VP 301: Caesar Cipher (52 pts)

Purpose

Encrypt data with the Caesar Cipher.

Flag VP 301.1: Encrypt Text (2 pts)

Encrypt this text with a key of 7:
HELLO   
The flag is the ciphertext, as a five-letter word.

Flag VP 301.2: Decrypt Text Without the Key (5 pts)

Decrypt this ciphertext:
VCVDVEKRIP   
The key is between 1 and 25.

Flag VP 301.3: Decrypt Binary Data (10 pts)

Decrypt this ciphertext, which is in hex encoding.
eb11060cdfc5eafdf9eaf3e9eae904e8e6eaf8e6f7   
The key is between 1 and 255. The data was encrypted by adding the key to the bytes and wrapping around for totals larger than 255.

Flag VP 301.4: Decrypt Image (15 pts)

Download this file:
https://samsclass.info/124/proj14/VP301-4
Decrypt it as you did in the previous challenge.

The key is between 0 and 255.

The decrypted file is a PNG image.

View the decrypted image to see the flag.

You will find it helpful to read this:

PNG (Portable Network Graphics) Specification

Flag VP 301.5: Vigenère Cipher (20 pts)

Download this file:
VP301-5a
There are eight keys, used in sequence to encrypt each of the first eight bytes.

The same eight keys are used for all the other eight-byte blocks.

Each key is between 0 and 255.

The decrypted file is a PNG image.

View the decrypted image to see the flag.

References

Python Bytes, Bytearray

Posted 7-2-2020
Plaintext for 301.1 fixed 7-6-2020
Download link changed for 301-5