# credit-tier-v1: key ceremony transcript

Everything below is also in `circuit.json` (field `ceremony`). Times are UTC.

| | |
|---|---|
| Circuit | `credit-tier-v1` = zk-kit `threshold_b3_n` (threshold, {"bits":3,"nonce":true}), 250 constraints |
| circuitId | `0xda6c12665684695797838670a2465d6ba9f2bf812b8629506d9dbc573d8cc9d0` = keccak256("credit-tier-v1") |
| Public signals | `commitment`, `threshold`, `nonce` |
| vkHash | `0xfd31a9160ce340b7ce4bdb66ae4fdfa9f146920c81d2ab466dd4261b9e3e3a26` = keccak256(JCS(verification_key.json)) |
| ceremonyContributions (registry) | 1 |

## Phase 1: public Powers of Tau

The PSE Perpetual Powers of Tau (80 participants, closed with a pre-announced Ethereum randao
beacon), response 0080 prepared for phase 2 and truncated to 2^13.

| | |
|---|---|
| URL | https://pse-trusted-setup-ppot.s3.eu-central-1.amazonaws.com/pot28_0080/ppot_0080_13.ptau |
| Size | 9,530,514 bytes |
| blake2b-512 | `bf0c2d498f1197ad04ec0dbfcdda6df6348cbd793759f1f986e5cdf1a4100842293dfad6b8961f64b7ba35c162b5c821c4c097a52f3a639b55b0e765ec311b44` |
| sha256 | `ccee28086e4b81d81a6e16fdee054d1dbd5276362e2662d4205d31de45cb930f` |
| Header power | 2^13 (read from the file header) |
| S3 ETag | `bb54c403a93fabdabb99520b9fd94f56-2` (last modified Tue, 09 Apr 2024 07:06:01 GMT); multipart ETag recomputed with 8 MiB parts: matches |
| Downloaded | 2026-09-27T02:44:12.606Z |

PSE publishes no hash list for the prepared files, so the checks above are what could be made: the
header, the byte count, and the S3 multipart ETag recomputed from the bytes (a transport check, not
an authenticity check). snarkjs's full powers-of-tau verification was not run: it did not finish in
10 minutes even for the 2^8 file on the build machine. Download the file yourself and compare the
blake2b-512 before you rely on it.

## Phase 2

1. **Initial key** `_0000` = snarkjs `zkey new` of `credit-tier-v1.r1cs` on the phase-1 file. It is
   deterministic; anyone can recreate it (141,980 bytes, blake2b-512
   `66a9c04b022f013c5cd780becaa204e6e9fa8fa358ddcd47b04fa062befd5fbbde69301090dec25a4e9d6c80f20ab2c4dfb29b9dde349e5274544e8f01a9f34b`).
2. **Contribution #1: Super Wallet (SeoulLabs) phase-2 contribution**, 2026-09-27T02:44:49.684Z to 2026-09-27T02:44:49.731Z.
   Contribution hash:

   ```
   a16f30830150c37dba1c7c589e84ef083c44530045d3518959bc1ef2d64e829ac650b7689129add87a19a099cf4a7393095d1e9c3041e1fd429bc2fe62c3366b
   ```

   Entropy: 64 bytes from the operating system CSPRNG (`node:crypto` randomBytes), passed in
   memory to snarkjs, which mixes in its own random bytes. It was not written to disk, a log or a
   terminal, and the process has exited. All six production circuits were contributed in one run
   that finished at 2026-09-27T02:44:49.737Z.
3. **Beacon.** The rule, fixed in `zk-kit/scripts/production-ceremony.ts` before the run: after
   every contribution has finished, take the latest Xphere mainnet block whose timestamp is later
   than that moment, and apply its hash with 2^10 iterations (snarkjs `zkey beacon`).

