switch to maintained lib (#16532)

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Andrew Thornton <art27@cantab.net>

vendor/github.com/golang-jwt/jwt/rsa_pss.go

@@ -0,0 +1,142 @@
+// +build go1.4
+
+package jwt
+
+import (
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+)
+
+// Implements the RSAPSS family of signing methods signing methods
+type SigningMethodRSAPSS struct {
+	*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
+)
+
+func init() {
+	// 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 {
+		return SigningMethodPS256
+	})
+
+	// 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 {
+		return SigningMethodPS384
+	})
+
+	// 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 {
+		return SigningMethodPS512
+	})
+}
+
+// Implements the Verify method from SigningMethod
+// For this verify method, key must be an rsa.PublicKey struct
+func (m *SigningMethodRSAPSS) Verify(signingString, signature string, key interface{}) error {
+	var err error
+
+	// Decode the signature
+	var sig []byte
+	if sig, err = DecodeSegment(signature); err != nil {
+		return err
+	}
+
+	var rsaKey *rsa.PublicKey
+	switch k := key.(type) {
+	case *rsa.PublicKey:
+		rsaKey = k
+	default:
+		return ErrInvalidKey
+	}
+
+	// Create hasher
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	opts := m.Options
+	if m.VerifyOptions != nil {
+		opts = m.VerifyOptions
+	}
+
+	return rsa.VerifyPSS(rsaKey, m.Hash, hasher.Sum(nil), sig, opts)
+}
+
+// Implements the Sign method from SigningMethod
+// For this signing method, key must be an rsa.PrivateKey struct
+func (m *SigningMethodRSAPSS) Sign(signingString string, key interface{}) (string, error) {
+	var rsaKey *rsa.PrivateKey
+
+	switch k := key.(type) {
+	case *rsa.PrivateKey:
+		rsaKey = k
+	default:
+		return "", ErrInvalidKeyType
+	}
+
+	// Create the hasher
+	if !m.Hash.Available() {
+		return "", ErrHashUnavailable
+	}
+
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Sign the string and return the encoded bytes
+	if sigBytes, err := rsa.SignPSS(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil), m.Options); err == nil {
+		return EncodeSegment(sigBytes), nil
+	} else {
+		return "", err
+	}
+}