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crypto: add outputLength option to crypto.createHash

This change adds an outputLength option to crypto.createHash which
allows users to produce variable-length hash values using XOF hash
functons.

Fixes: #28757
PR-URL: #28805
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
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tniessen authored and targos committed Jul 19, 2019
1 parent d3426ee commit b7c6ad595b80442e433c6308dc5b80ed641866e0
Showing with 133 additions and 11 deletions.
  1. +6 −1 doc/api/crypto.md
  2. +5 −2 lib/internal/crypto/hash.js
  3. +49 −4 src/node_crypto.cc
  4. +7 −4 src/node_crypto.h
  5. +66 −0 test/parallel/test-crypto-hash.js
@@ -1785,14 +1785,19 @@ and description of each available elliptic curve.
### crypto.createHash(algorithm[, options])
<!-- YAML
added: v0.1.92
changes:
- version: REPLACEME
pr-url: https://github.com/nodejs/node/pull/28805
description: The `outputLength` option was added for XOF hash functions.
-->
* `algorithm` {string}
* `options` {Object} [`stream.transform` options][]
* Returns: {Hash}

Creates and returns a `Hash` object that can be used to generate hash digests
using the given `algorithm`. Optional `options` argument controls stream
behavior.
behavior. For XOF hash functions such as `'shake256'`, the `outputLength` option
can be used to specify the desired output length in bytes.

The `algorithm` is dependent on the available algorithms supported by the
version of OpenSSL on the platform. Examples are `'sha256'`, `'sha512'`, etc.
@@ -25,7 +25,7 @@ const {
ERR_CRYPTO_HASH_UPDATE_FAILED,
ERR_INVALID_ARG_TYPE
} = require('internal/errors').codes;
const { validateString } = require('internal/validators');
const { validateString, validateUint32 } = require('internal/validators');
const { normalizeEncoding } = require('internal/util');
const { isArrayBufferView } = require('internal/util/types');
const LazyTransform = require('internal/streams/lazy_transform');
@@ -36,7 +36,10 @@ function Hash(algorithm, options) {
if (!(this instanceof Hash))
return new Hash(algorithm, options);
validateString(algorithm, 'algorithm');
this[kHandle] = new _Hash(algorithm);
const xofLen = typeof options === 'object' ? options.outputLength : undefined;
if (xofLen !== undefined)
validateUint32(xofLen, 'options.outputLength');
this[kHandle] = new _Hash(algorithm, xofLen);
this[kState] = {
[kFinalized]: false
};
@@ -4569,15 +4569,21 @@ void Hash::New(const FunctionCallbackInfo<Value>& args) {

const node::Utf8Value hash_type(env->isolate(), args[0]);

Maybe<unsigned int> xof_md_len = Nothing<unsigned int>();
if (!args[1]->IsUndefined()) {
CHECK(args[1]->IsUint32());
xof_md_len = Just<unsigned int>(args[1].As<Uint32>()->Value());
}

Hash* hash = new Hash(env, args.This());
if (!hash->HashInit(*hash_type)) {
if (!hash->HashInit(*hash_type, xof_md_len)) {
return ThrowCryptoError(env, ERR_get_error(),
"Digest method not supported");
}
}


bool Hash::HashInit(const char* hash_type) {
bool Hash::HashInit(const char* hash_type, Maybe<unsigned int> xof_md_len) {
const EVP_MD* md = EVP_get_digestbyname(hash_type);
if (md == nullptr)
return false;
@@ -4586,6 +4592,18 @@ bool Hash::HashInit(const char* hash_type) {
mdctx_.reset();
return false;
}

md_len_ = EVP_MD_size(md);
if (xof_md_len.IsJust() && xof_md_len.FromJust() != md_len_) {
// This is a little hack to cause createHash to fail when an incorrect
// hashSize option was passed for a non-XOF hash function.
if ((EVP_MD_meth_get_flags(md) & EVP_MD_FLAG_XOF) == 0) {
EVPerr(EVP_F_EVP_DIGESTFINALXOF, EVP_R_NOT_XOF_OR_INVALID_LENGTH);
return false;
}
md_len_ = xof_md_len.FromJust();
}

return true;
}

@@ -4634,13 +4652,40 @@ void Hash::HashDigest(const FunctionCallbackInfo<Value>& args) {
encoding = ParseEncoding(env->isolate(), args[0], BUFFER);
}

if (hash->md_len_ == 0) {
// TODO(tniessen): SHA3_squeeze does not work for zero-length outputs on all
// platforms and will cause a segmentation fault if called. This workaround
// causes hash.digest() to correctly return an empty buffer / string.
// See https://github.com/openssl/openssl/issues/9431.
if (!hash->has_md_ && hash->md_len_ == 0) {
hash->has_md_ = true;
}

if (!hash->has_md_) {
// Some hash algorithms such as SHA3 do not support calling
// EVP_DigestFinal_ex more than once, however, Hash._flush
// and Hash.digest can both be used to retrieve the digest,
// so we need to cache it.
// See https://github.com/nodejs/node/issues/28245.
EVP_DigestFinal_ex(hash->mdctx_.get(), hash->md_value_, &hash->md_len_);

