ARC4_Algorithm

A simple command line tool to encrypt / decrypt some data using the well known ARC4 algorithm

Compiling

See makefile

Using GCC on Linux or on Cygwin

make all

OR

make all clean

(to clean .o files after compiling)

Using MinGW GCC 64 bits on Windows (compilation made under Cygwin with correct packages installed)

make SPECIFIC_CC=x86_64-w64-mingw32-gcc specific_gcc clean

Using MinGW GCC 32 bits on Windows (compilation made under Cygwin with correct packages installed)

make SPECIFIC_CC=i686-w64-mingw32-gcc specific_gcc clean

Using any other compiler

make SPECIFIC_CC=the-name-of-your-compiler specific_gcc clean

Usage

ARC4_Algorithm -k [Encryption Key] -i [input data do cipher/decipher]

[Encryption Key]    : An hexadecimal ASCII key (up to 64 bytes [128 ASCII characters or 512 bits key])
                      Example : "12"                 = 1 byte  ( 8 bits key)
                      Example : "ABCD"               = 2 bytes (16 bits key)
                      Example : "AABBCCDDEE"         = 5 bytes (40 bits key)
                      Example : "AABBCCDDEEFF112233" = 9 bytes (72 bits key)
                      Example : "000000000000000001" = 9 bytes (72 bits key)
                      Example : "A"                  = Will be considered as 1 byte [0xA0] (8 bits key)
                      Note    : For good decoding a key length with a multiple of 8 bits should be preferred [8, 16, 24, 32, 40, 44, 48... bits]

[input data do encrypt/decrypt] : An hexadecimal ASCII string to cipher or decipher (up to 4096 bytes [8192 ASCII characters])
                      Example : "DEADBEEF"           = 4 bytes (32 bits) of data to cipher/decipher
                      Example : "CAFEDECADEADBEEF"   = 8 bytes (64 bits) of data to cipher/decipher
                      Example : "ABC"                = will be considered as 2 bytes (16 bits : [0xAB-0xC0]) of data to cipher/decipher

Examples

Encrypt the following HEX string : "00112233445566778899AABBCCDDEEFF" (total 16 bytes) With the following encryption key : "DEADBEEF" (total 4 bytes)

Call the program with the following syntax :

ARC4_Algorithm -k "DEADBEEF" -i "00112233445566778899AABBCCDDEEFF"

The argument -k [Encryption Key] is mandatory, launching the software without this argument will causes an error

The argument -i [input data do cipher/decipher] is optional, if no argument is passed, then the tool will display at output the key stream produced by the ARC4 algorithm (4096 bytes will be diplayed as defined by the constant MAX_OUTPUT_KEY_STREAM_LENGTH).

Note : To ensure a good working of this software it is preferable to pass a key and data with a multiple of 8 bits (8, 16, 24, 32, 40... bits).

Limitations

The encryption key length (parameter -k [Encryption Key]) is limited by the constant MAX_ARC4_INPUT_KEY_LENGTH to 64 bytes

The input data to cipher/decipher length (parameter -i [input data do cipher/decipher]) is limited by the constant MAX_OUTPUT_KEY_STREAM_LENGTH to 4096 bytes

Modify these two constant if you want to increase the capability of this software