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crypto: add Hash.prototype.copy() method · nodejs/node@5dd72a6 · GitHub

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Commit 5dd72a6

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bnoordhuis
authored and
BethGriggs
committed
crypto: add Hash.prototype.copy() method
Make it possible to clone the internal state of a Hash object into a new Hash object, i.e., to fork the state of the object. Fixes: #29903 PR-URL: #29910 Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Sam Roberts <vieuxtech@gmail.com> Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>
1 parent cab905f commit 5dd72a6

5 files changed

Lines changed: 94 additions & 8 deletions

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‎doc/api/crypto.md‎

Lines changed: 37 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1041,6 +1041,43 @@ console.log(hash.digest('hex'));
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// 6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
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```
10431043

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### `hash.copy([options])`
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<!-- YAML
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added:
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- version: REPLACEME
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pr-url: https://github.com/nodejs/node/pull/29910
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-->
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* `options` {Object} [`stream.transform` options][]
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* Returns: {Hash}
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Creates a new `Hash` object that contains a deep copy of the internal state
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of the current `Hash` object.
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The optional `options` argument controls stream behavior. For XOF hash
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functions such as `'shake256'`, the `outputLength` option can be used to
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specify the desired output length in bytes.
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An error is thrown when an attempt is made to copy the `Hash` object after
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its [`hash.digest()`][] method has been called.
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```js
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// Calculate a rolling hash.
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const crypto = require('crypto');
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const hash = crypto.createHash('sha256');
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hash.update('one');
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console.log(hash.copy().digest('hex'));
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hash.update('two');
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console.log(hash.copy().digest('hex'));
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hash.update('three');
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console.log(hash.copy().digest('hex'));
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// Etc.
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```
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### `hash.digest([encoding])`
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<!-- YAML
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added: v0.1.92

‎lib/internal/crypto/hash.js‎

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -36,7 +36,8 @@ const kFinalized = Symbol('kFinalized');
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function Hash(algorithm, options) {
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if (!(this instanceof Hash))
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return new Hash(algorithm, options);
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validateString(algorithm, 'algorithm');
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if (!(algorithm instanceof _Hash))
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validateString(algorithm, 'algorithm');
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const xofLen = typeof options === 'object' && options !== null ?
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options.outputLength : undefined;
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if (xofLen !== undefined)
@@ -51,6 +52,14 @@ function Hash(algorithm, options) {
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Object.setPrototypeOf(Hash.prototype, LazyTransform.prototype);
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Object.setPrototypeOf(Hash, LazyTransform);
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55+
Hash.prototype.copy = function copy(options) {
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const state = this[kState];
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if (state[kFinalized])
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throw new ERR_CRYPTO_HASH_FINALIZED();
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return new Hash(this[kHandle], options);
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};
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5463
Hash.prototype._transform = function _transform(chunk, encoding, callback) {
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this[kHandle].update(chunk, encoding);
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callback();

‎src/node_crypto.cc‎

Lines changed: 17 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -4721,7 +4721,16 @@ void Hash::Initialize(Environment* env, Local<Object> target) {
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void Hash::New(const FunctionCallbackInfo<Value>& args) {
47224722
Environment* env = Environment::GetCurrent(args);
47234723

4724-
const node::Utf8Value hash_type(env->isolate(), args[0]);
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const Hash* orig = nullptr;
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const EVP_MD* md = nullptr;
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if (args[0]->IsObject()) {
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ASSIGN_OR_RETURN_UNWRAP(&orig, args[0].As<Object>());
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md = EVP_MD_CTX_md(orig->mdctx_.get());
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} else {
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const node::Utf8Value hash_type(env->isolate(), args[0]);
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md = EVP_get_digestbyname(*hash_type);
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}
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Maybe<unsigned int> xof_md_len = Nothing<unsigned int>();
47274736
if (!args[1]->IsUndefined()) {
@@ -4730,17 +4739,19 @@ void Hash::New(const FunctionCallbackInfo<Value>& args) {
47304739
}
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47324741
Hash* hash = new Hash(env, args.This());
4733-
if (!hash->HashInit(*hash_type, xof_md_len)) {
4742+
if (md == nullptr || !hash->HashInit(md, xof_md_len)) {
47344743
return ThrowCryptoError(env, ERR_get_error(),
47354744
"Digest method not supported");
47364745
}
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4747+
if (orig != nullptr &&
4748+
0 >= EVP_MD_CTX_copy(hash->mdctx_.get(), orig->mdctx_.get())) {
4749+
return ThrowCryptoError(env, ERR_get_error(), "Digest copy error");
4750+
}
47374751
}
47384752

