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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 | 1x 1x 9x 1x 8x 8x 8x 8x 8x 8x 8x 8x 8x 8x 1x | /**
* @file MFKDF HMAC-SHA1 Factor Setup
* @copyright Multifactor, Inc. 2022–2025
*
* @description
* Derive an HMAC-SHA1 challenge-response factor for multi-factor key derivation
*
* @author Vivek Nair (https://nair.me) <vivek@nair.me>
*/
const crypto = require('crypto')
const { encrypt, decrypt } = require('../../crypt')
/**
* Derive a YubiKey-compatible MFKDF HMAC-SHA1 challenge-response factor
*
* @example
* // setup key with hmacsha1 factor
* const setup = await mfkdf.setup.key([
* await mfkdf.setup.factors.hmacsha1()
* ])
*
* // calculate response; could be done using hardware device
* const secret = setup.outputs.hmacsha1.secret
* const challenge = Buffer.from(setup.policy.factors[0].params.challenge, 'hex')
* const response = crypto.createHmac('sha1', secret).update(challenge).digest()
*
* // derive key with hmacsha1 factor
* const derive = await mfkdf.derive.key(setup.policy, {
* hmacsha1: mfkdf.derive.factors.hmacsha1(response)
* })
*
* setup.key.toString('hex') // -> 01d0…2516
* derive.key.toString('hex') // -> 01d0…2516
*
* @param {Buffer} response - HMAC-SHA1 response
* @returns {function(config:Object): Promise<MFKDFFactor>} Async function to generate MFKDF factor information
* @author Vivek Nair (https://nair.me) <vivek@nair.me>
* @since 0.21.0
* @memberof derive.factors
*/
function hmacsha1 (response) {
if (!Buffer.isBuffer(response)) {
throw new TypeError('response must be a buffer')
}
return async (params) => {
const oldPaddedKey = Buffer.concat([response, Buffer.alloc(12)])
const secret = decrypt(Buffer.from(params.pad, 'hex'), oldPaddedKey)
return {
type: 'hmacsha1',
data: secret,
params: async ({ key }) => {
const challenge = crypto.randomBytes(64)
const response = crypto
.createHmac('sha1', secret.subarray(0, 20))
.update(challenge)
.digest()
const paddedKey = Buffer.concat([response, Buffer.alloc(12)])
const pad = encrypt(secret, paddedKey)
return {
challenge: challenge.toString('hex'),
pad: pad.toString('hex')
}
},
output: async () => {
return { secret }
}
}
}
}
module.exports.hmacsha1 = hmacsha1
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