   | | |
   |---|---|
   | Chain | Xphere mainnet, chain id 20250217 (read from https://en-hkg.x-phere.com) |
   | Block | 49677068 |
   | Block hash | `0x004d454b466cfbe88eedad46ef160b140124683eab1432b108a54b3111fac37a` |
   | Block time | 2026-09-27T02:44:58.000Z (fetched 2026-09-27T02:44:57.539Z) |
   | Iterations | 2^10 |
   | Beacon contribution hash | `14b7a65f1ba9dc29f0ee64899f84b521439d060b8c1141508ea149124701d33c4f2cbc56e271fc1a020a5c5354b2fe79add637548669652df2b2b0b04c700924` |

   Check the block: `curl -s -X POST -H 'content-type: application/json' --data '{"jsonrpc":"2.0","id":1,"method":"eth_getBlockByNumber","params":["0x2f6030c",false]}' https://en-hkg.x-phere.com`
   and compare `hash`, or open https://xp.tamsa.io/block/49677068.

## What this ceremony does and does not give you

A Groth16 phase 2 is sound if **at least one** contributor destroyed their randomness. This key has
**one** contributor, Super Wallet, so its soundness rests on Super Wallet having done so. The public
beacon makes the final key depend on a value nobody knew when the contribution was made, but it is
public and adds no secret: it does not replace a second, independent contributor. The block number
was not announced in advance; the rule for picking it was fixed in the script, and the block came
after the contribution. The registry records `ceremonyContributions = 1` as it is.

**An institution that wants to add its own contribution** takes `credit-tier-v1.zkey` (this key; the
contribution chain inside it continues), checks it with `zk-kit verify-ceremony`, runs
`zk-kit contribute`, and hands the result back; Super Wallet then applies a new, pre-announced
beacon with `zk-kit finalize`. The result is a new key and therefore a new circuit id,
`credit-tier-v2`, registered alongside this one with ceremonyContributions = 2. A
key is never swapped in under an existing circuit id.

## Result

| | |
|---|---|
| verifyFromR1cs (r1cs + phase-1 file + zkey) | OK |
| Circuit hash (snarkjs) | `72bfe09bb80447956e017ad526c67cc72f4e0db732e3fe0808c2cda64b379f50c3716661e81437f9d70c13c5aff48be6f9435050dec36643d4cc1e6e2750fb08` |
| `credit-tier-v1.zkey` | 142,885 bytes, sha256 `e867a430610071db899c6ad0486f23667a7b7b3efdfc9dca4510311a93bf14b3`, blake2b-512 `b38046f810a94ed512f3fa14e61c3a7504eed2b3965b6c169d0308ef80d9dc32569895684ccc28881706eac38917f6fa538bb9cd5834ae9713fb765f46755f78` |
| `credit-tier-v1.r1cs` | 116,188 bytes, sha256 `fab328b540d782e2c84b2efb163db946d063f8b081084df53f62f7193fc63776` |
| `credit-tier-v1.wasm` | 1,752,421 bytes, sha256 `485bd9712ffaffb87abd286957a8dddff270c65b84b33847f199d7be34021189` |
| vkHash | `0xfd31a9160ce340b7ce4bdb66ae4fdfa9f146920c81d2ab466dd4261b9e3e3a26` |
| Verifier.sol runtime keccak256 (solc 0.8.24, optimizer 200, paris) | `0x6e61443bbb7d1a42ac152a1407c6b40de81c6f1417173a81e1a1b721243831d6` |

## Check it yourself

```sh
npm install /path/to/zk-kit          # or: npm install snarkjs@0.7.6 and use snarkjs directly
npx zk-kit ptau --power 13 --public --out ppot_0080_13.ptau   # compare blake2b512 above
npx zk-kit verify-ceremony --r1cs credit-tier-v1.r1cs --ptau ppot_0080_13.ptau --zkey credit-tier-v1.zkey
# prints: zkey VALID, then #1 Super Wallet (SeoulLabs) phase-2 contribution: a16f30830150c37d...
#                             #2 Xphere mainnet block 49677068 beacon [beacon 004d454b466cfbe8..., 2^10 iterations]
```