crypto: support outputLength option in crypto.hash for XOF functions

Support `outputLength` option in crypto.hash() for XOF hash
functions to align with the behaviour of crypto.createHash()
API

closes: nodejs/node#57312

Co-authored-by: Filip Skokan <[email protected]>
PR-URL: nodejs/node#58121
Fixes: nodejs/node#57312
Reviewed-By: Joyee Cheung <[email protected]>
Reviewed-By: Filip Skokan <[email protected]>
Reviewed-By: Rafael Gonzaga <[email protected]>

Author: 2 people

include/ncrypto.h

@@ -284,8 +284,13 @@ class Digest final {
   const EVP_MD* md_ = nullptr;
 };
 
+// Computes a fixed-length digest.
 DataPointer hashDigest(const Buffer<const unsigned char>& data,
                        const EVP_MD* md);
+// Computes a variable-length digest for XOF algorithms (e.g. SHAKE128).
+DataPointer xofHashDigest(const Buffer<const unsigned char>& data,
+                          const EVP_MD* md,
+                          size_t length);
 
 class Cipher final {
  public:

src/ncrypto.cpp

@@ -4384,6 +4384,22 @@ DataPointer hashDigest(const Buffer<const unsigned char>& buf,
   return data.resize(result_size);
 }
 
+DataPointer xofHashDigest(const Buffer<const unsigned char>& buf,
+                          const EVP_MD* md,
+                          size_t output_length) {
+  if (md == nullptr) return {};
+
+  EVPMDCtxPointer ctx = EVPMDCtxPointer::New();
+  if (!ctx) return {};
+  if (ctx.digestInit(md) != 1) {
+    return {};
+  }
+  if (ctx.digestUpdate(reinterpret_cast<const Buffer<const void>&>(buf)) != 1) {
+    return {};
+  }
+  return ctx.digestFinal(output_length);
+}
+
 // ============================================================================
 
 X509Name::X509Name() : name_(nullptr), total_(0) {}