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Nayuta Core

Latest release: Varies with device ( 16th December 2021 ) 🔍 Last analysed 15th January 2022 . No source for current release found Not functioning anymore
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Try out searching for "lost bitcoins", "stole my money" or "scammers" together with the wallet's name, even if you think the wallet is generally trustworthy. For all the bigger wallets you will find accusations. Make sure you understand why they were made and if you are comfortable with the provider's reaction.

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The Analysis 

Update 2022-01-15: This app is not on the Store anymore.

Updated Review 2021-12-21

New information was presented that has made this project closed source. Details can be found here:

The current app is built from a new private repo, this is because the app has had a major refactor and is in testing on google play, once it is in a stable state it will be updated here or this repo will be closed an a new public one made

App Description

This bitcoin and lightning network app allows on-chain as well as lightning payments. It claims to be self-custodial and allows users to backup and restore from a 24 word seed.

However, according to its terms and conditions:

Intellectual Property
The Service and its original content, features and functionality are and will remain the exclusive property of Nayuta Inc. and its licensors. The Service is protected by copyright, trademark, and other laws of both the Japan and foreign countries. Our trademarks and trade dress may not be used in connection with any product or service without the prior written consent of Nayuta Inc..

Verdict

This app is self-custodial and though it claims to have “exclusive ownership” of the “original content, features and functionality”, the wallet’s source code is available on Github.

(dg)

Verdict Explained

Without public source of the reviewed release available, this product cannot be verified!

As part of our Methodology, we ask:

No Source!

Is the source code publicly available?

If the answer is "no", we mark it as "No source for current release found".

A wallet that claims to not give the provider the means to steal the users’ funds might actually be lying. In the spirit of “Don’t trust - verify!” you don’t want to take the provider at his word, but trust that people hunting for fame and bug bounties could actually find flaws and back-doors in the wallet so the provider doesn’t dare to put these in.

Back-doors and flaws are frequently found in closed source products but some remain hidden for years. And even in open source security software there might be catastrophic flaws undiscovered for years.

An evil wallet provider would certainly prefer not to publish the code, as hiding it makes audits orders of magnitude harder.

For your security, you thus want the code to be available for review.

If the wallet provider doesn’t share up to date code, our analysis stops there as the wallet could steal your funds at any time, and there is no protection except the provider’s word.

“Up to date” strictly means that any instance of the product being updated without the source code being updated counts as closed source. This puts the burden on the provider to always first release the source code before releasing the product’s update. This paragraph is a clarification to our rules following a little poll.

We are not concerned about the license as long as it allows us to perform our analysis. For a security audit, it is not necessary that the provider allows others to use their code for a competing wallet. You should still prefer actual open source licenses as a competing wallet won’t use the code without giving it careful scrutiny.

But we also ask:

Defunct!

Is the product still supported by the still existing provider?

If the answer is "no", we mark it as "Not functioning anymore".

Discontinued products or worse, products of providers that are not active anymore, are problematic, especially if they were not formerly reproducible and well audited to be self-custodial following open standards. If the provider hasn’t answered inquiries for a year but their server is still running or similar circumstances might get this verdict, too.