diff --git a/bun.lockb b/bun.lockb
index 6aa5b9e..1cca6fa 100755
Binary files a/bun.lockb and b/bun.lockb differ
diff --git a/src/github/handlers/index.ts b/src/github/handlers/index.ts
index d476b46..0c7344e 100644
--- a/src/github/handlers/index.ts
+++ b/src/github/handlers/index.ts
@@ -106,7 +106,7 @@ async function handleEvent(event: EmitterWebhookEvent, eventHandler: InstanceTyp
         repository: plugin.repo,
         workflowId: plugin.workflowId,
         ref: plugin.ref,
-        inputs: inputs.getWorkflowInputs(),
+        inputs: await inputs.getWorkflowInputs(),
       });
     }
   }
diff --git a/src/github/handlers/repository-dispatch.ts b/src/github/handlers/repository-dispatch.ts
index 7795b51..510a8c1 100644
--- a/src/github/handlers/repository-dispatch.ts
+++ b/src/github/handlers/repository-dispatch.ts
@@ -73,7 +73,7 @@ export async function repositoryDispatch(context: GitHubContext<"repository_disp
       repository: nextPlugin.plugin.repo,
       ref: nextPlugin.plugin.ref,
       workflowId: nextPlugin.plugin.workflowId,
-      inputs: inputs.getWorkflowInputs(),
+      inputs: await inputs.getWorkflowInputs(),
     });
   } else {
     await dispatchWorker(nextPlugin.plugin, await inputs.getWorkerInputs());
diff --git a/src/github/types/plugin.ts b/src/github/types/plugin.ts
index 79b4cec..cac7f2a 100644
--- a/src/github/types/plugin.ts
+++ b/src/github/types/plugin.ts
@@ -45,8 +45,8 @@ export class PluginInput<T extends EmitterWebhookEventName = EmitterWebhookEvent
     this.ref = ref;
   }
 
-  public getWorkflowInputs() {
-    return {
+  public async getWorkflowInputs() {
+    const inputs = {
       stateId: this.stateId,
       eventName: this.eventName,
       eventPayload: JSON.stringify(this.eventPayload),
@@ -54,6 +54,11 @@ export class PluginInput<T extends EmitterWebhookEventName = EmitterWebhookEvent
       authToken: this.authToken,
       ref: this.ref,
     };
+    const signature = await this.eventHandler.signPayload(JSON.stringify(inputs));
+    return {
+      ...inputs,
+      signature,
+    };
   }
 
   public async getWorkerInputs() {
diff --git a/src/sdk/actions.ts b/src/sdk/actions.ts
index 90b93d8..577d71d 100644
--- a/src/sdk/actions.ts
+++ b/src/sdk/actions.ts
@@ -8,6 +8,8 @@ import { config } from "dotenv";
 import { Context } from "./context";
 import { customOctokit } from "./octokit";
 import { sanitizeMetadata } from "./util";
+import { verifySignature } from "./signature";
+import { KERNEL_PUBLIC_KEY } from "./constants";
 
 config();
 
@@ -16,6 +18,7 @@ interface Options {
   postCommentOnError?: boolean;
   settingsSchema?: TAnySchema;
   envSchema?: TAnySchema;
+  kernelPublicKey?: string;
 }
 
 const inputSchema = T.Object({
@@ -25,6 +28,7 @@ const inputSchema = T.Object({
   authToken: T.String(),
   settings: T.String(),
   ref: T.String(),
+  signature: T.String(),
 });
 
 export async function createActionsPlugin<TConfig = unknown, TEnv = unknown, TSupportedEvents extends WebhookEventName = WebhookEventName>(
@@ -36,20 +40,29 @@ export async function createActionsPlugin<TConfig = unknown, TEnv = unknown, TSu
     postCommentOnError: options?.postCommentOnError || true,
     settingsSchema: options?.settingsSchema,
     envSchema: options?.envSchema,
+    kernelPublicKey: options?.kernelPublicKey || KERNEL_PUBLIC_KEY,
   };
 
