Reward Ad SSV

{
  "encrypted": "<ivHex>:<tagHex>:<ciphertextHex>"
}

import { createDecipheriv, createHash } from 'node:crypto'
import express from 'express'

function decryptSsvPayload(encrypted, apiKey) {
  const [ivHex, tagHex, ciphertextHex] = encrypted.split(':')
  const key = createHash('sha256').update(apiKey).digest() // 32 bytes

  const decipher = createDecipheriv('aes-256-gcm', key, Buffer.from(ivHex, 'hex'))
  decipher.setAuthTag(Buffer.from(tagHex, 'hex'))

  const plaintext = Buffer.concat([
    decipher.update(Buffer.from(ciphertextHex, 'hex')),
    decipher.final()
  ]).toString('utf8')

  return JSON.parse(plaintext)
}

const app = express()

app.post('/ssv-callback', express.json(), (req, res) => {
  const payload = decryptSsvPayload(req.body.encrypted, process.env.ADROP_API_KEY)
  // Grant rewards based on payload.userId, payload.customData, payload.rewardAmount, etc.
  res.sendStatus(200)
})

import hashlib
import json
from cryptography.hazmat.primitives.ciphers.aead import AESGCM

def decrypt_ssv_payload(encrypted: str, api_key: str) -> dict:
    iv_hex, tag_hex, ciphertext_hex = encrypted.split(':')
    key = hashlib.sha256(api_key.encode()).digest()  # 32 bytes

    aesgcm = AESGCM(key)
    # AESGCM expects ciphertext concatenated with the authentication tag
    plaintext = aesgcm.decrypt(
        bytes.fromhex(iv_hex),
        bytes.fromhex(ciphertext_hex) + bytes.fromhex(tag_hex),
        None
    )
    return json.loads(plaintext)