From 347388350724cff99962a3c95b91c8ec0b688454 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hatvani=20Tam=C3=A1s?= <hatvanitamas09@gmail.com>
Date: Thu, 9 Apr 2026 12:57:39 +0200
Subject: [PATCH] added negative check for euclidian algo res and implemented
 crt

---
 main.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 3 deletions(-)

diff --git a/main.c b/main.c
index 60ed194..f2ef23d 100644
--- a/main.c
+++ b/main.c
@@ -5,6 +5,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <sys/types.h>
 #include <time.h>
 
 #include "helper.c"
@@ -156,19 +157,45 @@ euklidian_result_t euklidian_algorigthm_extended(unsigned __int128 a, unsigned _
     return res;
 }
 
-void kinai_maradek_tetel() {
+unsigned __int128 kinai_maradek_tetel(uint64_t *m, uint64_t d, prime_test_t *p, prime_test_t *q) {
     // sum(i: 1,2): Ci * Yi * Mi mod M
     // M: P*Q, Mp: M/P, Mq: M/Q
+    unsigned __int128 M = p->prime * q->prime;
+    uint64_t Mp = q->prime;
+    uint64_t Mq = p->prime;
+
     // C1: c^(d mod P-1) mod P
+    uint64_t temp_exponent = d % (p->prime - 1);
+    uint64_t m_bin_length = 0;
+    uint64_t *m_as_binary = dec_to_bin(*m, &m_bin_length);
+    uint64_t c1 = quick_pow(m_as_binary, p->base, p->prime, m_bin_length);
+
     // C2: c^(d mod Q-1) mod Q
+    temp_exponent = d % (q->prime - 1);
+    uint64_t c2 = quick_pow(m_as_binary, q->base, q->prime, m_bin_length);
+    free(m_as_binary);
+
+    euklidian_result_t y = euklidian_algorigthm_extended(Mp, Mq); // in the struct the x will mean the y1 and y will mean the y2
+
+    // if either of them is less then 0 shift them into postive range with fi_n
+    while (y.x < 0) {
+        y.x += p->prime;
+    }
+    while (y.y < 0) {
+        y.y += q->prime;
+    }
+
+    return (c1 * y.x * Mp) + (c2 * y.y * Mq) % M;
 }
 
 unsigned __int128 rsa_encrypt(uint64_t *m, prime_test_t *p, prime_test_t *q) {
     unsigned __int128 n = p->prime * q->prime;
+    printf("n: ");
     print_uint128(n);
     printf("\n");
 
     unsigned __int128 fi_n = (p->prime - 1) * (q->prime - 1);
+    printf("fi_n: ");
     print_uint128(fi_n);
     printf("\n");
 
@@ -179,6 +206,13 @@ unsigned __int128 rsa_encrypt(uint64_t *m, prime_test_t *p, prime_test_t *q) {
     } while (e <= 1 && e >= fi_n && prime_test(e, p->base)); // the p and q base is used everywhere anyways, i wont pass in another arg
 
     euklidian_result_t calc_d = euklidian_algorigthm_extended(fi_n, e);
+    // if either of them is less then 0 shift them into postive range with fi_n
+    while (calc_d.x < 0) {
+        calc_d.x += fi_n;
+    }
+    while (calc_d.y < 0) {
+        calc_d.y += fi_n;
+    }
     __int128 d = calc_d.y;
 
     uint64_t length = 0;
@@ -192,9 +226,9 @@ unsigned __int128 rsa_encrypt(uint64_t *m, prime_test_t *p, prime_test_t *q) {
 }
 
 int main() {
-    uint64_t m = 0;
+    /*uint64_t m = 0;
     printf("give input for m: \n");
-    scanf("%ju", &m);
+    scanf("%ju", &m);*/
 
     srand(time(NULL));
 
@@ -210,5 +244,17 @@ int main() {
     pthread_join(thread_q, NULL);
     printf("\n");
 
+    // for testing i will overwrite the value
+    uint64_t m = 111;
+    p.prime = 107;
+    q.prime = 103;
+    rsa_encrypt(&m, &p, &q);
+
+    printf("\nkinai maradek tetel:\n");
+    unsigned __int128 S = kinai_maradek_tetel(&m, 2263, &p, &q);
+    printf("S: ");
+    print_uint128(S);
+    printf("\n");
+
     return 0;
 }