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crypto: allow non-multiple of 8 in SubtleCrypto.deriveBits · nodejs/node@9ee9f52 · GitHub

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Commit 9ee9f52

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panva
authored and
ruyadorno
committed
crypto: allow non-multiple of 8 in SubtleCrypto.deriveBits
PR-URL: #55296 Reviewed-By: James M Snell <jasnell@gmail.com>
1 parent bfe7982 commit 9ee9f52

5 files changed

Lines changed: 28 additions & 27 deletions

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‎doc/api/webcrypto.md‎

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@@ -598,9 +598,6 @@ Using the method and parameters specified in `algorithm` and the keying
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material provided by `baseKey`, `subtle.deriveBits()` attempts to generate
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`length` bits.
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The Node.js implementation requires that `length`, when a number, is a multiple
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of `8`.
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When `length` is not provided or `null` the maximum number of bits for a given
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algorithm is generated. This is allowed for the `'ECDH'`, `'X25519'`, and `'X448'`
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algorithms, for other algorithms `length` is required to be a number.

‎lib/internal/crypto/diffiehellman.js‎

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@@ -5,6 +5,7 @@ const {
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MathCeil,
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ObjectDefineProperty,
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SafeSet,
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Uint8Array,
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} = primordials;
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const { Buffer } = require('buffer');
@@ -295,6 +296,8 @@ function diffieHellman(options) {
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return statelessDH(privateKey[kHandle], publicKey[kHandle]);
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}
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let masks;
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// The ecdhDeriveBits function is part of the Web Crypto API and serves both
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// deriveKeys and deriveBits functions.
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async function ecdhDeriveBits(algorithm, baseKey, length) {
@@ -341,18 +344,25 @@ async function ecdhDeriveBits(algorithm, baseKey, length) {
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// If the length is not a multiple of 8 the nearest ceiled
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// multiple of 8 is sliced.
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length = MathCeil(length / 8);
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const { byteLength } = bits;
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const sliceLength = MathCeil(length / 8);
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const { byteLength } = bits;
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// If the length is larger than the derived secret, throw.
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// Otherwise, we either return the secret or a truncated
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// slice.
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if (byteLength < length)
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if (byteLength < sliceLength)
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throw lazyDOMException('derived bit length is too small', 'OperationError');
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return length === byteLength ?
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bits :
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ArrayBufferPrototypeSlice(bits, 0, length);
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const slice = ArrayBufferPrototypeSlice(bits, 0, sliceLength);
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const mod = length % 8;
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if (mod === 0)
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return slice;
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// eslint-disable-next-line no-sparse-arrays
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masks ||= [, 0b10000000, 0b11000000, 0b11100000, 0b11110000, 0b11111000, 0b11111100, 0b11111110];
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const masked = new Uint8Array(slice);
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masked[sliceLength - 1] = masked[sliceLength - 1] & masks[mod];
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return masked.buffer;
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}
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module.exports = {

‎test/parallel/test-webcrypto-derivebits-cfrg.js‎

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@@ -140,9 +140,11 @@ async function prepareKeys() {
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public: publicKey
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}, privateKey, 8 * size - 11);
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assert.strictEqual(
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Buffer.from(bits).toString('hex'),
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result.slice(0, -2));
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const expected = Buffer.from(result.slice(0, -2), 'hex');
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expected[size - 2] = expected[size - 2] & 0b11111000;
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assert.deepStrictEqual(
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Buffer.from(bits),
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expected);
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}
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}));
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‎test/parallel/test-webcrypto-derivebits-ecdh.js‎

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Original file line numberDiff line numberDiff line change
@@ -161,9 +161,11 @@ async function prepareKeys() {
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public: publicKey
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}, privateKey, 8 * size - 11);
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assert.strictEqual(
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Buffer.from(bits).toString('hex'),
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result.slice(0, -2));
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const expected = Buffer.from(result.slice(0, -2), 'hex');
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expected[size - 2] = expected[size - 2] & 0b11111000;
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assert.deepStrictEqual(
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Buffer.from(bits),
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expected);
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}
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}));
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‎test/wpt/status/WebCryptoAPI.cjs‎

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@@ -8,16 +8,6 @@ module.exports = {
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'algorithm-discards-context.https.window.js': {
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'skip': 'Not relevant in Node.js context',
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},
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'derive_bits_keys/derived_bits_length.https.any.js': {
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'fail': {
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// See https://github.com/nodejs/node/pull/55296
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// The fix is pending a decision whether truncation in ECDH/X* will be removed from the spec entirely
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'expected': [
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"ECDH derivation with 230 as 'length' parameter",
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"X25519 derivation with 230 as 'length' parameter",
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],
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},
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},
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'historical.any.js': {
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'skip': 'Not relevant in Node.js context',
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},

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