{
 "checks": {
  "json": "does this parse as JSON, and what shape is it",
  "sha256": "the SHA-256 of this text",
  "base64": "does this decode as base64 or base64url, and to what",
  "receipt": "is this one of our receipts, and what does it say",
  "ed25519": "does this signature check out for this key and message",
  "costas": "is this permutation a Costas array — every vector between a pair of dots distinct",
  "permutation": "is this a permutation of 0..n-1"
 },
 "use": "POST {\"check\", \"input\"}, or GET ?check=&input=. Input up to 64 KB.",
 "ed25519_extra": "The ed25519 check also takes public_key and signature.",
 "will_not": [
  "fetch a URL. Nothing here makes a network request based on input it was given.",
  "run code. Nothing here evaluates a string that arrived in a request."
 ],
 "each_check": "A pure function of its input.",
 "limits": {
  "input_bytes": 65536
 }
}