81 lines
1.8 KiB
Go
81 lines
1.8 KiB
Go
package sec
|
|
|
|
import (
|
|
"crypto/rsa"
|
|
"crypto/x509"
|
|
"encoding/base64"
|
|
"encoding/pem"
|
|
"fmt"
|
|
"github.com/golang-jwt/jwt/v5"
|
|
"math/big"
|
|
"os"
|
|
)
|
|
|
|
type JwtReader struct {
|
|
key *rsa.PublicKey
|
|
}
|
|
|
|
func NewJwtReader(fp string) (*JwtReader, error) {
|
|
rawKey, err := os.ReadFile(fp)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
block, _ := pem.Decode(rawKey)
|
|
if block == nil || block.Type != "PUBLIC KEY" {
|
|
return nil, fmt.Errorf("failed to decode PEM block containing private key")
|
|
}
|
|
|
|
anyPk, err := x509.ParsePKIXPublicKey(block.Bytes)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
pk, ok := anyPk.(*rsa.PublicKey)
|
|
if !ok {
|
|
return nil, fmt.Errorf("not an RSA public key")
|
|
}
|
|
|
|
return &JwtReader{
|
|
key: pk,
|
|
}, nil
|
|
}
|
|
|
|
// ReadJwt is the helper method to help me validate and parse jwt.
|
|
// 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 {
|
|
return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
|
|
}
|
|
return v.key, nil
|
|
})
|
|
if err != nil {
|
|
return out, err
|
|
} else if !token.Valid {
|
|
return out, fmt.Errorf("token is not valid")
|
|
}
|
|
|
|
if claims, ok := token.Claims.(T); ok {
|
|
return claims, nil
|
|
} else {
|
|
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))),
|
|
}
|
|
}
|