47394753

4740-
bool Hash::HashInit(const char* hash_type, Maybe<unsigned int> xof_md_len) {
4741-
const EVP_MD* md = EVP_get_digestbyname(hash_type);
4742-
if (md == nullptr)
4743-
return false;
4754+
bool Hash::HashInit(const EVP_MD* md, Maybe<unsigned int> xof_md_len) {
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mdctx_.reset(EVP_MD_CTX_new());
47454756
if (!mdctx_ || EVP_DigestInit_ex(mdctx_.get(), md, nullptr) <= 0) {
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mdctx_.reset();

‎src/node_crypto.h‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -591,7 +591,7 @@ class Hash : public BaseObject {
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SET_MEMORY_INFO_NAME(Hash)
592592
SET_SELF_SIZE(Hash)
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594-
bool HashInit(const char* hash_type, v8::Maybe<unsigned int> xof_md_len);
594+
bool HashInit(const EVP_MD* md, v8::Maybe<unsigned int> xof_md_len);
595595
bool HashUpdate(const char* data, int len);
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protected:

‎test/parallel/test-crypto-hash.js‎

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Original file line numberDiff line numberDiff line change
@@ -192,14 +192,27 @@ common.expectsError(
192192
assert.strictEqual(crypto.createHash('shake256').digest('hex'),
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'46b9dd2b0ba88d13233b3feb743eeb24' +
194194
'3fcd52ea62b81b82b50c27646ed5762f');
195+
assert.strictEqual(crypto.createHash('shake256', { outputLength: 0 })
196+
.copy() // Default outputLength.
197+
.digest('hex'),
198+
'46b9dd2b0ba88d13233b3feb743eeb24' +
199+
'3fcd52ea62b81b82b50c27646ed5762f');
195200

196201
// Short outputLengths.
197202
assert.strictEqual(crypto.createHash('shake128', { outputLength: 0 })
198203
.digest('hex'),
199204
'');
205+
assert.strictEqual(crypto.createHash('shake128', { outputLength: 5 })
206+
.copy({ outputLength: 0 })
207+
.digest('hex'),
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'');
200209
assert.strictEqual(crypto.createHash('shake128', { outputLength: 5 })
201210
.digest('hex'),
202211
'7f9c2ba4e8');
212+
assert.strictEqual(crypto.createHash('shake128', { outputLength: 0 })
213+
.copy({ outputLength: 5 })
214+
.digest('hex'),
215+
'7f9c2ba4e8');
203216
assert.strictEqual(crypto.createHash('shake128', { outputLength: 15 })
204217
.digest('hex'),
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'7f9c2ba4e88f827d61604550760585');
@@ -249,3 +262,19 @@ common.expectsError(
249262
{ code: 'ERR_OUT_OF_RANGE' });
250263
}
251264
}
265+
266+
{
267+
const h = crypto.createHash('sha512');
268+
h.digest();
269+
common.expectsError(() => h.copy(), { code: 'ERR_CRYPTO_HASH_FINALIZED' });
270+
common.expectsError(() => h.digest(), { code: 'ERR_CRYPTO_HASH_FINALIZED' });
271+
}
272+
273+
{
274+
const a = crypto.createHash('sha512').update('abc');
275+
const b = a.copy();
276+
const c = b.copy().update('def');
277+
const d = crypto.createHash('sha512').update('abcdef');
278+
assert.strictEqual(a.digest('hex'), b.digest('hex'));
279+
assert.strictEqual(c.digest('hex'), d.digest('hex'));
280+
}

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