From 8df5a6344e169748536bbf06a88c21577fa60118 Mon Sep 17 00:00:00 2001
From: "Alexander \"Arav\" Andreev" <me@arav.su>
Date: Sun, 24 Mar 2024 04:41:08 +0400
Subject: [PATCH] Another change of main to show an example of key exchange and
 data encryption.

---
 src/main.c | 95 +++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 61 insertions(+), 34 deletions(-)

diff --git a/src/main.c b/src/main.c
index 65ff704..e4aadbd 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,7 +1,6 @@
 #include <sodium/utils.h>
 #include <stdio.h>
 #include <string.h>
-#include <errno.h>
 
 #include "audio.h"
 #include "crypt.h"
@@ -21,61 +20,89 @@ int main(int argc, char **argv) {
         return -1;
     }
 
-    crypt_key_t own, ownr;
+    crypt_key_t own, remote;
 
     if (crypt_key_gen(&own) < 0) {
         fprintf(stderr, "Failed to generate the keys.");
         return -1;
     }
 
-    FILE *fp = fopen("own_pub_key", "w+");
-    FILE *fs = fopen("own_sec_key", "w+");
-
-    if (fp == NULL) {
-        fprintf(stderr, "fp err: %s\n", strerror(errno));
-        return 0;
+    if (crypt_key_gen(&remote) < 0) {
+        fprintf(stderr, "Failed to generate the keys.");
+        return -1;
     }
 
-    if (fs == NULL) {
-        fprintf(stderr, "fs err: %s\n", strerror(errno));
-        return 0;
+    unsigned char *oh = crypt_hello(&own);
+    unsigned char *rh = crypt_hello(&remote);
+
+    int rt = 0;
+
+    if (crypt_hello_verify(oh, &own) < 0) {
+        fprintf(stderr, "oh v fail");
+        rt = -1;
+        goto cleanup;
     }
 
-    char phex[CRYPT_PKEY_HEXLEN], shex[CRYPT_SKEY_HEXLEN];
+    if (crypt_hello_verify(rh, &remote) < 0) {
+        fprintf(stderr, "rh v fail");
+        rt = -1;
+        goto cleanup;
+    }
 
-    crypt_key_export_public(&own, phex);
-    crypt_key_export_secret(&own, shex);
+    const unsigned char *nonce_own = crypt_hello_get_nonce(oh, rh, false);
+    const unsigned char *nonce_rem = crypt_hello_get_nonce(rh, oh, true);
 
-    crypt_store_key(&own, fp, fs);
+    for (unsigned int i = 0; i < CRYPT_NONCE_LEN; ++i)
+        if (nonce_own[i] != nonce_rem[i]) {
+            fprintf(stderr, "A nonce mismatch occured.");
+            rt = -1;
+            goto cleanup;
+        }
 
+    crypt_session_t os, rs;
 
-    fflush(fp);
-    fflush(fs);
-    fseek(fp, 0, SEEK_SET);
-    fseek(fs, 0, SEEK_SET);
+    if (crypt_session_init(&os, &own, &remote, nonce_own, true) < 0) {
+        rt = -1;
+        goto cleanup;
+    }
 
-    crypt_load_key(&ownr, fp, fs);
+    if (crypt_session_init(&rs, &remote, &own, nonce_rem, false) < 0) {
+        rt = -1;
+        goto cleanup;
+    }
 
-    char phexr[CRYPT_PKEY_HEXLEN], shexr[CRYPT_SKEY_HEXLEN];
+    char msg[] = "Hello!";
+    unsigned long long msglen = 6;
 
-    crypt_key_export_public(&ownr, phexr);
-    crypt_key_export_secret(&ownr, shexr);
+    unsigned long long ocl = 0;
+    unsigned char *oc = crypt_session_encrypt(&os, (unsigned char *)msg, msglen, &ocl);
 
-    fclose(fp);
-    fclose(fs);
+    if (oc == NULL) {
+        fprintf(stderr, "oc is null");
+        rt = -1;
+        goto cleanup;
+    }
 
-    unsigned char *h = crypt_hello(&own);
+    unsigned long long rml = 0;
+    char *rmsg = (char *)crypt_session_decrypt(&rs, oc, ocl, &rml);
 
-    int o = crypt_hello_verify(h, &ownr);
-    printf("o = %i\n", o);
+    if (rmsg == NULL) {
+        rt = -1;
+        goto cleanup;
+    }
+
+    if (strcmp(msg, rmsg) != 0)
+        fprintf(stderr, "Yikes!");
+
+cleanup:
+    free(oh);
+    free(rh);
 
     crypt_key_destroy(&own);
-    crypt_key_destroy(&ownr);
+    crypt_key_destroy(&remote);
 
-    sodium_memzero(phex, CRYPT_PKEY_HEXLEN);
-    sodium_memzero(phexr, CRYPT_PKEY_HEXLEN);
-    sodium_memzero(shex, CRYPT_SKEY_HEXLEN);
-    sodium_memzero(shexr, CRYPT_SKEY_HEXLEN);
+    crypt_session_destroy(&os);
+    crypt_session_destroy(&rs);
 
     // audio_t aud;
 
@@ -93,5 +120,5 @@ int main(int argc, char **argv) {
 
     // audio_destroy(&aud);
 
-    return 0;
+    return rt;
 }
\ No newline at end of file