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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.
The Analysis ¶
This wallet has a really short description. Here it is in full:
Eclair Mobile is a next generation, Lightning-ready Bitcoin wallet. It can be used as a regular Bitcoin wallet, and can also connect to the Lightning Network for cheap and instant payments.
This software is based on eclair, and follows the Lightning Network standard.
No word on custodial or not.
Their website is more informative if only for the link to their GitHub.
eclair-mobile sounds promising.
There, in the description again we find no hints at it being non-custodial.
But in the repository’s wiki finally we find:
Is Eclair Mobile a “real” Lightning Node ?
Yes it is. Eclair Mobile is a real, self-contained lightning node that runs on your phone. It does not require you to run another Lightning Node node at home or in the cloud. It is not a custodial wallet either, you are in full control of your funds.
So … can we reproduce the build?
The build instructions are not very plentiful on the repo’s description:
- clone this project
clone eclair and checkout the android branch.
Follow the steps here to build the eclair-core library.
- Open the Eclair Mobile project with Android studio. You should now be able to install it on your phone/on an emulator.
This has two immediate issues:
- How do we know which version of “eclair” should we use? This should be resolved with a git submodule.
- Compiling with Android Studio is not easy to automate and should not be necessary.
- Branches are not a good way of referencing revisions of a repository. The “android branch” has 1938 revisions and if I want to check anything but the latest revision I have little to go by to find which app would match to which state of the branch.
but let’s see how compiling looks once these issues are resolved as we have little hope to verify the current apk …
$ git clone email@example.com:ACINQ/eclair-mobile.git $ git clone firstname.lastname@example.org:ACINQ/eclair.git $ cd eclair $ git checkout android $ docker run -it -v $PWD/eclair:/eclair -v $PWD/eclair-mobile:/eclair-mobile --workdir / electrum-android-builder-img user@d0cf683a144a:/$ sudo su - root@d0cf683a144a:~# apt update root@d0cf683a144a:~# apt install maven root@d0cf683a144a:~# mvn install -DskipTests ... [INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ eclair-core_2.11 --- [INFO] Nothing to compile - all classes are up to date [INFO] [INFO] --- scala-maven-plugin:3.4.2:testCompile (scalac) @ eclair-core_2.11 --- [INFO] /eclair/eclair-core/src/test/java:-1: info: compiling [INFO] /eclair/eclair-core/src/test/scala:-1: info: compiling [INFO] Compiling 114 source files to /eclair/eclair-core/target/test-classes at 1577007350665 [ERROR] /eclair/eclair-core/src/test/scala/fr/acinq/eclair/blockchain/bitcoind/BitcoindService.scala:74: error: value writeString is not a member of object java.nio.file.Files [ERROR] Files.writeString(new File(PATH_BITCOIND_DATADIR.toString, "bitcoin.conf").toPath, conf) [ERROR] ^ [ERROR] one error found [INFO] ------------------------------------------------------------------------ [INFO] Reactor Summary for eclair_2.11 0.3.4-android-SNAPSHOT: [INFO] [INFO] eclair_2.11 ........................................ SUCCESS [ 1.951 s] [INFO] eclair-core_2.11 ................................... FAILURE [ 28.245 s] [INFO] eclair-node ........................................ SKIPPED [INFO] ------------------------------------------------------------------------ [INFO] BUILD FAILURE
So following the instructions we didn’t get far and for now hope for better documentation and remain with the verdict: This app is not verifiable.
We could not verify that the provided code matches the binary!
As part of our Methodology, we ask:Is the published binary matching the published source code? If not, we tag it
Published code doesn’t help much if it is not what the published app was built from. That is why we try to reproduce the binary. We
- obtain the binary from the provider
- compile the published source code using the published build instructions into a binary
- compare the two binaries
- we might spend some time working around issues that are easy to work around
If this fails, we might search if other revisions match or if we can deduct the source of the mismatch but generally consider it on the provider to provide the correct source code and build instructions to reproduce the build, so we usually open a ticket in their code repository.
In any case, the result is a discrepancy between the app we can create and the app we can find on the app store and any discrepancy might leak your backup to the server on purpose or by accident.
As we cannot verify that the source provided is the source the app was compiled from, this category is only slightly better than closed source but for now we have hope projects come around and fix verifiability issues.
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