Signature functions about php-curve25519 HOT 7 CLOSED

Hi,

This library is for key exchange, for signing you want to use the Poly1305 library.

https://github.com/lt/PHP-Poly1305

Cheers.

from php-curve25519.

Hello,

Thank you for your prompt answer. I am porting TextSecure to PHP and it seems your library is missing some functions which are needed. Please see:

https://github.com/WhisperSystems/TextSecure/blob/master/libaxolotl/src/main/java/org/whispersystems/libaxolotl/ecc/Curve25519.java

The needed functions are:

calculateAgreement()
generatePublicKey()
generatePrivateKey()
calculateSignature()
verifySignature()

Any pointers on how to implement these functions in your Curve25519 implementation?

Many thanks.

from php-curve25519.

Public key signing can be done with ed25519, but not with this library. (Twisted Edwards curves are a bit more complicated than I have time for right now, it's on my list, but I'm quite busy with some other projects).

A cursory search shows there is a PHP implementation here: https://github.com/trianglman/sqrl/blob/master/src/Trianglman/Sqrl/Ed25519/Crypto.php

It uses BCMath though, so it's going to be incredibly slow.

from php-curve25519.

Thank you! I'll have a look at it.

from php-curve25519.

Sorry, one last question:

Based on your good information I have found some Ed25519 libraries which look usable for the signature calculations. However, first I need to convert Curve25519 keys into Ed25519 keys. Any pointers how to implement this in PHP?

Found more info here: http://crypto.stackexchange.com/questions/13077/can-curve25519-keys-be-used-with-ed25519-keys

Thanks!

from php-curve25519.

Do you really need to convert the keys? I.e. do you need to use the same key for Curve25519 and Ed25519 operations?

Ed25519 keys can be generated independently from random bytes, check out the NaCl reference implementation

If you really need to "convert" them (there is no standard process for this, as far as I am aware), you could seed the sha512 step with the Curve25519 private key.

from php-curve25519.

I think I have to yes. TextSecure made some changes it seems: https://github.com/WhisperSystems/TextSecure-Browser/blob/master/nacl/ed25519/additions/curve_sigs.c

For now my work-around is to compile the C source and call it from PHP. Not pretty but porting the C code to PHP with my limited knowledge of what is happening there is probably not a good idea ;)

Once again thanks for your help. Your library is working excellent!

from php-curve25519.