Understanding Jamtis: A New Addressing Scheme for Monero

As cryptocurrency users, we all value privacy, security, and efficiency when it comes to managing our digital assets. Over the years, Monero has become a popular choice for people who prioritize these qualities. Now, with a major upgrade to Monero’s transaction protocol on the horizon, called Seraphis, the way we use addresses is about to change dramatically.

Why A New Address Format?

The Monero community is working on major improvements to privacy and efficiency. While Seraphis is a future possibility, FCMP++ will likely come first to improve the current system without requiring significant changes for users. Once Seraphis is ready, it will enable much larger ring sizes, dramatically boosting privacy. However, Seraphis will require new addresses because traditional Monero addresses (based on CryptoNote) won’t be compatible. This presents an opportunity to introduce a new addressing scheme called Jamtis, which improves security and usability.

Let’s dive into the details and explore how Jamtis addresses benefit your wallet’s security, privacy, and ease of use.

The Problems with Current Monero Addresses

Before we jump into what Jamtis brings, it’s important to understand why the current CryptoNote-based addresses have limitations:

1. Hard to Read and Share: Current Monero addresses are long, case-sensitive, and not very human-friendly.
2. Privacy Leaks When Delegating Scanning: If you let a third party (like a wallet service) scan the blockchain for your transactions, too much information about your wallet is leaked.
3. Subaddress Generation Issues: Generating subaddresses (for better privacy) requires access to your wallet’s view keys, which could compromise your security if not handled properly.
4. View-Only Wallets Lack Spending Detection: You must import key images to detect spent outputs (money you’ve already used).
5. Janus Attack Vulnerability: In a specific attack (called Janus), your subaddresses can be linked, compromising your privacy.
6. Missed Outputs: The current system sometimes misses outputs (i.e., incoming payments) because it relies on a lookup table that’s not always reliable.

So, what’s the solution? Enter Jamtis.

What Is Jamtis?

Jamtis is the new addressing scheme built for the Seraphis protocol. It addresses (pun intended!) many of the issues in the current system. Here’s what it brings to the table:

A New Address Format

Jamtis addresses start with the prefix xmra and are 196 characters long. All Jamtis addresses are essentially subaddresses, so there’s no concept of a “main address” anymore. Here’s an example of a Jamtis address:

xmra1mj0b1977bw3ympyh2yxd7hjymrw8crc9kin0dkm8d3wdu8jdhf3fkdpmgxfkbywbb9mdwkhkya4jtfn0d5h7s49bfyji1936w19tyf3906ypj09n64runqjrxwp6k2s3phxwm6wrb5c0b6c1ntrg2muge0cwdgnnr7u7bgknya9arksrj0re7whkckh51ik

While this may seem long and hard to share, Jamtis introduces a Recipient ID (RID) for easier communication. The RID is a 25-character identifier that can be shared instead of the full address. For example, the above address has the RID:

regne_hwbna_u21gh_b54n0_8x36q

By using RIDs, you can confirm recipient addresses over the phone or in a message—without needing to share the full address over insecure channels.

Enhanced Wallet Security and Privacy

Enhanced Wallet Security and Privacy

Jamtis introduces new wallet types that limit exposure of your private information while offering convenience:

• FindReceived Wallets: These wallets can scan the blockchain for your transactions and improve sync speed by filtering 99.6% of irrelevant data. However, they cannot generate new addresses or decode transaction amounts. This allows third parties to process your blockchain data without compromising your security, making it useful for light wallet setups.

• Address Generator Wallets: Ideal for merchants, these wallets can generate new addresses but cannot check whether payments have been received. This wallet type is perfect for generating new payment addresses on-demand while keeping more sensitive wallet functions offline.

• Payment Validator Wallets: These wallets can generate addresses and also check for incoming payments without seeing outgoing transactions. This makes them ideal for point-of-sale terminals that need to confirm payments without exposing sensitive data, providing a balance of privacy and functionality for merchants.

Janus Attack Mitigation

The Janus attack is a specific threat in which an attacker can determine if two different addresses belong to the same wallet. With Jamtis, this attack is no longer a threat, as it allows the recipient to detect Janus outputs and avoid revealing unnecessary information to attackers.

Reliable Output Detection

Instead of relying on error-prone lookup tables to detect incoming payments, Jamtis uses encrypted address tags that enable more robust output detection. You’ll never miss a payment again because the system is much more reliable at detecting which outputs belong to your wallet.

Light Wallet Scanning: Faster and More Efficient

One of the key benefits of Jamtis is its ability to make light wallet scanning faster. Wallets using Jamtis can now include a FindReceived component, which stays connected to the blockchain network, filters outputs, and speeds up synchronization by over 256x when you bring your full wallet online.

This means you can quickly catch up with the blockchain without waiting for a full rescan, making your wallet experience much smoother, especially on mobile devices.

What About View-Only Wallets?

View-only wallets are often used for security, allowing you to check your balance and transactions without having access to your spending keys. However, the current system doesn’t let these wallets see which outputs are spent. Jamtis fixes this by enabling full view-only wallets that can detect spent outputs, showing you an accurate balance at all times.

Improving Merchant Security

For businesses accepting Monero, Jamtis introduces wallet tiers that provide more control over payment handling:

• Address Generator: Perfect for generating addresses without exposing the wallet.
• Payment Validator: Useful for confirming payments without risking the wallet’s full control.

With these new tools, merchants can ensure greater security and privacy when handling Monero payments.

Seraphis and Jamtis: A Deeper Look

To understand how Jamtis fits into the larger Monero upgrade, we need to look at Seraphis, the underlying transaction protocol.

Although Seraphis isn’t likely to be implemented in the near future, it’s worth understanding its potential benefits. Seraphis will introduce linking tags, which replace key images. The new cryptographic structure will make it harder to trace the origins and destinations of funds, improving privacy. Paired with Jamtis, Seraphis will create a more private and efficient transaction environment for Monero users.

However this would still be a game-changer for Monero users, as it reduces the risk of transaction correlation—the ability for attackers to link multiple transactions to the same user. Paired with Jamtis, which improves address and output handling, Seraphis ensures that your financial privacy is maintained at an even deeper level.

Jamtis vs Traditional Multi-Sig

While multisig functionality in Monero doesn’t involve on-chain signatures, Jamtis still improves multisig setups by ensuring privacy and efficiency. In traditional multisig setups outside Monero, multiple signatures for a transaction input can reveal information about the parties involved. Jamtis offers a more scalable and efficient solution by aggregating signatures and preventing privacy leaks.

With these improvements, Jamtis is more private, efficient, and scalable for users who need multi-sig functionality, making it a perfect fit for large organizations or collaborative groups using Monero.

Conclusion

Monero’s transition to Jamtis, alongside upgrades like FCMP++ (again, is much more likely to be implemented sooner than Jamtis) will significantly improve privacy, security, and efficiency for all users. Jamtis introduces features that make addresses easier to use, wallets faster to sync, and outputs