`crypto_hash_sha256()` not exported?

[jamesruan]

Our project need a browser version of SHA-256. I would like to use libsodium.js for that. To my surprise, I find this function is deliberately not exported.

I see crypto_hash() (which is supposed to be a SHA-512-256) is exported. Is there any reason not to export it?

Thanks.

[jedisct1]

Hi James,

This function is available in the sumo build.

It is not included in the standard build since no high-level APIs are using it.

SHA-256 is slower than other options and vulnerable to length extension attacks (unlike SHA-512/256 and Blake2), so the only reason for explicitly requiring it is compatibility with legacy applications.

The sumo build includes everything, not only high-level APIs. So just include the content of browsers-sumo or modules-sumo and you will have it!

[jamesruan]

Thanks for your reply.

I didn't find documents about the 'sumo' version. We will try it.

[ben1226q]

I'm a colleague of James.

I've download the 'sumo' build, and list all exported functions. Still, the crypto_hash_sha256() is not in the list.

for(var v in sodium){
        console.log(v);
    }

[jedisct1]

$ node
> let sodium = require('libsodium-wrappers')
> sodium
{ add: [Function: add],
  compare: [Function: compare],
  from_base64: [Function: from_base64],
  from_hex: [Function: from_hex],
  from_string: [Function: from_string],
  increment: [Function: increment],
...
  crypto_hash: [Function: crypto_hash],
  crypto_hash_sha256: [Function: crypto_hash_sha256],
  crypto_hash_sha512: [Function: crypto_hash_sha512],
...
  crypto_sign_SEEDBYTES: 32,
  SODIUM_VERSION_STRING: '1.0.10',
  crypto_pwhash_STRPREFIX: '$argon2i$',
  crypto_pwhash_scryptsalsa208sha256_STRPREFIX: '$7$' }

[jamesruan]

Thanks for your patience.

We probably downloaded an error built version. Current version is OK.