diff --git a/package-lock.json b/package-lock.json
index 0ada429..c41f668 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "mesg-js",
-  "version": "4.3.0-beta",
+  "version": "4.3.0-beta.1",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
@@ -338,6 +338,14 @@
         }
       }
     },
+    "base-x": {
+      "version": "3.0.6",
+      "resolved": "https://registry.npmjs.org/base-x/-/base-x-3.0.6.tgz",
+      "integrity": "sha512-4PaF8u2+AlViJxRVjurkLTxpp7CaFRD/jo5rPT9ONnKxyhQ8f59yzamEvq7EkriG56yn5On4ONyaG75HLqr46w==",
+      "requires": {
+        "safe-buffer": "^5.0.1"
+      }
+    },
     "binary-extensions": {
       "version": "1.13.1",
       "resolved": "https://registry.npmjs.org/binary-extensions/-/binary-extensions-1.13.1.tgz",
@@ -3273,8 +3281,7 @@
     "safe-buffer": {
       "version": "5.1.2",
       "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.1.2.tgz",
-      "integrity": "sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g==",
-      "dev": true
+      "integrity": "sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g=="
     },
     "safe-regex": {
       "version": "1.1.0",
diff --git a/package.json b/package.json
index 8671c05..f70ed33 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mesg-js",
-  "version": "4.3.0-beta",
+  "version": "4.3.0-beta.1",
   "description": "",
   "main": "lib/index.js",
   "scripts": {
@@ -15,6 +15,7 @@
   "license": "ISC",
   "dependencies": {
     "@grpc/proto-loader": "^0.5.1",
+    "base-x": "^3.0.6",
     "grpc": "^1.21.1",
     "js-yaml": "^3.13.1",
     "pb-util": "^0.1.1",
diff --git a/src/api/mock.ts b/src/api/mock.ts
index 078c515..ea63a9e 100644
--- a/src/api/mock.ts
+++ b/src/api/mock.ts
@@ -3,7 +3,7 @@ import { API } from './types'
 import { Stream } from '../util/grpc';
 import { encode } from '../util/encoder';
 
-const hash = 'hash'
+const hash = Buffer.from('hash')
 
 class StreamMock<T> implements Stream<T> {
   private eventEmitter = new EventEmitter()
@@ -30,7 +30,7 @@ export default (endpoint: string): API => ({
   },
   execution: {
     create() { return Promise.resolve({ hash }) },
-    get() { return Promise.resolve({ parentHash: hash, eventHash: 'xxx', status: 0, instanceHash: hash, taskKey: 'xxx', inputs: encode({}) }) },
+    get() { return Promise.resolve({ parentHash: hash, eventHash: Buffer.from('xxx'), status: 0, instanceHash: hash, taskKey: 'xxx', inputs: encode({}) }) },
     stream() { return streams.execution },
     update() { return Promise.resolve({}) }
   },
diff --git a/src/api/typedef/event.d.ts b/src/api/typedef/event.d.ts
index 52758cf..71da4dd 100644
--- a/src/api/typedef/event.d.ts
+++ b/src/api/typedef/event.d.ts
@@ -11,10 +11,10 @@ declare namespace mesg {
         interface IEvent {
 
             /** Event hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
 
             /** Event instanceHash */
-            instanceHash?: (string|null);
+            instanceHash?: (Uint8Array|null);
 
             /** Event key */
             key?: (string|null);
@@ -33,10 +33,10 @@ declare namespace mesg {
             constructor(properties?: types.IEvent);
 
             /** Event hash. */
-            public hash: string;
+            public hash: Uint8Array;
 
             /** Event instanceHash. */
-            public instanceHash: string;
+            public instanceHash: Uint8Array;
 
             /** Event key. */
             public key: string;
@@ -238,10 +238,10 @@ declare namespace mesg {
             interface IFilter {
 
                 /** Filter hash */
-                hash?: (string|null);
+                hash?: (Uint8Array|null);
 
                 /** Filter instanceHash */
-                instanceHash?: (string|null);
+                instanceHash?: (Uint8Array|null);
 
                 /** Filter key */
                 key?: (string|null);
@@ -257,10 +257,10 @@ declare namespace mesg {
                 constructor(properties?: api.StreamEventRequest.IFilter);
 
                 /** Filter hash. */
-                public hash: string;
+                public hash: Uint8Array;
 
                 /** Filter instanceHash. */
-                public instanceHash: string;
+                public instanceHash: Uint8Array;
 
                 /** Filter key. */
                 public key: string;
@@ -271,7 +271,7 @@ declare namespace mesg {
         interface ICreateEventRequest {
 
             /** CreateEventRequest instanceHash */
-            instanceHash?: (string|null);
+            instanceHash?: (Uint8Array|null);
 
             /** CreateEventRequest key */
             key?: (string|null);
@@ -290,7 +290,7 @@ declare namespace mesg {
             constructor(properties?: api.ICreateEventRequest);
 
             /** CreateEventRequest instanceHash. */
-            public instanceHash: string;
+            public instanceHash: Uint8Array;
 
             /** CreateEventRequest key. */
             public key: string;
@@ -303,7 +303,7 @@ declare namespace mesg {
         interface ICreateEventResponse {
 
             /** CreateEventResponse hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a CreateEventResponse. */
@@ -316,7 +316,7 @@ declare namespace mesg {
             constructor(properties?: api.ICreateEventResponse);
 
             /** CreateEventResponse hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
     }
 }
diff --git a/src/api/typedef/execution.d.ts b/src/api/typedef/execution.d.ts
index 40521fc..bb8a0a8 100644
--- a/src/api/typedef/execution.d.ts
+++ b/src/api/typedef/execution.d.ts
@@ -20,19 +20,19 @@ declare namespace mesg {
         interface IExecution {
 
             /** Execution hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
 
             /** Execution parentHash */
-            parentHash?: (string|null);
+            parentHash?: (Uint8Array|null);
 
             /** Execution eventHash */
-            eventHash?: (string|null);
+            eventHash?: (Uint8Array|null);
 
             /** Execution status */
             status?: (types.Status|null);
 
             /** Execution instanceHash */
-            instanceHash?: (string|null);
+            instanceHash?: (Uint8Array|null);
 
             /** Execution taskKey */
             taskKey?: (string|null);
@@ -50,7 +50,7 @@ declare namespace mesg {
             tags?: (string[]|null);
 
             /** Execution workflowHash */
-            workflowHash?: (string|null);
+            workflowHash?: (Uint8Array|null);
 
             /** Execution stepID */
             stepID?: (string|null);
@@ -66,19 +66,19 @@ declare namespace mesg {
             constructor(properties?: types.IExecution);
 
             /** Execution hash. */
-            public hash: string;
+            public hash: Uint8Array;
 
             /** Execution parentHash. */
-            public parentHash: string;
+            public parentHash: Uint8Array;
 
             /** Execution eventHash. */
-            public eventHash: string;
+            public eventHash: Uint8Array;
 
             /** Execution status. */
             public status: types.Status;
 
             /** Execution instanceHash. */
-            public instanceHash: string;
+            public instanceHash: Uint8Array;
 
             /** Execution taskKey. */
             public taskKey: string;
@@ -96,7 +96,7 @@ declare namespace mesg {
             public tags: string[];
 
             /** Execution workflowHash. */
-            public workflowHash: string;
+            public workflowHash: Uint8Array;
 
             /** Execution stepID. */
             public stepID: string;
@@ -315,7 +315,7 @@ declare namespace mesg {
         interface ICreateExecutionRequest {
 
             /** CreateExecutionRequest instanceHash */
-            instanceHash?: (string|null);
+            instanceHash?: (Uint8Array|null);
 
             /** CreateExecutionRequest taskKey */
             taskKey?: (string|null);
@@ -337,7 +337,7 @@ declare namespace mesg {
             constructor(properties?: api.ICreateExecutionRequest);
 
             /** CreateExecutionRequest instanceHash. */
-            public instanceHash: string;
+            public instanceHash: Uint8Array;
 
             /** CreateExecutionRequest taskKey. */
             public taskKey: string;
@@ -353,7 +353,7 @@ declare namespace mesg {
         interface ICreateExecutionResponse {
 
             /** CreateExecutionResponse hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a CreateExecutionResponse. */
@@ -366,14 +366,14 @@ declare namespace mesg {
             constructor(properties?: api.ICreateExecutionResponse);
 
             /** CreateExecutionResponse hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
 
         /** Properties of a GetExecutionRequest. */
         interface IGetExecutionRequest {
 
             /** GetExecutionRequest hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a GetExecutionRequest. */
@@ -386,7 +386,7 @@ declare namespace mesg {
             constructor(properties?: api.IGetExecutionRequest);
 
             /** GetExecutionRequest hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
 
         /** Properties of a StreamExecutionRequest. */
@@ -418,7 +418,7 @@ declare namespace mesg {
                 statuses?: (types.Status[]|null);
 
                 /** Filter instanceHash */
-                instanceHash?: (string|null);
+                instanceHash?: (Uint8Array|null);
 
                 /** Filter taskKey */
                 taskKey?: (string|null);
@@ -440,7 +440,7 @@ declare namespace mesg {
                 public statuses: types.Status[];
 
                 /** Filter instanceHash. */
-                public instanceHash: string;
+                public instanceHash: Uint8Array;
 
                 /** Filter taskKey. */
                 public taskKey: string;
@@ -454,7 +454,7 @@ declare namespace mesg {
         interface IUpdateExecutionRequest {
 
             /** UpdateExecutionRequest hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
 
             /** UpdateExecutionRequest outputs */
             outputs?: (google.protobuf.IStruct|null);
@@ -473,7 +473,7 @@ declare namespace mesg {
             constructor(properties?: api.IUpdateExecutionRequest);
 
             /** UpdateExecutionRequest hash. */
-            public hash: string;
+            public hash: Uint8Array;
 
             /** UpdateExecutionRequest outputs. */
             public outputs?: (google.protobuf.IStruct|null);
diff --git a/src/api/typedef/instance.d.ts b/src/api/typedef/instance.d.ts
index 24ba03e..8e8378d 100644
--- a/src/api/typedef/instance.d.ts
+++ b/src/api/typedef/instance.d.ts
@@ -11,10 +11,10 @@ declare namespace mesg {
         interface IInstance {
 
             /** Instance hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
 
             /** Instance serviceHash */
-            serviceHash?: (string|null);
+            serviceHash?: (Uint8Array|null);
         }
 
         /** Represents an Instance. */
@@ -27,10 +27,10 @@ declare namespace mesg {
             constructor(properties?: types.IInstance);
 
             /** Instance hash. */
-            public hash: string;
+            public hash: Uint8Array;
 
             /** Instance serviceHash. */
-            public serviceHash: string;
+            public serviceHash: Uint8Array;
         }
     }
 
@@ -140,7 +140,7 @@ declare namespace mesg {
         interface IGetInstanceRequest {
 
             /** GetInstanceRequest hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a GetInstanceRequest. */
@@ -153,14 +153,14 @@ declare namespace mesg {
             constructor(properties?: api.IGetInstanceRequest);
 
             /** GetInstanceRequest hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
 
         /** Properties of a ListInstancesRequest. */
         interface IListInstancesRequest {
 
             /** ListInstancesRequest serviceHash */
-            serviceHash?: (string|null);
+            serviceHash?: (Uint8Array|null);
         }
 
         /** Represents a ListInstancesRequest. */
@@ -173,7 +173,7 @@ declare namespace mesg {
             constructor(properties?: api.IListInstancesRequest);
 
             /** ListInstancesRequest serviceHash. */
-            public serviceHash: string;
+            public serviceHash: Uint8Array;
         }
 
         /** Properties of a ListInstancesResponse. */
@@ -200,7 +200,7 @@ declare namespace mesg {
         interface ICreateInstanceRequest {
 
             /** CreateInstanceRequest serviceHash */
-            serviceHash?: (string|null);
+            serviceHash?: (Uint8Array|null);
 
             /** CreateInstanceRequest env */
             env?: (string[]|null);
@@ -216,7 +216,7 @@ declare namespace mesg {
             constructor(properties?: api.ICreateInstanceRequest);
 
             /** CreateInstanceRequest serviceHash. */
-            public serviceHash: string;
+            public serviceHash: Uint8Array;
 
             /** CreateInstanceRequest env. */
             public env: string[];
@@ -226,7 +226,7 @@ declare namespace mesg {
         interface ICreateInstanceResponse {
 
             /** CreateInstanceResponse hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a CreateInstanceResponse. */
@@ -239,14 +239,14 @@ declare namespace mesg {
             constructor(properties?: api.ICreateInstanceResponse);
 
             /** CreateInstanceResponse hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
 
         /** Properties of a DeleteInstanceRequest. */
         interface IDeleteInstanceRequest {
 
             /** DeleteInstanceRequest hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
 
             /** DeleteInstanceRequest deleteData */
             deleteData?: (boolean|null);
@@ -262,7 +262,7 @@ declare namespace mesg {
             constructor(properties?: api.IDeleteInstanceRequest);
 
             /** DeleteInstanceRequest hash. */
-            public hash: string;
+            public hash: Uint8Array;
 
             /** DeleteInstanceRequest deleteData. */
             public deleteData: boolean;
diff --git a/src/api/typedef/service.d.ts b/src/api/typedef/service.d.ts
index aa361ca..25482cd 100644
--- a/src/api/typedef/service.d.ts
+++ b/src/api/typedef/service.d.ts
@@ -11,7 +11,7 @@ declare namespace mesg {
         interface IService {
 
             /** Service hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
 
             /** Service sid */
             sid?: (string|null);
@@ -51,7 +51,7 @@ declare namespace mesg {
             constructor(properties?: types.IService);
 
             /** Service hash. */
-            public hash: string;
+            public hash: Uint8Array;
 
             /** Service sid. */
             public sid: string;
@@ -509,7 +509,7 @@ declare namespace mesg {
         interface ICreateServiceResponse {
 
             /** CreateServiceResponse hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a CreateServiceResponse. */
@@ -522,14 +522,14 @@ declare namespace mesg {
             constructor(properties?: api.ICreateServiceResponse);
 
             /** CreateServiceResponse hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
 
         /** Properties of a DeleteServiceRequest. */
         interface IDeleteServiceRequest {
 
             /** DeleteServiceRequest hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a DeleteServiceRequest. */
@@ -542,7 +542,7 @@ declare namespace mesg {
             constructor(properties?: api.IDeleteServiceRequest);
 
             /** DeleteServiceRequest hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
 
         /** Properties of a DeleteServiceResponse. */
@@ -563,7 +563,7 @@ declare namespace mesg {
         interface IGetServiceRequest {
 
             /** GetServiceRequest hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a GetServiceRequest. */
@@ -576,7 +576,7 @@ declare namespace mesg {
             constructor(properties?: api.IGetServiceRequest);
 
             /** GetServiceRequest hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
 
         /** Properties of a ListServiceRequest. */
diff --git a/src/api/typedef/workflow.d.ts b/src/api/typedef/workflow.d.ts
index a312c22..451f5f6 100644
--- a/src/api/typedef/workflow.d.ts
+++ b/src/api/typedef/workflow.d.ts
@@ -11,7 +11,7 @@ declare namespace mesg {
         interface IWorkflow {
 
             /** Workflow hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
 
             /** Workflow key */
             key?: (string|null);
@@ -36,7 +36,7 @@ declare namespace mesg {
             constructor(properties?: types.IWorkflow);
 
             /** Workflow hash. */
-            public hash: string;
+            public hash: Uint8Array;
 
             /** Workflow key. */
             public key: string;
@@ -57,7 +57,7 @@ declare namespace mesg {
             interface ITrigger {
 
                 /** Trigger instanceHash */
-                instanceHash?: (string|null);
+                instanceHash?: (Uint8Array|null);
 
                 /** Trigger taskKey */
                 taskKey?: (string|null);
@@ -82,7 +82,7 @@ declare namespace mesg {
                 constructor(properties?: types.Workflow.ITrigger);
 
                 /** Trigger instanceHash. */
-                public instanceHash: string;
+                public instanceHash: Uint8Array;
 
                 /** Trigger taskKey. */
                 public taskKey: string;
@@ -151,7 +151,7 @@ declare namespace mesg {
                 key?: (string|null);
 
                 /** Node instanceHash */
-                instanceHash?: (string|null);
+                instanceHash?: (Uint8Array|null);
 
                 /** Node taskKey */
                 taskKey?: (string|null);
@@ -170,7 +170,7 @@ declare namespace mesg {
                 public key: string;
 
                 /** Node instanceHash. */
-                public instanceHash: string;
+                public instanceHash: Uint8Array;
 
                 /** Node taskKey. */
                 public taskKey: string;
@@ -184,6 +184,9 @@ declare namespace mesg {
 
                 /** Edge dst */
                 dst?: (string|null);
+
+                /** Edge inputs */
+                inputs?: (types.Workflow.Edge.IInput[]|null);
             }
 
             /** Represents an Edge. */
@@ -200,6 +203,70 @@ declare namespace mesg {
 
                 /** Edge dst. */
                 public dst: string;
+
+                /** Edge inputs. */
+                public inputs: types.Workflow.Edge.IInput[];
+            }
+
+            namespace Edge {
+
+                /** Properties of an Input. */
+                interface IInput {
+
+                    /** Input key */
+                    key?: (string|null);
+
+                    /** Input ref */
+                    ref?: (types.Workflow.Edge.Input.IReference|null);
+                }
+
+                /** Represents an Input. */
+                class Input implements IInput {
+
+                    /**
+                     * Constructs a new Input.
+                     * @param [properties] Properties to set
+                     */
+                    constructor(properties?: types.Workflow.Edge.IInput);
+
+                    /** Input key. */
+                    public key: string;
+
+                    /** Input ref. */
+                    public ref?: (types.Workflow.Edge.Input.IReference|null);
+
+                    /** Input value. */
+                    public value?: "ref";
+                }
+
+                namespace Input {
+
+                    /** Properties of a Reference. */
+                    interface IReference {
+
+                        /** Reference nodeKey */
+                        nodeKey?: (string|null);
+
+                        /** Reference key */
+                        key?: (string|null);
+                    }
+
+                    /** Represents a Reference. */
+                    class Reference implements IReference {
+
+                        /**
+                         * Constructs a new Reference.
+                         * @param [properties] Properties to set
+                         */
+                        constructor(properties?: types.Workflow.Edge.Input.IReference);
+
+                        /** Reference nodeKey. */
+                        public nodeKey: string;
+
+                        /** Reference key. */
+                        public key: string;
+                    }
+                }
             }
         }
     }
@@ -348,7 +415,7 @@ declare namespace mesg {
         interface ICreateWorkflowResponse {
 
             /** CreateWorkflowResponse hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a CreateWorkflowResponse. */
@@ -361,14 +428,14 @@ declare namespace mesg {
             constructor(properties?: api.ICreateWorkflowResponse);
 
             /** CreateWorkflowResponse hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
 
         /** Properties of a DeleteWorkflowRequest. */
         interface IDeleteWorkflowRequest {
 
             /** DeleteWorkflowRequest hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a DeleteWorkflowRequest. */
@@ -381,7 +448,7 @@ declare namespace mesg {
             constructor(properties?: api.IDeleteWorkflowRequest);
 
             /** DeleteWorkflowRequest hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
 
         /** Properties of a DeleteWorkflowResponse. */
@@ -402,7 +469,7 @@ declare namespace mesg {
         interface IGetWorkflowRequest {
 
             /** GetWorkflowRequest hash */
-            hash?: (string|null);
+            hash?: (Uint8Array|null);
         }
 
         /** Represents a GetWorkflowRequest. */
@@ -415,7 +482,7 @@ declare namespace mesg {
             constructor(properties?: api.IGetWorkflowRequest);
 
             /** GetWorkflowRequest hash. */
-            public hash: string;
+            public hash: Uint8Array;
         }
 
         /** Properties of a ListWorkflowRequest. */
diff --git a/src/api/types.ts b/src/api/types.ts
index e30d5f1..815f0af 100644
--- a/src/api/types.ts
+++ b/src/api/types.ts
@@ -5,7 +5,7 @@ import * as InstanceType from './typedef/instance'
 import * as ServiceType from './typedef/service'
 import * as WorkflowType from './typedef/workflow'
 
-export type hash = string
+export type hash = Uint8Array
 
 export const ExecutionStatus = {
   UNKNOWN: 0,
diff --git a/src/application/application.ts b/src/application/application.ts
index 0c25164..5b595ed 100644
--- a/src/application/application.ts
+++ b/src/application/application.ts
@@ -2,7 +2,7 @@ import * as uuidv4 from 'uuid/v4'
 import { google } from "../api/typedef/execution";
 import { decode, encode } from '../util/encoder'
 import { checkStreamReady, errNoStatus, Stream } from '../util/grpc';
-import { API, ExecutionCreateInputs, ExecutionCreateOutputs, EventStreamInputs, Event, ExecutionStreamInputs, Execution, ExecutionStatus } from '../api';
+import { API, ExecutionCreateInputs, ExecutionCreateOutputs, EventStreamInputs, Event, ExecutionStreamInputs, Execution, ExecutionStatus, hash } from '../api';
 import { resolveSID } from '../util/resolve';
 
 type Options = {
@@ -25,7 +25,7 @@ class Application {
     return encode(data)
   }
 
-  resolve(sid: string): Promise<string> {
+  resolve(sid: string): Promise<hash> {
     return resolveSID(this.api, sid)
   }
 
diff --git a/src/application/application_test.ts b/src/application/application_test.ts
index 63140f2..0488c7b 100644
--- a/src/application/application_test.ts
+++ b/src/application/application_test.ts
@@ -9,9 +9,9 @@ test('listenEvent() should listen for events and return a stream', (t) => {
   const api = Api('')
   const application = new Application(api);
   const spy = sinon.spy(api.event, 'stream')
-  application.listenEvent({ filter: { instanceHash: '1', key: '2' } })
+  application.listenEvent({ filter: { instanceHash: Buffer.from('1'), key: '2' } })
   const req = spy.getCall(0).args[0]
-  t.equal(req.filter.instanceHash, '1')
+  t.ok(req.filter.instanceHash.equals(Buffer.from('1')))
   t.equal(req.filter.key, '2')
   spy.restore()
 });
@@ -23,12 +23,12 @@ test('listenResult() should listen for results and return a stream', (t) => {
   const spy = sinon.spy(api.execution, 'stream')
   application.listenResult({
     filter: {
-      instanceHash: '1',
+      instanceHash: Buffer.from('1'),
       statuses: [ExecutionStatus.COMPLETED]
     }
   })
   const req = spy.getCall(0).args[0]
-  t.equal(req.filter.instanceHash, '1')
+  t.ok(req.filter.instanceHash.equals(Buffer.from('1')))
   t.equal(req.filter.statuses[0], ExecutionStatus.COMPLETED)
   spy.restore()
 });
@@ -39,13 +39,13 @@ test('executeTask() should execute a task', (t) => {
   const application = new Application(api);
   const spy = sinon.spy(api.execution, 'create')
   application.executeTask({
-    instanceHash: '1',
+    instanceHash: Buffer.from('1'),
     taskKey: '2',
     inputs: application.encodeData({ foo: 'bar' }),
     tags: ['4', '5']
   })
   const req = spy.getCall(0).args[0]
-  t.equal(req.instanceHash, '1')
+  t.ok(req.instanceHash.equals(Buffer.from('1')))
   t.equal(req.taskKey, '2')
   t.equal(application.decodeData(req.inputs).foo, 'bar')
   t.same(req.tags, ['4', '5'])
@@ -56,13 +56,13 @@ test('executeTask() should resolve promise with reply', (t) => {
   t.plan(1);
   const api = Api('');
   const application = new Application(api);
-  const reply = { hash: '1' }
+  const reply = { hash: Buffer.from('1') }
   const stub = sinon.stub(api.execution, 'create').callsFake(res => Promise.resolve(reply))
   application.executeTask({
-    instanceHash: '2',
+    instanceHash: Buffer.from('2'),
     taskKey: '3',
     inputs: {}
-  }).then(reply => t.equal(reply.hash, '1'))
+  }).then(reply => t.ok(Buffer.from('1').equals(reply.hash)))
   stub.restore()
 });
 
@@ -72,7 +72,7 @@ test('executeTask() should reject promise with err', (t) => {
   const application = new Application(api);
   const stub = sinon.stub(api.execution, 'create').callsFake(() => Promise.reject(new Error('1')))
   application.executeTask({
-    instanceHash: '2',
+    instanceHash: Buffer.from('2'),
     taskKey: '3',
     inputs: {}
   }).catch((err) => t.equal(err.message, '1'))
@@ -84,9 +84,9 @@ test('executeTaskAndWaitResult() should listen for results', (t) => {
   const api = Api('');
   const application = new Application(api);
   const spy = sinon.spy(api.execution, 'stream')
-  application.executeTaskAndWaitResult({ instanceHash: '1', taskKey: '2', inputs: {} })
+  application.executeTaskAndWaitResult({ instanceHash: Buffer.from('1'), taskKey: '2', inputs: {} })
   const req = spy.getCall(0).args[0]
-  t.equal(req.filter.instanceHash, '1')
+  t.ok(req.filter.instanceHash.equals(Buffer.from('1')))
   spy.restore()
 });
 
@@ -95,7 +95,7 @@ test('executeTaskAndWaitResult() should reject and cancel result stream on `erro
   const api = Api('');
   const application = new Application(api);
   const spy = sinon.spy(streams.execution, 'cancel')
-  application.executeTaskAndWaitResult({ instanceHash: '2', taskKey: '3', inputs: {} })
+  application.executeTaskAndWaitResult({ instanceHash: Buffer.from('2'), taskKey: '3', inputs: {} })
     .catch((err) => t.equal(err, '1'))
   streams.execution.emit('error', '1')
   t.ok(spy.called)
@@ -107,7 +107,7 @@ test('executeTaskAndWaitResult() should resolve and cancel result stream on firs
   const api = Api('');
   const application = new Application(api);
   const spy = sinon.spy(streams.execution, 'cancel')
-  application.executeTaskAndWaitResult({ instanceHash: '2', taskKey: '3', inputs: {} })
+  application.executeTaskAndWaitResult({ instanceHash: Buffer.from('2'), taskKey: '3', inputs: {} })
     .then((result) => t.equal(result.hash, '2'))
   streams.execution.emit('data', { hash: '2' })
   t.ok(spy.called)
@@ -119,10 +119,10 @@ test('executeTaskAndWaitResult() should execute task', (t) => {
   const api = Api('');
   const application = new Application(api);
   const spy = sinon.spy(api.execution, 'create')
-  application.executeTaskAndWaitResult({ instanceHash: '2', taskKey: '3', inputs: application.encodeData({ foo: 'bar' }) })
+  application.executeTaskAndWaitResult({ instanceHash: Buffer.from('2'), taskKey: '3', inputs: application.encodeData({ foo: 'bar' }) })
   streams.execution.emit('metadata', { get() { return ['ready'] } })
   const req = spy.getCall(0).args[0]
-  t.equal(req.instanceHash, '2')
+  t.ok(req.instanceHash.equals(Buffer.from('2')))
   t.equal(req.taskKey, '3')
   t.equal(application.decodeData(req.inputs).foo, 'bar')
   t.ok(isUUID.v4(req.tags[0]))
diff --git a/src/protobuf/api/event.proto b/src/protobuf/api/event.proto
index e8920bf..0b76519 100644
--- a/src/protobuf/api/event.proto
+++ b/src/protobuf/api/event.proto
@@ -24,10 +24,10 @@ message StreamEventRequest {
   // Filter contains filtering criteria.
   message Filter {
     // hash to filter events.
-    string hash = 1;
+    bytes hash = 1;
 
     // instance's hash to filter events.
-    string instanceHash = 2;
+    bytes instanceHash = 2;
 
     // key is the key of the event.
     string key = 3;
@@ -40,7 +40,7 @@ message StreamEventRequest {
 // CreateEventRequest defines request for execution update.
 message CreateEventRequest {
   // instanceHash is hash of instance that can proceed an execution.
-  string instanceHash = 1;
+  bytes instanceHash = 1;
 
   // key is the key of the event.
   string key = 2;
@@ -52,5 +52,5 @@ message CreateEventRequest {
 // CreateEventResponse defines response for execution update.
 message CreateEventResponse {
   // Hash represents event.
-  string hash = 1;
+  bytes hash = 1;
 }
diff --git a/src/protobuf/api/execution.proto b/src/protobuf/api/execution.proto
index b9e1e6e..fc1ca26 100644
--- a/src/protobuf/api/execution.proto
+++ b/src/protobuf/api/execution.proto
@@ -28,7 +28,7 @@ service Execution {
 
 // CreateExecutionRequest defines request to create a single execution.
 message CreateExecutionRequest {
-  string instanceHash = 1;
+  bytes instanceHash = 1;
   string taskKey = 2;
   google.protobuf.Struct inputs = 3;
   repeated string tags = 4;
@@ -37,13 +37,13 @@ message CreateExecutionRequest {
 // CreateExecutionResponse defines response for execution creation.
 message CreateExecutionResponse {
   // Execution's hash.
-  string hash = 1;
+  bytes hash = 1;
 }
 
 // GetExecutionRequest defines request to retrieve a single execution.
 message GetExecutionRequest {
   // Execution's hash to fetch.
-  string hash = 1;
+  bytes hash = 1;
 }
 
 // StreamExecutionRequest defines request to retrieve a stream of executions.
@@ -54,7 +54,7 @@ message StreamExecutionRequest{
     repeated types.Status statuses = 1;
 
     // Instance's hash to filter executions.
-    string instanceHash = 2;
+    bytes instanceHash = 2;
 
     // taskKey to filter executions.
     string taskKey = 3;
@@ -70,7 +70,7 @@ message StreamExecutionRequest{
 // UpdateExecutionRequest defines request for execution update.
 message UpdateExecutionRequest {
   // Hash represents execution.
-  string hash = 1;
+  bytes hash = 1;
 
   // result pass to execution
   oneof result {
diff --git a/src/protobuf/api/instance.proto b/src/protobuf/api/instance.proto
index 29e7761..12c7691 100644
--- a/src/protobuf/api/instance.proto
+++ b/src/protobuf/api/instance.proto
@@ -27,13 +27,13 @@ service Instance {
 
 // The request's data for the `Get` API.
 message GetInstanceRequest {
-  string hash = 1;
+  bytes hash = 1;
 }
 
 // The request's data for the `List` API.
 message ListInstancesRequest {
   // Filter by Services' hash.
-  string serviceHash = 1;
+  bytes serviceHash = 1;
 }
 
 // The response's data for the `List` API.
@@ -45,7 +45,7 @@ message ListInstancesResponse {
 // The request's data for the `Create` API.
 message CreateInstanceRequest {
   // Service's hash.
-  string serviceHash = 1;
+  bytes serviceHash = 1;
 
   // Environmental variables to apply to the Instance.
   repeated string env = 2;
@@ -54,13 +54,13 @@ message CreateInstanceRequest {
 // The response's data for the `Create` API.
 message CreateInstanceResponse {
   // The instance's hash created.
-  string hash = 1;
+  bytes hash = 1;
 }
 
 // The request's data for the `Delete` API.
 message DeleteInstanceRequest {
   // Instance's hash
-  string hash = 1;
+  bytes hash = 1;
 
