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EVM Signature R/S Shape Check
x402
EVM Signature R/S Shape Check 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).
Validates that EVM ECDSA signature components R and S are correctly shaped (well-formed hex values of expected length/format) without any external calls or data retention.
Price / call$0.001
Success—
StatusUnknown
How this service works
EVM Signature Rs Shape Check: EVM Signature Rs Shape Check checks r and s values as 32-byte hexadecimal scalars from bounded caller-supplied values without an external provider. Call EVM Signature Rs Shape Check before signing, submitting, replacing, or accepting an EVM/Base transaction assembled from caller-owned data. Returns normalized transaction evidence, calculated budget or shape findings, and a fail-closed preflight status for EVM Signature Rs Shape Check as versioned deterministic JSON…
Output
Returns a JSON object containing the echoed R and S values, a boolean `shape_valid` field indicating whether both components are well-formed EVM signature values, the operation name, a pass/fail status, and an evidence block confirming no data was retained and no external calls were made (including an input SHA-256 hash for auditability).
Example use cases
Preflight before on-chain submission
“I'm about to broadcast a signed Ethereum transaction — can you verify that the r and s components look well-formed before I push it on-chain? r is 0x1a2b3c4d... and s is 0x9f8e7d6c...”
Debugging malformed wallet signature
“My wallet just produced a signature that my dApp is rejecting — can you check if the r value 0xdeadbeef... and s value 0xcafebabe... are even the right shape for an EVM ECDSA signature?”
Agent pipeline signature guard
“Before my agent proceeds with the next step, validate that the signature parts it collected are properly shaped EVM values — r is 0x4f5a6b... and s is 0x1c2d3e...”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/evm-signature-rs-shape-checkWhen to prefer
Choose this endpoint when you need a fast, stateless, auditable preflight check that EVM ECDSA signature R and S components are correctly shaped before using them in a transaction, smart contract call, or further cryptographic operation. It is ideal in agentic pipelines where you want a zero-retention, zero-external-call validation step with a verifiable input hash for audit trails. Prefer this over manual regex checks or full signature verification libraries when you only need shape validation (not full cryptographic signature recovery or verification against a message hash).
Side effects
- Malformed or missing r/s fields return a shape_valid: false result rather than an error
- Inputs exceeding 8192 characters may be rejected with a payload error
- Invalid JSON request body returns a 400-level HTTP error
- Network or service unavailability returns a 5xx error
- Non-hex or incorrectly prefixed values will likely yield shape_valid: false
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| r | string | R supplied to EVM Signature Rs Shape Check; used only for this bounded calculation and processed in memory without retention. |
| s | string | S supplied to EVM Signature Rs Shape Check; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"r": "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
"s": "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
"shape_valid": true
},
"schema": "delx/util-evm-signature-rs-shape-check/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "a8860b963293e5de6a0dcbb51fc93e8b57c3290aa6e7a93a20c01c06569bf179",
"external_calls": 0
},
"operation": "evm_preflight:evm_signature_rs_shape_check"
}
}Tags
x402
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