# KHOTEM Cryptographic Document Seal — Document #15

> KHOTEM Cryptographic Document Seal — Document #15 is a paid API for AI agents from khotem.com, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-15).

Returns a cryptographically sealed document (doc #15) with a SHA hash and payment seal after USDC micropayment verification on Base

## Facts

- Endpoint: POST https://khotem.com/api/doc/15
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/khotem-cryptographic-document-seal-document-15-995c2950
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_oaWv_K7QPVI116C9JTj8u

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 khotem-cryptographic-document-seal-document-15-995c2950 -d '<json body>'
```

Example prompt: Retrieve KHOTEM document #15 with a cryptographic seal — I need the SHA hash and payment seal as tamper-evident proof that this document was accessed and verified.

## When to prefer this

Choose this endpoint when you need cryptographic proof-of-retrieval for a specific document, want a blockchain-anchored witness seal without signup or KYC, and are comfortable with USDC micropayments on Base via x402. Prefer this over traditional notary services when you need a decentralized, permissionless, instantly verifiable attestation tied to a specific document hash and payment event.

## Known failure modes

- Payment not received or insufficient USDC: 402 Payment Required response, document not returned
- Invalid or expired payment: seal not issued, transaction rejected
- Document ID not found: 404 or empty content response
- Network or Base blockchain congestion: delayed payment confirmation, timeout
- Malformed request body: 400 Bad Request

## How this service works

Paid cryptographic witness services for autonomous agents and humans: seals, attestations, verification, audit, sealed document thread. x402-native micropayments, USDC on Base / Polygon / Solana, direct on-chain verification. No accounts, no API keys, no KYC.

## Output

Returns a JSON object containing the document ID (15), the document content in markdown format, a 16-character SHA hash (sha16) of the document, and a payment_seal value that cryptographically links the payment on Base to the document retrieval event — together forming a tamper-evident witness record.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "properties": {
  "input": {
   "type": "object",
   "properties": {
    "queryParams": {
     "type": "object",
     "properties": {},
     "description": "No input — GET returns the document after payment.",
     "additionalProperties": false
    }
   }
  },
  "output": {
   "type": "object",
   "properties": {
    "example": {
     "doc": "15",
     "sha16": "a1b2c3d4e5f60708",
     "content": "<document 15, markdown>",
     "payment_seal": "1020304050607080"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/khotem-cryptographic-document-seal-document-15-995c2950/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from khotem.com](https://www.zero.xyz/host/khotem.com/llms.txt)