# HMAC Signature Generation API

> HMAC Signature Generation API is a paid API for AI agents from agent-chain-kit-solana.vercel.app, paid per call via x402, $0.0005/call, status unknown (last checked 2026-10-09).

Computes an HMAC signature (SHA-256, SHA-512, or SHA-1) over arbitrary text input and returns the hex, base64, and byte-length of the digest.

## Facts

- Endpoint: POST https://agent-chain-kit-solana.vercel.app/v1/hmac?utm_source=zero.xyz
- Price: $0.0005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-09
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/hmac-signature-generation-api-2f011bed
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_QaSJuBU6RM4s78WqogZ0F

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 hmac-signature-generation-api-2f011bed -d '<json body>'
```

Example prompt: Compute the HMAC-SHA256 of the message 'order-12345:1700000000' using secret key 'mySecretKey99' and give me the hex and base64 result.

## When to prefer this

Choose this endpoint when you need a quick, deterministic, pay-per-call HMAC digest without setting up your own crypto library or managing API keys. It is ideal for AI agents needing to sign messages, validate webhook payloads, or produce integrity tokens on the fly using SHA-256, SHA-512, or SHA-1, and where paying micro-amounts per call (via x402 or MPP) is acceptable.

## Known failure modes

- Missing required 'text' or 'key' query parameters returns a validation error
- Invalid algorithm value (not sha256, sha512, or sha1) causes rejection
- Using an HTTP method other than GET/HEAD/DELETE is rejected by the schema
- Payment failure via x402/MPP results in 402 response and no computation
- Overly long input strings may result in timeout or truncation

## How this service works

Global current weather, hourly forecasts, foreign-exchange rates, EVM reads, and deterministic utilities for AI agents. Pay per call with MPP or x402; no API key.

## Output

Returns a JSON object containing the HMAC digest in hex string format, base64 string format, the byte length of the digest, and the algorithm that was applied (e.g. sha256, sha512, sha1).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "text",
      "key"
     ],
     "properties": {
      "key": {
       "type": "string"
      },
      "text": {
       "type": "string"
      },
      "algorithm": {
       "enum": [
        "sha256",
        "sha512",
        "sha1"
       ],
       "type": "string"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "hex": "88aab3ede8d3adf94d26ab90d3bafd4a...",
  "bytes": 5,
  "base64": "iKqz7ejTrflNJquQ07r9Sg==",
  "algorithm": "sha256"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/hmac-signature-generation-api-2f011bed/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-chain-kit-solana.vercel.app](https://www.zero.xyz/host/agent-chain-kit-solana.vercel.app/llms.txt)