AdvancedTopic 85 of 104Software & Computing
Cryptography basics
Symmetric and public-key encryption and hashing protect data.
In depth
Symmetric encryption (AES) uses one key; asymmetric (RSA, ECC) uses key pairs for exchange and signatures; hash functions (SHA-256) provide integrity; MACs and AEAD ensure authenticity. TLS combines them. Never design your own cryptography; use vetted libraries and manage keys carefully.
Key points
- Key exchange (Diffie-Hellman)
- Digital signatures
- Salted password hashing
ExampleHTTPS uses asymmetric crypto to agree a symmetric session key.
What is Cryptography basics?
Symmetric and public-key encryption and hashing protect data.
Why is it important to understand cryptography basics?
Cryptography protects data confidentiality and integrity, so it is needed for any system that handles private or valuable information.
What is the difference between symmetric and public-key encryption?
Symmetric encryption uses one shared key that is fast for bulk data, while public-key encryption uses a key pair so the public key can be shared without exposing the private key.
Why is hashing not encryption?
A hash is one-way and fixed in size, so it cannot be reversed to recover the input, which is why it suits password storage.
How is Cryptography basics used in practice?
Typical applications include encrypting a backup file with a symmetric key, signing a software update with a private key so devices can verify it and storing passwords as salted hashes rather than in plain text.
What should I learn before Cryptography basics?
Study "Message queues and streaming" first (topic 84 of 104 in Software & Computing). It covers the groundwork this topic builds on.
What are the key points of Cryptography basics?
Key exchange (Diffie-Hellman). Digital signatures. Salted password hashing.
Can you give an example of Cryptography basics?
HTTPS uses asymmetric crypto to agree a symmetric session key.
What comes after Cryptography basics?
The next topic is "Authentication and authorisation", which builds directly on this one.
How difficult is Cryptography basics?
It is classed as Advanced in Software & Computing (topic 85 of 104). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Software & Computing.