rsa_pss.go

//go:build go1.4
// +build go1.4

package jwt

import (
"crypto"
"crypto/rand"
"crypto/rsa"
)

// SigningMethodRSAPSS implements the RSAPSS family of signing methods signing methods
typeSigningMethodRSAPSSstruct {
*SigningMethodRSA
Options*rsa.PSSOptions
// VerifyOptions is optional. If set overrides Options for rsa.VerifyPPS.
// Used to accept tokens signed with rsa.PSSSaltLengthAuto, what doesn't follow
// https://tools.ietf.org/html/rfc7518#section-3.5 but was used previously.
// See https://github.com/dgrijalva/jwt-go/issues/285#issuecomment-437451244 for details.
VerifyOptions*rsa.PSSOptions
}

// Specific instances for RS/PS and company.
var (
SigningMethodPS256*SigningMethodRSAPSS
SigningMethodPS384*SigningMethodRSAPSS
SigningMethodPS512*SigningMethodRSAPSS
)

funcinit() {
// PS256
SigningMethodPS256=&SigningMethodRSAPSS{
SigningMethodRSA: &SigningMethodRSA{
Name: "PS256",
Hash: crypto.SHA256,
 },
Options: &rsa.PSSOptions{
SaltLength: rsa.PSSSaltLengthEqualsHash,
 },
VerifyOptions: &rsa.PSSOptions{
SaltLength: rsa.PSSSaltLengthAuto,
 },
 }
RegisterSigningMethod(SigningMethodPS256.Alg(), func() SigningMethod {
returnSigningMethodPS256
 })

// PS384
SigningMethodPS384=&SigningMethodRSAPSS{
SigningMethodRSA: &SigningMethodRSA{
Name: "PS384",
Hash: crypto.SHA384,
 },
Options: &rsa.PSSOptions{
SaltLength: rsa.PSSSaltLengthEqualsHash,
 },
VerifyOptions: &rsa.PSSOptions{
SaltLength: rsa.PSSSaltLengthAuto,
 },
 }
RegisterSigningMethod(SigningMethodPS384.Alg(), func() SigningMethod {
returnSigningMethodPS384
 })

// PS512
SigningMethodPS512=&SigningMethodRSAPSS{
SigningMethodRSA: &SigningMethodRSA{
Name: "PS512",
Hash: crypto.SHA512,
 },
Options: &rsa.PSSOptions{
SaltLength: rsa.PSSSaltLengthEqualsHash,
 },
VerifyOptions: &rsa.PSSOptions{
SaltLength: rsa.PSSSaltLengthAuto,
 },
 }
RegisterSigningMethod(SigningMethodPS512.Alg(), func() SigningMethod {
returnSigningMethodPS512
 })
}

// Verify implements token verification for the SigningMethod.
// For this verify method, key must be an rsa.PublicKey struct
func (m*SigningMethodRSAPSS) Verify(signingStringstring, sig []byte, keyinterface{}) error {
varrsaKey*rsa.PublicKey
switchk:=key.(type) {
case*rsa.PublicKey:
rsaKey=k
default:
returnnewError("RSA-PSS verify expects *rsa.PublicKey", ErrInvalidKeyType)
 }

// Create hasher
if!m.Hash.Available() {
returnErrHashUnavailable
 }
hasher:=m.Hash.New()
hasher.Write([]byte(signingString))

opts:=m.Options
ifm.VerifyOptions!=nil {
opts=m.VerifyOptions
 }

returnrsa.VerifyPSS(rsaKey, m.Hash, hasher.Sum(nil), sig, opts)
}

// Sign implements token signing for the SigningMethod.
// For this signing method, key must be an rsa.PrivateKey struct
func (m*SigningMethodRSAPSS) Sign(signingStringstring, keyinterface{}) ([]byte, error) {
varrsaKey*rsa.PrivateKey

switchk:=key.(type) {
case*rsa.PrivateKey:
rsaKey=k
default:
returnnil, newError("RSA-PSS sign expects *rsa.PrivateKey", ErrInvalidKeyType)
 }

// Create the hasher
if!m.Hash.Available() {
returnnil, ErrHashUnavailable
 }

hasher:=m.Hash.New()
hasher.Write([]byte(signingString))

// Sign the string and return the encoded bytes
ifsigBytes, err:=rsa.SignPSS(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil), m.Options); err==nil {
returnsigBytes, nil
 } else {
returnnil, err
 }
}