This library implements some hash and cryptographic algorithms.

Dependents:   mBuinoBlinky PB_Emma_Ethernet SLOTrashHTTP Garagem ... more

This library implements the following algorithms :

  • RC4
  • AES (AES-128, AES-192, AES-256)
  • DES
  • Triple DES (EDE)
  • MD2
  • MD4
  • MD5
  • SHA-1
  • SHA-2 (SHA-224, SHA-256, SHA-384, SHA-512)

The hash algorithms have been optimized for the mbed and you should get decent performance. However, I did not optimize the ciphers. Also, I did not test extensively these algorithms : it should work but you may find some bugs. Block ciphers support two modes : ECB and CBC.

Warning

If you are using SHA-384 or SHA-512, be aware that it produces large binary files and the compilation (using the online compiler) takes much longer to execute. It may happen that the compiler stops because it timed-out. In this case, just compile again and it should work.

Computing hash

You can compute the hash of some data in two different ways. The first one is the easiest, each hash algorithm has a static method that takes some data and compute the hash from it.

Computing hash using method 1

#include "Crypto.h"
#include "mbed.h"

static const char msg[] = "mbed is great !";

int main()
{
    uint8_t hash[16];
    MD2::computeHash(hash, (uint8_t*)msg, strlen(msg));
    printf("hash: ");
    for(int i = 0; i < 16; ++i)
        printf("%02x", hash[i]);
    printf("\n");
    
    return 0;
}

The second one is slightly slower (around 2-3% slower) but it allows you to compute the hash of some data in several steps (by calling update method). This is the method you should use if you need to compute the hash from a large source and you don't have enough memory to store it in a single buffer.

Computing hash using method 2

#include "Crypto.h"
#include "mbed.h"

static const char msg[] = "mbed is great !";

int main()
{
    uint8_t hash[16];
    MD2 h;
    h.update((uint8_t*)msg, strlen(msg));
    h.finalize(hash);
    printf("hash: ");
    for(int i = 0; i < 16; ++i)
        printf("%02x", hash[i]);
    printf("\n");
    
    return 0;
}

TODO

  • optimize ciphers
  • add doc
Committer:
feb11
Date:
Thu Sep 12 15:08:51 2013 +0000
Revision:
5:06cd9c8afa0b
Parent:
0:7a1237bd2d13
Child:
6:19aa835f2bbb
change API & small improvements in SHA-2

Who changed what in which revision?

UserRevisionLine numberNew contents of line
feb11 0:7a1237bd2d13 1 #ifndef MD5_H
feb11 0:7a1237bd2d13 2 #define MD5_H
feb11 0:7a1237bd2d13 3
feb11 0:7a1237bd2d13 4 #include "HashAlgorithm.h"
feb11 0:7a1237bd2d13 5
feb11 0:7a1237bd2d13 6
feb11 0:7a1237bd2d13 7 class MD5 : public HashAlgorithm
feb11 0:7a1237bd2d13 8 {
feb11 0:7a1237bd2d13 9 public :
feb11 0:7a1237bd2d13 10
feb11 0:7a1237bd2d13 11 MD5();
feb11 0:7a1237bd2d13 12
feb11 5:06cd9c8afa0b 13 virtual void update(uint8_t *in, uint32_t length);
feb11 5:06cd9c8afa0b 14 virtual void finalize(uint8_t *out);
feb11 0:7a1237bd2d13 15 virtual uint8_t outputSize() const;
feb11 0:7a1237bd2d13 16
feb11 0:7a1237bd2d13 17 static void computeDigest(uint8_t *digest, uint8_t *in, uint32_t length);
feb11 0:7a1237bd2d13 18
feb11 0:7a1237bd2d13 19 private :
feb11 0:7a1237bd2d13 20
feb11 0:7a1237bd2d13 21 static void computeRounds(uint32_t *a2, uint32_t *b2, uint32_t *c2, uint32_t *d2, uint8_t *buffer);
feb11 0:7a1237bd2d13 22
feb11 0:7a1237bd2d13 23 uint32_t a,b,c,d;
feb11 0:7a1237bd2d13 24 uint32_t totalBufferLength;
feb11 0:7a1237bd2d13 25 uint8_t buffer[64];
feb11 0:7a1237bd2d13 26 uint8_t bufferLength;
feb11 0:7a1237bd2d13 27 };
feb11 0:7a1237bd2d13 28
feb11 0:7a1237bd2d13 29 #endif