Spacegate/1.Crap

1. Implementation von SHA256 inkl. UART gelaber (noch mit human Stuff)

#include <sha256.h>
#define LITTLE_ENDIAN

uint8_t summed[32];
char input[32];
int poscnt = 0;
byte recdata;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("Input");
}

void serialEvent() {
  recdata = Serial.read();
  if (recdata == 0x0D && poscnt == 0) {
    Serial.println();
    Serial.println("Input");
  }
  
  if (poscnt >=32 || recdata == 0x0D) {
    Serial.println();
    Serial.print("Received: ");
    Serial.println(input);
    sha256(&summed, input, poscnt*8);
    Serial.print("SHA256: ");
    for (int i = 0; i <= 31; i++) {
      Serial.print(summed[i], HEX);
      input[i] = NULL;
    }
    Serial.println();
    poscnt = 0;
    Serial.print("Input");
  }
  else {
    input[poscnt] = recdata;
    Serial.println(input);
    poscnt++;
  }


}

void loop() {

}



// AVR crypto lib
uint32_t sha256_init_vector[]={
  0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A,
  0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19 };


/*************************************************************************/

/**
 * \brief \c sh256_init initialises a sha256 context for hashing.
 * \c sh256_init c initialises the given sha256 context for hashing
 * @param state pointer to a sha256 context
 * @return none
 */
void sha256_init(sha256_ctx_t *state){
  state->length=0;
  memcpy(state->h, sha256_init_vector, 8*4);
}

/*************************************************************************/

/**
 * rotate x right by n positions
 */
uint32_t rotr32( uint32_t x, uint8_t n){
  return ((x>>n) | (x<<(32-n)));
}


/*************************************************************************/

// #define CHANGE_ENDIAN32(x) (((x)<<24) | ((x)>>24) | (((x)& 0x0000ff00)<<8) | (((x)& 0x00ff0000)>>8))

uint32_t change_endian32(uint32_t x){
  return (((x)<<24) | ((x)>>24) | (((x)& 0x0000ff00)<<8) | (((x)& 0x00ff0000)>>8));
}


/*************************************************************************/

/* sha256 functions as macros for speed and size, cause they are called only once */

#define CH(x,y,z)  (((x)&(y)) ^ ((~(x))&(z)))
#define MAJ(x,y,z) (((x)&(y)) ^ ((x)&(z)) ^ ((y)&(z)))

#define SIGMA0(x) (rotr32((x),2) ^ rotr32((x),13) ^ rotr32((x),22))
#define SIGMA1(x) (rotr32((x),6) ^ rotr32((x),11) ^ rotr32((x),25))
#define SIGMA_a(x) (rotr32((x),7)  ^ rotr32((x),18) ^ ((x)>>3))
#define SIGMA_b(x) (rotr32((x),17) ^ rotr32((x),19) ^ ((x)>>10))


uint32_t k[]={
  0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
  0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
  0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
  0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
  0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
  0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
  0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
  0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
};


/*************************************************************************/

/**
 * block must be, 512, Bit = 64, Byte, long !!!
 */
void sha256_nextBlock (sha256_ctx_t *state, const void* block){
  uint32_t w[64]; 	/* this is 256, byte, large, */
  uint8_t  i;
  uint32_t a[8],t1,t2;

  /* init w */
#if defined LITTLE_ENDIAN
  for (i=0; i<16; ++i){
    w[i]= change_endian32(((uint32_t*)block)[i]);
  }
#elif defined BIG_ENDIAN
  memcpy((void*)w, block, 64);
#endif
  for (i=16; i<64; ++i){
    w[i] = SIGMA_b(w[i-2]) + w[i-7] + SIGMA_a(w[i-15]) + w[i-16];
  }

  /* init working variables */
  memcpy((void*)a,(void*)(state->h), 8*4);

  /* do the, fun stuff, */
  for (i=0; i<64; ++i){
    t1 = a[7] + SIGMA1(a[4]) + CH(a[4],a[5],a[6]) + k[i] + w[i];
    t2 = SIGMA0(a[0]) + MAJ(a[0],a[1],a[2]);
    memmove(&(a[1]), &(a[0]), 7*4); 	/* a[7]=a[6]; a[6]=a[5]; a[5]=a[4]; a[4]=a[3]; a[3]=a[2]; a[2]=a[1]; a[1]=a[0]; */
    a[4] += t1;
    a[0] = t1 + t2;
  }

  /* update, the, state, */
  for (i=0; i<8; ++i){
    state->h[i] += a[i];
  }
  state->length += 512;
}


/*************************************************************************/

/**
 * \brief function to process the last block being hashed
 * @param state Pointer to the context in which this block should be processed.
 * @param block Pointer to the message wich should be hashed.
 * @param length is the length of only THIS block in BITS not in bytes!
 *  bits are big endian, meaning high bits come first.
 * 	if you have a message with bits at the end, the byte must be padded with zeros
 */
void sha256_lastBlock(sha256_ctx_t *state, const void* block, uint16_t length){
  uint8_t lb[SHA256_BLOCK_BITS/8]; /* local block */
  while(length>=SHA256_BLOCK_BITS){
    sha256_nextBlock(state, block);
    length -= SHA256_BLOCK_BITS;
    block = (uint8_t*)block+SHA256_BLOCK_BYTES;
  }

  state->length += length;
  memcpy (&(lb[0]), block, length/8);

  /* set the final one bit */
  if (length & 0x7){ // if we have single bits at the end
    lb[length/8] = ((uint8_t*)(block))[length/8];
  } 
  else {
    lb[length/8] = 0;
  }
  lb[length/8] |= 0x80>>(length & 0x7);
  length =(length >> 3) + 1; /* from now on length contains the number of BYTES in lb*/
  /* pad with zeros */
  if (length>64-8){ /* not enouth space for 64bit length value */
    memset((void*)(&(lb[length])), 0, 64-length);
    sha256_nextBlock(state, lb);
    state->length -= 512;
    length = 0;
  }
  memset((void*)(&(lb[length])), 0, 56-length);
  /* store the 64bit length value */
#if defined LITTLE_ENDIAN
  /* this is now rolled up */
  uint8_t i;
  for (i=1; i<=8; ++i){
    lb[55+i] = (uint8_t)(state->length>>(64- 8*i));
  }
#elif defined BIG_ENDIAN
  *((uint64_t)&(lb[56])) = state->length;
#endif
  sha256_nextBlock(state, lb);
}


/*************************************************************************/

/*
 * length in bits!
 */
void sha256(sha256_hash_t *dest, const void* msg, uint32_t length){ /* length could be choosen longer but this is for µC */
  sha256_ctx_t s;
  sha256_init(&s);
  while(length >= SHA256_BLOCK_BITS){
    sha256_nextBlock(&s, msg);
    msg = (uint8_t*)msg + SHA256_BLOCK_BITS/8;
    length -= SHA256_BLOCK_BITS;
  }
  sha256_lastBlock(&s, msg, length);
  sha256_ctx2hash(dest,&s);
}



/*************************************************************************/

void sha256_ctx2hash(sha256_hash_t *dest, const sha256_ctx_t *state){
#if defined LITTLE_ENDIAN
  uint8_t i;
  for(i=0; i<8; ++i){
    ((uint32_t*)dest)[i] = change_endian32(state->h[i]);
  }
#elif BIG_ENDIAN
  if (dest != state->h)
    memcpy(dest, state->h, SHA256_HASH_BITS/8);
#else

#endif
}