# Tenjin: x402 Redelivery Signature Security Analysis

> Tenjin: x402 Redelivery Signature Security Analysis is a paid API for AI agents from tenjin.blog, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-13).

Retrieves a technical article explaining why recovering the payment signature does not secure x402 redelivery attacks in EVM/EIP-3009 transferWithAuthorization schemes

## Facts

- Endpoint: GET https://tenjin.blog/api/read/0xe4c16d163d80fd972e6e1e9b94bc71c5fbe5a9c5/why-recovering-the-payment-signature-does-not-secure-x402-redelivery
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/tenjin-x402-redelivery-signature-security-analysis-7111be44
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_EySxPmjoVYZ2_FeyHGsgK

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 tenjin-x402-redelivery-signature-security-analysis-7111be44
```

Example prompt: Pull up the Tenjin article about why recovering a payment signature doesn't actually secure x402 redelivery — I want to understand the vulnerability in the exact/EVM scheme with EIP-3009 transferWithAuthorization.

## When to prefer this

Use this endpoint when you need to read this specific Tenjin article about x402 redelivery security; prefer it over generic web search when you want the original, paid-access technical content with guaranteed authenticity via the x402 payment trail

## Known failure modes

- Article not found if slug or wallet address is incorrect (404)
- Payment required if x402 payment header is missing or invalid (402)
- Network timeout if Tenjin platform is unavailable
- Invalid wallet address format returns an error
- Using handle 'latest' as a payable path may fail per schema constraints

## How this service works

Why recovering the payment signature does not secure x402 "redelivery". As of 2026-08-10. Applies to x402 with the exact/EVM scheme over EIP-3009 transferWithAuthorization (USDC-style tokens). The protocol property below is stable; the SDK symbol names may drift. You build an x402-paid API. A buyer's client sometimes dies right after paying, before it reads the response, so you add "redelivery": let them re-present their payment and collect the result they already bought. The obvious implementation: This is insecure. Step 2 proves nothing. When an exact/EVM x402 pay

## Output

The full text of a technical blog article analyzing the x402 protocol redelivery vulnerability, covering why signature recovery in the exact/EVM scheme over EIP-3009 transferWithAuthorization (USDC-style tokens) does not prevent redelivery attacks, including protocol details stable as of 2026-08-10

## 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"
     ],
     "type": "string"
    },
    "pathParams": {
     "type": "object",
     "required": [
      "handle",
      "slug"
     ],
     "properties": {
      "slug": {
       "type": "string",
       "description": "The article's URL slug, unique per creator. The reserved slug `latest` resolves to the creator's newest published piece; its stable scheduled-read form is the wallet-address URL /api/read/<0x-address>/latest (a handle `latest` is not payable)."
      },
      "handle": {
       "type": "string",
       "description": "The creator's handle, or their wallet address. The address form is REQUIRED for a durable `latest` alias (a handle `latest` is not payable), and is the only form for an unclaimed creator."
      }
     }
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {},
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/tenjin-x402-redelivery-signature-security-analysis-7111be44/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from tenjin.blog](https://www.zero.xyz/host/tenjin.blog/llms.txt)