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Bitcoin Paper Wallet

Latest release: VARY ( 5th November 2021 ) 🔍 Last analysed 2nd November 2022 . Failed to build from source provided! Not updated in a while
4.6 ★★★★★
163 ratings
10 thousand
19th April 2013

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Older reviews (show 0 of 1 reproducible)

Do your own research!

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.

If you find something we should include, you can create an issue or edit this analysis yourself and create a merge request for your changes.

The Analysis 

Update: After feedback from the developer we removed the mention of disable 'TrulyRandom', "GoogleAppIndexingWarning", added more files to the list of worry-some binaries and hope for feedback regarding App Bundles as this appears to be the first Bitcoin Wallet we came across that uses this new format promoted by Google.

This app is an open source paper wallet generator but can we reproduce the build 3.2.0 from Google Play?

$ git clone https://github.com/ValleZ/Paper-Wallet
$ cd Paper-Wallet/
$ git tag | grep 3....
3.0.0

not good but

$ git log -n 1
commit 06b3e50e798bb2219b327dc4bba636343ca9f678 (HEAD -> master, origin/master, origin/HEAD)
Author: Valentin Konovalov <valle.ketsujin@gmail.com>
Date:   Wed Mar 25 20:46:53 2020 -0400

    3.2.0

So the last commit had the label 3.2.0 which looks like the author just did not tag it. Let’s see …

As there are no build instructions, we took the freedom and looked around a bit. Normally we do not provide code reviews and our findings are so blatant that they might actually be irrelevant upon deeper inspection but just in case this app turns out to be reproducible/reproducible, the following two items require a deeper look:

  1. This binary blob is not accounted for. Where does it come from? Can it be reproduced?
  2. The developer pointed us to more binary blobs in these folders, too.

Anyway … back to reproducibility:

$ docker run -it --volume $PWD:/mnt --workdir /mnt --rm beevelop/cordova bash
root@971258b281bb:/mnt# yes | /opt/android/tools/bin/sdkmanager "build-tools;29.0.3"
root@971258b281bb:/mnt# ./gradlew :app:assemble
BUILD SUCCESSFUL in 6m 18s
50 actionable tasks: 50 executed
root@971258b281bb:/mnt# exit
$ apktool d -o fromBuild app/build/outputs/apk/release/app-release-unsigned.apk
$ apktool d -o fromGoogle "/path/to/Paper Wallet 3.2.0 (ru.valle.btc).apk"
$ diff --recursive --brief from*
Files fromBuild/AndroidManifest.xml and fromGoogle/AndroidManifest.xml differ
Files fromBuild/apktool.yml and fromGoogle/apktool.yml differ
Only in fromBuild: lib
Files fromBuild/original/AndroidManifest.xml and fromGoogle/original/AndroidManifest.xml differ
Only in fromGoogle/original/META-INF: CERT.RSA
Only in fromGoogle/original/META-INF: CERT.SF
Files fromBuild/original/META-INF/MANIFEST.MF and fromGoogle/original/META-INF/MANIFEST.MF differ
Only in fromBuild/res: drawable-hdpi
Only in fromBuild/res: drawable-ldpi
Only in fromBuild/res: drawable-mdpi
Only in fromBuild/res: drawable-night-hdpi
Only in fromBuild/res: drawable-night-ldpi
Only in fromBuild/res: drawable-night-mdpi
Only in fromBuild/res: drawable-night-xhdpi
Only in fromBuild/res: drawable-night-xxhdpi
Only in fromBuild/res: drawable-night-xxxhdpi
Only in fromBuild/res: drawable-xhdpi
Only in fromBuild/res: drawable-xxhdpi
Only in fromBuild/res: drawable-xxxhdpi
Files fromBuild/res/layout/main.xml and fromGoogle/res/layout/main.xml differ
Files fromBuild/res/layout-v22/main.xml and fromGoogle/res/layout-v22/main.xml differ
Files fromBuild/res/menu/main.xml and fromGoogle/res/menu/main.xml differ
Files fromBuild/res/menu-v11/main.xml and fromGoogle/res/menu-v11/main.xml differ
Files fromBuild/res/values/public.xml and fromGoogle/res/values/public.xml differ
Only in fromGoogle/res: values-anydpi-v21
Only in fromBuild/res: values-ja
Only in fromBuild/res: values-pt
Only in fromBuild/res: values-ru
Only in fromGoogle/res/xml: splits0.xml

