This call was removed in v385

This call is no longer available in the current runtime. Existed from v361 to v385. Shown here for historical reference.

mark_decryption_failed

Call Removed v361 → v385 (removed) #3

Marks an encrypted submission as failed to decrypt, removing it from storage .

Call Workflow

1. Validation

Signature, nonce, mortality, fees

Signature

Nonce

Mortality

Fee payment

2. Pre-dispatch

Permission & state checks

Permission checks

State validation

3. Dispatch

Execute logic, modify state

DecryptionFailed Submissions

4. Post-dispatch

Final result & fee settlement

ExtrinsicSuccess

Fees settled

Svelte Flow

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Used by: validators

The Big Picture

Sometimes decryption fails - maybe the user encrypted with the wrong key, used invalid format, or the ciphertext was corrupted. Validators use this call to formally mark such failures, which removes the submission and emits an event so the user knows what happened.

Why This Matters

Without a formal failure mechanism, failed decryptions would leave orphaned submissions in storage. This call provides transparency - users can see DecryptionFailed events and understand why their transaction didn't execute.

Example Scenario

You're a validator processing encrypted submissions. One submission fails ML-KEM decapsulation (wrong key epoch). You call mark_decryption_failed(submission_id, 'ML-KEM decapsulate failed'). The DecryptionFailed event fires, the submission is removed, and the user can diagnose the issue.

Common Questions

What are common decryption failure reasons?: 1) User encrypted with wrong epoch's key (KeyExpired), 2) Invalid ciphertext format, 3) AEAD authentication failed (corruption), 4) ML-KEM decapsulation error.
Can validators abuse this to reject valid transactions?: They could, but it's auditable - all mark_decryption_failed calls are on-chain with reasons. Validators who falsely reject valid submissions would be identified and lose reputation.

Use Cases

Handle malformed encrypted submissions
Report encryption failures to users via events
Clean up failed submissions from storage

From Chain Metadata

Marks a submission as failed to decrypt and removes it from storage. Called by the block author when decryption fails at any stage (e.g., ML-KEM decapsulate failed, AEAD decrypt failed, invalid ciphertext format, etc.). This allows clients to be notified of decryption failures through on-chain events.

Part of: MEV Shield

Input Parameters

#	Name	Type	Description
0	id	H256	id (H256)
1	reason	BoundedVec	reason (BoundedVec)

Permissions

Origin

Unknown

Required Role

Any

Permission data inferred from metadata. May be incomplete.

Requirements

Caller is the current block author (validator)
Submission with given ID exists in Submissions
Decryption genuinely failed (ML-KEM, AEAD, or format error)

Effects

Events Emitted

DecryptionFailed

Storage Modified

Submissions

Postconditions

Submission removed from Submissions storage
DecryptionFailed event emitted with reason

Side Effects

User's encrypted transaction will not execute
Provides audit trail of why decryption failed

Code Examples

import { ApiPromise, WsProvider } from "@polkadot/api";
import { stringCamelCase } from "@polkadot/util";

const provider = new WsProvider("wss://entrypoint-finney.opentensor.ai:443");
const api = await ApiPromise.create({ provider });

// Build mark_decryption_failed call
const id = 0 as any /* H256 */;
const reason = 0 as any /* BoundedVec */;

const call = api.tx[stringCamelCase("MevShield")][stringCamelCase("mark_decryption_failed")](
  id,
  reason
);

Runtime Info

View Source

Pallet Index: 30
Call Index: 3
First Version: v361
Removed In: v385

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