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

SHA1.cpp

Committer:
feb11
Date:
2013-09-09
Revision:
1:14a7cea431aa
Parent:
0:7a1237bd2d13
Child:
2:473bac39ae7c

File content as of revision 1:14a7cea431aa:

#include "SHA1.h"
#include <string.h>

static uint32_t f(uint8_t t, uint32_t B, uint32_t C, uint32_t D)
{
    if(t <= 19)
        return (B & C) | ((~B) & D);
    else if(t <= 39)
        return B ^ C ^ D;
    else if(t <= 59)
        return (B & C) | (B & D) | (C & D);
    else if(t <= 79)
        return B ^ C ^ D;
    
    return 0;
}

static uint32_t K(uint8_t t)
{
    if(t <= 19)
      return 0x5A827999;
    else if(t <= 39)
      return 0x6ED9EBA1;
    else if(t <= 59)
      return 0x8F1BBCDC;
    else if(t <= 79)
      return 0xCA62C1D6;
    
    return 0;
}

static uint32_t rotLeft(uint32_t w, uint8_t n)
{
    return (w << n) | (w >> (32-n));
}

static const uint32_t H0 = 0x67452301;
static const uint32_t H1 = 0xEFCDAB89;
static const uint32_t H2 = 0x98BADCFE;
static const uint32_t H3 = 0x10325476;
static const uint32_t H4 = 0xC3D2E1F0;
static const uint32_t MASK = 0x0000000F;


SHA1::SHA1():
HashAlgorithm(),
h0(H0),
h1(H1),
h2(H2),
h3(H3),
h4(H4),
totalBufferLength(0),
buffer(),
bufferLength(0)
{
}

uint8_t SHA1::outputSize() const
{
    return 20;
}

void SHA1::add(uint8_t *in, uint32_t length)
{
    if(length < 64-bufferLength)
    {
        memcpy(&buffer[bufferLength], in, length);
        bufferLength += length;
        totalBufferLength += length;
        return;
    }
    int offset = 64-bufferLength;
    memcpy(&buffer[bufferLength], in, offset);
    computeBlock(&h0,&h1,&h2,&h3,&h4, buffer);
    while(length-offset > 64)
    {
        memcpy(buffer, &in[offset], 64);
        computeBlock(&h0,&h1,&h2,&h3,&h4, buffer);
        offset += 64;
    }
    if(offset > length)
        offset -= 64;
    bufferLength = length - offset;
    memcpy(buffer, &in[offset], bufferLength);
    totalBufferLength += length;
}

void SHA1::computeDigest(uint8_t *digest)
{
    uint16_t padding;
    if(totalBufferLength % 64 < 56)
        padding = 56 - (totalBufferLength % 64);
    else
        padding = 56 + (64 - (totalBufferLength % 64));
    uint8_t val = 0x80;
    add(&val, 1);
    val = 0;
    for(int i = 0; i < padding-1; ++i)
        add(&val,1);
    totalBufferLength -= padding;
    uint64_t lengthBit = totalBufferLength * 8;
    uint32_t lengthBitLow = lengthBit;
    uint32_t lengthBitHigh = lengthBit >> 32;
    uint8_t l[4];

    l[0] = lengthBitHigh >> 24;
    l[1] = lengthBitHigh >> 16;
    l[2] = lengthBitHigh >> 8;
    l[3] = lengthBitHigh;
    add(l, 4);
    l[0] = lengthBitLow >> 24;
    l[1] = lengthBitLow >> 16;
    l[2] = lengthBitLow >> 8;
    l[3] = lengthBitLow;
    add(l, 4);

    digest[0] = h0 >> 24;
    digest[1] = h0 >> 16;
    digest[2] = h0 >> 8;
    digest[3] = h0;
    digest[4] = h1 >> 24;
    digest[5] = h1 >> 16;
    digest[6] = h1 >> 8;
    digest[7] = h1;
    digest[8] = h2 >> 24;
    digest[9] = h2 >> 16;
    digest[10] = h2 >> 8;
    digest[11] = h2;
    digest[12] = h3 >> 24;
    digest[13] = h3 >> 16;
    digest[14] = h3 >> 8;
    digest[15] = h3;
    digest[16] = h4 >> 24;
    digest[17] = h4 >> 16;
    digest[18] = h4 >> 8;
    digest[19] = h4;
    
