No Code Needed for this one! EASY & SIMPLE
A cryptographer used a 4-bit LFSR to create a stream cipher.
She sents the first message: "you left the stove on" to her partner.
The first character 'y' of the message is encrypted as 0x3e.
What are the tap bits of the cryptographer's LFSR?
What is the initial state?
Draw a picture of it in ASCII.
How is the 'o' encrypted in the message?
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Easy & Simple/ C++ Code
Perform a chosen plaintext attack to break the RC4 stream cipher.
The following files are: rc4, [login to view URL]
The file called rc4 is a compiled executable which is a homebrew implementation of the ARC4 stream cipher.
You can use it like this: $ ./rc4 infile outfile
The infile is an input file, which is what is to be encrypted, and outfile is the resulting ciphertext.
The keystream that rc4 generates is in this case based on a password which is compiled into the binary.
Meaning that the keystream it generates is always the same.
This same keystream was used to produce the file ciphertxt.bin.
Your job is to use a chosen plaintext attack to recover the keystream, and then use the result to decrypt ciphertxt.bin.
Include:
1. A file called [login to view URL] that explains how you solved the problem
2. Code you wrote to solve the problem asexplained in outline in [login to view URL]
3. The plaintext for [login to view URL]
I Pay afer I make sure it's what I am looking for, this is a serious task. Bonus also if done correctly.