Description
1 Project Description
In bitcoin mining, the most important step is to find solutions for Proof of Work (POW). In this project,
you will need to simulate the mining process by implementing Proof of Work (POW). More specifically,
– Given a POW difficulty d, your program should be able to compute a target t based on this POW
difficulty d, where the first d bits in this target are all 0s and the rest of the bits in this target are 1s.
In addition, you program should be able to write this target to a file.
– Given an input m and a target t, your program should be able to compute a POW solution s, s.t.,
Hash(m||s) ≤ t
where || is a concatenation operator. For example, if m = bear and s = cats, then m||s = bearcats.
In addition, you program should be able to write this solution s to a file.
– Given an input m, a POW solution s, and a target t, your program should be able to verify whether
this POW solution is a valid solution for input m. Specifically, you program should output
1, if Hash(m||s) ≤ t
0, otherwise
In this project, you should use SHA256 as your hash function.
2 Basic Requirements
Programming Language: You can use either C/C++, Python or Java. If you choose to use C/C++,
CMake is recommended (but not required). You can choose any IDE you like, the code you submit should
be able to compile and run in Linux or Windows. Please provide a clear description about how to compile
and run your code in the Readme file.
Crypto Libraries: You can leverage third-party libraries, such as openssl (C/C++), BouncyCastle
(Java), etc., to implement SHA256. You do not need to build the functions of SHA256 by yourself.
Program Directory: Please name your project folder as pow m123456, where pow is the name of this
project and m123456 is your UCID. The recommended directories of your program should be organized as
follows:
./ pow_m123456 / src
./ pow_m123456 / build
./ pow_m123456 / data
./ pow_m123456 / Readme . txt
2 CS 5158/6058
Normally, folder src should include all the source files and your own header files, e.g., .cpp and .h files.
All the object files and executable files, e.g., .o files, should be under folder build. Folder data has all the
given files and data, and also includes all the files and results generated by the program. In Readme.txt
file, you should write a description of your code, show which language and version you use, and illustrate
how to compile, run and use your code.
3 Project Details
In this project, you should use SHA256 as your hash function. Assume a message m is stored in file
“../data/input.txt”, and assume this message is your UCID, for example
m123456
1. Target Generation Function:
(a) Given a POW difficulty d from the command line, compute a target t based on this POW difficulty d,
where the first d bits in this target are all 0s and the rest of the bits in this target are 1s. Since we use
SHA256 in this project, it indicates that given d, the first d bits are 0s and the rest of 256 − d bits in
this target are 1s, e.g.,
t = 00…00
| {z }
d
11…11
| {z }
256−d
You also need to print this target in the terminal, and write this target to file “../data/target.txt”.
There is no requirement in terms of the format of this target as long as it is consistent with your read
function.
2. Solution Generation Function:
(a) Read a target t from file “../data/target.txt, and read an input m from file “../data/input.txt,
find a solution s, s.t.,
Hash(m||s) ≤ t
print this solution, and write this solution to file “../data/solution.txt”. Note that since everyone’s
input message (i.e., UCID) is different, the solution for each student might be different. You code should
be generic, i.e., it should be able to find solutions for other inputs as well.
3. Verification Function:
(a) Read an input m from file “../data/input.txt, read a solution from file “../data/solution.txt”,
read a target t from file “../data/target.txt, output and print 1 if this solution is valid, i.e.,
Hash(m||s) ≤ t; otherwise, output and print 0.
4. (CS6058 Only) Performance of POW:
(a) Given an input m (i.e., your UCID) from file “../data/input.txt”, generate 6 different solutions for
6 different difficulties. More specifically, generate a solution si for each difficulty i, where 21 ≤ i ≤ 26.
All the 6 solutions should be different. Record and compare the running time of finding each of
those solutions, and include the solutions you found, the running time and comparison in your one-page
report (in pdf). In your report, please describe details of your implementation, such as OS, language,
crypto libraries, etc. You can use tables or figures to present the comparison. Please put this report
under your project folder and submit it together with your code.
3 CS 5158/6058
4 Evaluation
Your project will be evaluated in three aspects.
1. Correctness of Functions (75%): Your program should be able to correctly run all the functions
described in this project. If for some reason, your code cannot be compiled but the logic of your code
is correct, you will still get partial credits.
2. Comments and Descriptions (15%): Write comments and explain each function in your code, such
as inputs, outputs, etc. You may need some of the functions in other projects. Detailed comments on
each function can save your time in other projects. In addition, please clearly explain how to compile
and run your code in Readme.txt. For graduate students, the scores of your report in Task 4 will be
included in this aspect. Undergraduate students do not need to submit a report, since Task 4 is for
graduate students only.
3. Coding Style (10%): A good coding style is always important, especially for large projects. Please
keep each function simple, try to avoid long functions, and create multiple .h and .cpp files if needed.
For example, it is not a good idea to put everything in the main function.
5 Examples
This section provides some examples, which can help you understand the functions of your project. If
your code can provide the same functionalities, you can customize the number of arguments and the order
of arguments, as long as you describe it clearly in the Readme file.
Example 1: The following command generates a target based on a difficulty
pow target d ../ data / target . txt
where pow is the name of your executable file, target is the argument for target generation function, d is
difficulty, and the result of this target will be written to file ../data/target.txt. Note that, depending
on where your executable file is, the paths of your input and output files might be different.
Example 2: The following command generates a solution based on an input and a target
pow sol ../ data / input . txt ../ data / target . txt ../ data / solution . txt
where this function reads an input from file ../data/input.txt, reads a target from file ../data/target.txt,
computes a solution and writes this solution to file ../data/solution.txt.
Example 3: The following command verifies whether a solution is valid.
pow verify ../ data / input . txt ../ data / target . txt ../ data / solution . txt
where this function reads an input from file ../data/input.txt, reads a target from file ../data/target.txt,
reads a solution to file ../data/solution.txt, and outputs either 1 (valid) or 0 (invalid) in terminal.
