func (s *Server) AuthHandler() http.Handler {
handler := func(w http.ResponseWriter, r *http.Request) {
/*
Parse form data and handle error messages. Might not be the most visible to the end user.
*/
err := r.ParseForm()
if err != nil {
fmt.Println(err)
return
}
message := r.FormValue("message")
signature := r.FormValue("signature")
publicKey := r.FormValue("publicKey")
/*
Decode publicKey and signature to a byte array using base64url package
*/
pubBytes, pubErr := base64url.Decode(publicKey)
if pubErr != nil {
fmt.Println(pubErr)
}
signBytes, signErr := base64url.Decode(signature)
if signErr != nil {
fmt.Println(signErr)
}
/*
Change the byte array to an object with the correct sizes used by the ed25519 implementation
*/
var pk *[ed25519.PublicKeySize]byte
pk = new([ed25519.PublicKeySize]byte)
subtle.ConstantTimeCopy(1, pk[:32], pubBytes)
var sig *[ed25519.SignatureSize]byte
sig = new([ed25519.SignatureSize]byte)
subtle.ConstantTimeCopy(1, sig[:64], signBytes)
/*
Verify the signature and return verified or not depending on the result.
*/
w.Header().Add("Content-Type", "text/html")
if ed25519.Verify(pk, []byte(message), sig) {
io.WriteString(w, "{result:true}Verified")
} else {
io.WriteString(w, "{result:false}Not Verified")
}
}
return http.HandlerFunc(handler)
}
/*
Test base64url.Decode function using a hex encoded string corresponding to an Base64URLEncoded string.
First we decode the Base64URLEncoded string checking the error condition so we have a correctly encoded string.
Then we hex encode the result and check it against the corresponding hex encoded string.
*/
func TestDecode(t *testing.T) {
resultBytes, err := base64url.Decode(Base64URLEncoded)
if err != nil {
t.Errorf("Could not decode Base64URLEncoded string: ", err)
}
hexEncodedBytes := make([]byte, len(resultBytes)*2)
hex.Encode(hexEncodedBytes, resultBytes)
resultStr := string(hexEncodedBytes)
if HEXEncoded != resultStr {
t.Errorf(HEXEncoded + " not equal with " + resultStr)
}
// Should error when an illegal character is encountered.
resultBytes, err = base64url.Decode(Base64URLEncoded + "+")
if err == nil {
t.Errorf("Should throw error when an illegal character is encountered.")
}
}