XOF hash function changed their default outputLength to zero byte

Version

v22.14.0

Platform

Linux ### 6.15.2-arch1-1 #1 SMP PREEMPT_DYNAMIC Tue, 10 Jun 2025 21:32:33 +0000 x86_64 GNU/Linux

Subsystem

crypto

What steps will reproduce the bug?

Try to hash anything using a variable length hash function (e.g. shake128), without any options you get an empty buffer/string.

How often does it reproduce? Is there a required condition?

Reproducible, but I haven't dissected the exact version the default changed. I known it is somewhere between v14.21.3 and v22.14.0 and yes I realize this is a very large window 😕

What is the expected behavior? Why is that the expected behavior?

shake128 should default to outputLength = 16 as in earlier Node.JS versions. Other variable-length (XOF) hashes should also default to sensible non-zero length.

I believe it is sane to expect the following assertion:

const {getHashes, createHash } = require('crypto');
assert.equal( 0 , getHashes().filter( h => !createHash(h).digest().length ).length )

What do you see instead?

getHashes().filter( h => !createHash(h).digest().length ) == [ 'shake128', 'shake256' ]

Additional information

Node 12.8.0 introduced the outputLength option to crypto.createHash
In Node 14.21.3 and earlier, when the option is omitted, shake128 defaults to 16 bytes output
In Node 22.14.0 and later, the default is zero, which results in empty hashes:

> require('crypto').createHash('shake128').update('test').digest()
<Buffer >

There are two issues here:

It is not backward compatible, and unless I missed something this breaking change is not documented, which resulted in breaking our app when upgrading node
In general, defaulting to null length by default is very countrer-intuitive

@antoinep92

I'm not able to reproduce this issue with bundled OpenSSL

$ node -p 'process.versions'
{
  node: '22.14.0',
  acorn: '8.14.0',
  ada: '2.9.2',
  amaro: '0.3.0',
  ares: '1.34.4',
  brotli: '1.1.0',
  cjs_module_lexer: '1.4.1',
  cldr: '46.0',
  icu: '76.1',
  llhttp: '9.2.1',
  modules: '127',
  napi: '10',
  nbytes: '0.1.1',
  ncrypto: '0.0.1',
  nghttp2: '1.64.0',
  nghttp3: '1.6.0',
  ngtcp2: '1.10.0',
  openssl: '3.0.15+quic',
  simdjson: '3.10.1',
  simdutf: '6.0.3',
  sqlite: '3.47.2',
  tz: '2024b',
  undici: '6.21.1',
  unicode: '16.0',
  uv: '1.49.2',
  uvwasi: '0.0.21',
  v8: '12.4.254.21-node.22',
  zlib: '1.3.0.1-motley-82a5fec'
}
$ node -p "require('crypto').createHash('shake128').update('test').digest().byteLength"
16

But suspect this has to with using linked OpenSSL >= 3.4, @antoinep92 can you confirm?

The issue is not Node changing the default, it's OpenSSL.

While we are testing on later OpenSSL versions I am unsure about how "supported" they actually are meant to be. I've identified the issue and opened a PR to work around the OpenSSL breaking change.

@panva

But suspect this has to with using linked OpenSSL >= 3.4, @antoinep92 can you confirm?

Hi @panva indeed I confirm I have OpenSSL 3.5 installed. Thanks for tracking this down and the PR 👍
I haven't found any maximum supported version for OpenSSL either, but it makes sense that not all versions of all shared libs can be tested.

crypto: fix SHAKE128/256 breaking change introduced with OpenSSL 3.4

Fixed in

crypto: fix SHAKE128/256 breaking change introduced with OpenSSL 3.4

Navigation Menu

Repository navigation

XOF hash function changed their default outputLength to zero byte #58913

Version

Platform

Subsystem

What steps will reproduce the bug?

How often does it reproduce? Is there a required condition?

What is the expected behavior? Why is that the expected behavior?

What do you see instead?

Additional information

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

XOF hash function changed their default outputLength to zero byte #58913

Description

Version

Platform

Subsystem

What steps will reproduce the bug?

How often does it reproduce? Is there a required condition?

What is the expected behavior? Why is that the expected behavior?

What do you see instead?

Additional information

Activity

panva commented on Jul 3, 2025

panva commented on Jul 3, 2025

antoinep92 commented on Jul 3, 2025

panva commented on Aug 1, 2025

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions