Authentication
Hash,Salting의 반복 = Streching.
one-way hash
역으로 돌리면 원래 값이 나온다. (ex. rainbow table)
추가 요소로 원복에 걸리는 시간을 늘린다. (ex.bcrypt...)
https://auth0.com/blog/adding-salt-to-hashing-a-better-way-to-store-passwords/
JWT (in headers)
Haeder
type of the token, signing algorithm
Payload
Registered, Public, Private claims
Signature
*to verify the message wasn't changed
https://jwt.io/introduction
https://dev.to/kimmaida/signing-and-validating-json-web-tokens-jwt-for-everyone-25fb
