# Ed25519 Receipt Verification

> Ed25519 Receipt Verification is a paid API for AI agents from www.mahastrategies.com, paid per call via x402, $0.012501/call, status unknown (last checked 2026-10-28).

Verifies a single Ed25519 cryptographic signature over up to 8,000 characters of exact UTF-8 receipt text using a caller-supplied 32-byte public key, returning cryptographic validity and message hash.

## Facts

- Endpoint: POST https://www.mahastrategies.com/api/v1/verify/receipts/signature?utm_source=zero.xyz
- Price: $0.012501/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-28
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ed25519-receipt-verification-cbd9c89f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_SKI_7ZlDqMG6JTaT4CA0j

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 ed25519-receipt-verification-cbd9c89f -d '<json body>'
```

Example prompt: Can you verify that this Ed25519 signature over my receipt text is cryptographically valid? The receipt message is 'Order #4521 total $42.00 paid 2024-06-01', the public key in base64 is 'MCowBQYDK2VdAyEA...' and the signature in base64 is 'abc123sig==', treat the data as public and encoding as exact-utf8.

## When to prefer this

Choose this endpoint when you need to verify a single Ed25519 digital signature over a short-to-medium UTF-8 receipt or document text using a caller-supplied public key, without needing issuer identity resolution, timestamp authority, or licensing checks. Prefer this over general-purpose signature libraries when you need a hosted, pay-per-call verification service that returns a message hash alongside validity, and when the receipt text fits within 8,000 characters.

## Known failure modes

- Invalid or malformed base64 public key (wrong length or format)
- Signature base64 exceeds 88-character limit or is malformed
- Message text exceeds 8,000 character limit
- Signature is cryptographically invalid for the given message and public key
- Unsupported encoding value other than 'exact-utf8'
- Private key supplied instead of public key (rejected by design)
- Missing required fields such as message, publicKeyBase64, or signatureBase64

## How this service works

Verify one Ed25519 signature over up to 8,000 characters of exact UTF-8 receipt text using a supplied 32-byte public key. Returns cryptographic validity and message hash. Does not establish issuer identity, trusted time, licensing or the truth of the receipt. No private keys accepted. New modular adapter: retained result recovery for 24 hours, minimal receipt metadata for 90 days. Existing live route unchanged.

## Output

Returns whether the Ed25519 signature is cryptographically valid for the supplied message and public key, along with the hash of the message. Does not confirm issuer identity, trusted timestamp, licensing status, or the truthfulness of the receipt contents. Results are retained for 24 hours and minimal receipt metadata for 90 days.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "message": {
   "type": "string",
   "maxLength": 8000,
   "minLength": 1
  },
  "encoding": {
   "enum": [
    "exact-utf8"
   ],
   "type": "string"
  },
  "dataClass": {
   "enum": [
    "public",
    "synthetic"
   ],
   "type": "string"
  },
  "publicKeyBase64": {
   "type": "string",
   "maxLength": 44
  },
  "signatureBase64": {
   "type": "string",
   "maxLength": 88
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ed25519-receipt-verification-cbd9c89f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from www.mahastrategies.com](https://www.zero.xyz/host/www.mahastrategies.com/llms.txt)