Die Seite wurde neu angelegt: „1. Implementation von SHA256 inkl. UART gelaber (noch...

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+1. Implementation von SHA256 inkl. UART gelaber (noch mit human Stuff)
+
+<syntaxhighlight lang="C++">
+#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
+}
+
+
+
+
+</syntaxhighlight>