adding relay url hashes to nostr keys

nostr-key-obfuscation.md

see https://njump.me/note1artmd2xwklx6mkqfdz539a29z380fyk2uzwfr2c4fau0m3ys3dqqt0rdrx

output

original keypair:
     a987223eeae5151a288fa29e6385b31db9c71eb3fcd50d6e2e1950c1c308971b =>
   02627895b1b0feab4445fe3a35013d7865ec9fba4d671474c2499baa83c4689532
hash:
     7b539d3ad7d7213c8fdc4ab60cbe4ae54303cc0b99d685772c378efb4d1e16df =>
   02f5bb62900b0a777957697904e3aff10db89456274fc0fba5e91b2fd1b5ba7511
derived keypair:
     24dabf79c2bc3656b86bed547043fe04421c0dd8e762f2a99a7e81303ff06cb9 =>
   02b50553723ea4765da9b24f589217860f44d425da6f335dc97e4e1b74875b0eeb
result of adding hash point to original pubkey:
   02b50553723ea4765da9b24f589217860f44d425da6f335dc97e4e1b74875b0eeb
result of subtracting hash point from derived pubkey:
   02627895b1b0feab4445fe3a35013d7865ec9fba4d671474c2499baa83c4689532

relay-hash-key-tweak.js

import {secp256k1} from '@noble/curves/secp256k1'
import {
  bytesToHex,
  bytesToNumberBE,
  numberToBytesBE
} from '@noble/curves/abstract/utils'
import {sha256} from '@noble/hashes/sha256' // ECMAScript modules (ESM) and Common.js

const originalPriv = secp256k1.utils.randomPrivateKey()
const originalPub = secp256k1.getPublicKey(originalPriv)
console.log(
  'original keypair:\n    ',
  bytesToHex(originalPriv),
  '=>\n  ',
  bytesToHex(originalPub)
)

const relay = 'wss://inbox.nostr.wine'
const hashPriv = sha256(relay)
const hashPub = secp256k1.getPublicKey(hashPriv)
console.log('hash:\n    ', bytesToHex(hashPriv), '=>\n  ', bytesToHex(hashPub))

const derivedPriv = numberToBytesBE(
  (bytesToNumberBE(originalPriv) + bytesToNumberBE(hashPriv)) %
    secp256k1.CURVE.n,
  32
)
const derivedPub = secp256k1.getPublicKey(derivedPriv)
console.log(
  'derived keypair:\n    ',
  bytesToHex(derivedPriv),
  '=>\n  ',
  bytesToHex(derivedPub)
)

const originalPoint = secp256k1.ProjectivePoint.fromHex(originalPub)
const hashPoint = secp256k1.ProjectivePoint.fromHex(hashPub)
const result = originalPoint.add(hashPoint)
console.log(
  'result of adding hash point to original pubkey:\n  ',
  result.toHex()
)

const derivedPoint = secp256k1.ProjectivePoint.fromHex(derivedPub)
const result2 = derivedPoint.subtract(hashPoint)
console.log(
  'result of subtracting hash point from derived pubkey:\n  ',
  result2.toHex()
)