Add stream support

README.md

@@ -48,6 +48,23 @@ API. All parameters must also fulfill the following constraints, or an
   use this parameter as a kind of app id, or global versioning scheme. This
   value is not required to be secret.
 
+### `var instance = blake2b.instance(outlen, [key], [salt], [personal], [noAssert = false])`
+
+Like the above method, but allows your to update the hash as you can access more
+data. `noAssert` will also disable asserts in `.update` and `.final` methods.
+Note that `outlen` should be a number, and that you pass the `Buffer` in the
+`.final` method
+
+### `instance.update(input)`
+
+Update the hash with new `input`. Calling this method after `.final` will throw
+an error.
+
+### `instance.final(out)`
+
+Finalise the the hash and write the digest to `out`. `out` must be exactly equal
+to `outlen` given in the `.instance` method.
+
 ### Constants
 
 * `blake2b.BYTES_MIN` Minimum length of `out`

example.js

@@ -1,7 +1,7 @@
 var blake2b = require('./index.js')
 
 var output = new Uint8Array(64)
-var input = Buffer.from('hello world')
+var input = Buffer.allocUnsafe(2048)
 
 blake2b(output, input)
 

index.js

@@ -227,7 +227,7 @@ function blake2bUpdate (ctx, input) {
 
 // Completes a BLAKE2b streaming hash
 // Returns a Uint8Array containing the message digest
-function blake2bFinal (out, ctx) {
+function blake2bFinal (ctx, out) {
   ctx.t += ctx.c // mark last block offset
 
   while (ctx.c < 128) { // fill up with zeros
@@ -256,7 +256,41 @@ module.exports = function blake2b (out, input, key, salt, personal, noAssert) {
   // do the math
   var ctx = blake2bInit(out.length, key, salt, personal)
   blake2bUpdate(ctx, input)
-  return blake2bFinal(out, ctx)
+  return blake2bFinal(ctx, out)
+}
+
+module.exports.instance = function instance (outlen, key, salt, personal, noAssert) {
+  if (noAssert !== true) {
+    assert(outlen >= BYTES_MIN)
+    assert(outlen <= BYTES_MAX)
+    assert(key == null ? true : key.length >= KEYBYTES_MIN)
+    assert(key == null ? true : key.length <= KEYBYTES_MAX)
+    assert(salt == null ? true : salt.length === SALTBYTES)
+    assert(personal == null ? true : personal.length === PERSONALBYTES)
+  }
+
+  var ctx = blake2bInit(outlen, key, salt, personal)
+  var finalised = false
+
+  return {
+    update: function (input) {
+      if (finalised === true) throw new Error('hash has been finalised')
+      if (noAssert !== true) {
+        assert(input != null)
+      }
+
+      blake2bUpdate(ctx, input)
+    },
+    final: function (out) {
+      if (noAssert !== true) {
+        assert(out != null)
+        assert(out.length === outlen)
+      }
+
+      finalised = true
+      return blake2bFinal(ctx, out)
+    }
+  }
 }
 
 var BYTES_MIN = module.exports.BYTES_MIN = 16

test.js

@@ -34,6 +34,64 @@ test('works with buffers', function (assert) {
   assert.end()
 })
 
+test('streaming', function (t) {
+  var isntance = blake2b.instance(blake2b.BYTES)
+  var buf = new Buffer('Hej, Verden')
+
+  for (var i = 0; i < 10; i++) isntance.update(buf)
+
+  var out = Buffer.alloc(blake2b.BYTES)
+  isntance.final(out)
+
+  t.same(out.toString('hex'), 'cbc20f347f5dfe37dc13231cbf7eaa4ec48e585ec055a96839b213f62bd8ce00', 'streaming hash')
+  t.end()
+})
+
+test('streaming with key', function (t) {
+  var key = Buffer.alloc(blake2b.KEYBYTES)
+  key.fill('lo')
+
+  var instance = blake2b.instance(blake2b.BYTES, key)
+  var buf = new Buffer('Hej, Verden')
+
+  for (var i = 0; i < 10; i++) instance.update(buf)
+
+  var out = Buffer.alloc(blake2b.BYTES)
+  instance.final(out)
+
+  t.same(out.toString('hex'), '405f14acbeeb30396b8030f78e6a84bab0acf08cb1376aa200a500f669f675dc', 'streaming keyed hash')
+  t.end()
+})
+
+test('streaming with hash length', function (t) {
+  var isntance = blake2b.instance(blake2b.BYTES_MIN)
+  var buf = new Buffer('Hej, Verden')
+
+  for (var i = 0; i < 10; i++) isntance.update(buf)
+
+  var out = Buffer.alloc(blake2b.BYTES_MIN)
+  isntance.final(out)
+
+  t.same(out.toString('hex'), 'decacdcc3c61948c79d9f8dee5b6aa99', 'streaming short hash')
+  t.end()
+})
+
+test('streaming with key and hash length', function (t) {
+  var key = Buffer.alloc(blake2b.KEYBYTES)
+  key.fill('lo')
+
+  var instance = blake2b.instance(blake2b.BYTES_MIN, key)
+  var buf = new Buffer('Hej, Verden')
+
+  for (var i = 0; i < 10; i++) instance.update(buf)
+
+  var out = Buffer.alloc(blake2b.BYTES_MIN)
+  instance.final(out)
+
+  t.same(out.toString('hex'), 'fb43f0ab6872cbfd39ec4f8a1bc6fb37', 'streaming short keyed hash')
+  t.end()
+})
+
 function hexWrite (buf, string) {
   // must be an even number of digits
   var strLen = string.length