THM - Cryptography for Dummies

TryHackMe | Cryptography for Dummies

Michael Jack | 06/2022https://tryhackme.com/room/cryptographyfordummies

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Task 1 - Intro

Without encryption communications over the internet will be very insecure, and it would be very easy for someone to see your data. Fortunately this isn’t true, and almost all of the data you get/send over the internet is encrypted and cannot be seen in plain text by someone who got access to it.

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Task 2 - Types of Cryptography

There are two different categories of cryptography. Symmetric and Asymmetric.

This rerers to how in symmetric cryptography the keys used to encrypt and decrypt are the same, hence the process is symmetric.

In asymmetric cryptography the keys used for encoding and decoding are different. The encryption key is typically called the Public key and the decryption key the Private key.

An example of asymmetric cryptography:

Alice wants to talk to Google Google gives Alice the Public key. Alice encrypts her message with the public key and sends it to Google. Google decrypts the message with his private key and sends back what Alice wanted.
And that’s how the conversation goes…

Questions

What type of cryptography is more secure?

asymmetric

What type of cryptography is faster?

symmetric

What type of cryptography will a Bank site use?

asymmetric

What will you use to encrypt your messages in asymmetric cryptography?

public key

What will you use to decrypt messages in asymmetric cryptography?

private key

Does symmetric cryptography use two different keys for encryption/decryption? (aye/nay)

nay

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Task 3 - What is a hash?

A hash is the result of a hashing algorithm. These are special because they are one-way operations that cannot be reversed to get what the input was.

Common hashing algorithms are MD5 (Message Digest 5), and SHA (Secure Hashing Algorithm). *Note: There are different versions of SHA such as SHA256 and SHA512

To get md5 hash of string in terminal use: echo -n "string" | md5sum

Questions

What’s the MD5 hash of “hashes are cool”?

f762d32e3c160900d94b683e927555b9

What does MD5 stand for?

Message Digest 5

Who created MD5?

Ronald Rivest

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Task 4 - Decoding/Encoding

There’s difference between encoding and encrypting. Let’s say you have an encrypted file, the only way to decrypt it is using key. While encoded data can be decoded immediately, without keys. It’s NOT a form of encryption, it just a way of representing data.

Questions

Encode the string “cryptographyisuseful” with Base64

Y3J5cHRvZ3JhcGh5aXN1c2VmdWwK

Decode the string dGhlIHNlY3JldCB3b3JkIGlzIDogd2F0ZXJtZWxvbg== . What is the secret word?

the secret word is : watermelon

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