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