deny (restricted)

Published: March 2025 | Last updated: March 2025

Overview

The deny RPC method revokes a tenant's authorization from the Lynx blockchain storage system. This command allows the blockchain manager to remove storage privileges from existing tenants, preventing them from further authentication and data storage operations. The revocation is recorded on the blockchain as a permanent record, ensuring the network consistently enforces access controls.

Syntax

deny <hash160>

Description

When you invoke the deny method as the blockchain manager, the Lynx daemon creates and broadcasts a special revocation transaction that removes a tenant from the authorized list. Similar to the authorization process, this revocation is implemented as a blockchain transaction containing a timestamped payload with the tenant's identifier and a revocation flag. Once this transaction is confirmed, the specified tenant can no longer authenticate or perform storage operations.

This command is the counterpart to the allow command and completes the lifecycle management of tenant authorizations. Together, these commands provide the blockchain manager with complete control over who can utilize the blockchain storage system.

Parameters

Parameter	Type	Required	Description
hash160	string	Yes	The RIPEMD-160 hash of the tenant's public key in hexadecimal format. This is a 40-character hexadecimal string (e.g., 00112233445566778899aabbccddeeff00112233) that uniquely identifies the tenant to be removed.

Returns

The method returns a string indicating the result of the operation:

• success - The tenant has been successfully removed from the system

• hash160-wrong-size - The provided hash is not the correct length (must be 40 hexadecimal characters)

• Role-based restriction: Current role cannot perform this action - The authenticated user is not the blockchain manager

• error-generating-authpayload - An error occurred while generating the authentication payload

• error-generating-authtransaction - An error occurred while creating the authentication transaction

• failure - A general failure occurred, which typically indicates an authentication problem

Access Control

The deny command has strict access control requirements:

• Only the blockchain manager (initial authentication user defined in consensus parameters) can execute this command

• The manager must be authenticated via the auth command before using deny

• Regular tenants cannot revoke access for themselves or other tenants

• This role-based restriction ensures centralized control over tenant authorization management

Revocation Transaction

When a tenant's access is revoked, the system:

1. Generates a special authentication payload containing:

   • Operation type (1 for revoking a tenant, as opposed to 0 for adding)

   • Current timestamp

   • The tenant's hash160 identifier

2. Creates a blockchain transaction with this payload embedded as an OP_RETURN output

3. Broadcasts this transaction to the network, where it will be mined into a block

This transaction serves as a permanent, immutable record of tenant revocation that all nodes can verify.

Examples

Revoke a tenant's access

As the blockchain manager:

lynx-cli deny 00112233445566778899aabbccddeeff00112233

Output:

success

Using JSON-RPC:

curl --user manager:password --data-binary '{"jsonrpc": "1.0", "id": "curltest", "method": "deny", "params": ["00112233445566778899aabbccddeeff00112233"]}' -H 'content-type: text/plain;' http://127.0.0.1:9332/

Error Handling

The method will return a failure message in the following scenarios:

• The provided hash160 is not exactly 40 characters long (20 bytes in hexadecimal)

• The user is not authenticated or is not authenticated as the blockchain manager

• There is an error in generating the authentication payload or transaction

• The authentication system cannot validate the current user's credentials

Implementation Notes

• The command verifies the user's authentication status using the is_auth_member function

• It validates that the authenticated user is the blockchain manager using consensus parameters

• The operation type is set to 1 (for revocation), as opposed to 0 (for authorization)

• The current timestamp is obtained using TicksSinceEpoch<std::chrono::seconds>(GetAdjustedTime())

• The authentication payload is generated with the generate_auth_payload function

• The authentication transaction is created and broadcast with the generate_auth_transaction function

• Unlike the allow command which returns an array, this command returns a simple string response

Tenant Access After Revocation

When a tenant's access is revoked:

• The tenant can no longer authenticate using the auth command

• Any existing authentication sessions will continue until they expire (approximately 6 hours)

• Existing files stored by the tenant remain on the blockchain and can still be retrieved

• The tenant will no longer appear in the list returned by the tenants command

This behavior ensures that revocation prevents future access while preserving existing data integrity.