Varun Bahl / Mbed 2 deprecated Decryptulator

UpdatedDecryp

Dependencies:   BahlDecrypModified CyaSSL mbed nRF51822

Fork of Decryptulator by Mobius IoT

Hashes/sfh_mbed.cpp@13:8b706583610a, 2017-05-09 (annotated)

Committer:
vbahl2
Date:
Tue May 09 03:06:55 2017 +0000
Revision:
13:8b706583610a
UpdatedDecryp

Who changed what in which revision?

UserRevisionLine numberNew contents of line
vbahl2 13:8b706583610a 1 #include "sfh_mbed.h"
vbahl2 13:8b706583610a 2 #include "SlidingWindow.h"
vbahl2 13:8b706583610a 3 #include "LookupTable.h"
vbahl2 13:8b706583610a 4
vbahl2 13:8b706583610a 5 #define LOOKUP_TABLE_SIZE 3000
vbahl2 13:8b706583610a 6 #define SLIDING_WINDOW_SIZE 300
vbahl2 13:8b706583610a 7
vbahl2 13:8b706583610a 8 //static uint32_t sliding_window_index = 0;
vbahl2 13:8b706583610a 9
vbahl2 13:8b706583610a 10
vbahl2 13:8b706583610a 11 uint32_t hash (const char *data, uint16_t len) {
vbahl2 13:8b706583610a 12 // This is mostly Paul Hsieh's original code
vbahl2 13:8b706583610a 13 uint32_t hash, tmp;
vbahl2 13:8b706583610a 14 int rem;
vbahl2 13:8b706583610a 15
vbahl2 13:8b706583610a 16 if (len <= 0 || data == 0) {
vbahl2 13:8b706583610a 17 return 0;
vbahl2 13:8b706583610a 18 }
vbahl2 13:8b706583610a 19
vbahl2 13:8b706583610a 20 hash = len;
vbahl2 13:8b706583610a 21 rem = len & 3;
vbahl2 13:8b706583610a 22 len >>= 2;
vbahl2 13:8b706583610a 23
vbahl2 13:8b706583610a 24 /* Main loop */
vbahl2 13:8b706583610a 25 while (len > 0) {
vbahl2 13:8b706583610a 26 hash += *((uint16_t *) data);
vbahl2 13:8b706583610a 27
vbahl2 13:8b706583610a 28 /* To make a long story short, the C standard states that the
vbahl2 13:8b706583610a 29 * shift operator's operands must be promoted to (unsigned) int,
vbahl2 13:8b706583610a 30 * which is (usually) 32 bits wide on PC and 16 on Arduino. This
vbahl2 13:8b706583610a 31 * results in different behaviour, since part of the result gets
vbahl2 13:8b706583610a 32 * truncated on Arduino, so we cast the result to make sure all
vbahl2 13:8b706583610a 33 * bits are kept.
vbahl2 13:8b706583610a 34 */
vbahl2 13:8b706583610a 35 tmp = ((uint32_t) (*((uint16_t *) (data + 2))) << 11) ^ hash;
vbahl2 13:8b706583610a 36
vbahl2 13:8b706583610a 37 hash = (hash << 16) ^ tmp;
vbahl2 13:8b706583610a 38 data += 2 * sizeof (uint16_t);
vbahl2 13:8b706583610a 39 hash += hash >> 11;
vbahl2 13:8b706583610a 40 len--;
vbahl2 13:8b706583610a 41 }
vbahl2 13:8b706583610a 42
vbahl2 13:8b706583610a 43 /* Handle end cases */
vbahl2 13:8b706583610a 44 switch (rem) {
vbahl2 13:8b706583610a 45 case 3:
vbahl2 13:8b706583610a 46 hash += * ((uint16_t *) data);
vbahl2 13:8b706583610a 47 hash ^= hash << 16;
vbahl2 13:8b706583610a 48 hash ^= ((signed char) data[2]) << 18;
vbahl2 13:8b706583610a 49 hash += hash >> 11;
vbahl2 13:8b706583610a 50 break;
vbahl2 13:8b706583610a 51
vbahl2 13:8b706583610a 52 case 2:
vbahl2 13:8b706583610a 53 hash += * ((uint16_t *) data);
vbahl2 13:8b706583610a 54 hash ^= hash << 11;
vbahl2 13:8b706583610a 55 hash += hash >> 17;
vbahl2 13:8b706583610a 56 break;
vbahl2 13:8b706583610a 57
vbahl2 13:8b706583610a 58 case 1:
vbahl2 13:8b706583610a 59 hash += (signed char) * data;
vbahl2 13:8b706583610a 60 hash ^= hash << 10;
vbahl2 13:8b706583610a 61 hash += hash >> 1;
vbahl2 13:8b706583610a 62 }
vbahl2 13:8b706583610a 63
vbahl2 13:8b706583610a 64 /* Force "avalanching" of final 127 bits */
vbahl2 13:8b706583610a 65 hash ^= hash << 3;
vbahl2 13:8b706583610a 66 hash += hash >> 5;
vbahl2 13:8b706583610a 67 hash ^= hash << 4;
vbahl2 13:8b706583610a 68 hash += hash >> 17;
vbahl2 13:8b706583610a 69 hash ^= hash << 25;
vbahl2 13:8b706583610a 70 hash += hash >> 6;
vbahl2 13:8b706583610a 71
vbahl2 13:8b706583610a 72 return hash;
vbahl2 13:8b706583610a 73 }