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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 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 | 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 252x 252x 252x 251x 2x 249x 249x 249x 249x 446x 376x 375x 3x 372x 1x 371x 371x 371x 371x 2x 2x 64x 64x 2x 2x 1x 373x 373x 373x 70x 70x 443x 3x 243x 243x 50x 193x 243x 243x 243x 438x 372x 372x 243x 243x 160x 160x 160x 8x 235x 177x 177x 177x 177x 235x 235x 1x | /** * @file Multi-factor Key Derivation * @copyright Multifactor, Inc. 2022–2025 * * @description * Derive a multi-factor derived key * * @author Vivek Nair (https://nair.me) <[email protected]> */ const Ajv = require('ajv') const policySchema = require('./policy.json') const combine = require('../secrets/combine').combine const recover = require('../secrets/recover').recover const { hkdfSync } = require('crypto') const { argon2id } = require('hash-wasm') const MFKDFDerivedKey = require('../classes/MFKDFDerivedKey') const { decrypt } = require('../crypt') const { extract } = require('../integrity') const crypto = require('crypto') /** * Derive a key from multiple factors of input * * @example * // setup 16 byte 2-of-3-factor multi-factor derived key with a password, HOTP code, and UUID recovery code * const setup = await mfkdf.setup.key([ * await mfkdf.setup.factors.password('password'), * await mfkdf.setup.factors.hotp({ secret: Buffer.from('abcdefghijklmnopqrst') }), * await mfkdf.setup.factors.uuid({ id: 'recovery', uuid: '9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d' }) * ], {threshold: 2}) * * // derive key using 2 of the 3 factors * const derive = await mfkdf.derive.key(setup.policy, { * password: mfkdf.derive.factors.password('password'), * hotp: mfkdf.derive.factors.hotp(241063) * }) * * setup.key.toString('hex') // -> 34d2…5771 * derive.key.toString('hex') // -> 34d2…5771 * * @param {Object} policy - The key policy for the key being derived * @param {Object.<string, MFKDFFactor>} factors - Factors used to derive this key * @param {boolean} [verify=true] - Whether to verify the integrity of the policy after deriving (recommended) * @returns {MFKDFDerivedKey} A multi-factor derived key object * @author Vivek Nair (https://nair.me) <[email protected]> * @since 0.9.0 * @async * @memberOf derive */ async function key (policy, factors, verify = true, stack = false) { const ajv = new Ajv() const valid = ajv.validate(policySchema, policy) if (!valid) throw new TypeError('invalid key policy', ajv.errors) if (Object.keys(factors).length < policy.threshold) { throw new RangeError('insufficient factors provided to derive key') } const shares = [] const newFactors = [] const outputs = {} for (const factor of policy.factors) { if (factors[factor.id] && typeof factors[factor.id] === 'function') { const material = await factors[factor.id](factor.params) let share if (material.type === 'persisted') { share = material.data } else { if (material.type !== factor.type) { throw new TypeError( 'wrong factor material function used for this factor type' ) } const pad = Buffer.from(factor.pad, 'base64') const stretched = Buffer.from( hkdfSync( 'sha256', material.data, Buffer.from(factor.salt, 'base64'), 'mfkdf2:factor:pad:' + factor.id, 32 ) ) share = decrypt(pad, stretched) if (factor.hint) { const buffer = Buffer.from( hkdfSync( 'sha256', stretched, Buffer.from(factor.salt, 'base64'), 'mfkdf2:factor:hint:' + factor.id, 32 ) ) const binaryString = [...buffer] .map((byte) => byte.toString(2).padStart(8, '0')) .reduce((acc, bits) => acc + bits, '') const hint = binaryString.slice(-1 * factor.hint.length) if (hint !== factor.hint) { throw new RangeError('hint does not match for factor ' + factor.id) } } } shares.push(share) if (material.output) outputs[factor.id] = await material.output() newFactors.push(material.params) } else { shares.push(null) newFactors.push(null) } } if (shares.filter((x) => Buffer.isBuffer(x)).length < policy.threshold) { throw new RangeError('insufficient factors provided to derive key') } const secret = combine(shares, policy.threshold, policy.factors.length) let kek if (stack) { kek = Buffer.from( hkdfSync( 'sha256', secret, Buffer.from(policy.salt, 'base64'), 'mfkdf2:stack:' + policy.$id, 32 ) ) } else { kek = Buffer.from( await argon2id({ password: secret, salt: Buffer.from(policy.salt, 'base64'), hashLength: 32, parallelism: 1, iterations: 2 + Math.max(0, parseInt(policy.time) || 0), memorySize: 19456 + Math.max(0, parseInt(policy.memory) || 0), outputType: 'binary' }) ) } const key = decrypt(Buffer.from(policy.key, 'base64'), kek) const newPolicy = JSON.parse(JSON.stringify(policy)) for (const [index, factor] of newFactors.entries()) { if (typeof factor === 'function') { const paramsKey = Buffer.from( hkdfSync( 'sha256', key, Buffer.from(newPolicy.factors[index].salt, 'base64'), 'mfkdf2:factor:params:' + newPolicy.factors[index].id, 32 ) ) newPolicy.factors[index].params = await factor({ key: paramsKey }) } } const integrityKey = hkdfSync( 'sha256', key, Buffer.from(policy.salt, 'base64'), 'mfkdf2:integrity', 32 ) if (verify) { const integrityData = await extract(policy) const hmac = crypto .createHmac('sha256', integrityKey) .update(integrityData) .digest('base64') if (policy.hmac !== hmac) { throw new RangeError('key policy integrity check failed') } } if (policy.hmac) { const newPolicyData = await extract(newPolicy) const newHmac = crypto.createHmac('sha256', integrityKey) newHmac.update(newPolicyData) newPolicy.hmac = newHmac.digest('base64') } const originalShares = recover( shares, policy.threshold, policy.factors.length ) return new MFKDFDerivedKey(newPolicy, key, secret, originalShares, outputs) } module.exports.key = key |