mac.go raw

   1  // Copyright 2015 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 pkcs12
   6  
   7  import (
   8  	"crypto/hmac"
   9  	"crypto/sha1"
  10  	"crypto/x509/pkix"
  11  	"encoding/asn1"
  12  )
  13  
  14  type macData struct {
  15  	Mac        digestInfo
  16  	MacSalt    []byte
  17  	Iterations int `asn1:"optional,default:1"`
  18  }
  19  
  20  // from PKCS#7:
  21  type digestInfo struct {
  22  	Algorithm pkix.AlgorithmIdentifier
  23  	Digest    []byte
  24  }
  25  
  26  var (
  27  	oidSHA1 = asn1.ObjectIdentifier([]int{1, 3, 14, 3, 2, 26})
  28  )
  29  
  30  func verifyMac(macData *macData, message, password []byte) error {
  31  	if !macData.Mac.Algorithm.Algorithm.Equal(oidSHA1) {
  32  		return NotImplementedError("unknown digest algorithm: " + macData.Mac.Algorithm.Algorithm.String())
  33  	}
  34  
  35  	key := pbkdf(sha1Sum, 20, 64, macData.MacSalt, password, macData.Iterations, 3, 20)
  36  
  37  	mac := hmac.New(sha1.New, key)
  38  	mac.Write(message)
  39  	expectedMAC := mac.Sum(nil)
  40  
  41  	if !hmac.Equal(macData.Mac.Digest, expectedMAC) {
  42  		return ErrIncorrectPassword
  43  	}
  44  	return nil
  45  }
  46