Week 10 - 2023

The weeknote for 3/6 - 3/12.

Job

I was working on polyfills of node:crypto and mainly on AES cipher via crypto.createCipehriv API. This time I first learned AES in details, and I found it's very interesting. AES was selected from 15 candidates algorithms. NIST chose Rijndael algotihm as AES and published it as FIPS PUB 197. I still haven't understood it completely. I started the reading notes of AES spec in scrapbox. https://scrapbox.io/kt3k/AES_spec_reading

AES itself is not enough for implementing crypto.createCipheriv. We also need to implement block operation mode to make it work. AES itself can only encrypt 128 bits input data, and it doesn't work for arbitrary length of data. To make it work for arbitrary length data, we need to choose block operation modes such as ECB, CBC, GCM, etc. These are also very complex and I still keep learning it. Interesting thing about it is that these block operation modes are defined independent of the block ciphers. They can be used together with any block ciphers.