woodpecker/vendor/github.com/dgrijalva/jwt-go/hmac.go

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2015-05-22 18:37:40 +00:00
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
}
func (m *SigningMethodHMAC) Verify(signingString, signature string, key interface{}) error {
if keyBytes, ok := key.([]byte); ok {
var sig []byte
var err error
if sig, err = DecodeSegment(signature); err == nil {
if !m.Hash.Available() {
return ErrHashUnavailable
}
hasher := hmac.New(m.Hash.New, keyBytes)
hasher.Write([]byte(signingString))
if !hmac.Equal(sig, hasher.Sum(nil)) {
err = ErrSignatureInvalid
}
}
return err
}
return ErrInvalidKey
}
// 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
}