From 25ab1371739b03a5e569a7d32a1b6315fb4aa9b9 Mon Sep 17 00:00:00 2001
From: LittleSheep <littlesheep.code@hotmail.com>
Date: Sat, 23 Nov 2024 13:06:05 +0800
Subject: [PATCH] :sparkles: Support build jwk from jwt reader

---
 pkg/nex/sec/jwt_reader.go | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/pkg/nex/sec/jwt_reader.go b/pkg/nex/sec/jwt_reader.go
index 9963bfe..2584a26 100644
--- a/pkg/nex/sec/jwt_reader.go
+++ b/pkg/nex/sec/jwt_reader.go
@@ -3,9 +3,11 @@ package sec
 import (
 	"crypto/rsa"
 	"crypto/x509"
+	"encoding/base64"
 	"encoding/pem"
 	"fmt"
 	"github.com/golang-jwt/jwt/v5"
+	"math/big"
 	"os"
 )
 
@@ -40,8 +42,8 @@ func NewJwtReader(fp string) (*JwtReader, error) {
 }
 
 // ReadJwt is the helper method to help me validate and parse jwt.
-// To use it, pass the initialized jwt reader which contains public key.
-// And pass the token string, and a pointer struct (you must initialize it, which it cannot be nil) of your claims
+// To use it, pass the initialized jwt reader which contains a public key.
+// And pass the token string and a pointer struct (you must initialize it, which it cannot be nil) of your claims
 func ReadJwt[T jwt.Claims](v *JwtReader, in string, out T) (T, error) {
 	token, err := jwt.ParseWithClaims(in, out, func(token *jwt.Token) (interface{}, error) {
 		if _, ok := token.Method.(*jwt.SigningMethodRSA); !ok {
@@ -61,3 +63,18 @@ func ReadJwt[T jwt.Claims](v *JwtReader, in string, out T) (T, error) {
 		return out, err
 	}
 }
+
+func (v *JwtReader) BuildJwk(kid string) map[string]any {
+	encodeBigInt := func(i *big.Int) string {
+		return base64.RawURLEncoding.EncodeToString(i.Bytes())
+	}
+
+	return map[string]any{
+		"kid": kid,
+		"kty": "RSA",
+		"use": "sig",
+		"alg": "RS256",
+		"n":   encodeBigInt(v.key.N),
+		"e":   encodeBigInt(big.NewInt(int64(v.key.E))),
+	}
+}