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CHash 1.5 - An MFC hashing class

, 8 Aug 2005 156.1K 6.4K 104
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An MFC implementation of hashing files and strings with CRC32, GOST-Hash, MD2, MD4, MD5, SHA-1 and SHA-2 (256/384/512).

Introduction

A few times I've seen implementations of individual hashing algorithms, and thought it may be a good idea to group them together in an easy to use class. Well, here it is.

What are hashes anyway?

Hashes are a string of letters/numbers. They are used as a representation of an amount of data, but they are one way, you cannot go from a hash back to the original data; as hashes are fixed length, you also cannot determine the length or amount of the data represented. This lends hashes to practical security uses, as well as integrity uses.

Why use hashes?

There are multiple uses for hashes, the main one being data integrity. For example, a P2P client would use hashes to validate a file on completion, to check it's not corrupt or "fake". In this way, by generating a hash of a file, you can compare it against another hash, and check whether the files are the same.

Using the code

Putting CHash into use is relatively simple.

The main functions that will be used are:

  • DoHash
  • SetHashAlgorithm
  • SetHashFile
  • SetHashOperation
  • SetHashString

An example of hashing a string with MD5:

// Define a CHash object
CHash hashObj;

// Set the algorithm
hashObj.SetHashAlgorithm(MD5);

// Set the operation
hashObj.SetHashOperation(STRING_HASH);

// Set the string
hashObj.SetHashString("String to hash");

// Hash the string
CString outHash = hashObj.DoHash();

An example of hashing a file with SHA-1:

// Define a CHash object
CHash hashObj;

// Set the algorithm
hashObj.SetHashAlgorithm(SHA1);

// Set the operation
hashObj.SetHashOperation(FILE_HASH);

// Set the file
hashObj.SetHashFile("C:\\Windows\\Explorer.exe");

// Hash the file
CString outHash = hashObj.DoHash();

The code is the same throughout, except for SHA-2, which has an extra function, SetSHA2Strength, which takes one parameter, the strength of the hash, which can be 256, 384 or 512.

An example usage of this is:

// Define a CHash object
CHash hashObj;

// Set the operation
hashObj.SetHashOperation(FILE_HASH);

// Set the algorithm
hashObj.SetHashAlgorithm(SHA2);

// Set the SHA-2 strength
hashObj.SetSHA2Strength(256);

// Set the file
hashObj.SetHashFile("C:\\Windows\\Explorer.exe");

// Hash the file
CString outHash = hashObj.DoHash();

Choosing which algorithms to include

In version 1.5, I made the class modular, so you can exclude/include specific algorithms (cutting down on unnecessary code if you don't want certain ones). To choose which you want to use, go to CHash.h, and find:

// Choose which algorithms you want
// Put 1s to support algorithms, else 0 to not support

Under here you will find defines such as:

#define        SUPPORT_CRC32          1 

Change the 1s to 0s if you wish to exclude an algorithm.

Hashing styles

In version 1.2, I added hashing styles. This allows the programmer to customize the output hashes. There are four styles:

  • Lowercase, no spaces:
    b4df98798c02b7c7a500d18632bf5b7d
  • Lowercase, spaces:
    b4 df 98 79 8c 02 b7 c7 a5 00 d1 86 32 bf 5b 7d
  • Uppercase, no spaces:
    B4DF98798C02B7C7A500D18632BF5B7Dd
  • Uppercase, spaces:
    B4 DF 98 79 8C 02 B7 C7 A5 00 D1 86 32 BF 5B 7D

These can be set with SetHashFormat().

Acknowledgements

  • Thanks to Dominik Reichl for his excellent ReHash program.
  • Thanks to Markku-Juhani O. Saarinen for his GOST-Hash implementation.
  • Thanks to Dr. Brian Gladman for the SHA-1/SHA-2 implementations.

