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: https://github.com/nodejs/node/issues/28757
PR-URL: https://github.com/nodejs/node/pull/28805
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/lib/internal/crypto/hash.js b/lib/internal/crypto/hash.js
index a581648021..667624dce0 100644
--- a/lib/internal/crypto/hash.js
+++ b/lib/internal/crypto/hash.js
@@ -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
   };