From 10fe26cca11884b1c2d6b3adfcd68d778e978f14 Mon Sep 17 00:00:00 2001
From: ENGO150 <v.smejkal06@gmail.com>
Date: Wed, 20 Nov 2024 16:32:13 +0100
Subject: [PATCH] using rolling-hash-like way to count why2_sum_segment
---
include/crypto.h | 3 +--
src/core/lib/utils/crypto.c | 13 +++++++------
2 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/include/crypto.h b/include/crypto.h
index 3155400..6dcce70 100644
--- a/include/crypto.h
+++ b/include/crypto.h
@@ -24,8 +24,7 @@ extern "C" {
#endif
//MACROS
-#define WHY2_CHECKSUM_SEGMENT_SIZE 32 //SEGMENT SIZE FOR CALCULATING SUM
-#define WHY2_CHECKSUM_PRIME 11 //PRIME NUMBER FOR ROTATION
+#define WHY2_SUM_SEGMENT_SIZE 32 //SEGMENT SIZE FOR CALCULATING SUM
#define WHY2_SUM_BASE_PRIME 31 //PRIME FOR SUM BASE
#define WHY2_SUM_MOD_PRIME 4294967295UL //PRIME FOR SUM MODULUS
diff --git a/src/core/lib/utils/crypto.c b/src/core/lib/utils/crypto.c
index 852eac9..6c3dace 100644
--- a/src/core/lib/utils/crypto.c
+++ b/src/core/lib/utils/crypto.c
@@ -24,18 +24,19 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
unsigned long why2_sum_segment(char *input) //I ABSOLUTELY DO NOT RECOMMEND USING THIS WITH LARGE KEYS!!!
{
unsigned long input_size = strlen(input);
- unsigned long segmented_input_size = ceil(input_size / (double) WHY2_CHECKSUM_SEGMENT_SIZE) * WHY2_CHECKSUM_SEGMENT_SIZE; //CALCULATE CLOSEST 4*n TO input
+ unsigned long segmented_input_size = ceil(input_size / (double) WHY2_SUM_SEGMENT_SIZE) * WHY2_SUM_SEGMENT_SIZE; //CALCULATE CLOSEST 32*n (OR WHY2_SUM_SEGMENT_SIZE*n, IF YOU WILL) TO input
unsigned long output = 0;
- for (unsigned long i = 0; i < segmented_input_size / WHY2_CHECKSUM_SEGMENT_SIZE; i++) //DIVIDE buffer INTO SEGMENTS, XOR EACH OTHER AND ADD TO output
+ for (unsigned long i = 0; i < segmented_input_size / WHY2_SUM_SEGMENT_SIZE; i++) //DIVIDE buffer INTO SEGMENTS, XOR EACH OTHER AND ADD TO output
{
unsigned long output_buffer = 0;
- for (unsigned long j = 0; j < WHY2_CHECKSUM_SEGMENT_SIZE; j++)
+ for (unsigned long j = 0; j < WHY2_SUM_SEGMENT_SIZE; j++)
{
- unsigned long index_buffer = i * WHY2_CHECKSUM_SEGMENT_SIZE + j;
+ unsigned long index_buffer = i * WHY2_SUM_SEGMENT_SIZE + j;
+ char value_buffer = (input_size > index_buffer) ? input[index_buffer] : 0;
- output_buffer ^= (input_size > index_buffer) ? input[index_buffer] : 0; //XORING
- output_buffer = (output_buffer << WHY2_CHECKSUM_PRIME) | (output_buffer >> (sizeof(unsigned long) * 8 - WHY2_CHECKSUM_PRIME)); //ROTATE
+ output_buffer ^= value_buffer; //XORING
+ output_buffer = (output_buffer * WHY2_SUM_BASE_PRIME + value_buffer) % WHY2_SUM_MOD_PRIME;
}
output += output_buffer; //ADD