+  const githubInputs = { ...github.context.payload.inputs };
+  const signature = githubInputs.signature;
+  delete githubInputs.signature;
+  if (!(await verifySignature(pluginOptions.kernelPublicKey, githubInputs, signature))) {
+    core.setFailed(`Error: Invalid signature`);
+    return;
+  }
+
   const inputs = Value.Decode(inputSchema, github.context.payload.inputs);
 
   let config: TConfig;
   if (pluginOptions.settingsSchema) {
-    config = Value.Decode(pluginOptions.settingsSchema, JSON.parse(inputs.settings));
+    config = Value.Decode(pluginOptions.settingsSchema, Value.Default(pluginOptions.settingsSchema, JSON.parse(inputs.settings)));
   } else {
     config = JSON.parse(inputs.settings) as TConfig;
   }
 
   let env: TEnv;
   if (pluginOptions.envSchema) {
-    env = Value.Decode(pluginOptions.envSchema, process.env);
+    env = Value.Decode(pluginOptions.envSchema, Value.Default(pluginOptions.envSchema, process.env));
   } else {
     env = process.env as TEnv;
   }
diff --git a/src/sdk/server.ts b/src/sdk/server.ts
index 4c01ec3..ec5cb42 100644
--- a/src/sdk/server.ts
+++ b/src/sdk/server.ts
@@ -52,14 +52,14 @@ export async function createPlugin<TConfig = unknown, TEnv = unknown, TSupported
 
     let config: TConfig;
     if (pluginOptions.settingsSchema) {
-      config = Value.Decode(pluginOptions.settingsSchema, payload.settings);
+      config = Value.Decode(pluginOptions.settingsSchema, Value.Default(pluginOptions.settingsSchema, payload.settings));
     } else {
       config = payload.settings as TConfig;
     }
 
     let env: TEnv;
     if (pluginOptions.envSchema) {
-      env = Value.Decode(pluginOptions.envSchema, ctx.env);
+      env = Value.Decode(pluginOptions.envSchema, Value.Default(pluginOptions.envSchema, ctx.env));
     } else {
       env = ctx.env as TEnv;
     }
diff --git a/src/sdk/signature.ts b/src/sdk/signature.ts
index 8981c12..fe0c58d 100644
--- a/src/sdk/signature.ts
+++ b/src/sdk/signature.ts
@@ -1,20 +1,25 @@
 export async function verifySignature(publicKeyPem: string, payload: unknown, signature: string) {
-  const pemContents = publicKeyPem.replace("-----BEGIN PUBLIC KEY-----", "").replace("-----END PUBLIC KEY-----", "").trim();
-  const binaryDer = Uint8Array.from(atob(pemContents), (c) => c.charCodeAt(0));
+  try {
+    const pemContents = publicKeyPem.replace("-----BEGIN PUBLIC KEY-----", "").replace("-----END PUBLIC KEY-----", "").trim();
+    const binaryDer = Uint8Array.from(atob(pemContents), (c) => c.charCodeAt(0));
 
-  const publicKey = await crypto.subtle.importKey(
-    "spki",
-    binaryDer,
-    {
-      name: "RSASSA-PKCS1-v1_5",
-      hash: "SHA-256",
-    },
-    true,
-    ["verify"]
-  );
+    const publicKey = await crypto.subtle.importKey(
+      "spki",
+      binaryDer,
+      {
+        name: "RSASSA-PKCS1-v1_5",
+        hash: "SHA-256",
+      },
+      true,
+      ["verify"]
+    );
 
-  const signatureArray = Uint8Array.from(atob(signature), (c) => c.charCodeAt(0));
-  const dataArray = new TextEncoder().encode(JSON.stringify(payload));
+    const signatureArray = Uint8Array.from(atob(signature), (c) => c.charCodeAt(0));
+    const dataArray = new TextEncoder().encode(JSON.stringify(payload));
 
