shlima / srp6ago

go implementation of SRP-6a (RFC-5054, RFC-2945)

srp6ago

This is tiny golang SRP6a implementation fully complies with the RFC-5054/RFC-2945.

This server is used with javascript SRP6a client implementation.

Installation

go get github.com/wault-pw/srp6ago

Usage

All returned values are bytes, so it's up to you how to encode the communication between server and client (protobuf or HEX representation with JSON).

Login flow

package main

import (
    "github.com/wault-pw/srp6ago"
)

func main() {
	// verifier and salt come from database
	// after user registration
	verifier, salt := []byte{}, []byte{}
	server := srp6ago.NewServer(verifier, salt, srp6ago.RFC5054b1024Sha1)
	
	// 1) send salt and server public key to the client
	serverPublicKey, _ := server.PublicKey()
	
	// 2) retrieve client's public key and a proof
	clientPublicKey, clientProof := []byte{}, []byte{}
	err := server.SetClientPublicKey(clientPublicKey)
	if err != nil {
        panic("server aborts")
	}
	
	// 3) Validate client proof
	// if OK, user is authenticates
	server.IsProofValid(clientProof)
	
	// 4) Now you have identical session key
	// with client
	server.SecretKey()
	
	// 5) You may send server proof back to the client
	server.Proof()
}

You can marshal SRP server and restore its state between HTTP requests:

server := srp6ago.NewServer(verifier, salt, srp6ago.RFC5054b1024Sha1)
bin := server.Marshal()
server, _ = srp6ago.UnmarshalServer(bin)

SRP Group Parameters

Preconfigured RFC-5054 SRP Group Parameters:

package main

import (
    "github.com/wault-pw/srp6ago"
)

func main() {
	// RFC-5054 complicated params set:
	srp6ago.RFC5054b1024Sha1
	srp6ago.RFC5054b1536Sha1
	srp6ago.RFC5054b2048Sha1
	srp6ago.RFC5054b3072Sha1
	srp6ago.RFC5054b4096Sha1
	srp6ago.RFC5054b6144Sha1
	srp6ago.RFC5054b8192Sha1

	// RFC-5054 complicated set,
	// with non-standart hash function SHA-256
	srp6ago.RFC5054b8192Sha256
	srp6ago.RFC5054b6144Sha256
	srp6ago.RFC5054b4096Sha256
	srp6ago.RFC5054b1024Sha256
	srp6ago.RFC5054b1536Sha256
	srp6ago.RFC5054b2048Sha256
	srp6ago.RFC5054b3072Sha256	
}