hash->md_value_ = MallocOpenSSL<unsigned char>(hash->md_len_);

size_t default_len = EVP_MD_CTX_size(hash->mdctx_.get());
int ret;
if (hash->md_len_ == default_len) {
ret = EVP_DigestFinal_ex(hash->mdctx_.get(), hash->md_value_,
&hash->md_len_);
} else {
ret = EVP_DigestFinalXOF(hash->mdctx_.get(), hash->md_value_,
hash->md_len_);
}

if (ret != 1) {
OPENSSL_free(hash->md_value_);
hash->md_value_ = nullptr;
return ThrowCryptoError(env, ERR_get_error());
}

hash->has_md_ = true;
}

Local<Value> error;
@@ -585,7 +585,7 @@ class Hash : public BaseObject {
SET_MEMORY_INFO_NAME(Hash)
SET_SELF_SIZE(Hash)

bool HashInit(const char* hash_type);
bool HashInit(const char* hash_type, v8::Maybe<unsigned int> xof_md_len);
bool HashUpdate(const char* data, int len);

protected:
@@ -596,18 +596,21 @@ class Hash : public BaseObject {
Hash(Environment* env, v8::Local<v8::Object> wrap)
: BaseObject(env, wrap),
mdctx_(nullptr),
md_len_(0) {
has_md_(false),
md_value_(nullptr) {
MakeWeak();
}

~Hash() override {
OPENSSL_cleanse(md_value_, md_len_);
if (md_value_ != nullptr)
OPENSSL_clear_free(md_value_, md_len_);
}

private:
EVPMDPointer mdctx_;
unsigned char md_value_[EVP_MAX_MD_SIZE];
bool has_md_;
unsigned int md_len_;
unsigned char* md_value_;
};

class SignBase : public BaseObject {
@@ -185,3 +185,69 @@ common.expectsError(
assert(instance instanceof Hash, 'Hash is expected to return a new instance' +
' when called without `new`');
}

// Test XOF hash functions and the outputLength option.
{
// Default outputLengths.
assert.strictEqual(crypto.createHash('shake128').digest('hex'),
'7f9c2ba4e88f827d616045507605853e');
assert.strictEqual(crypto.createHash('shake256').digest('hex'),
'46b9dd2b0ba88d13233b3feb743eeb24' +
'3fcd52ea62b81b82b50c27646ed5762f');

// Short outputLengths.
assert.strictEqual(crypto.createHash('shake128', { outputLength: 0 })
.digest('hex'),
'');
assert.strictEqual(crypto.createHash('shake128', { outputLength: 5 })
.digest('hex'),
'7f9c2ba4e8');
assert.strictEqual(crypto.createHash('shake128', { outputLength: 15 })
.digest('hex'),
'7f9c2ba4e88f827d61604550760585');
assert.strictEqual(crypto.createHash('shake256', { outputLength: 16 })
.digest('hex'),
'46b9dd2b0ba88d13233b3feb743eeb24');

// Large outputLengths.
assert.strictEqual(crypto.createHash('shake128', { outputLength: 128 })
.digest('hex'),
'7f9c2ba4e88f827d616045507605853e' +
'd73b8093f6efbc88eb1a6eacfa66ef26' +
'3cb1eea988004b93103cfb0aeefd2a68' +
'6e01fa4a58e8a3639ca8a1e3f9ae57e2' +
'35b8cc873c23dc62b8d260169afa2f75' +
'ab916a58d974918835d25e6a435085b2' +
'badfd6dfaac359a5efbb7bcc4b59d538' +
'df9a04302e10c8bc1cbf1a0b3a5120ea');
const superLongHash = crypto.createHash('shake256', {
outputLength: 1024 * 1024
}).update('The message is shorter than the hash!')
.digest('hex');
assert.strictEqual(superLongHash.length, 2 * 1024 * 1024);
assert.ok(superLongHash.endsWith('193414035ddba77bf7bba97981e656ec'));
assert.ok(superLongHash.startsWith('a2a28dbc49cfd6e5d6ceea3d03e77748'));

// Non-XOF hash functions should accept valid outputLength options as well.
assert.strictEqual(crypto.createHash('sha224', { outputLength: 28 })
.digest('hex'),
'd14a028c2a3a2bc9476102bb288234c4' +
'15a2b01f828ea62ac5b3e42f');

// Passing invalid sizes should throw during creation.
common.expectsError(() => {
crypto.createHash('sha256', { outputLength: 28 });
}, {
code: 'ERR_OSSL_EVP_NOT_XOF_OR_INVALID_LENGTH'
});

for (const outputLength of [null, {}, 'foo', false]) {
common.expectsError(() => crypto.createHash('sha256', { outputLength }),
{ code: 'ERR_INVALID_ARG_TYPE' });
}

for (const outputLength of [-1, .5, Infinity, 2 ** 90]) {
common.expectsError(() => crypto.createHash('sha256', { outputLength }),
{ code: 'ERR_OUT_OF_RANGE' });
}
}

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