@credentum/parse-lei

Validate and parse Legal Entity Identifiers (LEI, ISO 17442).

Decomposes a 20-character LEI into LOU prefix, entity code, and check digits. Verifies check digits via MOD 97-10 (ISO/IEC 7064).

Zero dependencies. Pure functions. TypeScript-first.

Installation

npm install @credentum/parse-lei

Usage

import { parseLEI, isValidLEI, computeCheckDigits } from '@credentum/parse-lei';

// Parse Apple Inc.'s LEI
const result = parseLEI('HWUPKR0MPOU8FGXBT394');
// {
//   raw: 'HWUPKR0MPOU8FGXBT394',
//   valid: true,
//   lou: 'HWUP',              // Local Operating Unit
//   entity: 'KR0MPOU8FGXBT3', // Entity-specific code
//   checkDigits: '94',         // Provided check digits
//   computedCheckDigits: '94'  // Computed check digits
// }

// Quick validation
isValidLEI('INR2EJN1ERAN0W5ZP974'); // true (Microsoft)
isValidLEI('INR2EJN1ERAN0W5ZP900'); // false (wrong check digits)

// Compute check digits for an 18-character body
computeCheckDigits('HWUPKR0MPOU8FGXBT3'); // '94'

API

parseLEI(lei: string): LEIResult

Parse a 20-character LEI string into structured data.

isValidLEI(lei: string): boolean

Returns true if the input is a valid LEI with correct check digits.

computeCheckDigits(body: string): string

Compute two check digits for an 18-character LEI body. Returns '' on invalid input.

LEIResult

interface LEIResult {
  raw: string;                // Original input
  valid: boolean;             // Structurally valid with correct check digits
  lou: string;                // Characters 1-4: LOU prefix
  entity: string;             // Characters 5-18: Entity code
  checkDigits: string;        // Characters 19-20: Provided check digits
  computedCheckDigits: string; // Computed via MOD 97-10
}

Why Use This?

| Use Case | Function | |----------|----------| | "Is this LEI valid?" | isValidLEI(lei) | | "What LOU issued this?" | parseLEI(lei).lou | | "What check digit should this be?" | computeCheckDigits(body) | | "Show me the full breakdown" | parseLEI(lei) |

Tested Against Real LEIs

• Apple Inc. (HWUPKR0MPOU8FGXBT394)
• Microsoft Corporation (INR2EJN1ERAN0W5ZP974)
• The Goldman Sachs Group (784F5XWPLTWKTBV3E584)
• Goldman Sachs International (W22LROWP2IHZNBB6K528)
• Apple Distribution International (54930027SQL2KPSDBM58)

All verified against GLEIF registry.

License

MIT