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