> For the complete documentation index, see [llms.txt](https://learn.cypherock.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://learn.cypherock.com/design-decision/pin-protection-on-cypherock-x0.md).

# Pin Protection on Cypherock X0

Cypherock X0 makes PIN protection a part of every wallet. Each of the 4 wallets the user creates or imports on Cypherock X0 is protected by its own alphanumeric PIN of 4–8 characters, chosen by the user during wallet setup. A key derived from the PIN is used to encrypt all 5 shards of the wallet: the 4 shards stored on the X0 Cards and the shard stored on the user's smartphone.

The PIN is verified only inside the X0 Card. When an operation requires the PIN, the user enters it in the X0 Wallet App and taps an X0 Card. The PIN is sent to the card over an encrypted NFC session, and the card decides whether it is correct. The X0 Wallet App itself never verifies the PIN. Because the PIN is also needed to derive the key that decrypts the shards, even an attacker who managed to tamper with the PIN check would still be unable to use the wallet without knowing the PIN.

{% hint style="warning" %}
The wallet PIN is permanent. Once it is set, it cannot be changed, so it is important to choose it carefully and keep it safe.
{% endhint %}

If you ever believe your PIN has been exposed, create a new wallet with a new PIN and move your funds to it. If you forget your PIN, you will not be able to access the wallet.

Read [Difference between backing up your PIN vs. Seed Phrase](/design-decision/pin-protection-on-cypherock-x1/difference-between-backing-up-your-pin-vs.-seed-phrase.md) to understand why backing up your PIN is far safer than backing up a seed phrase.

## CyLock

PIN protection on the X0 Card also comes with CyLock, Cypherock's proof-of-work lock system.

After 3 wrong PIN attempts, the wallet is locked, and every further attempt is only possible after the X0 Wallet App completes a security wait. Each wrong PIN makes the next security wait longer, and repeated wrong attempts eventually lock the wallet permanently.

The security wait is a proof-of-work puzzle that the X0 Card verifies before it accepts the next attempt, so it cannot be skipped.