226 lines
7.0 KiB
C
226 lines
7.0 KiB
C
/*
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* Derived from the RSA Data Security, Inc. MD5 Message-Digest Algorithm
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* and modified slightly to be functionally identical but condensed into control structures.
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*/
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#include "md5.h"
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/*
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* Constants defined by the MD5 algorithm
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*/
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#define A 0x67452301
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#define B 0xefcdab89
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#define C 0x98badcfe
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#define D 0x10325476
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static uint32_t S[] = {7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
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5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20,
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4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
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6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21};
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static uint32_t K[] = {0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
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0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
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0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
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0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
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0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
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0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
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0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
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0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
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0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
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0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
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0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05,
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0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
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0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
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0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
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0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
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0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391};
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/*
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* Bit-manipulation functions defined by the MD5 algorithm
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*/
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#define F(X, Y, Z) ((X & Y) | (~X & Z))
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#define G(X, Y, Z) ((X & Z) | (Y & ~Z))
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#define H(X, Y, Z) (X ^ Y ^ Z)
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#define I(X, Y, Z) (Y ^ (X | ~Z))
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/*
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* Padding used to make the size (in bits) of the input congruent to 448 mod 512
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*/
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static uint8_t PADDING[] = {0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
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/*
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* Initialize a context
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*/
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void md5Init(MD5Context *ctx){
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ctx->size = (uint64_t)0;
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ctx->buffer[0] = (uint32_t)A;
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ctx->buffer[1] = (uint32_t)B;
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ctx->buffer[2] = (uint32_t)C;
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ctx->buffer[3] = (uint32_t)D;
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}
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/*
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* Add some amount of input to the context
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*
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* If the input fills out a block of 512 bits, apply the algorithm (md5Step)
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* and save the result in the buffer. Also updates the overall size.
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*/
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void md5Update(MD5Context *ctx, uint8_t *input_buffer, size_t input_len){
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uint32_t input[16];
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unsigned int offset = ctx->size % 64;
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ctx->size += (uint64_t)input_len;
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// Copy each byte in input_buffer into the next space in our context input
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for(unsigned int i = 0; i < input_len; ++i){
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ctx->input[offset++] = (uint8_t)*(input_buffer + i);
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// If we've filled our context input, copy it into our local array input
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// then reset the offset to 0 and fill in a new buffer.
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// Every time we fill out a chunk, we run it through the algorithm
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// to enable some back and forth between cpu and i/o
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if(offset % 64 == 0){
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for(unsigned int j = 0; j < 16; ++j){
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// Convert to little-endian
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// The local variable `input` our 512-bit chunk separated into 32-bit words
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// we can use in calculations
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input[j] = (uint32_t)(ctx->input[(j * 4) + 3]) << 24 |
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(uint32_t)(ctx->input[(j * 4) + 2]) << 16 |
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(uint32_t)(ctx->input[(j * 4) + 1]) << 8 |
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(uint32_t)(ctx->input[(j * 4)]);
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}
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md5Step(ctx->buffer, input);
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offset = 0;
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}
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}
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}
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/*
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* Pad the current input to get to 448 bytes, append the size in bits to the very end,
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* and save the result of the final iteration into digest.
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*/
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void md5Finalize(MD5Context *ctx){
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uint32_t input[16];
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unsigned int offset = ctx->size % 64;
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unsigned int padding_length = offset < 56 ? 56 - offset : (56 + 64) - offset;
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// Fill in the padding andndo the changes to size that resulted from the update
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md5Update(ctx, PADDING, padding_length);
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ctx->size -= (uint64_t)padding_length;
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// Do a final update (internal to this function)
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// Last two 32-bit words are the two halves of the size (converted from bytes to bits)
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for(unsigned int j = 0; j < 14; ++j){
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input[j] = (uint32_t)(ctx->input[(j * 4) + 3]) << 24 |
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(uint32_t)(ctx->input[(j * 4) + 2]) << 16 |
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(uint32_t)(ctx->input[(j * 4) + 1]) << 8 |
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(uint32_t)(ctx->input[(j * 4)]);
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}
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input[14] = (uint32_t)(ctx->size * 8);
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input[15] = (uint32_t)((ctx->size * 8) >> 32);
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md5Step(ctx->buffer, input);
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// Move the result into digest (convert from little-endian)
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for(unsigned int i = 0; i < 4; ++i){
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ctx->digest[(i * 4) + 0] = (uint8_t)((ctx->buffer[i] & 0x000000FF));
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ctx->digest[(i * 4) + 1] = (uint8_t)((ctx->buffer[i] & 0x0000FF00) >> 8);
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ctx->digest[(i * 4) + 2] = (uint8_t)((ctx->buffer[i] & 0x00FF0000) >> 16);
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ctx->digest[(i * 4) + 3] = (uint8_t)((ctx->buffer[i] & 0xFF000000) >> 24);
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}
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}
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/*
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* Step on 512 bits of input with the main MD5 algorithm.
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*/
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void md5Step(uint32_t *buffer, uint32_t *input){
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uint32_t AA = buffer[0];
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uint32_t BB = buffer[1];
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uint32_t CC = buffer[2];
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uint32_t DD = buffer[3];
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uint32_t E;
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unsigned int j;
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for(unsigned int i = 0; i < 64; ++i){
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switch(i / 16){
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case 0:
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E = F(BB, CC, DD);
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j = i;
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break;
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case 1:
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E = G(BB, CC, DD);
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j = ((i * 5) + 1) % 16;
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break;
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case 2:
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E = H(BB, CC, DD);
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j = ((i * 3) + 5) % 16;
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break;
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default:
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E = I(BB, CC, DD);
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j = (i * 7) % 16;
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break;
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}
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uint32_t temp = DD;
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DD = CC;
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CC = BB;
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BB = BB + rotateLeft(AA + E + K[i] + input[j], S[i]);
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AA = temp;
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}
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buffer[0] += AA;
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buffer[1] += BB;
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buffer[2] += CC;
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buffer[3] += DD;
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}
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/*
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* Functions that will return a pointer to the hash of the provided input
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*/
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uint8_t* md5String(char *input){
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MD5Context ctx;
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md5Init(&ctx);
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md5Update(&ctx, (uint8_t *)input, strlen(input));
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md5Finalize(&ctx);
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uint8_t *result = malloc(16);
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memcpy(result, ctx.digest, 16);
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return result;
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}
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uint8_t* md5File(FILE *file){
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char *input_buffer = malloc(1024);
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size_t input_size = 0;
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MD5Context ctx;
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md5Init(&ctx);
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while((input_size = fread(input_buffer, 1, 1024, file)) > 0){
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md5Update(&ctx, (uint8_t *)input_buffer, input_size);
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}
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md5Finalize(&ctx);
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free(input_buffer);
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uint8_t *result = malloc(16);
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memcpy(result, ctx.digest, 16);
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return result;
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}
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/*
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* Rotates a 32-bit word left by n bits
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*/
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uint32_t rotateLeft(uint32_t x, uint32_t n){
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return (x << n) | (x >> (32 - n));
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}
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