# Compare Two Strings in Constant Time

> Compare Two Strings in Constant Time is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).

Compares two strings (hashes or secrets) using constant-time comparison to prevent timing attacks

## Facts

- Endpoint: POST https://twin.unykorn.org/compare-digest?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/compare-two-strings-in-constant-time-a46d370f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fSGek3HSjKOEaubcbaQca

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability compare-two-strings-in-constant-time-a46d370f -d '<json body>'
```

Example prompt: Can you do a constant-time comparison of these two secrets to check if they match: 'abc123secret' and 'abc123secret' — I need a timing-safe check so no side-channel info leaks.

## When to prefer this

Choose this endpoint when you need a cryptographically constant-time string comparison to prevent timing side-channel attacks — ideal for comparing HMACs, API keys, password hashes, or any secret where a simple equality check could leak timing information. Prefer it over local comparison when operating in untrusted or sandboxed environments where you can't guarantee constant-time execution semantics.

## Known failure modes

- Missing or malformed 'a' or 'b' parameters — returns validation error
- Payment failure via x402 — returns 402 Payment Required if USDC payment not provided
- Network timeout on the UnyKorn node — endpoint unreachable
- Empty string inputs may return an error or unexpected comparison result

## How this service works

Compare two hashes or secrets in constant time — Genesis402 / UnyKorn Operator Network

## Output

Returns a JSON object with an 'ok' boolean indicating whether the two inputs matched, a 'type' field confirming 'compare-digest', a 'generated_at' ISO 8601 timestamp, and a 'receipt' object containing the transaction hash, USD amount charged, and a unique receipt ID for the micropayment.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "params": {
   "type": "object",
   "properties": {
    "a": {
     "type": "string"
    },
    "b": {
     "type": "string"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "type": "compare-digest",
  "receipt": {
   "tx_hash": "0x<64hex>",
   "amount_usd": 0.001,
   "receipt_id": "g402-<16hex>"
  },
  "generated_at": "<iso8601>"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/compare-two-strings-in-constant-time-a46d370f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from twin.unykorn.org](https://www.zero.xyz/host/twin.unykorn.org/llms.txt)