Add signedCall api method

package.json

@@ -33,6 +33,7 @@
   },
   "homepage": "https://github.com/steemit/steem-js#readme",
   "dependencies": {
+    "@steemit/rpc-auth": "^1.1.0",
     "bigi": "^1.4.2",
     "bluebird": "^3.4.6",
     "browserify-aes": "^1.0.6",

src/api/index.js

@@ -15,6 +15,9 @@ import {
 import {
     jsonRpc
 } from './transports/http';
+import {
+    sign as signRequest
+} from '@steemit/rpc-auth';
 
 class Steem extends EventEmitter {
     constructor(options = {}) {
@@ -154,6 +157,23 @@ class Steem extends EventEmitter {
             .then(res => { callback(null, res) }, err => { callback(err) });
     }
 
+    signedCall(method, params, account, key, callback) {
+        if (this._transportType !== 'http') {
+            callback(new Error('RPC methods can only be called when using http transport'));
+            return;
+        }
+        const id = ++this.seqNo;
+        let request;
+        try {
+            request = signRequest({method, params, id}, account, [key]);
+        } catch (error) {
+            callback(error);
+            return;
+        }
+        jsonRpc(this.options.uri, request)
+            .then(res => { callback(null, res) }, err => { callback(err) });
+    }
+
     setOptions(options) {
         Object.assign(this.options, options);
         this._setLogger(options);

yarn.lock

@@ -2,6 +2,16 @@
 # yarn lockfile v1
 
 
+"@steemit/libcrypto@^1.0.1":
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/@steemit/libcrypto/-/libcrypto-1.0.1.tgz#c31ab3e5deb667628169b3d54d746b015de31a79"
+
+"@steemit/rpc-auth@^1.1.0":
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/@steemit/rpc-auth/-/rpc-auth-1.1.0.tgz#4170c04d928ef37af5bdbde3f517ef74909480bd"
+  dependencies:
+    "@steemit/libcrypto" "^1.0.1"
+
 abbrev@1:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/abbrev/-/abbrev-1.1.0.tgz#d0554c2256636e2f56e7c2e5ad183f859428d81f"