Today I Learned

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2 posts about #computer-science

Casting graphql types with inline fragments

Graphql works with a type system. You ask for fruit and it returns fruit, but that fruit could be a pear or an orange.

(contrived example apologies)

interface Fruit {
  seedless: Boolean

type Pear implements Fruit {
  color: String

type Apple implements Fruit {
  size: Int

So when you ask for fruit, and you want the size of the apple, you have to let graphql know that you want an Apple and are expecting an Apple and while I’m thinking about this as casting the graphql docs call it inline fragments.

  query {
    fruit {
      ... on Pear {
      ... on Apple {

The ... is a syntactic element not a writing convention.

Size of RSA encrypted content

RSA encryption (publickey/privatekey) is powerful encryption but its really only meant to encrypt small things like other encryption keys. The maximum size of the amount of data an rsa public key can encrypt is:

(key_size/8).floor - 11

So in the case of a key thats 1024 bits it can only encrypt data up to 117 bytes long. Not long enough for documents of any size or variable length.