open-consul/vendor/github.com/SermoDigital/jose/crypto/hmac.go

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2018-06-21 14:49:35 +00:00
package crypto
import (
"crypto"
"crypto/hmac"
"encoding/json"
"errors"
)
// SigningMethodHMAC implements the HMAC-SHA family of SigningMethods.
type SigningMethodHMAC struct {
Name string
Hash crypto.Hash
_ struct{}
}
// Specific instances of HMAC-SHA SigningMethods.
var (
// SigningMethodHS256 implements HS256.
SigningMethodHS256 = &SigningMethodHMAC{
Name: "HS256",
Hash: crypto.SHA256,
}
// SigningMethodHS384 implements HS384.
SigningMethodHS384 = &SigningMethodHMAC{
Name: "HS384",
Hash: crypto.SHA384,
}
// SigningMethodHS512 implements HS512.
SigningMethodHS512 = &SigningMethodHMAC{
Name: "HS512",
Hash: crypto.SHA512,
}
// ErrSignatureInvalid is returned when the provided signature is found
// to be invalid.
ErrSignatureInvalid = errors.New("signature is invalid")
)
// Alg implements the SigningMethod interface.
func (m *SigningMethodHMAC) Alg() string { return m.Name }
// Verify implements the Verify method from SigningMethod.
// For this signing method, must be a []byte.
func (m *SigningMethodHMAC) Verify(raw []byte, signature Signature, key interface{}) error {
keyBytes, ok := key.([]byte)
if !ok {
return ErrInvalidKey
}
hasher := hmac.New(m.Hash.New, keyBytes)
hasher.Write(raw)
if hmac.Equal(signature, hasher.Sum(nil)) {
return nil
}
return ErrSignatureInvalid
}
// Sign implements the Sign method from SigningMethod for this signing method.
// Key must be a []byte.
func (m *SigningMethodHMAC) Sign(data []byte, key interface{}) (Signature, error) {
keyBytes, ok := key.([]byte)
if !ok {
return nil, ErrInvalidKey
}
hasher := hmac.New(m.Hash.New, keyBytes)
hasher.Write(data)
return Signature(hasher.Sum(nil)), nil
}
// Hasher implements the SigningMethod interface.
func (m *SigningMethodHMAC) Hasher() crypto.Hash { return m.Hash }
// MarshalJSON implements json.Marshaler.
// See SigningMethodECDSA.MarshalJSON() for information.
func (m *SigningMethodHMAC) MarshalJSON() ([]byte, error) {
return []byte(`"` + m.Alg() + `"`), nil
}
var _ json.Marshaler = (*SigningMethodHMAC)(nil)