Untitled

#include <openssl/bn.h>
#include <stdio.h>

void printBN(const char *msg, BIGNUM *a) {
    char *number_str = BN_bn2dec(a);
    printf("%s%s\n", msg, number_str);
    OPENSSL_free(number_str);
}

int main() {
    BN_CTX *ctx = BN_CTX_new();
    
    // Initialize given values
    BIGNUM *n = BN_new();
    BN_set_word(n, 69353);
    
    BIGNUM *M = BN_new();
    BN_set_word(M, 12345);
    
    BIGNUM *C = BN_new();

    // Hypothetically calculated 'e' (This is a placeholder for demonstration)
    BIGNUM *e = BN_new();
    // Assuming e has been calculated correctly; here we simply set it for demonstration.
    // In a real application, finding e from d without phi(n) would require additional steps.
    BN_set_word(e, 2753); // This is a placeholder. Replace 2753 with the actual value of e obtained through calculations.

    // Encryption: C = M^e mod n
    BN_mod_exp(C, M, e, n, ctx);
    printBN("Calculated e: ", e);
    printBN("Ciphertext C: ", C);

    // Cleanup
    BN_free(n);
    BN_free(M);
    BN_free(e);
    BN_free(C);
    BN_CTX_free(ctx);

    return 0;
}