pezkuwi-common/packages/keyring/pair/decode.js

import { u8aEq } from '@pezkuwi/util';
import { jsonDecryptData } from '@pezkuwi/util-crypto';
import { PAIR_DIV, PAIR_HDR, PUB_LENGTH, SEC_LENGTH, SEED_LENGTH } from './defaults.js';
const SEED_OFFSET = PAIR_HDR.length;
/**
 * Decode a pair, taking into account the generation-specific formats and headers
 *
 * For divisor/headers, don't rely on the magic being static. These will
 * change between generations, aka with the long-awaited 4th generation
 * of the format. The external decode interface is the only way to use and decode these.
 **/
export function decodePair(passphrase, encrypted, _encType) {
    const encType = Array.isArray(_encType) || _encType === undefined
        ? _encType
        : [_encType];
    const decrypted = jsonDecryptData(encrypted, passphrase, encType);
    const header = decrypted.subarray(0, PAIR_HDR.length);
    // check the start header (generations 1-3)
    if (!u8aEq(header, PAIR_HDR)) {
        throw new Error('Invalid encoding header found in body');
    }
    // setup for generation 3 format
    let secretKey = decrypted.subarray(SEED_OFFSET, SEED_OFFSET + SEC_LENGTH);
    let divOffset = SEED_OFFSET + SEC_LENGTH;
    let divider = decrypted.subarray(divOffset, divOffset + PAIR_DIV.length);
    // old-style (generation 1 & 2), we have the seed here
    if (!u8aEq(divider, PAIR_DIV)) {
        divOffset = SEED_OFFSET + SEED_LENGTH;
        secretKey = decrypted.subarray(SEED_OFFSET, divOffset);
        divider = decrypted.subarray(divOffset, divOffset + PAIR_DIV.length);
        // check the divisior at this point (already checked for generation 3)
        if (!u8aEq(divider, PAIR_DIV)) {
            throw new Error('Invalid encoding divider found in body');
        }
    }
    const pubOffset = divOffset + PAIR_DIV.length;
    const publicKey = decrypted.subarray(pubOffset, pubOffset + PUB_LENGTH);
    return {
        publicKey,
        secretKey
    };
}