    // reset state
    h0 = H0;
    h1 = H1;
    h2 = H2;
    h3 = H3;
    h4 = H4;
    totalBufferLength = 0;
    bufferLength = 0;
}

void SHA1::computeBlock(uint32_t *h02, uint32_t *h12, uint32_t *h22, uint32_t *h32, uint32_t *h42, uint8_t *buffer)
{
    uint32_t w[16];
    for(int j = 0; j < 16; ++j)
        w[j] = (buffer[j*4] << 24) | (buffer[j*4+1] << 16) | (buffer[j*4+2] << 8) | buffer[j*4+3];
    
    uint32_t a = *h02, b = *h12, c = *h22, d = *h32, e = *h42;
    for(uint8_t t = 0; t < 80; ++t)
    {
        uint32_t s = t & MASK;
        if(t >= 16)
        {
            w[s%16] = w[((s + 13) & MASK)%16] ^ w[((s + 8) & MASK)%16] ^ w[((s + 2) & MASK)%16] ^ w[s%16];
            w[s%16] = rotLeft(w[s%16], 1);
        }
        
        uint32_t temp = rotLeft(a, 5) + f(t, b, c, d) + e + w[s%16] + K(t);
        e = d;
        d = c;
        c = rotLeft(b,30);
        b = a;
        a = temp;
    }
    *h02 += a;
    *h12 += b;
    *h22 += c;
    *h32 += d;
    *h42 += e;
}



/* method 2 */
void SHA1::computeDigest(uint8_t *digest, uint8_t *in, uint32_t length)
{
    uint16_t padding;
    if(length % 64 < 56)
        padding = 56 - (length % 64);
    else
        padding = 56 + (64 - (length % 64));
        
    uint32_t h0 = H0, h1 = H1, h2 = H2, h3 = H3, h4 = H4;
    uint32_t offset = 0;
    while(length - offset >= 64)
    {
        computeBlock(&h0,&h1,&h2,&h3,&h4, &in[offset]);
        offset += 64;
    }

    uint8_t bufferLength = length - offset;
    uint8_t buffer[64];
    memcpy(buffer, &in[offset], bufferLength);
    buffer[bufferLength++] = 0x80;
    padding--;
    while(padding > 0)
    {
        if(bufferLength == 64)
        {
            computeBlock(&h0,&h1,&h2,&h3,&h4, buffer);
            bufferLength++;
        }
        buffer[bufferLength++] = 0;
        padding--;
    }
    uint64_t lengthBit = length * 8;
    uint32_t lengthBitLow = lengthBit;
    uint32_t lengthBitHigh = lengthBit >> 32;
    uint8_t l[4];
    l[0] = lengthBitLow >> 24;
    l[1] = lengthBitLow >> 16;
    l[2] = lengthBitLow >> 8;
    l[3] = lengthBitLow;
    memcpy(&buffer[60], l, 4);
    l[0] = lengthBitHigh >> 24;
    l[1] = lengthBitHigh >> 16;
    l[2] = lengthBitHigh >> 8;
    l[3] = lengthBitHigh;
    memcpy(&buffer[56], l, 4);
    
    computeBlock(&h0,&h1,&h2,&h3,&h4, buffer);

    digest[0] = h0 >> 24;
    digest[1] = h0 >> 16;
    digest[2] = h0 >> 8;
    digest[3] = h0;
    digest[4] = h1 >> 24;
    digest[5] = h1 >> 16;
    digest[6] = h1 >> 8;
    digest[7] = h1;
    digest[8] = h2 >> 24;
    digest[9] = h2 >> 16;
    digest[10] = h2 >> 8;
    digest[11] = h2;
    digest[12] = h3 >> 24;
    digest[13] = h3 >> 16;
    digest[14] = h3 >> 8;
    digest[15] = h3;
    digest[16] = h4 >> 24;
    digest[17] = h4 >> 16;
    digest[18] = h4 >> 8;
    digest[19] = h4;
}