diff --git a/src/signature.ts b/src/signature.ts
index e818ffb..38597cf 100644
--- a/src/signature.ts
+++ b/src/signature.ts
@@ -7,14 +7,29 @@ import * as libmisc from 'misc'
 export async function gen(extractable: boolean = true): Promise<CryptoKeyPair> {
   return await crypto.subtle.generateKey(consts.SIGNATURE_KEY, extractable, ['sign', 'verify'])
 }
-export async function sign(message: Uint8Array, privkey: CryptoKey): Promise<Uint8Array> {
+export async function sign(message: Uint8Array, privkey: CryptoKey): Promise<Uint8Array | null> {
   log.trace('sign')
-  const buffer = await crypto.subtle.sign(consts.SIGNATURE_ALGO, privkey, message)
+
+  let buffer: ArrayBuffer
+  try {
+    buffer = await crypto.subtle.sign(consts.SIGNATURE_ALGO, privkey, message)
+  } catch (e) {
+    log.warn('Failed to sign')
+    log.debug('Error :', e)
+    return null
+  }
+
   return new Uint8Array(buffer)
 }
 export async function verify(message: Uint8Array, pubkey: CryptoKey, signature: Uint8Array): Promise<boolean> {
   log.trace('verify')
-  return await crypto.subtle.verify(consts.SIGNATURE_ALGO, pubkey, signature, message)
+  try {
+    return await crypto.subtle.verify(consts.SIGNATURE_ALGO, pubkey, signature, message)
+  } catch (e) {
+    log.warn('Failed to verify')
+    log.debug('Error :', e)
+    return false
+  }
 }
 
 export async function pubkey_toString(pubkey: CryptoKey): Promise<string> {
diff --git a/test/signature.test.ts b/test/signature.test.ts
index ac48892..7bb480e 100644
--- a/test/signature.test.ts
+++ b/test/signature.test.ts
@@ -10,7 +10,8 @@ test('base case', async () => {
   const data = new TextEncoder().encode('Message 123 !')
 
   const sig = await sign(data, keypair.privateKey)
-  const verification = await verify(data, keypair.publicKey, sig)
+  expect(sig).not.toBeNull()
+  const verification = await verify(data, keypair.publicKey, sig!)
 
   expect(verification).toBe(true)
 })
@@ -33,7 +34,8 @@ test('inverted keys', async () => {
   const keypair = await signature.gen()
   const data = new TextEncoder().encode('Message 123 !')
 
-  expect(async () => await sign(data, keypair.publicKey)).toThrow()
+  const sig = await sign(data, keypair.publicKey)
+  expect(sig).toBeNull()
 })
 
 test('tampered message', async () => {
@@ -43,7 +45,8 @@ test('tampered message', async () => {
   expect(data1).not.toEqual(data2)
 
   const sig = await sign(data1, keypair.privateKey)
-  const verification = await verify(data2, keypair.publicKey, sig)
+  expect(sig).not.toBeNull()
+  const verification = await verify(data2, keypair.publicKey, sig!)
 
   expect(verification).toBe(false)
 })
@@ -54,7 +57,8 @@ test('different keypair', async () => {
   const data = new TextEncoder().encode('Message 123 !')
 
   const sig = await sign(data, keypair.privateKey)
-  const verification = await verify(data, keypair2.publicKey, sig)
+  expect(sig).not.toBeNull()
+  const verification = await verify(data, keypair2.publicKey, sig!)
 
   expect(verification).toBe(false)
 })
@@ -64,14 +68,15 @@ test('tampered signature', async () => {
   const data = new TextEncoder().encode('Message 123 !')
 
   const sig = await sign(data, keypair.privateKey)
-  sig[0] ^= 1
-  const verification = await verify(data, keypair.publicKey, sig)
+  expect(sig).not.toBeNull()
+  sig![0] ^= 1
+  const verification = await verify(data, keypair.publicKey, sig!)
 
   expect(verification).toBe(false)
 })
 
 /*describe('Derive array', () => {
-  test('Case derive key and use it', async () => {
+  test('Base case', async () => {
     const data = new Uint8Array([1])
     const kp = await derive_keypair(data)