Comment by madars | Hacker News Reader

Comment by madars | Hacker News Reader

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TLS does this with GREASE (Generate Random Extensions And Sustain Extensibility) - https://www.rfc-editor.org/rfc/rfc8701.html . HN discussion: https://news.ycombinator.com/item?id=39416277 (19 points, 8 comments)

Go's implementation of JSON format for protobufs also does this: https://protobuf.dev/reference/go/faq/#unstable-json

> To avoid giving the illusion that the output is stable, we deliberately introduce minor differences so that byte-for-byte comparisons are likely to fail.

Go also randomizes the iteration of map keys, to emphasize that maps are unordered and code should not rely on insertion order. For demonstration:

  package main
  
  import "fmt"
  
  func main() {
    m := map[string]int{"a": 1, "b": 2, "c": 3}
    for k, _ := range m {
      fmt.Println(k)
    }
    for k, _ := range m {
      fmt.Println(k)
    }
  }

Sample output:

  c
  a
  b
  a
  b
  c

Each run may produce different key orders.

I was under the assumption most languages to this.

Very few do, and only quite modern ones. Although I believe there are hashtable libraries where the iteration order is unspecified but generally consistent, only changing when a resize shuffles the elements into different buckets.

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