   // If true, any persistent data (volumes) that belongs to the instance and its dependencies will also be deleted.
   bool deleteData = 2;
diff --git a/src/protobuf/api/service.proto b/src/protobuf/api/service.proto
index c63909c..9dbaa2c 100644
--- a/src/protobuf/api/service.proto
+++ b/src/protobuf/api/service.proto
@@ -59,13 +59,13 @@ message CreateServiceRequest {
 // The response's data for the `Create` API.
 message CreateServiceResponse {
   // The service's hash created.
-  string hash = 1;
+  bytes hash = 1;
 }
 
 // The request's data for the `Delete` API.
 message DeleteServiceRequest {
   // The service's hash to delete.
-  string hash = 1;
+  bytes hash = 1;
 }
 
 // The response's data for the `Delete` API, doesn't contain anything.
@@ -75,7 +75,7 @@ message DeleteServiceResponse {
 // The request's data for the `Get` API.
 message GetServiceRequest {
   // The service's hash to fetch.
-  string hash = 1;
+  bytes hash = 1;
 }
 
 // The request's data for the `List` API.
diff --git a/src/protobuf/api/workflow.proto b/src/protobuf/api/workflow.proto
index adffb72..8e690c8 100644
--- a/src/protobuf/api/workflow.proto
+++ b/src/protobuf/api/workflow.proto
@@ -37,13 +37,13 @@ message CreateWorkflowRequest {
 // The response's data for the `Create` API.
 message CreateWorkflowResponse {
   // The workflow's hash created.
-  string hash = 1;
+  bytes hash = 1;
 }
 
 // The request's data for the `Delete` API.
 message DeleteWorkflowRequest {
   // The workflow's hash to delete.
-  string hash = 1;
+  bytes hash = 1;
 }
 
 // The response's data for the `Delete` API, doesn't contain anything.
@@ -53,7 +53,7 @@ message DeleteWorkflowResponse {
 // The request's data for the `Get` API.
 message GetWorkflowRequest {
   // The workflow's hash to fetch.
-  string hash = 1;
+  bytes hash = 1;
 }
 
 // The request's data for the `List` API.
diff --git a/src/protobuf/types/event.proto b/src/protobuf/types/event.proto
index d93ef0a..81fc5c2 100644
--- a/src/protobuf/types/event.proto
+++ b/src/protobuf/types/event.proto
@@ -8,10 +8,10 @@ option go_package = "github.com/mesg-foundation/engine/protobuf/types";
 // Event represents a single event run in engine.
 message Event {
   // Hash is a unique hash to identify event.
-  string hash = 1;
+  bytes hash = 1;
 
   // instanceHash is hash of instance that can proceed an execution.
-  string instanceHash = 2;
+  bytes instanceHash = 2;
 
   // key is the key of the event.
   string key = 3;
diff --git a/src/protobuf/types/execution.proto b/src/protobuf/types/execution.proto
index b3279e8..6da4f24 100644
--- a/src/protobuf/types/execution.proto
+++ b/src/protobuf/types/execution.proto
@@ -28,19 +28,19 @@ enum Status {
 // Execution represents a single execution run in engine.
 message Execution {
   // Hash is a unique hash to identify execution.
-  string hash = 1;
+  bytes hash = 1;
 
   // parentHash is the unique hash of parent execution. if execution is triggered by another one, dependency execution considered as the parent.
-  string parentHash = 2;
+  bytes parentHash = 2;
 
   // eventHash is unique event hash.
-  string eventHash = 3;
+  bytes eventHash = 3;
 
   // Status is the current status of execution.
   Status status = 4;
 
   // instanceHash is hash of the instance that can proceed an execution
-  string instanceHash = 5;
+  bytes instanceHash = 5;
 
   // taskKey is the key of the task of this execution.
   string taskKey = 6;
@@ -58,7 +58,7 @@ message Execution {
   repeated string tags = 10;
 
   // workflowHash is the unique hash of the workflow associated to this execution.
-  string workflowHash = 11;
+  bytes workflowHash = 11;
 
   // step of the workflow.
   string stepID = 12;
diff --git a/src/protobuf/types/instance.proto b/src/protobuf/types/instance.proto
index f0c53d1..5731fbb 100644
--- a/src/protobuf/types/instance.proto
+++ b/src/protobuf/types/instance.proto
@@ -5,6 +5,6 @@ option go_package = "github.com/mesg-foundation/engine/protobuf/types";
 
 // Instance represents service's instance.
 message Instance {
-  string hash = 1;
-  string serviceHash = 2;
+  bytes hash = 1;
+  bytes serviceHash = 2;
 }
diff --git a/src/protobuf/types/service.proto b/src/protobuf/types/service.proto
index e57ee7d..8677058 100644
--- a/src/protobuf/types/service.proto
+++ b/src/protobuf/types/service.proto
@@ -1,68 +1,229 @@
 syntax = "proto3";
 
+import "gogo/protobuf/gogoproto/gogo.proto";
+
 package types;
-option go_package = "github.com/mesg-foundation/engine/protobuf/types";
+option go_package = "github.com/mesg-foundation/engine/service";
+
+option (gogoproto.goproto_getters_all) = false;
 
 // Service represents the service's type.
 message Service {
+
   // Events are emitted by the service whenever the service wants.
   message Event {
-    string key = 4;                   // Event's key.
-    string name = 1;                  // Event's name.
-    string description = 2;           // Event's description.
-    repeated Parameter data = 3;      // List of data of this event.
+    // Event's key.
+    string key = 4 [
+      (gogoproto.moretags) = 'hash:"name:1" validate:"printascii"'
+    ];
+
+    // Event's name.
+    string name = 1 [
+      (gogoproto.moretags) = 'hash:"name:2" validate:"printascii"'
+    ];
+
+    // Event's description.
+    string description = 2 [
+      (gogoproto.moretags) = 'hash:"name:3" validate:"printascii"'
+    ];
+
+    // List of data of this event.
+    repeated Parameter data = 3 [
+      (gogoproto.moretags) = 'hash:"name:4" validate:"dive,required"'
+    ];
   }
 
