• Rezepte
• Kalender
• Code
• Impressum

Crypto

• CurvedSalsa 

Network

• UPnPControl 

OpenGL

• Tetris 

Introduction

CurvedSalsa is a program capable of encrypting/decrypting files with the ChaCha variant of Salsa20 (Snuffle 2008) via a shared key calculated from a Diffie-Hellman-Key-Exchange using D. J. Bernstein's  curve25519.

• curve25519-donna for the calculation of the shared secret.
• Boost for the commandline-options parsing
• QT4 for the GUI

In a nutshell it works like this:
Alice wants to send a confidential file to Bob over an unencrypted/insecure line. Bob and Alice exchange their public keys in an authenticated way (i.e. via phone or personally). The public keys can be exchanged over an insecure line, but must be authenticated to prevent man-in-the-middle attacks. Alice encrypts/signs the file with a shared secret key composed from Bob's public key and her own private passphrase. Bob decrypts/checks the signature of the file by calculating the same shared secret key from Alice's public Key and his private passphrase.
Neither the private keys nor the shared secret itself are ever exchanged.

This is basically the same as using traditional RSA based private/public-key encryption but has some major advantages:

• The public key is shorter than an RSA public key of the same strength due to the use of eliptic curve cryptography (~256bit vs. 3072bit for the same security)
• The private passphrase can be chosen freely and does not have to be generated for security reasons (RSA keys can not)
• Encryption/signing and decryption/signiture verification takes place in a single step

Screenshots

Download

A current development snapshot can be obtained from the Mercurial repository via:

hg clone http://www.miller-online.eu/hg/curvedsalsa

The changelog to the repository can be viewed here.

License

CurvedSalsa is released in the public domain.