This repository contains two command line applications, encryption and decryption.
Both programs are designed to be executed from the command line.
encryption encrypts the input using one of the supported algorithms.
To select the desired algorithm, the parameter -a <algorithm name> or --algorithm <algorithm name> shall be used.
Each algorithm uses certain settings/keys.
If a value for one of these settings is supplied as a command line parameter, only this value for this setting will be used.
If the setting is not supplied, all possible values for this setting will be used in succession, returning multiple different ciphers.
The input text can be supplied as the first parameter (otherwise the user has to input it later on).
xor:-k <key>or--key <key>: each number (representing a single character using ASCII) get xored with this number-b <base>or--base <base>: sets base, every encrypted number shall be represented in-d <delimiter>or--delim <delimiter>: if not supplied, the encrypted numbers won't be separated, if the<delimiter>is omitted, a space will be used-o: when set, each encrypted number will have the same length (0s will be used as a padding)
plow:-k <key>: sets the width of the array, the input gets read into
transpose:-k <key>: sets the width of the array, the input gets read into
fence
These examples are from linux, windows users have to replace ./encryption with encryption.exe.
./encryption "Hello World!" -a xor -b 16 -k 42 -0 -d
This command returns the cipher 62 4f 46 46 45 0a 7d 45 58 46 4e 0b using the xor encryption algorithm with the key 42. The encrypted characters are represented in base-16 (hex), separated with spaces and padded with 0s.
./encryption "Hello World!" -a xor -b 16 -0 -d
This command does the same as the one prior with the difference that all possible keys (0-255) are used in succession.
decryption is able to decrypt certain ciphers automatically.
The user gives the program as much information as she has and it tries its best to decrypt the entered cipher.
The program uses brute force by default, creating all decryptions using all possible settings and decryption algorithms.
Each decrypted string gets a score based on its human comprehensibility.
To determine the score of a given string, a dictionary of English and German words is being used.
The user is able to add custom words into user_dict.dic in the resource folder.
Thus anything that can't be found in the dictionaries, like links or telephone numbers, will receive bad scores.
That's why this program won't be able to automatically decrypt these, manual decryption is necessary in this case.
The user can use the -m 0 parameter and redirect the output into a file to achieve that.
The input cipher can be supplied as the first parameter (otherwise the user has to input it later on).
These parameters are supported with all algorithms:
-a <algorithms...>or--algorithm <algorithms...>: This can be set toxorand/ortransform-m <amount>or--amount <amount>: By default the program returns the best decryptions it can find. With this parameter only a certain amount of decryptions will be generated. (0will print all found decryptions.)-f <input_file_path> <output_file_path>or--file <input_file_path> <output_file_path>: When this flag is used, each line from<input_file_path>will be treated as an individual cipher and decrypted into<output_file_path>. Every line can use a different algorithm / settings.
The program starts by separating the cipher into individual encrypted numbers. There are two ways of doing this:
- Search for characters that can't be decrypted (like spaces) and cut at those delimiters. <- requires delimiter
- Ignore all of these possible delimiters and cut into numbers of equal length. <- requires encrypted numbers to be of equal length
The program will perform both of these methods (unless ordered not to), which may lead to the decrypted text being returned twice.
It will use all possible values for each setting unless otherwise specified. These are the supported parameters:
-d <delimiters...>or--delim <delimiters...>: Only these supplied delimiters will be used to split the encrypted numbers. The program won't attempt to separate the cipher with the length of the encrypted numbers, unless explicitly requested.-l <lengths...>or--len <lengths...>: Only these encrypted numbers lengths will be used. Analogue to the delimiters, all delimiters are getting ignored if not explicitly requested.-b <bases...>or--base <bases...>: If this parameter is used, only these bases will be tested.-k <keys...>or--key <keys...>: Only these keys will be tested if supplied.
This implements multiple decryption algorithms (plow, transpose and fence).
The cipher gets read into a 2D array row by row.
The widths of the array that shall be tested can be specified with -k <keys...> or --key <keys...>.
Each algorithm is characterized by a certain transformation used on the 2D array.
Once that is done, the transformed 2D array gets read row by row.
The used transformation can be specified with -t <transformations...> or --transform <transformations...>.
plow and transpose are supported.
Fence decryption can be achieved by using a transpose transformation with half the length of the cipher as key, rounded up.
These examples are from linux, windows users have to replace ./decryption with decryption.exe.
./decryption "HloWrdel ol"
In this case the user doesn't know anything about the used encryption process, thus no parameters are supplied.
./decryption "HloWrdel ol" -a transform -t transpose -k 6
This cipher has been created using the fence encryption and has the length 11. Therefore the transform algorithm with the transpose transformation can be used with the key 6.
The latest build for both linux and windows can be downloaded here.
This repository uses premake5 as its build system. Therefore premake5 can be used to create e.g. Makefiles, Visual Studio .sln and .vcxproj files, etc... Once the files for the compiler of your liking have been created, you can use that compiler to build the projects.
This repository consists of three projects, encryption, decryption and utils.
This is a statically linked library containing:
- an abstraction layer for console arguments,
- an implementation of the Trie data structure
- string transformation functionality used for both encrypting and decrypting transformation ciphers and
- generally useful preprocessor macros and functions.