How Sentz Puts You in Control: Understanding Self-Custody and Secure Backups

With Sentz, you’re in full control of your funds. Unlike a bank that manages access to your account, Sentz gives you self-custody, meaning only you can access and secure your wallet. As we upgrade our PIN-based wallet recovery system in March 2025, it’s a great time to ensure your wallet is fully protected. 

What makes Sentz self custodial?

When the Sentz app creates your unique wallet, it picks a number at random that is the foundation of your wallet’s security. This secret number, also sometimes called a private key, is impossible to guess. It could be any of 7,237,005,577,332,262,213,973,186,563,042,994,240,829,374,041,602,535,252,466,099,000,494,570,602,496 possible choices. That’s about the same as the number of atoms in the entire universe.

Your secret number is the key to your wallet—used to check your balance, send funds, and access your money. Only your Sentz app can access it, not our servers, giving you full control of your funds. That’s self-custody—no one can take your funds from you.

To keep your funds secure, the Sentz app stores this secret number locally on your phone and never shares it with anyone, including us. To protect against loss, like if your phone breaks or the app is uninstalled, Sentz offers three recovery options, all fully under your control:

1. Secret Recovery Phrase
2. PIN-based server backup
3. Cloud Backups

We recommend using all three, as no single method is foolproof. Below, we’ll break down the pros and cons of each, but the Secret Recovery Phrase is the most important—it’s the only method that is completely under your own control and not dependent on 3rd parties or technology that is out of our or your own control.

What is a Secret Recovery Phrase?

Simply put, your Secret Recovery Phrase is a reliable way to record the secret that secures your wallet.

Long strings of 76+ digits, like the one securing your wallet, are commonly used in mathematical algorithms like cryptography, but they are very difficult for people to write down without making errors.

Even small mistakes can make recovery impossible. A 24-word Secret Recovery Phrase fixes this by turning your wallet’s secret number into a phrase made up of 24 easy-to-write words from a set list of 2,048 dictionary words. This makes it simpler to write down and double-check.

We strongly recommend that all customers write it down and store it securely—never take a screenshot or save it in a cloud document, as anyone with access can steal your funds.

For extra security, consider storing it in a trusted password manager instead of just on paper.

Why offer other methods of backup?

You might be wondering why Sentz has two additional backup methods. There are a few reasons for this:

• People make mistakes writing down words onto paper
• People plan to backup their recovery phrase, and then they forget
• Scraps of paper (and access to password managers) get lost over time
• Restoring from a recovery phrase can be slow and inconvenient 

An estimated $287 billion in Bitcoin has been lost due to misplaced self-custodial keys—we think it is worth having a belt and suspenders for safeguarding your self-custodial funds.

What is PIN-based backup and how does it work?

Sentz has a cluster of special servers in the cloud that are dedicated to helping recover lost Sentz wallets. These servers use special high-security CPU features and encrypted memory so that even the owners of the servers can’t access stored data.

For the PIN-based backup, Sentz stores a securely encrypted version of your Secret Recovery Phrase. The encryption scrambles the recovery phrase using your telephone number and something only you know: your PIN, ensuring that only you can descramble the phrase during recovery.

Think of PIN-based backup as a shorter-term backup. These servers never store data externally and prioritize security over persistence, meaning backups may expire if you don’t use Sentz for a while.

PIN-based backup and recovery add a layer of protection on top of manually backing up your Secret Recovery Phrase. Restoring using the PIN-based backup can also be quicker and more convenient than locating your copy of your Secret Recovery Phrase and re-entering it. However, PIN-based backups have their own set of limitations and should not be relied on alone:

• You must remember your PIN to recover your wallet.
• Backups don’t last indefinitely—if you take a break from using Sentz, they may no longer exist.

What are Cloud Backups?

The Sentz app also creates encrypted backups of your Secret Recovery Phrase using your phone’s cloud service (e.g., iCloud for Apple, Google Cloud for Android). These backups are encrypted but don’t require your Sentz PIN to restore—just the security of your phone and cloud service.

You can opt-out of Cloud Backups by deleting yours under Profile > Privacy & Security.

Important Considerations:

• Cloud backups require access to the cloud provider they were made on (e.g., Apple or Google).
• Sufficient storage space is needed on your cloud plan; if there's no space, there won’t be a backup to restore.
• Cloud backups are tied to your phone provider; iPhone backups can’t be restored on Android phones and vice versa.

In conclusion, while having multiple backup methods provides added layers of security, it's important to understand the strengths and limitations of each. We recommend using all available backup options for maximum protection, but always remember to keep your recovery phrase secure and stored in a trusted location. By staying proactive, you can confidently manage and protect your funds with Sentz.