fix: .createHash() returning wrong hashes / not working

README.md

@@ -94,6 +94,7 @@ multihashing(buf, 'sha1')
 multihashing.digest(buf, 'sha1')
 
 // Use `.createHash(...)` for a `crypto.createHash` interface.
+// NOTE: The interface does not support streaming and only exposes .update(buffer) and .digest(type)
 var h = multihashing.createHash('sha1')
 h.update(buf)
 h.digest()

src/index.js

@@ -32,7 +32,26 @@ mh.createHash = function (func, length) {
     throw new Error('multihash function ' + func + ' not yet supported')
   }
 
-  return mh.functions[func]()
+  const fnc = mh.functions[func]()
+
+  return {
+    update: (buf) => fnc.update(buf),
+    digest: (type) => {
+      let digest = fnc.digest()
+
+      if (length) {
+        digest = digest.slice(0, length)
+      }
+
+      let hash = multihash.encode(digest, func, length)
+
+      if (type) { // e.x. .digest('hex')
+        return hash.toString(type)
+      } else {
+        return hash
+      }
+    }
+  }
 }
 
 mh.verify = function (hash, buf) {

src/sha3.js

@@ -19,16 +19,17 @@ class Hasher {
   constructor (hashFunc, arg) {
     this.hf = hashFunc
     this.arg = arg
-    this.input = null
+    this.input = []
   }
 
   update (buf) {
-    this.input = buf
+    this.input.push(buf)
     return this
   }
 
   digest () {
-    const input = this.input
+    const input = Buffer.concat(this.input)
+    this.input = null
     const arg = this.arg
     return Buffer.from(this.hf(input, arg), 'hex')
   }

test/index.spec.js

@@ -71,6 +71,17 @@ describe('multihashing', () => {
         expect(multihashing.verify(output, input)).to.be.eql(true)
       }
     })
+
+    it(algo + ' stream', () => {
+      for (const test of tests[algo]) {
+        const input = Buffer.from(test[0])
+        const output = Buffer.from(test[1], 'hex')
+        const slices = test[0].split('').map(Buffer.from)
+        const h = multihashing.createHash(algo)
+        slices.forEach(h.update)
+        expect(multihashing.verify(h.digest(), input)).to.be.eql(true)
+      }
+    })
   }
 
   it('cuts the length', () => {