History

  • 1.0
    • 1st May, 2005: First public release.
  • 1.1
    • 2nd May, 2005: Added SetHashAlgorithm() and DoHash() as recommended.
  • 1.2
    • 3rd May, 2005:
      • Added hashing styles.
      • Added the GOSTHash algorithm.
      • Added GetHashAlgorithm().
      • Rewrote the hashing functions to be more efficient.
  • 1.3
    • 4th May, 2005: Updated the demo project.
  • 1.5
    • 8th May, 2005:
      • Added CRC32.
      • Made the class "modular" so that you can exclude algorithms from compile.
      • Added GetHashFormat().
      • Updated the code as suggested.
  • 1.6
    • 3rd August, 2005:
      • Fixed a memory leak.
      • Made each hash more efficient, tidied up code in general.
  • License

    This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

    A list of licenses authors might use can be found here

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    About the Author

    .rich.w
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    United States United States
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    Comments and Discussions

     
    GeneralMy vote of 5 Pin
    toann29-Jul-11 7:41
    membertoann29-Jul-11 7:41 
    Generalsome function suggestions Pin
    xtrmblop20-May-10 4:54
    memberxtrmblop20-May-10 4:54 
    Generalsmall bug in CHash.cpp Pin
    xtrmblop20-May-10 0:15
    memberxtrmblop20-May-10 0:15 
    GeneralRe: small bug in CHash.cpp Pin
    Omar.Pessoa26-Jan-12 0:13
    memberOmar.Pessoa26-Jan-12 0:13 
    Generalsmall bug [modified] Pin
    atom6667-Nov-08 2:04
    memberatom6667-Nov-08 2:04 
    Generalerror when choosing algorithms to support Pin
    breakpoint4-Apr-06 1:00
    memberbreakpoint4-Apr-06 1:00 
    GeneralDecrypt back to plaintext Pin
    shinyhui26-Sep-05 14:27
    membershinyhui26-Sep-05 14:27 
    GeneralRe: Decrypt back to plaintext Pin
    .rich.w27-Sep-05 4:07
    member.rich.w27-Sep-05 4:07 
    GeneralRe: Decrypt back to plaintext Pin
    shinyhui27-Sep-05 14:17
    membershinyhui27-Sep-05 14:17 
    Of course i understand what is that!! just wanna ask whether got any to decrypt it back to plaintext or not...
    GeneralRe: Decrypt back to plaintext Pin
    .rich.w28-Sep-05 4:00
    member.rich.w28-Sep-05 4:00 
    GeneralRe: Decrypt back to plaintext Pin
    shinyhui28-Sep-05 15:10
    membershinyhui28-Sep-05 15:10 
    GeneralRe: Decrypt back to plaintext Pin
    banjaxx6-Mar-06 20:37
    memberbanjaxx6-Mar-06 20:37 
    GeneralI vote Pin
    peder88819-Aug-05 4:40
    memberpeder88819-Aug-05 4:40 
    Generalreturn values not defined... Pin
    bevpet9-Aug-05 6:48
    memberbevpet9-Aug-05 6:48 
    QuestionWhy all these seperate classes? Pin
    Geert van Horrik9-Aug-05 1:07
    memberGeert van Horrik9-Aug-05 1:07 
    AnswerRe: Why all these seperate classes? Pin
    bevpet9-Aug-05 6:59
    memberbevpet9-Aug-05 6:59 
    GeneralRe: Why all these seperate classes? Pin
    .rich.w19-Aug-05 19:59
    member.rich.w19-Aug-05 19:59 
    GeneralUsing hash on files Pin
    Geert van Horrik9-Aug-05 1:04
