# Digest Header Verify

> Digest Header Verify is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Verifies a SHA-256 Digest header value against caller-supplied text bytes, returning a deterministic pass/fail result with computed hash evidence.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/digest-header-verify
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/digest-header-verify-37dbb7f2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2h7B4TPEhFODG03xF_d0T

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 digest-header-verify-37dbb7f2 -d '<json body>'
```

Example prompt: Check whether this SHA-256 Digest header value matches the response body I got — the text is 'Hello, world!', the algorithm is 'sha-256', and the digest_base64 is 'ZOyIygCyaOW6GjVnihtTFtIS9PNmskdyMlNKiuyjfzw='.

## When to prefer this

Choose this endpoint when you need a stateless, first-party, deterministic SHA-256 Digest header verification with no external dependencies and explicit pass/fail evidence — especially as a preflight before caching, accepting, redirecting, or retrying an HTTP response. Prefer it over rolling your own crypto check when you need versioned, auditable JSON output that records both the input evidence and the computed result.

## Known failure modes

- Digest mismatch: computed hash does not equal supplied digest_base64, returns advisory/fail status
- Invalid base64: malformed digest_base64 input causes parsing error
- Unsupported algorithm: algorithm value other than sha-256 may return an error or advisory
- Text exceeds 8192 character limit: input truncation or rejection
- Payment failure: x402 USDC payment not completed, request rejected

## How this service works

Digest Header Verify: Digest Header Verify verifies a sha-256 Digest value against caller-supplied text bytes from bounded caller-supplied values without an external provider. Call Digest Header Verify before accepting, caching, redirecting, or retrying a caller-supplied web response. Returns normalized web evidence, the computed finding, and an explicit pass or advisory status for Digest Header Verify as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base. First-party, stateless,…

## Output

Returns versioned deterministic JSON containing: the normalized input evidence (text, algorithm, and expected digest), the computed SHA-256 hash of the supplied text, and an explicit pass or advisory status indicating whether the computed digest matches the supplied digest_base64 value.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "text": {
   "type": "string",
   "maxLength": 8192,
   "description": "Text supplied to Digest Header Verify; used only for this bounded calculation and processed in memory without retention."
  },
  "algorithm": {
   "type": "string",
   "maxLength": 8192,
   "description": "Algorithm supplied to Digest Header Verify; used only for this bounded calculation and processed in memory without retention."
  },
  "digest_base64": {
   "type": "string",
   "maxLength": 8192,
   "description": "Digest Base64 supplied to Digest Header Verify; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "matched": true,
   "algorithm": "sha-256",
   "actual_base64": "ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0="
  },
  "schema": "delx/util-digest-header-verify/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "e2887c004f75ecae89be72af3d1ed97e6058d581b75c207eebceba1ccc080397",
   "external_calls": 0
  },
  "operation": "web_reliability:digest_header_verify"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/digest-header-verify-37dbb7f2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)