Remove junk, add testing and assertions

Makefile

@@ -1,4 +1,5 @@
-REV := master
+# 'master' or hash
+REV := 8ba9981e5
 BASE := https://raw.githubusercontent.com/cnlohr/ch32v003fun/$(REV)
 CURL_FLAGS := -O -\# --fail --location --tlsv1.3 --proto =https --max-time 300
 

assert.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include <stdint.h>
+#include <stdio.h>
+
+#define ASSERT(expr)                                                        \
+    do {                                                                       \
+        if (!(expr)) {                                                         \
+            printf("ASSERTION FAILED: %s at %s:%d\n", #expr, __FILE__,         \
+                   __LINE__);                                                  \
+            while (1);                                                         \
+        }                                                                      \
+    } while (0)
+
+#define ASSERT_EQ(expr, expected)                                              \
+    do {                                                                       \
+        uint64_t result = (expr);                                              \
+        if (result != (expected)) {                                            \
+            printf("ASSERTION FAILED: %s at %s:%d\n", #expr, __FILE__,         \
+                   __LINE__);                                                  \
+            printf("Expected: %lu, Got: %lu\n", (unsigned long)(expected),     \
+                   (unsigned long)result);                                     \
+            while (1);                                                         \
+        }                                                                      \
+    } while (0)

funconfig.h

@@ -1,7 +1,18 @@
+#include <stdint.h>
+
 #ifndef _FUNCONFIG_H
 #define _FUNCONFIG_H
 
 #define CH32V003 1
 
-#endif
+#define NULL ((void *)0)
 
+typedef int8_t i8;
+typedef uint8_t u8;
+typedef int16_t i16;
+typedef uint32_t u32;
+typedef int32_t i32;
+typedef int64_t i64;
+typedef uint64_t u64;
+
+#endif

main.c

@@ -1,10 +1,14 @@
+#include "assert.h"
 #include <ch32fun.h>
 #include <rand.h>
 #include <rsa.h>
 #include <stdint.h>
 #include <stdio.h>
+#include <string.h>
 
 #define LED_PIN PD6
+#define RANDOM
+#define W 16
 
 void exit_blink() {
     for (int i = 0; i < 4; i++) {
@@ -24,6 +28,30 @@ void enter_blink() {
     }
 }
 
+void test_mulmod() {
+    ASSERT_EQ(mulmod(3, 2, 4), 2);
+    ASSERT_EQ((3 * 2) % 4, 2);
+
+    ASSERT_EQ(mulmod(31, 3, 8), 5);
+    ASSERT_EQ(mulmod((u64)1 << 63, 2, 1000000007ULL), 582344008);
+}
+
+void test_modexp() {
+    ASSERT_EQ(modexp(3, 2, 4), 1);
+    ASSERT_EQ((3 ^ 2) % 4, 1);
+
+    ASSERT_EQ(modexp(31, 3, 8), 7);
+    ASSERT_EQ(modexp((u64)1 << 63, 2, 1000000007ULL), 319908071);
+}
+
+void debug_string(char *str) {
+    printf("Got string: %s\n", str);
+    for (int i = 0; i < strlen(str); i++) {
+        printf("decoded[%d] = '%c' (ASCII: %d)\n", i, str[i],
+               str[i]); // Print decoded chars and ASCII values
+    }
+}
+
 int main() {
     SystemInit();
     sprand(0);
@@ -33,54 +61,59 @@ int main() {
 
     enter_blink();
 
-#ifdef RANDOM
-    uint64_t p = gen_prime(1 << 15, 1 << 16);
-    uint64_t q = p;
+    test_mulmod();
+    test_modexp();
 
-    while (p == q) p = gen_prime(1 << 15, 1 << 16);
-#else
-    uint64_t p = 56857;
-    uint64_t q = 47963;
-#endif
+    const u64 p = gen_prime(1 << (W - 1), 1 << W);
+    printf("P: %u\n", (u32)p);
 
-    uint64_t n = p * q;
-    uint64_t phi_n = (p - 1) * (q - 1);
+    u64 qprev = p;
+    while (p == qprev) qprev = gen_prime(1 << (W - 1), 1 << W);
 
-    // 'e' is public. E for encrypt.
-    uint64_t e = 0;
-    while (gcd(e, phi_n) != 1) e = prand_range(3, phi_n - 1);
+    const u64 q = qprev;
+    printf("Q: %u\n", (u32)q);
 
-    // 'd' is our private key. D as in decrypt
-    uint64_t d = mod_inverse(e, phi_n);
+    ASSERT(gcd(p - 1, PUBEXP) == 1);
+    ASSERT(gcd(q - 1, PUBEXP) == 1);
+
+    u64 n = p * q;
+    printf("N: %u\n", (u32)n);
+
+    u64 phi_n = (p - 1) * (q - 1);
+    printf("Phi_N: %u\n", (u32)phi_n);
+
+    u64 d = mod_inverse(PUBEXP, phi_n);
+    printf("D: %u\n", (u32)d);
     if (d == 0 || d == 1) {
         printf("Modular inverse not found...");
-        while (1);
     }
 
