1//go:build go1.4
2// +build go1.4
3
4package jwt
5
6import (
7 "crypto"
8 "crypto/rand"
9 "crypto/rsa"
10)
11
12// SigningMethodRSAPSS implements the RSAPSS family of signing methods signing methods
13type SigningMethodRSAPSS struct {
14 *SigningMethodRSA
15 Options *rsa.PSSOptions
16 // VerifyOptions is optional. If set overrides Options for rsa.VerifyPPS.
17 // Used to accept tokens signed with rsa.PSSSaltLengthAuto, what doesn't follow
18 // https://tools.ietf.org/html/rfc7518#section-3.5 but was used previously.
19 // See https://github.com/dgrijalva/jwt-go/issues/285#issuecomment-437451244 for details.
20 VerifyOptions *rsa.PSSOptions
21}
22
23// Specific instances for RS/PS and company.
24var (
25 SigningMethodPS256 *SigningMethodRSAPSS
26 SigningMethodPS384 *SigningMethodRSAPSS
27 SigningMethodPS512 *SigningMethodRSAPSS
28)
29
30func init() {
31 // PS256
32 SigningMethodPS256 = &SigningMethodRSAPSS{
33 SigningMethodRSA: &SigningMethodRSA{
34 Name: "PS256",
35 Hash: crypto.SHA256,
36 },
37 Options: &rsa.PSSOptions{
38 SaltLength: rsa.PSSSaltLengthEqualsHash,
39 },
40 VerifyOptions: &rsa.PSSOptions{
41 SaltLength: rsa.PSSSaltLengthAuto,
42 },
43 }
44 RegisterSigningMethod(SigningMethodPS256.Alg(), func() SigningMethod {
45 return SigningMethodPS256
46 })
47
48 // PS384
49 SigningMethodPS384 = &SigningMethodRSAPSS{
50 SigningMethodRSA: &SigningMethodRSA{
51 Name: "PS384",
52 Hash: crypto.SHA384,
53 },
54 Options: &rsa.PSSOptions{
55 SaltLength: rsa.PSSSaltLengthEqualsHash,
56 },
57 VerifyOptions: &rsa.PSSOptions{
58 SaltLength: rsa.PSSSaltLengthAuto,
59 },
60 }
61 RegisterSigningMethod(SigningMethodPS384.Alg(), func() SigningMethod {
62 return SigningMethodPS384
63 })
64
65 // PS512
66 SigningMethodPS512 = &SigningMethodRSAPSS{
67 SigningMethodRSA: &SigningMethodRSA{
68 Name: "PS512",
69 Hash: crypto.SHA512,
70 },
71 Options: &rsa.PSSOptions{
72 SaltLength: rsa.PSSSaltLengthEqualsHash,
73 },
74 VerifyOptions: &rsa.PSSOptions{
75 SaltLength: rsa.PSSSaltLengthAuto,
76 },
77 }
78 RegisterSigningMethod(SigningMethodPS512.Alg(), func() SigningMethod {
79 return SigningMethodPS512
80 })
81}
82
83// Verify implements token verification for the SigningMethod.
84// For this verify method, key must be an rsa.PublicKey struct
85func (m *SigningMethodRSAPSS) Verify(signingString string, sig []byte, key interface{}) error {
86 var rsaKey *rsa.PublicKey
87 switch k := key.(type) {
88 case *rsa.PublicKey:
89 rsaKey = k
90 default:
91 return newError("RSA-PSS verify expects *rsa.PublicKey", ErrInvalidKeyType)
92 }
93
94 // Create hasher
95 if !m.Hash.Available() {
96 return ErrHashUnavailable
97 }
98 hasher := m.Hash.New()
99 hasher.Write([]byte(signingString))
100
101 opts := m.Options
102 if m.VerifyOptions != nil {
103 opts = m.VerifyOptions
104 }
105
106 return rsa.VerifyPSS(rsaKey, m.Hash, hasher.Sum(nil), sig, opts)
107}
108
109// Sign implements token signing for the SigningMethod.
110// For this signing method, key must be an rsa.PrivateKey struct
111func (m *SigningMethodRSAPSS) Sign(signingString string, key interface{}) ([]byte, error) {
112 var rsaKey *rsa.PrivateKey
113
114 switch k := key.(type) {
115 case *rsa.PrivateKey:
116 rsaKey = k
117 default:
118 return nil, newError("RSA-PSS sign expects *rsa.PrivateKey", ErrInvalidKeyType)
119 }
120
121 // Create the hasher
122 if !m.Hash.Available() {
123 return nil, ErrHashUnavailable
124 }
125
126 hasher := m.Hash.New()
127 hasher.Write([]byte(signingString))
128
129 // Sign the string and return the encoded bytes
130 if sigBytes, err := rsa.SignPSS(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil), m.Options); err == nil {
131 return sigBytes, nil
132 } else {
133 return nil, err
134 }
135}