luc116.c (5612B)
1 /* Compile any C program into a .EXE or a .out file. Obtain SHA256 checksum of the file. 2 */ 3 /* Let Us C, Chap- 23 (Security Programming), Qn No.: D(b) */ 4 5 /* This file is auto-generated by a bot. */ 6 /* This code is not compiled; it is for reference only. */ 7 8 9 #include <stdio.h> 10 #include <stdlib.h> 11 #include <string.h> 12 #include <stdint.h> 13 14 /* * Self-contained SHA-256 Implementation 15 * Based on FIPS 180-2 reference logic. 16 */ 17 18 // --- SHA256 Implementation Start --- 19 typedef struct { 20 uint8_t data[64]; 21 uint32_t datalen; 22 uint64_t bitlen; 23 uint32_t state[8]; 24 } SHA256_CTX; 25 26 #define ROTRIGHT(a,b) (((a) >> (b)) | ((a) << (32-(b)))) 27 #define CH(x,y,z) (((x) & (y)) ^ (~(x) & (z))) 28 #define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z))) 29 #define EP0(x) (ROTRIGHT(x,2) ^ ROTRIGHT(x,13) ^ ROTRIGHT(x,22)) 30 #define EP1(x) (ROTRIGHT(x,6) ^ ROTRIGHT(x,11) ^ ROTRIGHT(x,25)) 31 #define SIG0(x) (ROTRIGHT(x,7) ^ ROTRIGHT(x,18) ^ ((x) >> 3)) 32 #define SIG1(x) (ROTRIGHT(x,17) ^ ROTRIGHT(x,19) ^ ((x) >> 10)) 33 34 static const uint32_t K[64] = { 35 0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5, 36 0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174, 37 0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da, 38 0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967, 39 0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85, 40 0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070, 41 0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3, 42 0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2 43 }; 44 45 void sha256_transform(SHA256_CTX *ctx, const uint8_t data[]) { 46 uint32_t a, b, c, d, e, f, g, h, i, j, t1, t2, m[64]; 47 48 for (i = 0, j = 0; i < 16; ++i, j += 4) 49 m[i] = (data[j] << 24) | (data[j + 1] << 16) | (data[j + 2] << 8) | (data[j + 3]); 50 for (; i < 64; ++i) 51 m[i] = SIG1(m[i - 2]) + m[i - 7] + SIG0(m[i - 15]) + m[i - 16]; 52 53 a = ctx->state[0]; b = ctx->state[1]; c = ctx->state[2]; d = ctx->state[3]; 54 e = ctx->state[4]; f = ctx->state[5]; g = ctx->state[6]; h = ctx->state[7]; 55 56 for (i = 0; i < 64; ++i) { 57 t1 = h + EP1(e) + CH(e, f, g) + K[i] + m[i]; 58 t2 = EP0(a) + MAJ(a, b, c); 59 h = g; g = f; f = e; e = d + t1; 60 d = c; c = b; b = a; a = t1 + t2; 61 } 62 63 ctx->state[0] += a; ctx->state[1] += b; ctx->state[2] += c; ctx->state[3] += d; 64 ctx->state[4] += e; ctx->state[5] += f; ctx->state[6] += g; ctx->state[7] += h; 65 } 66 67 void sha256_init(SHA256_CTX *ctx) { 68 ctx->datalen = 0; 69 ctx->bitlen = 0; 70 ctx->state[0] = 0x6a09e667; ctx->state[1] = 0xbb67ae85; 71 ctx->state[2] = 0x3c6ef372; ctx->state[3] = 0xa54ff53a; 72 ctx->state[4] = 0x510e527f; ctx->state[5] = 0x9b05688c; 73 ctx->state[6] = 0x1f83d9ab; ctx->state[7] = 0x5be0cd19; 74 } 75 76 void sha256_update(SHA256_CTX *ctx, const uint8_t data[], size_t len) { 77 for (size_t i = 0; i < len; ++i) { 78 ctx->data[ctx->datalen] = data[i]; 79 ctx->datalen++; 80 if (ctx->datalen == 64) { 81 sha256_transform(ctx, ctx->data); 82 ctx->bitlen += 512; 83 ctx->datalen = 0; 84 } 85 } 86 } 87 88 void sha256_final(SHA256_CTX *ctx, uint8_t hash[]) { 89 uint32_t i = ctx->datalen; 90 if (ctx->datalen < 56) { 91 ctx->data[i++] = 0x80; 92 while (i < 56) ctx->data[i++] = 0x00; 93 } else { 94 ctx->data[i++] = 0x80; 95 while (i < 64) ctx->data[i++] = 0x00; 96 sha256_transform(ctx, ctx->data); 97 memset(ctx->data, 0, 56); 98 } 99 100 ctx->bitlen += ctx->datalen * 8; 101 ctx->data[63] = ctx->bitlen; 102 ctx->data[62] = ctx->bitlen >> 8; 103 ctx->data[61] = ctx->bitlen >> 16; 104 ctx->data[60] = ctx->bitlen >> 24; 105 ctx->data[59] = ctx->bitlen >> 32; 106 ctx->data[58] = ctx->bitlen >> 40; 107 ctx->data[57] = ctx->bitlen >> 48; 108 ctx->data[56] = ctx->bitlen >> 56; 109 sha256_transform(ctx, ctx->data); 110 111 for (i = 0; i < 4; ++i) { 112 hash[i] = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff; 113 hash[i + 4] = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff; 114 hash[i + 8] = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff; 115 hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff; 116 hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff; 117 hash[i + 20] = (ctx->state[5] >> (24 - i * 8)) & 0x000000ff; 118 hash[i + 24] = (ctx->state[6] >> (24 - i * 8)) & 0x000000ff; 119 hash[i + 28] = (ctx->state[7] >> (24 - i * 8)) & 0x000000ff; 120 } 121 } 122 // --- SHA256 Implementation End --- 123 124 int main(int argc, char *argv[]) { 125 FILE *fp; 126 char filename[100]; 127 uint8_t buffer[1024]; 128 size_t bytesRead; 129 SHA256_CTX ctx; 130 uint8_t hash[32]; 131 int i; 132 133 // Get filename 134 if (argc < 2) { 135 printf("Enter filename to checksum (e.g., this_program.exe): "); 136 scanf("%s", filename); 137 } else { 138 strcpy(filename, argv[1]); 139 } 140 141 fp = fopen(filename, "rb"); // Open in binary mode 142 if (fp == NULL) { 143 printf("Error: Could not open file '%s'\n", filename); 144 return 1; 145 } 146 147 sha256_init(&ctx); 148 149 while ((bytesRead = fread(buffer, 1, sizeof(buffer), fp)) > 0) { 150 sha256_update(&ctx, buffer, bytesRead); 151 } 152 153 sha256_final(&ctx, hash); 154 fclose(fp); 155 156 printf("SHA256 Checksum of '%s':\n", filename); 157 for (i = 0; i < 32; i++) { 158 printf("%02x", hash[i]); 159 } 160 printf("\n"); 161 162 return 0; 163 }