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 #include "SHA256.h"
feb11 0:7a1237bd2d13 2
feb11 0:7a1237bd2d13 3
feb11 0:7a1237bd2d13 4 SHA256::SHA256():
feb11 0:7a1237bd2d13 5 HashAlgorithm(),
feb11 0:7a1237bd2d13 6 algo(SHA_256)
feb11 0:7a1237bd2d13 7 {
feb11 0:7a1237bd2d13 8 }
feb11 0:7a1237bd2d13 9
feb11 5:06cd9c8afa0b 10 void SHA256::update(uint8_t *in, uint32_t length)
feb11 0:7a1237bd2d13 11 {
feb11 5:06cd9c8afa0b 12 algo.update(in, length);
feb11 0:7a1237bd2d13 13 }
feb11 0:7a1237bd2d13 14
feb11 5:06cd9c8afa0b 15 void SHA256::finalize(uint8_t *out)
feb11 0:7a1237bd2d13 16 {
feb11 5:06cd9c8afa0b 17 algo.finalize(out);
feb11 0:7a1237bd2d13 18 }
feb11 0:7a1237bd2d13 19
feb11 0:7a1237bd2d13 20 uint8_t SHA256::outputSize() const
feb11 0:7a1237bd2d13 21 {
feb11 0:7a1237bd2d13 22 return 32;
feb11 0:7a1237bd2d13 23 }
feb11 0:7a1237bd2d13 24
feb11 0:7a1237bd2d13 25 void SHA256::computeDigest(uint8_t *digest, uint8_t *in, uint32_t length)
feb11 0:7a1237bd2d13 26 {
feb11 0:7a1237bd2d13 27 SHA2_32::computeDigest(SHA_256, digest, in, length);
feb11 0:7a1237bd2d13 28 }