   // Task is a function that requires inputs and returns output.
   message Task {
-    string key = 8;                     // Task's key.
-    string name = 1;                    // Task's name.
-    string description = 2;             // Task's description.
-    repeated Parameter inputs = 6;      // List inputs of this task.
-    repeated Parameter outputs = 7;     // List of tasks outputs.
+    // Task's key.
+    string key = 8 [
+      (gogoproto.moretags) = 'hash:"name:1" validate:"printascii"'
+    ];
+
+    // Task's name.
+    string name = 1 [
+      (gogoproto.moretags) = 'hash:"name:2" validate:"printascii"'
+    ];
+
+    // Task's description.
+    string description = 2 [
+      (gogoproto.moretags) = 'hash:"name:3" validate:"printascii"'
+    ];
+
+    // List inputs of this task.
+    repeated Parameter inputs = 6 [
+      (gogoproto.moretags) = 'hash:"name:4" validate:"dive,required"'
+    ];
+
+    // List of tasks outputs.
+    repeated Parameter outputs = 7 [
+      (gogoproto.moretags) = 'hash:"name:5" validate:"dive,required"'
+    ];
   }
 
   // Parameter describes the task's inputs, the task's outputs, and the event's data.
   message Parameter {
-    string key = 8;         // Parameter's key.
-    string name = 1;        // Parameter's name.
-    string description = 2; // Parameter's description.
-    string type = 3;        // Parameter's type: `String`, `Number`, `Boolean`, `Object` or `Any`.
-    bool optional = 4;      // Set the parameter as optional.
-    bool repeated = 9;      // Mark a parameter as an array of the defined type
-    repeated Parameter object = 10; // Optional object structure type when type is set to `Object`
+
+    // Parameter's key.
+    string key = 8 [
+      (gogoproto.moretags) = 'hash:"name:1" validate:"printascii"'
+    ];
+
+    // Parameter's name.
+    string name = 1 [
+      (gogoproto.moretags) = 'hash:"name:2" validate:"printascii"'
+    ];
+
+    // Parameter's description.
+    string description = 2 [
+      (gogoproto.moretags) = 'hash:"name:3" validate:"printascii"'
+    ];
+
+    // Parameter's type: `String`, `Number`, `Boolean`, `Object` or `Any`.
+    string type = 3 [
+      (gogoproto.moretags) = 'hash:"name:4" validate:"required,printascii,oneof=String Number Boolean Object Any"'
+    ];
+
+    // Set the parameter as optional.
+    bool optional = 4 [
+      (gogoproto.moretags) = 'hash:"name:5"'
+    ];
+
+    // Mark a parameter as an array of the defined type.
+    bool repeated = 9 [
+      (gogoproto.moretags) = 'hash:"name:7"'
+    ];
+
+    // Optional object structure type when type is set to `Object`.
+    repeated Parameter object = 10 [
+      (gogoproto.moretags) = 'hash:"name:7" validate:"unique,dive,required"'
+    ];
   }
 
   // A configuration is the configuration of the main container of the service's instance.
   message Configuration {
-    repeated string volumes = 1;      // List of volumes.
-    repeated string volumesFrom = 2;  // List of volumes mounted from other dependencies.
-    repeated string ports = 3;        // List of ports the container exposes.
-    repeated string args = 4;         // Args to pass to the container.
-    string command = 5;               // Command to run the container.
-    repeated string env = 6;          // Default env vars to apply to service's instance on runtime.
+    // List of volumes.
+    repeated string volumes = 1 [
+      (gogoproto.moretags) = 'hash:"name:1" validate:"unique,dive,printascii"'
+    ];
+
+    // List of volumes mounted from other dependencies.
+    repeated string volumesFrom = 2 [
+      (gogoproto.moretags) = 'hash:"name:2" validate:"unique,dive,printascii"'
+    ];
+
+    // List of ports the container exposes.
+    repeated string ports = 3 [
+      (gogoproto.moretags) = 'hash:"name:3" validate:"unique,dive,portmap"'
+    ];
+
+    // Args to pass to the container.
+    repeated string args = 4 [
+      (gogoproto.moretags) = 'hash:"name:5" validate:"dive,printascii"'
+    ];
+
+    // Command to run the container.
+    string command = 5 [
+      (gogoproto.moretags) = 'hash:"name:4" validate:"printascii"'
+    ];
+
+    // Default env vars to apply to service's instance on runtime.
+    repeated string env = 6 [
+      (gogoproto.moretags) = 'hash:"name:6" validate:"unique,dive,env"'
+    ];
   }
 
   // A dependency is a configuration of an other container that runs separately from the service.
   message Dependency {
-    string key = 8;                   // Dependency's key.
-    string image = 1;                 // Image's name of the container.
-    repeated string volumes = 2;      // List of volumes.
-    repeated string volumesFrom = 3;  // List of volumes mounted from other dependencies.
-    repeated string ports = 4;        // List of ports the container exposes.
-    repeated string args = 6;         // Args to pass to the container.
-    string command = 5;               // Command to run the container.
-    repeated string env = 9;          // Default env vars to apply to dependency on runtime.
+    // Dependency's key.
+    string key = 8 [
+      (gogoproto.moretags) = 'hash:"name:1" validate:"printascii"'
+    ];
+
+    // Image's name of the container.
+    string image = 1 [
+      (gogoproto.moretags) = 'hash:"name:2" validate:"printascii"'
+    ];
+
+    // List of volumes.
+    repeated string volumes = 2 [
+      (gogoproto.moretags) = 'hash:"name:3" validate:"unique,dive,printascii"'
+    ];
+
+    // List of volumes mounted from other dependencies.
+    repeated string volumesFrom = 3 [
+      (gogoproto.moretags) = 'hash:"name:4" validate:"unique,dive,printascii"'
+    ];
+
+    // List of ports the container exposes.
+    repeated string ports = 4 [
+      (gogoproto.moretags) = 'hash:"name:5" validate:"unique,dive,portmap"'
+    ];
+
+    // Args to pass to the container.
+    repeated string args = 6 [
+      (gogoproto.moretags) = 'hash:"name:6" validate:"dive,printascii"'
+    ];
+
+    // Command to run the container.
+    string command = 5 [
+      (gogoproto.moretags) = 'hash:"name:7" validate:"printascii"'
+    ];
+
+    // Default env vars to apply to service's instance on runtime.
+    repeated string env = 9 [
+      (gogoproto.moretags) = 'hash:"name:8" validate:"unique,dive,env"'
+    ];
   }
 
