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https://github.com/circulosmeos/triops.apk

triops port to Android - Encrypt and decrypt files using CHACHA20+KECCAK
https://github.com/circulosmeos/triops.apk

android-app apk chacha20 decryption encrypted-files encryption keccak

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triops port to Android - Encrypt and decrypt files using CHACHA20+KECCAK

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README 

          
triops.apk

==========



A simple Android tool for encryption/decryption of files.   



Last version available and compiled is v1.7. Check [list of changes between versions](Changes.md).   



apk available [here](https://github.com/circulosmeos/triops.apk/releases/download/v1.7/triops.apk):   

[http://wp.me/p2FmmK-8T](http://wp.me/p2FmmK-8T)



![](https://circulosmeos.files.wordpress.com/2015/09/triops-apk1.png)



It uses [CHACHA20](http://en.wikipedia.org/wiki/Salsa20#ChaCha_variant) as algorithm for encryption/decryption and [KECCAK](http://en.wikipedia.org/wiki/SHA-3)-512 as hash algorithm.   



It is based on command-line tool triops, available [here](https://www.github.com/circulosmeos/triops). The C code is exactly the same, used via JNI, with just a GUI frontend for Android.   



Features

======== 



* Support for "share with" and "open with" (*.*) Android behaviours.

* Same content produces different encrypted outputs every time. This is attained with a random initialization vector (IV) stored within the encrypted file.

* Files are (by default) encrypted/decrypted on-the-fly, so content is overwritten. This is interesting from a security point of view, as no clear content is left on disk.

* When decrypting, if password is not the one used for encrypting, the process is aborted, so the file cannot be rendered unusable. This behaviour is achieved thanks to a password hint stored within the encrypted file.

* Mentioned hint used to check that the password for decryption is correct is *not* the same used to encrypt (obviously!). Separate hashes are used for both purposes, though both are derived via different ways from the password and IV, using some 500-1000 concatenated KECCAK hashes.

* Encrypted files are appended the extension .ooo to filename, so they can be recognized.

* Password can be obtained from keyboard or from a file:

* Binary files can be used as passwords: for example jpg images, etc. Caution: do not lose this 'password' file and do not modify it!   

![](https://circulosmeos.files.wordpress.com/2015/09/triops-apk-file_as_password.png)

* Files bigger than 2 GiB can be managed.

* Speed is extremely high: the app uses a native OS library and CHACHA20 is a very fast encryption algorithm: it is as fast as RC4.

* Code for the Android file browser is a slightly modified version of ingyesid‘s [simple-file-chooser](https://github.com/ingyesid/simple-file-chooser): see [circulosmeos/simple-file-chooser](https://github.com/circulosmeos/simple-file-chooser).

* Licensed as [GPL v3](http://www.gnu.org/licenses/gpl-3.0.html)



Additional info

===============   

   

Please, refer to [triops](https://www.github.com/circulosmeos/triops) command-line project for more details.

      



Notes

===== 



* The sample encrypted file "gplv3.txt.ooo" can be decrypted with the password "triops!"   

   

* Files encrypted with version < 1.4 can be decrypted with greater versions, but in general files encrypted with version >=1.4 cannot be decrypted with previous versions. This is related to the change to cmdline triops's version >=9.0 : see [project notes here](https://github.com/circulosmeos/triops).   



* Version < 1.4 used the extension ".#$3" for encrypted files. It has been changed to ".ooo", though those files are correctly recognized and managed. See previous note.   



Known issues

============



Please, refer to [the issues page](https://github.com/circulosmeos/triops.apk/issues).	



* If you are using Android < 7 in a Samsung device, you may want to [install v1.4](https://github.com/circulosmeos/triops.apk/releases/download/v1.4/triops.apk), as it has Samsungs Multi-Windows support. This feature was removed in v1.5 as it is incompatible with Android N (7).



License

=======



Licensed as [GPL v3](http://www.gnu.org/licenses/gpl-3.0.en.html) or higher.