# util.beauty Crypto Key Derivation

> util.beauty Crypto Key Derivation is a paid API for AI agents from util.beauty, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Derives cryptographic keys from input material using standard key derivation functions, billed per request via USDC micropayment or API key.

## Facts

- Endpoint: POST https://util.beauty/v1/crypto/key_derivation
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/util-beauty-crypto-key-derivation-a95f5f6e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yrgXXNCbWsb0-7k2VAQoF

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 util-beauty-crypto-key-derivation-a95f5f6e -d '<json body>'
```

Example prompt: Derive a 32-byte key from my master secret using HKDF-SHA256 with the salt 'my-app-salt' and info context 'encryption-key-v1' — bill it via my prepaid API key.

## When to prefer this

Choose this endpoint when your agent or serverless pipeline needs cryptographic key derivation without bundling a crypto library, or when you want metered pay-per-use billing (USDC via x402 or prepaid key) for occasional KDF operations. Prefer it over running local crypto when operating in sandboxed environments or when auditability via requestId is needed.

## Known failure modes

- Invalid or missing input key material returns a 400 error with descriptive message
- Unsupported KDF algorithm returns an error indicating valid options
- Insufficient credits or payment failure returns a 402 Payment Required response
- Malformed JSON body returns a 400 parse error
- Network timeout results in no charge and a 5xx error

## How this service works

Metered web utilities for developers and AI agents: browser screenshot and PDF, crypto, DNS and net tools. Pay per request with x402 (USDC on Base) or prepaid API keys.

## Output

Returns a JSON object with ok (boolean), the utility name, a requestId for tracing, and chargedCredits indicating how many credits were consumed. The derived key material is returned in the utility-specific response fields.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "properties": {
  "input": {
   "type": "object",
   "properties": {
    "body": {
     "type": "object",
     "description": "JSON request body (see OpenAPI for the utility schema).",
     "additionalProperties": true
    }
   }
  },
  "output": {
   "type": "object",
   "properties": {
    "example": {
     "type": "object",
     "properties": {
      "ok": {
       "type": "boolean"
      },
      "utility": {
       "type": "string"
      },
      "requestId": {
       "type": "string"
      },
      "chargedCredits": {
       "type": "number"
      }
     },
     "additionalProperties": true
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "utility": "…",
  "requestId": "req_…",
  "chargedCredits": 1
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/util-beauty-crypto-key-derivation-a95f5f6e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from util.beauty](https://www.zero.xyz/host/util.beauty/llms.txt)