jwt/rs256.go

79 lines
1.9 KiB
Go

package jwt
import (
"crypto"
"crypto/rsa"
"crypto/sha256"
"crypto/x509"
"crypto/rand"
"encoding/pem"
"errors"
)
type SigningMethodRS256 struct{}
func init() {
RegisterSigningMethod("RS256", func() SigningMethod {
return new(SigningMethodRS256)
})
}
func (m *SigningMethodRS256) Alg()string {
return "RS256"
}
func (m *SigningMethodRS256) Verify(signingString, signature string, key []byte) (err error) {
// Key
var sig []byte
if sig, err = DecodeSegment(signature); err == nil {
var block *pem.Block
if block, _ = pem.Decode(key); block != nil {
var parsedKey interface{}
if parsedKey, err = x509.ParsePKIXPublicKey(block.Bytes); err == nil {
if rsaKey, ok := parsedKey.(*rsa.PublicKey); ok {
hasher := sha256.New()
hasher.Write([]byte(signingString))
err = rsa.VerifyPKCS1v15(rsaKey, crypto.SHA256, hasher.Sum(nil), sig)
} else {
err = errors.New("Key is not a valid RSA public key")
}
}
} else {
err = errors.New("Could not parse key data")
}
}
return
}
func (m *SigningMethodRS256) Sign(signingString string, key []byte)(sig string, err error) {
// Key
var rsaKey *rsa.PrivateKey
if rsaKey, err = m.parsePrivateKey(key); err == nil {
hasher := sha256.New()
hasher.Write([]byte(signingString))
var sigBytes []byte
if sigBytes, err = rsa.SignPKCS1v15(rand.Reader, rsaKey, crypto.SHA256, hasher.Sum(nil)); err == nil {
sig = EncodeSegment(sigBytes)
}
}
return
}
func (m *SigningMethodRS256) parsePrivateKey(key []byte)(pkey *rsa.PrivateKey, err error) {
var block *pem.Block
if block, _ = pem.Decode(key); block != nil {
var parsedKey interface{}
if parsedKey, err = x509.ParsePKCS1PrivateKey(block.Bytes); err != nil {
if parsedKey, err = x509.ParsePKCS8PrivateKey(block.Bytes); err != nil {
return nil, err
}
}
var ok bool
if pkey, ok = parsedKey.(*rsa.PrivateKey); !ok {
err = errors.New("Key is not a valid RSA private key")
}
}
return
}