-  return await crypto.subtle.verify("RSASSA-PKCS1-v1_5", publicKey, signatureArray, dataArray);
+    return await crypto.subtle.verify("RSASSA-PKCS1-v1_5", publicKey, signatureArray, dataArray);
+  } catch (error) {
+    console.error(error);
+    return false;
+  }
 }
diff --git a/tests/sdk.test.ts b/tests/sdk.test.ts
index 20b30ea..723e6dc 100644
--- a/tests/sdk.test.ts
+++ b/tests/sdk.test.ts
@@ -181,24 +181,34 @@ describe("SDK worker tests", () => {
 });
 
 describe("SDK actions tests", () => {
+  const repo = {
+    owner: "ubiquity",
+    repo: "ubiquity-os-kernel",
+  };
+
   it("Should accept correct request", async () => {
+    const inputs = {
+      stateId: "stateId",
+      eventName: issueCommented.eventName,
+      settings: "{}",
+      eventPayload: JSON.stringify(issueCommented.eventPayload),
+      authToken: "test",
+      ref: "",
+    };
+    const sign = crypto.createSign("SHA256");
+    sign.update(JSON.stringify(inputs)).end();
+    const signature = sign.sign(privateKey, "base64");
+
     jest.mock("@actions/github", () => ({
       context: {
         runId: "1",
         payload: {
           inputs: {
-            stateId: "stateId",
-            eventName: issueCommented.eventName,
-            settings: "{}",
-            eventPayload: JSON.stringify(issueCommented.eventPayload),
-            authToken: "test",
-            ref: "",
+            ...inputs,
+            signature,
           },
         },
-        repo: {
-          owner: "ubiquity",
-          repo: "ubiquity-os-kernel",
-        },
+        repo: repo,
       },
     }));
     const setOutput = jest.fn();
@@ -223,13 +233,18 @@ describe("SDK actions tests", () => {
     }));
     const { createActionsPlugin } = await import("../src/sdk/actions");
 
-    await createActionsPlugin(async (context: Context) => {
-      return {
-        event: context.eventName,
-      };
-    });
-    expect(setOutput).toHaveBeenCalledWith("result", { event: issueCommented.eventName });
+    await createActionsPlugin(
+      async (context: Context) => {
+        return {
+          event: context.eventName,
+        };
+      },
+      {
+        kernelPublicKey: publicKey,
+      }
+    );
     expect(setFailed).not.toHaveBeenCalled();
+    expect(setOutput).toHaveBeenCalledWith("result", { event: issueCommented.eventName });
     expect(createDispatchEvent).toHaveBeenCalledWith({
       event_type: "return-data-to-ubiquity-os-kernel",
       owner: "ubiquity",
@@ -240,4 +255,47 @@ describe("SDK actions tests", () => {
       },
     });
   });
+  it("Should deny invalid signature", async () => {
+    const inputs = {
+      stateId: "stateId",
+      eventName: issueCommented.eventName,
+      settings: "{}",
+      eventPayload: JSON.stringify(issueCommented.eventPayload),
+      authToken: "test",
+      ref: "",
+    };
+
+    jest.mock("@actions/github", () => ({
+      context: {
+        runId: "1",
+        payload: {
+          inputs: {
+            ...inputs,
+            signature: "invalid",
+          },
+        },
+        repo: repo,
+      },
+    }));
+    const setOutput = jest.fn();
+    const setFailed = jest.fn();
+    jest.mock("@actions/core", () => ({
+      setOutput,
+      setFailed,
+    }));
+    const { createActionsPlugin } = await import("../src/sdk/actions");
+
+    await createActionsPlugin(
+      async (context: Context) => {
+        return {
+          event: context.eventName,
+        };
+      },
+      {
+        kernelPublicKey: publicKey,
+      }
+    );
+    expect(setFailed).toHaveBeenCalledWith("Error: Invalid signature");
+    expect(setOutput).not.toHaveBeenCalled();
+  });
 });