vendor/golang.org/x/crypto/ssh/mac.go

   1 // Copyright 2012 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package ssh
   6
   7 // Message authentication support
   8
   9 import (
  10         "crypto/hmac"
  11         "crypto/sha1"
  12         "crypto/sha256"
  13         "hash"
  14 )
  15
  16 type macMode struct {
  17         keySize int
  18         etm     bool
  19         new     func(key []byte) hash.Hash
  20 }
  21
  22 // truncatingMAC wraps around a hash.Hash and truncates the output digest to
  23 // a given size.
  24 type truncatingMAC struct {
  25         length int
  26         hmac   hash.Hash
  27 }
  28
  29 func (t truncatingMAC) Write(data []byte) (int, error) {
  30         return t.hmac.Write(data)
  31 }
  32
  33 func (t truncatingMAC) Sum(in []byte) []byte {
  34         out := t.hmac.Sum(in)
  35         return out[:len(in)+t.length]
  36 }
  37
  38 func (t truncatingMAC) Reset() {
  39         t.hmac.Reset()
  40 }
  41
  42 func (t truncatingMAC) Size() int {
  43         return t.length
  44 }
  45
  46 func (t truncatingMAC) BlockSize() int { return t.hmac.BlockSize() }
  47
  48 var macModes = map[string]*macMode{
  49         "hmac-sha2-256-etm@openssh.com": {32, true, func(key []byte) hash.Hash {
  50                 return hmac.New(sha256.New, key)
  51         }},
  52         "hmac-sha2-256": {32, false, func(key []byte) hash.Hash {
  53                 return hmac.New(sha256.New, key)
  54         }},
  55         "hmac-sha1": {20, false, func(key []byte) hash.Hash {
  56                 return hmac.New(sha1.New, key)
  57         }},
  58         "hmac-sha1-96": {20, false, func(key []byte) hash.Hash {
  59                 return truncatingMAC{12, hmac.New(sha1.New, key)}
  60         }},
  61 }