1package jwt
2
3import (
4 "crypto"
5 "crypto/rand"
6 "crypto/rsa"
7)
8
9// SigningMethodRSA implements the RSA family of signing methods.
10// Expects *rsa.PrivateKey for signing and *rsa.PublicKey for validation
11type SigningMethodRSA struct {
12 Name string
13 Hash crypto.Hash
14}
15
16// Specific instances for RS256 and company
17var (
18 SigningMethodRS256 *SigningMethodRSA
19 SigningMethodRS384 *SigningMethodRSA
20 SigningMethodRS512 *SigningMethodRSA
21)
22
23func init() {
24 // RS256
25 SigningMethodRS256 = &SigningMethodRSA{"RS256", crypto.SHA256}
26 RegisterSigningMethod(SigningMethodRS256.Alg(), func() SigningMethod {
27 return SigningMethodRS256
28 })
29
30 // RS384
31 SigningMethodRS384 = &SigningMethodRSA{"RS384", crypto.SHA384}
32 RegisterSigningMethod(SigningMethodRS384.Alg(), func() SigningMethod {
33 return SigningMethodRS384
34 })
35
36 // RS512
37 SigningMethodRS512 = &SigningMethodRSA{"RS512", crypto.SHA512}
38 RegisterSigningMethod(SigningMethodRS512.Alg(), func() SigningMethod {
39 return SigningMethodRS512
40 })
41}
42
43func (m *SigningMethodRSA) Alg() string {
44 return m.Name
45}
46
47// Verify implements token verification for the SigningMethod
48// For this signing method, must be an *rsa.PublicKey structure.
49func (m *SigningMethodRSA) Verify(signingString string, sig []byte, key interface{}) error {
50 var rsaKey *rsa.PublicKey
51 var ok bool
52
53 if rsaKey, ok = key.(*rsa.PublicKey); !ok {
54 return newError("RSA verify expects *rsa.PublicKey", ErrInvalidKeyType)
55 }
56
57 // Create hasher
58 if !m.Hash.Available() {
59 return ErrHashUnavailable
60 }
61 hasher := m.Hash.New()
62 hasher.Write([]byte(signingString))
63
64 // Verify the signature
65 return rsa.VerifyPKCS1v15(rsaKey, m.Hash, hasher.Sum(nil), sig)
66}
67
68// Sign implements token signing for the SigningMethod
69// For this signing method, must be an *rsa.PrivateKey structure.
70func (m *SigningMethodRSA) Sign(signingString string, key interface{}) ([]byte, error) {
71 var rsaKey *rsa.PrivateKey
72 var ok bool
73
74 // Validate type of key
75 if rsaKey, ok = key.(*rsa.PrivateKey); !ok {
76 return nil, newError("RSA sign expects *rsa.PrivateKey", ErrInvalidKeyType)
77 }
78
79 // Create the hasher
80 if !m.Hash.Available() {
81 return nil, ErrHashUnavailable
82 }
83
84 hasher := m.Hash.New()
85 hasher.Write([]byte(signingString))
86
87 // Sign the string and return the encoded bytes
88 if sigBytes, err := rsa.SignPKCS1v15(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil)); err == nil {
89 return sigBytes, nil
90 } else {
91 return nil, err
92 }
93}