initial implementation of short authentication string generation

3 files changed, 125 insertions, 0 deletions

diff --git a/javascript/olm_post.js b/javascript/olm_post.js
index 8c06fff..3bf0d66 100644
--- a/javascript/olm_post.js
+++ b/javascript/olm_post.js
@@ -534,6 +534,7 @@ olm_exports["Session"] = Session;
 olm_exports["Utility"] = Utility;
 olm_exports["PkEncryption"] = PkEncryption;
 olm_exports["PkDecryption"] = PkDecryption;
+olm_exports["SAS"] = SAS;
 
 olm_exports["get_library_version"] = restore_stack(function() {
     var buf = stack(3);
diff --git a/javascript/olm_sas.js b/javascript/olm_sas.js
new file mode 100644
index 0000000..8fc535b
--- /dev/null
+++ b/javascript/olm_sas.js
@@ -0,0 +1,71 @@
+function SAS() {
+    var size = Module['_olm_sas_size']();
+    var random_length = Module['_olm_create_sas_random_length']();
+    var random = random_stack(random_length);
+    this.buf = malloc(size);
+    this.ptr = Module['_olm_sas'](this.buf);
+    Module['_olm_create_sas'](this.ptr, random, random_length);
+    bzero(random, random_length);
+}
+
+function sas_method(wrapped) {
+    return function() {
+        var result = wrapped.apply(this, arguments);
+        if (result === OLM_ERROR) {
+            var message = Pointer_stringify(
+                Module['_olm_sas_last_error'](arguments[0])
+            );
+            throw new Error("OLM." + message);
+        }
+        return result;
+    }
+}
+
+SAS.prototype['free'] = function() {
+    Module['_olm_clear_sas'](this.ptr);
+    free(this.ptr);
+};
+
+SAS.prototype['get_pubkey'] = restore_stack(function() {
+    var pubkey_length = sas_method(Module['_olm_sas_pubkey_length'])(this.ptr);
+    var pubkey_buffer = stack(pubkey_length + NULL_BYTE_PADDING_LENGTH);
+    sas_method(Module['_olm_sas_get_pubkey'])(this.ptr, pubkey_buffer, pubkey_length);
+    return Pointer_stringify(pubkey_buffer);
+});
+
+SAS.prototype['set_their_key'] = restore_stack(function(their_key) {
+    var their_key_array = array_from_string(their_key);
+    var their_key_buffer = stack(their_key_array);
+    sas_method(Module['_olm_sas_set_their_key'])(
+        this.ptr,
+        their_key_buffer, their_key_array.length
+    );
+});
+
+SAS.prototype['generate_bytes'] = restore_stack(function(length) {
+    var output_buffer = stack(length);
+    sas_method(Module['_olm_sas_generate_bytes'])(
+        this.ptr,
+        output_buffer, length
+    );
+    // The inner Uint8Array creates a view of the buffer.  The outer Uint8Array
+    // copies it to a new array to return, since the original buffer will get
+    // deallocated from the stack and could get overwritten.
+    var output_arr = new Uint8Array(
+        new Uint8Array(Module['HEAPU8'].buffer, output_buffer, length)
+    );
+    return output_arr;
+});
+
+SAS.prototype['calculate_mac'] = restore_stack(function(input) {
+    var input_array = array_from_string(input);
+    var input_buffer = stack(input_array)
+    var mac_length = sas_method(Module['_olm_sas_mac_length'])(this.ptr);
+    var mac_buffer = stack(mac_length + NULL_BYTE_PADDING_LENGTH);
+    sas_method(Module['_olm_sas_calculate_mac'])(
+        this.ptr,
+        input_buffer, input_array.length,
+        mac_buffer, mac_length
+    );
+    return Pointer_stringify(mac_buffer);
+});
diff --git a/javascript/test/sas.spec.js b/javascript/test/sas.spec.js
new file mode 100644
index 0000000..544131d
--- /dev/null
+++ b/javascript/test/sas.spec.js
@@ -0,0 +1,53 @@
+/*
+Copyright 2018 New Vector Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+var Olm = require('../olm');
+
+describe("sas", function() {
+    var alice, bob;
+
+    beforeEach(async function(done) {
+        Olm.init().then(function() {
+            alice = new Olm.SAS();
+            bob = new Olm.SAS();
+
+            done();
+        });
+    });
+
+    afterEach(function () {
+        if (alice !== undefined) {
+            alice.free();
+            alice = undefined;
+        }
+        if (bob !== undefined) {
+            bob.free();
+            bob = undefined;
+        }
+    });
+
+    it('should create matching SAS bytes', function () {
+        alice.set_their_key(bob.get_pubkey());
+        bob.set_their_key(alice.get_pubkey());
+        expect(alice.generate_bytes(5).toString()).toEqual(bob.generate_bytes(5).toString());
+    });
+
+    it('should create matching MACs', function () {
+        alice.set_their_key(bob.get_pubkey());
+        bob.set_their_key(alice.get_pubkey());
+        expect(alice.calculate_mac("test").toString()).toEqual(bob.calculate_mac("test").toString());
+    });
+});