    memberGeert van Horrik9-Aug-05 1:04 
    GeneralRe: Using hash on files Pin
    .rich.w19-Aug-05 19:58
    member.rich.w19-Aug-05 19:58 
    JokeC-Hash :-) Pin
    Nishant Sivakumar8-Aug-05 23:34
    staffNishant Sivakumar8-Aug-05 23:34 
    GeneralRe: C-Hash :-) Pin
    bevpet9-Aug-05 6:56
    memberbevpet9-Aug-05 6:56 
    Generalcheck if file exists before attempting hash Pin
    bevpet27-May-05 6:02
    memberbevpet27-May-05 6:02 
    GeneralRe: check if file exists before attempting hash Pin
    .rich.w31-May-05 0:37
    member.rich.w31-May-05 0:37 
    Generalnice work.. Pin
    bevpet26-May-05 18:00
    memberbevpet26-May-05 18:00 
    GeneralSpeed Pin
    dennisV24-May-05 19:08
    memberdennisV24-May-05 19:08 
    GeneralRe: Speed Pin
    .rich.w25-May-05 4:01
    member.rich.w25-May-05 4:01 
    GeneralNewbie on hashes Pin
    Johann Gerell14-May-05 22:46
    memberJohann Gerell14-May-05 22:46 
    GeneralRe: Newbie on hashes Pin
    .rich.w15-May-05 8:24
    member.rich.w15-May-05 8:24 
    GeneralRe: Newbie on hashes Pin
    Anonymous16-Jun-05 12:16
    sussAnonymous16-Jun-05 12:16 
    GeneralRe: Newbie on hashes Pin
    StrayJay12-Aug-05 9:54
    memberStrayJay12-Aug-05 9:54 
    GeneralGood work and a lot of updates Pin
    Mike Angel Martin7-May-05 8:21
    memberMike Angel Martin7-May-05 8:21 
    GeneralRe: Good work and a lot of updates Pin
    .rich.w7-May-05 22:53
    member.rich.w7-May-05 22:53 
    GeneralMake it more complete. Pin
    WREY3-May-05 5:31
    memberWREY3-May-05 5:31 
    GeneralRe: Make it more complete. Pin
    .rich.w3-May-05 5:48
    member.rich.w3-May-05 5:48 
    GeneralDone Pin
    .rich.w3-May-05 6:35
    member.rich.w3-May-05 6:35 
    GeneralVery Nice. Pin
    WREY8-May-05 12:13
    memberWREY8-May-05 12:13 
    GeneralHash Pin
    Anon E. Mouse2-May-05 9:42
    memberAnon E. Mouse2-May-05 9:42 
    GeneralRe: Hash Pin
    .rich.w2-May-05 10:11
    member.rich.w2-May-05 10:11 
    GeneralRe: Hash Pin
    Anon E. Mouse2-May-05 10:46
    memberAnon E. Mouse2-May-05 10:46 
    GeneralGood Work Pin
    Jaxyboi1-May-05 23:45
    memberJaxyboi1-May-05 23:45 
    GeneralGood Idea - Bad implementation Pin
    Mike Eriksson1-May-05 22:43
    memberMike Eriksson1-May-05 22:43 
    GeneralRe: Good Idea - Bad implementation Pin
    .rich.w1-May-05 23:39
    suss.rich.w1-May-05 23:39 
    GeneralRe: Good Idea - Bad implementation Pin
    Mike Eriksson1-May-05 23:53
    memberMike Eriksson1-May-05 23:53 
    GeneralNew implementation, article, source and demo updated Pin
    .rich.w2-May-05 0:00
    member.rich.w2-May-05 0:00 
    GeneralRe: Good Idea - Bad implementation Pin
    Blake Miller2-May-05 9:23
    memberBlake Miller2-May-05 9:23 
    GeneralRe: Good Idea - Bad implementation Pin
    StrayJay3-May-05 12:11
    memberStrayJay3-May-05 12:11 
    GeneralNew version, 1.5 Pin
    .rich.w7-May-05 0:45
    member.rich.w7-May-05 0:45 
    GeneralGood suggestions. Pin
    WREY8-May-05 11:57
    memberWREY8-May-05 11:57 

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