+    ASSERT_EQ(mulmod(PUBEXP, d, phi_n), 1);
+
     char msg[] = "Hello";
-    uint64_t coded[sizeof(msg)] = {0};
+    u64 coded[sizeof(msg)] = {0};
     char decoded[sizeof(msg)] = {0};
 
     // Encode the message
-    for (int i = 0; i < sizeof(msg); i++) {
-        coded[i] = (uint64_t)modexp((uint64_t)msg[i], e, n);
+    for (int i = 0; i < strlen(msg); i++) {
+        coded[i] = modexp((u64)msg[i], PUBEXP, n);
     }
 
     // Decode the message
-    for (int i = 0; i < sizeof(msg); i++) {
-        decoded[i] = (char)modexp(coded[i], d, n);
+    for (int i = 0; i < strlen(msg); i++) {
+        u64 dec = modexp(coded[i], d, n);
+        decoded[i] = dec & 0xFF;
     }
 
     {
-        printf("P: %u\n", (uint32_t)p);
-        printf("Q: %u\n", (uint32_t)q);
-        printf("N: %u\n", (uint32_t)n);
-        printf("Phi_N: %u\n", (uint32_t)phi_n);
-        printf("Pubkey (e): %u\n", (uint32_t)e);
-        printf("Privkey (d): %u\n", (uint32_t)d);
-
         printf("Message: %s\n", msg);
         printf("Decoded: %s\n", decoded);
+
+        for (int i = 0; i < strlen(msg); i++) {
+            printf("coded[%d] = 0x%016lx\n", i, (unsigned long)coded[i]);
+        }
+
+        debug_string(decoded);
     }
 
     // Exit and hang forever

rsa.c

@@ -1,15 +1,11 @@
 #include "rsa.h"
+#include "funconfig.h"
 #include "rand.h"
 #include <stdbool.h>
-#include <stdint.h>
 
-#define NULL ((void *)0)
+u64 gcd(u64 a, u64 b) { return extended_euclid(a, b, NULL, NULL); }
 
-uint64_t gcd(uint64_t a, uint64_t b) {
-    return extended_euclid(a, b, NULL, NULL);
-}
-
-int extended_euclid(int a, int b, int *x, int *y) {
+u64 extended_euclid(u64 a, u64 b, u64 *x, u64 *y) {
     if (b == 0) {
         if (x)
             *x = 1;
@@ -18,8 +14,8 @@ int extended_euclid(int a, int b, int *x, int *y) {
         return a;
     }
 
-    int x1, y1;
-    int gcd = extended_euclid(b, a % b, &x1, &y1);
+    u64 x1, y1;
+    u64 gcd = extended_euclid(b, a % b, &x1, &y1);
 
     if (x)
         *x = y1;
@@ -29,7 +25,7 @@ int extended_euclid(int a, int b, int *x, int *y) {
     return gcd;
 }
 
-int totient(int n) {
+u64 totient(u64 n) {
     int result = n;
 
     // Check for prime factors
@@ -51,23 +47,24 @@ int totient(int n) {
     return result;
 }
 
-uint64_t mulmod(uint64_t a, uint64_t b, uint64_t m) {
-    uint64_t result = 0;
+u64 mulmod(u64 a, u64 b, u64 m) {
+    u64 result = 0;
     a %= m;
 
+    // Perform the multiplication bit by bit (binary multiplication)
     while (b > 0) {
         if (b & 1) {
-            result = (result + a) % m; // Avoid overflow
+            result = (result + a) % m;
         }
-        a = (a * 2) % m; // Double a, keep within mod
-        b >>= 1;
+        a = (a * 2) % m;  // Double a, keep it within the modulus
+        b >>= 1;  // Right shift b (divide by 2)
     }
 
     return result;
 }
 
-uint64_t modexp(uint64_t a, uint64_t b, uint64_t m) {
-    uint64_t result = 1;
+u64 modexp(u64 a, u64 b, u64 m) {
+    u64 result = 1;
     a %= m;
 
     while (b > 0) {
@@ -81,14 +78,14 @@ uint64_t modexp(uint64_t a, uint64_t b, uint64_t m) {
     return result;
 }
 
-uint64_t gen_prime(uint64_t min, uint64_t max) {
-    uint64_t cand = 0;
+u64 gen_prime(u64 min, u64 max) {
+    u64 cand = 0;
     while (!miller_rabin(cand, 10)) cand = prand_range(min, max);
 
     return cand;
 }
 
-bool is_prime(int n) {
+bool is_prime(u64 n) {
     if (n < 2)
         return false;
 
@@ -100,26 +97,26 @@ bool is_prime(int n) {
     return true;
 }
 
-bool miller_rabin(uint64_t n, uint64_t k) {
+bool miller_rabin(u64 n, u64 k) {
     if (n < 2)
         return false;
 
