Testing curve255js...

gistfile1.js

// Converts key from plain hexadecimal to inverted-byte hexadecimal
function hex2ibh(x) {
    x = new Array(64 + 1 - x.length).join("0") + x; // Pad with '0' at the front
    // Invert bytes
    return x.split(/(..)/).reverse().join("");
}

function ibh2hex(x) {
    //assert(length(x) == 64);
    // Invert bytes
    return x.split(/(..)/).reverse().join("");
}

priv=ibh2hex('0300000000000000000000000000000000000000000000000000000000000000');
base=ibh2hex('0900000000000000000000000000000000000000000000000000000000000000');
console.log(priv);
pub = hex2ibh(c255lhexencode(curve25519(c255lhexdecode(priv), c255lhexdecode(base))));
expect='123c71fbaf030ac059081c62674e82f864ba1bc2914d5345e6ab576d1abc121c';
assert(pub == expect);