fix(core): update

ts/smartcrypto.classes.privatekey.ts

@@ -0,0 +1,20 @@
+import * as plugins from './smartcrypto.plugins';
+
+export class PrivateKey {
+  // STATIC
+  public static createFromPrivateKey(pemString: string) {
+    const privateKey = plugins.nodeForge.pki.privateKeyFromPem(pemString);
+    return new PrivateKey(privateKey);
+  }
+
+  // INSTANCE
+  public forgePrivateKey: plugins.nodeForge.pki.PrivateKey;
+
+  constructor(privateKeyArg: plugins.nodeForge.pki.PrivateKey) {
+    this.forgePrivateKey = privateKeyArg;
+  }
+
+  public toPemString(): string {
+    return plugins.nodeForge.pki.privateKeyToPem(this.forgePrivateKey);
+  }
+}