Introduced newDeriveKeyHasher(Hasher => Unit)

Author: catap

CHANGELOG.md

@@ -3,6 +3,7 @@
 All notable changes to this project will be documented in this file.
 
 ## [unreleased]
+- Introduced `newDeriveKeyHasher(Hasher => Unit)`.
 - Introduced `update(Short)`, `update(Int)` and `update(Long)`.
 
 ## [2.2.0] - 2021-01-05

shared/src/main/scala/ky/korins/blake3/Blake3.scala

@@ -33,15 +33,21 @@ object Blake3 {
   }
 
   /**
-   * A new hasher with derive key that might be any array of bytes
+   * A new hasher with derive key that should be initalized via callback
    */
-  def newDeriveKeyHasher(context: Array[Byte]): Hasher = {
-    val contextKey = new HasherImpl(IV, DERIVE_KEY_CONTEXT)
-      .update(context)
-      .done(KEY_LEN)
+  def newDeriveKeyHasher(cb: Hasher => Unit): Hasher = {
+    val contextKeyHasher = new HasherImpl(IV, DERIVE_KEY_CONTEXT)
+    cb(contextKeyHasher)
+    val contextKey = contextKeyHasher.done(KEY_LEN)
     new HasherImpl(wordsFromLittleEndianBytes(contextKey), DERIVE_KEY_MATERIAL)
   }
 
+  /**
+   * A new hasher with derive key that might be any array of bytes
+   */
+  def newDeriveKeyHasher(context: Array[Byte]): Hasher =
+    newDeriveKeyHasher(_.update(context))
+
   /**
    * A new hasher with derive key that might be any string
    */