Activity 4: Summary and next steps
Congratulations! You have come to the end of Activity 4. In this activity you learned about end-to-end encryption and where it is used. We also explored the idea of hash …
Course: An Introduction to Cryptography
Vulnerabilities of simple ciphers
All of the simple ciphers that we have considered so far are not safe to use as a cipher in modern times. This is because it is too easy to …
Digital signatures
Digital signatures are an important part of the internet. Digital signatures are primarily used to verify the authenticity and integrity of digital documents or messages. A digital signature is a …
Optional exercise: Hash functions
In the previous step you learned about what hashing and hash collisions are. In this step you will get some practical experience of hash functions. Hash generator Using the online …
Hash functions
Sometimes, we need to store data securely. For example, when you create an account on a website you normally set up a password so that you can log in. However, …
Solutions: Simple ciphers exercise
In this video Sam explains some sample solutions for the simple cipher task you tried in the last step. You’ll see an example of how to encrypt and decrypt using …
Your turn: Simple ciphers exercise
Now it’s your turn In this step, we have set out a number of exercises for you to do; decryptions and encryptions based on a Caesar cipher and a permutation …
Simple ciphers: Polygraphic ciphers
What is a polygraphic cipher? A polygraphic cipher is a type of substitution cipher that operates on groups of characters rather than individual characters. In other words, instead of substituting …
Modern cryptography: End-to-end encryption
End-to-end encryption (E2EE) is a type of encryption that is designed to protect the confidentiality and integrity of digital communications. It works by encrypting messages on the sender’s device and …
Activity 4: Overview
In the last activity we learned a little about a modern day cryptographic technique called RSA. We looked at the difference between public and private key cryptography. In this activity …
Activity 3: Summary and next steps
In this activity we have looked at some modern day cryptography. We have learned of two modern approaches: private key cryptography and public key cryptography. We looked at a specific …
Simple ciphers: Transposition ciphers
What is a transposition cipher? Earlier in the activity, we saw the scytale cipher. This is an example of a transposition cipher. In this type of cipher, the characters in …
Simple ciphers: Permutation ciphers
What is a permutation cipher? A permutation cipher is a special type of transposition cipher. In a permutation cipher we take blocks of characters from the plaintext and permute them. …