Extract multihash functions

app/lib/kredits/index.js

@@ -1,5 +1,8 @@
 import ContributorSerializer from './serializers/contributor';
+import { fromBytes32, toBytes32 } from './utils/multihash';
 
 export {
-  ContributorSerializer
+  ContributorSerializer,
+  fromBytes32,
+  toBytes32
 };

app/lib/kredits/utils/multihash.js

@@ -0,0 +1,33 @@
+import bs58 from 'npm:bs58';
+import NpmBuffer from 'npm:buffer';
+const Buffer = NpmBuffer.Buffer;
+
+function fromBytes32({ digest, hashFunction, hashSize }) {
+  if (hashSize === 0) {
+    return;
+  }
+
+  const hashBytes = Buffer.from(digest.slice(2), 'hex');
+  const multiHashBytes = new (hashBytes.constructor)(2 + hashBytes.length);
+
+  multiHashBytes[0] = hashFunction;
+  multiHashBytes[1] = hashSize;
+  multiHashBytes.set(hashBytes, 2);
+
+  return bs58.encode(multiHashBytes);
+}
+
+function toBytes32(string) {
+  const decoded = bs58.decode(string);
+
+  return {
+    digest: `0x${decoded.slice(2).toString('hex')}`,
+    hashFunction: decoded[0],
+    hashSize: decoded[1],
+  };
+}
+
+export {
+  fromBytes32,
+  toBytes32
+};