That is a big diff but on a closer look after the developer told us this was the result of an App Bundle it actually does not look that bad:

Extra “stuff” is mainly in what we built, not in the app we got from Google Play. Let’s remove that and the other known benign files from the list:

$ diff --recursive --brief from* | grep -v "Only in fromBuild" | grep -v "META-INF" | grep -v apktool
Files fromBuild/AndroidManifest.xml and fromGoogle/AndroidManifest.xml differ
Files fromBuild/original/AndroidManifest.xml and fromGoogle/original/AndroidManifest.xml differ
Files fromBuild/res/layout/main.xml and fromGoogle/res/layout/main.xml differ
Files fromBuild/res/layout-v22/main.xml and fromGoogle/res/layout-v22/main.xml differ
Files fromBuild/res/menu/main.xml and fromGoogle/res/menu/main.xml differ
Files fromBuild/res/menu-v11/main.xml and fromGoogle/res/menu-v11/main.xml differ
Files fromBuild/res/values/public.xml and fromGoogle/res/values/public.xml differ
Only in fromGoogle/res: values-anydpi-v21
Only in fromGoogle/res/xml: splits0.xml

Now looking into some of those diffs they look harmless. UI components with different labels. An extra res/values-anydpi-v21/drawables.xml and res/xml/splits0.xml for example:

$ cat fromGoogle/res/values-anydpi-v21/drawables.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
    <item type="drawable" name="APKTOOL_DUMMY_0">false</item>
</resources>
$ cat fromGoogle/res/xml/splits0.xml
$ cat fromGoogle/res/xml/splits0.xml
<?xml version="1.0" encoding="utf-8"?>
<splits>
    <module name="">
        <language>
            <entry key="ja" split="config.ja" />
            <entry key="pt" split="config.pt" />
            <entry key="ru" split="config.ru" />
        </language>
    </module>
</splits>

All that looks like it is following some automatism by Google but until we have a deterministic way of reproducing this, can we not reproduce this build and don’t feel comfortable dismissing the possibility of missing something. After all,

Binary files fromBuild/original/AndroidManifest.xml and fromGoogle/original/AndroidManifest.xml differ

does look a bit scary.

In summary, this app is not verifiable.

For later reference, the app from Google Play had the sha256sum ce90b2c62cae520a0f643a34b5a2a2a6b6961d5d194d06b07c21f2dd22748dea and the use of App Bundle can be detected in META-INF/MANIFEST.MF:

$ cat fromGoogle/original/META-INF/MANIFEST.MF | grep Built-By
Built-By: BundleTool

(lw)

Verdict Explained

We encountered a build error while compiling from source code!

As part of our Methodology, we ask:

Build Error!

Can the product be built from the source provided?

If the answer is "no", we mark it as "Failed to build from source provided!".

Published code doesn’t help much if the app fails to compile.

We try to compile the published source code using the published build instructions into a binary. If that fails, we might try to work around issues but if we consistently fail to build the app, we give it this verdict and open an issue in the issue tracker of the provider to hopefully verify their app later.

But we also ask:

Stale!

Was the product updated during the last year?

If the answer is "no", we mark it as "Not updated in a while".

Bitcoin wallets are complex products and Bitcoin is a new, advancing technolgy. Projects that don’t get updated in a year are probably not well maintained.

This verdict may not get applied if the provider is active and expresses good reasons for not updating the product.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.