feat: add randomBytes function (#45)

* feat: add randomBytes function

* fix: apply CR

README.md

@@ -185,6 +185,11 @@ Converts a private key object into a protobuf serialized private key.
 
 Converts a protobuf serialized private key into its representative object.
 
+### `randomBytes(number)`
+
+- `number: Number`
+
+Generates a Buffer with length `number` populated by random bytes.
 
 ## Contribute
 

src/index.js

@@ -71,3 +71,12 @@ exports.marshalPrivateKey = (key, type) => {
 
   return key.bytes
 }
+
+exports.randomBytes = (number) => {
+  if (!number || typeof number !== 'number') {
+    throw new Error('first argument must be a Number bigger than 0')
+  }
+  const buf = new Buffer(number)
+  c.rsa.getRandomValues(buf)
+  return buf
+}

test/index.spec.js

@@ -97,5 +97,18 @@ describe('libp2p-crypto', () => {
         true
       )
     })
+
+    it('randomBytes throws with no number passed', () => {
+      expect(() => {
+        crypto.randomBytes()
+      }).to.throw
+    })
+
+    it('randomBytes', () => {
+      const buf1 = crypto.randomBytes(10)
+      expect(buf1.length).to.equal(10)
+      const buf2 = crypto.randomBytes(10)
+      expect(buf1).to.not.eql(buf2)
+    })
   })
 })