nuts-foundation/nuts-node

/*
 * Copyright (C) 2024 Nuts community
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 */

package iam

import (
    "crypto/sha256"
    "encoding/base64"
    nutsCrypto "github.com/nuts-foundation/nuts-node/crypto"
)

// PKCEParams contains the PKCE parameters so they can be stored in both the client and server side session.
type PKCEParams struct {
    Challenge       string
    ChallengeMethod string
    Verifier        string
}

func generatePKCEParams() PKCEParams {
    verifier := nutsCrypto.GenerateNonce()
    sha := sha256.Sum256([]byte(verifier))
    challenge := base64.RawURLEncoding.EncodeToString(sha[:])
    return PKCEParams{
        Challenge:       challenge,
        ChallengeMethod: "S256",
        Verifier:        verifier,
    }
}

func validatePKCEParams(params PKCEParams) bool {
    switch params.ChallengeMethod {
    case "S256":
        sha := sha256.Sum256([]byte(params.Verifier))
        challenge := base64.RawURLEncoding.EncodeToString(sha[:])
        return challenge == params.Challenge
    default:
        return false
    }
}