Francois Berder / Crypto

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

Files at this revision

API Documentation at this revision

Revision 14:f04410cef037, committed 2014-05-11

Comitter:
feb11
Date:
Sun May 11 13:36:45 2014 +0000
Parent:
13:ac8e23b98dae
Commit message:
CBC mode completed

Changed in this revision

cipher/BlockCipher.cpp Show annotated file Show diff for this revision Revisions of this file 
diff -r ac8e23b98dae -r f04410cef037 cipher/BlockCipher.cpp
--- a/cipher/BlockCipher.cpp	Sun May 11 11:14:51 2014 +0000
+++ b/cipher/BlockCipher.cpp	Sun May 11 13:36:45 2014 +0000
@@ -32,19 +32,41 @@
 
 void BlockCipher::encrypt(uint8_t *out, uint8_t *in, uint32_t length)
 {
+    uint8_t *tmp = 0;
+    if(mode == CBC_MODE)
+        tmp = new uint8_t[getBlockSize()];
     for(uint32_t i = 0; i < length; i += getBlockSize())
     {
-        encryptBlock(&out[i], &in[i]);
+        if(mode == CBC_MODE)
+        {
+            memcpy(tmp, &in[i], getBlockSize());
+            for(int j = 0; j < (int)getBlockSize(); ++j)
+                tmp[j] ^= IV[j];
+                
+            encryptBlock(&out[i], tmp);
         
+            memcpy(IV, &out[i], getBlockSize());
+        }
+        else        
+            encryptBlock(&out[i], &in[i]);
     }
+    if(mode == CBC_MODE)
+        delete[] tmp;
 }
 
 void BlockCipher::decrypt(uint8_t *out, uint8_t *in, uint32_t length)
 {
     for(uint32_t i = 0; i < length; i += getBlockSize())
     {
-        decryptBlock(&out[i], &in[i]);
+        if(mode == CBC_MODE)
+        {
+            decryptBlock(&out[i], &in[i]);
+            for(int j = 0; j < (int)getBlockSize(); ++j)
+                out[i+j] ^= IV[j];
         
+            memcpy(IV, &in[i], getBlockSize());
+        }
+        else        
+            decryptBlock(&out[i], &in[i]);
     }
 }
-