/usr/share/gocode/src/github.com/dgrijalva/jwt-go/hmac.go is in golang-github-dgrijalva-jwt-go-dev 3.0.0.1+REALLY.2.6.0-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 | package jwt
import (
"crypto"
"crypto/hmac"
"errors"
)
// Implements the HMAC-SHA family of signing methods signing methods
type SigningMethodHMAC struct {
Name string
Hash crypto.Hash
}
// Specific instances for HS256 and company
var (
SigningMethodHS256 *SigningMethodHMAC
SigningMethodHS384 *SigningMethodHMAC
SigningMethodHS512 *SigningMethodHMAC
ErrSignatureInvalid = errors.New("signature is invalid")
)
func init() {
// HS256
SigningMethodHS256 = &SigningMethodHMAC{"HS256", crypto.SHA256}
RegisterSigningMethod(SigningMethodHS256.Alg(), func() SigningMethod {
return SigningMethodHS256
})
// HS384
SigningMethodHS384 = &SigningMethodHMAC{"HS384", crypto.SHA384}
RegisterSigningMethod(SigningMethodHS384.Alg(), func() SigningMethod {
return SigningMethodHS384
})
// HS512
SigningMethodHS512 = &SigningMethodHMAC{"HS512", crypto.SHA512}
RegisterSigningMethod(SigningMethodHS512.Alg(), func() SigningMethod {
return SigningMethodHS512
})
}
func (m *SigningMethodHMAC) Alg() string {
return m.Name
}
// Verify the signature of HSXXX tokens. Returns nil if the signature is valid.
func (m *SigningMethodHMAC) Verify(signingString, signature string, key interface{}) error {
// Verify the key is the right type
keyBytes, ok := key.([]byte)
if !ok {
return ErrInvalidKey
}
// Decode signature, for comparison
sig, err := DecodeSegment(signature)
if err != nil {
return err
}
// Can we use the specified hashing method?
if !m.Hash.Available() {
return ErrHashUnavailable
}
// This signing method is symmetric, so we validate the signature
// by reproducing the signature from the signing string and key, then
// comparing that against the provided signature.
hasher := hmac.New(m.Hash.New, keyBytes)
hasher.Write([]byte(signingString))
if !hmac.Equal(sig, hasher.Sum(nil)) {
return ErrSignatureInvalid
}
// No validation errors. Signature is good.
return nil
}
// Implements the Sign method from SigningMethod for this signing method.
// Key must be []byte
func (m *SigningMethodHMAC) Sign(signingString string, key interface{}) (string, error) {
if keyBytes, ok := key.([]byte); ok {
if !m.Hash.Available() {
return "", ErrHashUnavailable
}
hasher := hmac.New(m.Hash.New, keyBytes)
hasher.Write([]byte(signingString))
return EncodeSegment(hasher.Sum(nil)), nil
}
return "", ErrInvalidKey
}
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