-  string hash = 10;                         // Service's hash.
-  string sid = 12;                          // Service's sid.
-  string name = 1;                          // Service's name.
-  string description = 2;                   // Service's description.
-  Configuration configuration = 8;          // Configurations related to the service
-  repeated Task tasks = 5;                  // The list of tasks this service can execute.
-  repeated Event events = 6;                // The list of events this service can emit.
-  repeated Dependency dependencies = 7;     // The container dependencies this service requires.
-  string repository = 9;                    // Service's repository url.
-  string source = 13;                       // The hash id of service's source code on IPFS.
+  // Service's hash.
+  bytes hash = 10 [
+    (gogoproto.moretags) = 'validate:"required"'
+  ];
+
+  // Service's sid.
+  string sid = 12  [
+    (gogoproto.moretags) = 'validate:"required,printascii,max=63,domain"'
+  ];
+
+  // Service's name.
+  string name = 1 [
+    (gogoproto.moretags) = 'hash:"name:2" validate:"required,printascii"'
+  ];
+
+  // Service's description.
+  string description = 2 [
+    (gogoproto.moretags) = 'hash:"name:3" validate:"printascii"'
+  ];
+
+  // Configurations related to the service
+  Configuration configuration = 8 [
+    (gogoproto.moretags) = 'hash:"name:8" validate:"required"',
+    (gogoproto.nullable) = false
+  ];
+
+  // The list of tasks this service can execute.
+  repeated Task tasks = 5 [
+    (gogoproto.moretags) = 'hash:"name:4" validate:"dive,required"'
+  ];
+
+  // The list of events this service can emit.
+  repeated Event events = 6 [
+    (gogoproto.moretags) = 'hash:"name:5" validate:"dive,required"'
+  ];
+
+  // The container dependencies this service requires.
+  repeated Dependency dependencies = 7 [
+    (gogoproto.moretags) = 'hash:"name:6" validate:"dive,required"'
+  ];
+
+  // Service's repository url.
+  string repository = 9 [
+    (gogoproto.moretags) = 'hash:"name:7" validate:"omitempty,uri"'
+  ];
+
+  // The hash id of service's source code on IPFS.
+  string source = 13 [
+    (gogoproto.moretags) = 'hash:"name:9" validate:"required,printascii"'
+  ];
 }
diff --git a/src/protobuf/types/workflow.proto b/src/protobuf/types/workflow.proto
index 25d4a05..440903c 100644
--- a/src/protobuf/types/workflow.proto
+++ b/src/protobuf/types/workflow.proto
@@ -22,7 +22,7 @@ message Workflow {
       string value = 3;         // Value of the filter
     }
 
-    string instanceHash = 1;      // Hash of the instance that triggers the workflow.
+    bytes instanceHash = 1;      // Hash of the instance that triggers the workflow.
     // Workflow can be trigger by either an Event or a Task (not both).
     oneof key {
       string taskKey = 2;         // Key of the task that triggers the workflow.
@@ -35,16 +35,28 @@ message Workflow {
   // Definition of the node to execute when the workflow is triggered.
   message Node {
     string key = 1;           // Key that identifies the node.
-    string instanceHash = 2;  // Hash of the instance to execute.
+    bytes instanceHash = 2;  // Hash of the instance to execute.
     string taskKey = 3;       // Task of the instance to execute.
   }
 
   message Edge {
-    string src = 1; // Source of the edge.
-    string dst = 2; // Destination of the edge.
+    message Input {
+      message Reference {
+        string nodeKey = 1; // Key of the node in the graph. If empty, will be using the src of the edge.
+        string key = 2;     // Key of a specific parameter of the referenced node's output data.
+      }
+
+      string key = 1;       // Key of the input (as defined in the the service's task definition).
+      oneof value {
+        Reference ref = 2;  // Input defined as reference.
+      }
+    }
+    string src = 1;             // Source of the edge.
+    string dst = 2;             // Destination of the edge.
+    repeated Input inputs = 3;  // Inputs for the destination task.
   }
 
-  string hash = 1;          // Workflow's hash    
+  bytes hash = 1;          // Workflow's hash    
   string key = 2;           // Workflow's key
   Trigger trigger = 3;      // Trigger for the workflow.
   repeated Node nodes = 4;  // Nodes with information related to the execution to trigger.
diff --git a/src/service/index.ts b/src/service/index.ts
index cc9f9d5..379416b 100644
--- a/src/service/index.ts
+++ b/src/service/index.ts
@@ -2,17 +2,16 @@ import * as YAML from 'js-yaml'
 import * as fs from 'fs'
 import Service from './service'
 import API from '../api'
+import * as bs58 from '../util/base58';
 
-const token = process.env.MESG_TOKEN
-const endpoint = process.env.MESG_ENDPOINT
 const ymlPath = './mesg.yml'
 
 const serviceBuilder = (): Service => {
   const definition = YAML.safeLoad(fs.readFileSync(ymlPath));
   return new Service({
-    token: token,
+    token: bs58.decode(process.env.MESG_TOKEN),
     definition: definition,
-    API: API(endpoint)
+    API: API(process.env.MESG_ENDPOINT)
   });
 }
 
diff --git a/src/service/service.ts b/src/service/service.ts
index 30ee409..74a58fb 100644
--- a/src/service/service.ts
+++ b/src/service/service.ts
@@ -1,8 +1,8 @@
-import { API, ExecutionStatus, ExecutionStreamOutputs, EventCreateOutputs, Execution } from '../api';
+import { API, ExecutionStatus, ExecutionStreamOutputs, EventCreateOutputs, Execution, hash } from '../api';
 import { decode, encode } from '../util/encoder'
 
 type Options = {
-  token: string
+  token: hash
   definition: any
   API: API
 }
@@ -11,7 +11,7 @@ class Service {
   // api gives access to low level gRPC calls.
   private API: API
 
-  private token: string
+  private token: hash
   private definition: any
   private tasks: Tasks
 
diff --git a/src/service/service_test.ts b/src/service/service_test.ts
index 47acd48..08d65d6 100644
--- a/src/service/service_test.ts
+++ b/src/service/service_test.ts
@@ -4,7 +4,7 @@ import Service from './service'
 import Api, { API } from '../api/mock'
 import { encode } from '../util/encoder';
 
-const token = "token"
+const token = Buffer.from("token")
 
 function newService({
   definition = {},
diff --git a/src/util/base58.ts b/src/util/base58.ts
new file mode 100644
index 0000000..a8ebff8
--- /dev/null
+++ b/src/util/base58.ts
@@ -0,0 +1,5 @@
+const base = require('base-x')
+const bs58 = base('123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz')
+
+export const decode: (value: string) => Buffer = bs58.decode
+export const encode = (value: Uint8Array): string => bs58.encode(Buffer.from(value))