATE_DONE

public static final int STATE_DONE
Termination state.

STATE_ESCAPE

protected static final int STATE_ESCAPE
State when reading an escape sequence.

STATE_FINAL

protected static final int STATE_FINAL
State while exiting.

STATE_INITIAL

public static final int STATE_INITIAL
State on entry.

STATE_LENGTH

protected static final int STATE_LENGTH
State while reading the encoded length.

STATE_PREFIX

protected static final int STATE_PREFIX
State when reading up to decoded text.

Method Detail

decodeBase64

protected static long decodeBase64(char[] p)
Extract the base 64 encoded number. This is a very limited subset of base 64 encoded characters. Six characters are expected. These are translated into a single long value. For a more complete base 64 codec see for example the base64 package of iHarder.net

Parameters: p Six base 64 encoded digits.

Returns: The value of the decoded number.

Decode

public static String Decode(Page page, Cursor cursor)
Decode script encoded by the Microsoft obfuscator.

Parameters: page The source for encoded text. cursor The position at which to start decoding. This is advanced to the end of the encoded text.

Returns: The plaintext.

Throws: ParserException If an error is discovered while decoding.

HTML Parser is an open source library released under LGPL. SourceForge.net