Homework 1 F ileCipher

BBM 465: Information Security Laboratory
Information Security Lab.
Homework 1
Subject : Block Ciphers
Introduction:
You are expected to develop a simple encryption/decryption tool name F ileCipher.
Requirements:
For the tool F ileCipher, the requirements are listed below:
• The program must support four encryption modes (CBC, CFB, OFB, CTR) and two
encryption algorithms (DES, 3DES). These modes must be implemented via Electronic
Code Book (ECB) scheme. You can not use prebuild modes except ECB.1
• The program must be executed by command line arguments and print results on files.
• All encrypted and decrypted files should be placed in the folder where the original input
file is located.
• Block size for DES and 3DES has been selected as 64.
• You must record all operations (encryption/decryption) and their execution time (in
ms) in a log file. (named run.log)
• Don’t modify the input file via the program.
Implementation Details
Arguments
The program must be executed by command line arguments. The arguments are listed below;
F ileCipher −e −i inputF ile −o outF ile algorithm mode key f ile
– −e or −d denotes encryption and decryption. To encrypt input use −e, to decrypt
the input use −d.
– −i inputF ile denotes the name/path of the input file.
– −o outF ile denotes the name/path of the output file.
1https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation
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Fall 2022
BBM 465: Information Security Laboratory
– algorithm denotes the name of the encryption/decryption algorithm, which can
be DES or 3DES.
– mode denotes the mode of the encryption/decryption algorithm, which can be
CBC, CFB, OFB, or CTR.
– key f ile denotes the name/path of the file that contains the initialization vector,
key, and nonce values.
Examples:
Encryption:
F ileCipher −e −i inputf ile.txt −o encrypted.txt DES CBC key.txt
F ileCipher −e −i sample.txt −o secret.txt 3DES CT R key.txt
Decryption:
F ileCipher −d −i encrypted.txt −o decrypted.txt DES CBC key.txt
F ileCipher −d −i secret.txt −o solved.txt 3DES CT R key.txt
Key File
The key file must consist of Initialization Vector (IV), Key, and Nonce values. Each value
must be separated by ”-” in the file. The content of the key file;
IV - Key - Nonce
An example of the content of the key file:
key example1.txt
9eRecAhatUvYduFYPYbU - 5YBuFATucUweceMY - 3YXysuZy6YG49YKasa1U
or;
simple key.txt
write21Anything56For33IV2 - Also5For,The1Key97 - it2Is5ok7If0you5Keep7Secret
Log File
You must record all runs and their execution time in a log file. The execution time should
be in milliseconds. And the log file should be named run.log and placed in the folder where
the original input file is located. Each line in the log file must be recorded in the following
format:
inputF ile outF ile encordec algorithm mode execution time
An example of the content of the log file:
run.log
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Fall 2022
BBM 465: Information Security Laboratory
inputfile.txt encrypted.txt enc DES CBC 64
encrypted.txt decrypted.txt dec DES CBC 51
sample.txt secret.txt enc 3DES CTR 78
secret.txt solved.txt dec 3DES CTR 59
Your program should create run.log file if it does not exist in the working directory. Otherwise,
the program should open the existing log file and append the new entry at the end of the
file.
Notes:
1. You can use crypto API. But you can not use prebuild modes except ECB.
2. You must submit the homework in groups of two.
3. You should prepare a report that describes your approach to the problem with the
details of your implementation. You must write down all group members’ names and
ids. Reports will be graded too.
4. You can ask your questions about the homework via Piazza. (www.piazza.com/
hacettepe.edu.tr/fall2022/bbm465)
5. T.A. as himself has the right to partially change this document. However, the modifications will be announced in the Piazza system. In case, it is your obligation to check
the Piazza course page periodically.
6. You must compile and test your code on Eclipse Platform for Windows before submission.
7. You will submit your work via the submission system.
(www.submit.cs.hacettepe.edu.tr)
The submission format is given below:
→ <student id.zip>
→ src /*.java
→ report.pdf