-    uint64_t d = n - 1;
-    uint64_t s = 0;
+    u64 d = n - 1;
+    u64 s = 0;
 
     while (d % 2 == 0) {
         d /= 2;
         s++;
     }
 
-    for (uint64_t i = 0; i < k; i++) {
-        uint64_t a = prand_range(2, n - 2);
-        uint64_t x = modexp(a, d, n);
+    for (u64 i = 0; i < k; i++) {
+        u64 a = prand_range(2, n - 2);
+        u64 x = modexp(a, d, n);
 
         if (x == 1 || x == n - 1)
             continue;
 
-        for (uint64_t r = 1; r < s; r++) {
+        for (u64 r = 1; r < s; r++) {
             x = modexp(x, 2, n);
             if (x == n - 1)
                 break;
@@ -132,17 +129,18 @@ bool miller_rabin(uint64_t n, uint64_t k) {
     return true; // Likely prime
 }
 
-uint64_t mod_inverse(uint64_t a, uint64_t m) {
-    uint64_t m0 = m;
-    uint64_t y = 0, x = 1;
+u64 mod_inverse(u64 a, u64 m) {
+    u64 m0 = m;
+    u64 y = 0, x = 1;
 
+    // Modular inverse does not exist when m is 1
     if (m == 1)
         return 0;
 
     while (a > 1) {
         // q is quotient
-        uint64_t q = a / m;
-        uint64_t t = m;
+        u64 q = a / m;
+        u64 t = m;
 
         // m is remainder now
         m = a % m;

rsa.h

@@ -1,7 +1,11 @@
 #pragma once
+#include "funconfig.h"
 #include <stdbool.h>
 #include <stdint.h>
 
+// Common public exponent, in Fermat prime form
+#define PUBEXP ((1 << 16) | 0x1)
+
 /**
  * @brief Calculates greatest common divider of two integers using the euclidean
  * algorithm
@@ -10,7 +14,7 @@
  * @param b Second number
  * @return The greatest common divider
  */
-uint64_t gcd(uint64_t a, uint64_t b);
+u64 gcd(u64 a, u64 b);
 
 /**
  * @brief Computes Euler's Totient function φ(n), which counts the number of
@@ -19,7 +23,7 @@ uint64_t gcd(uint64_t a, uint64_t b);
  * @param n The input number.
  * @return The number of integers from 1 to n that are coprime to n.
  */
-int totient(int n);
+u64 totient(u64 n);
 
 /**
  * @brief Computes (a * b) % m safely without overflow.
@@ -32,7 +36,7 @@ int totient(int n);
  * @param m The modulus.
  * @return (a * b) % m computed safely.
  */
-uint64_t mulmod(uint64_t a, uint64_t b, uint64_t m);
+u64 mulmod(u64 a, u64 b, u64 m);
 
 /**
  * @brief Modular exponentiation (a^b) mod m
@@ -41,7 +45,7 @@ uint64_t mulmod(uint64_t a, uint64_t b, uint64_t m);
  * @param b The exponent
  * @param m The modulus
  */
-uint64_t modexp(uint64_t a, uint64_t b, uint64_t m);
+u64 modexp(u64 a, u64 b, u64 m);
 
 /**
  * @brief Computes the modular inverse of a modulo m.
@@ -50,7 +54,7 @@ uint64_t modexp(uint64_t a, uint64_t b, uint64_t m);
  * @param m The modulus.
  * @return The modular inverse of a modulo m, or -1 if no inverse exists.
  */
-uint64_t mod_inverse(uint64_t a, uint64_t m);
+u64 mod_inverse(u64 a, u64 m);
 
 /**
  * @brief Generates a random prime number within the given range.
@@ -59,7 +63,7 @@ uint64_t mod_inverse(uint64_t a, uint64_t m);
  * @param max The upper bound (inclusive).
  * @return A prime number in the range [min, max].
  */
-uint64_t gen_prime(uint64_t min, uint64_t max);
+u64 gen_prime(u64 min, u64 max);
 
 /**
  * @brief Checks if a number is prime.
@@ -67,7 +71,7 @@ uint64_t gen_prime(uint64_t min, uint64_t max);
  * @param n The number to check.
  * @return true if n is prime, false otherwise.
  */
-bool is_prime(int n);
+bool is_prime(u64 n);
 
 /**
  * @brief Performs the Miller-Rabin primality test to check if a number is
@@ -77,7 +81,7 @@ bool is_prime(int n);
  * @param k The number of rounds of testing to perform.
  * @return true if n is probably prime, false if n is composite.
  */
-bool miller_rabin(uint64_t n, uint64_t k);
+bool miller_rabin(u64 n, u64 k);
 
 /**
  * @brief Computes the greatest common divisor (GCD) of two integers a and b
@@ -92,4 +96,4 @@ bool miller_rabin(uint64_t n, uint64_t k);
  * + by = gcd(a, b).
  * @return The greatest common divisor (gcd) of a and b.
  */
-int extended_euclid(int a, int b, int *x, int *y);
+u64 extended_euclid(u64 a, u64 b, u64 *x, u64 *y);