defined why2_chat_ecc_verify_signature

one commit, 8 hours of going crazy together with AI

include/chat/crypto.h

@@ -23,6 +23,10 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 extern "C" {
 #endif
 
+#include <openssl/types.h>
+
+#include <why2/flags.h>
+
 #include <why2/chat/config.h>
 
 //MACROS
@@ -31,10 +35,13 @@ extern "C" {
 #define WHY2_CHAT_KEY_LOCATION WHY2_CONFIG_DIR "/keys" //KEYS LOCATION
 #define WHY2_CHAT_KEY "secp521r1.pem"
 
+#define WHY2_CHAT_BASE64_LENGTH_DELIMITER ':' //SEPARATES BASE64 FROM LENGTH (YnJhbWJvcmFrCg==:9)
+
 void why2_chat_init_keys(void); //INIT (POSSIBLY GENERATE) ECC KEYS
 void why2_chat_deallocate_keys(void); //DEALLOCATE :) (NO SLUR HERE)
 
 char *why2_chat_ecc_sign(char *message); //SIGN message WITH ECC KEY
+why2_bool why2_chat_ecc_verify_signature(char *message, char *signature, EVP_PKEY *key);
 
 char *why2_sha256(char *input); //HASH input USING SHA256 AND RETURN IN STRING
 

src/chat/crypto.c

@@ -35,7 +35,7 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 EVP_PKEY *keypair = NULL; //KEYPAIR
 
 //LOCAL
-char* base64_encode(char *message)
+char *base64_encode(char *message, size_t length)
 {
     //VARIABLES
     BIO *bio;
@@ -45,18 +45,20 @@ char* base64_encode(char *message)
 
     //INIT BIOs
     b64 = BIO_new(BIO_f_base64());
+    BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL); //DISABLE NEWLINES
     bio = BIO_new(BIO_s_mem());
     bio = BIO_push(b64, bio);
 
     //ENCODE
-    BIO_write(bio, message, strlen(message));
+    BIO_write(bio, message, length);
     BIO_flush(bio);
     BIO_get_mem_ptr(bio, &buffer_ptr);
 
     //COPY
-    encoded_message = why2_malloc(buffer_ptr -> length + 1);
+    encoded_message = why2_malloc(buffer_ptr -> length + why2_count_int_length((int) length) + 2);
     memcpy(encoded_message, buffer_ptr -> data, buffer_ptr -> length);
-    encoded_message[buffer_ptr -> length] = '\0';
+
+    sprintf(encoded_message + buffer_ptr -> length, "%c%zu%c", WHY2_CHAT_BASE64_LENGTH_DELIMITER, length, '\0'); //APPEND LENGTH
 
     //DEALLOCATION
     BIO_free_all(bio);
@@ -64,21 +66,27 @@ char* base64_encode(char *message)
     return encoded_message;
 }
 
-char* base64_decode(char *encoded_message)
+char *base64_decode(char *encoded_message, size_t *length)
 {
     //VARIABLES
     BIO *bio;
     BIO *b64;
-    size_t length = strlen(encoded_message);
+    char *separator_ptr = strrchr(encoded_message, WHY2_CHAT_BASE64_LENGTH_DELIMITER); //GET THE DELIMITER POINTER
-    char* decoded_message = why2_malloc(length);
+    *length = strtoull(separator_ptr + 1, NULL, 10);
+    char* decoded_message = why2_malloc(*length + 1);
+    int decoded_length;
 
     //INIT BIOs
     b64 = BIO_new(BIO_f_base64());
-    bio = BIO_new_mem_buf(encoded_message, length);
+    BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL); //DISABLE NEWLINES
+    bio = BIO_new_mem_buf(encoded_message, separator_ptr - encoded_message);
     bio = BIO_push(b64, bio);
 
+    //DECODE
+    decoded_length = BIO_read(bio, decoded_message, *length);
+
     //NULL-TERM
-    decoded_message[BIO_read(bio, decoded_message, length)] = '\0';
+    decoded_message[decoded_length] = '\0';
 
     //DEALLOCATION
     BIO_free_all(bio);
@@ -148,7 +156,7 @@ char *why2_chat_ecc_sign(char *message)
     sig = why2_malloc(siglen); //ALLOCATE SIGNATURE
     EVP_DigestSignFinal(mdctx, (unsigned char*) sig, &siglen);
 
-    encoded_sig = base64_encode(sig); //CONVERT sig TO BASE64
+    encoded_sig = base64_encode(sig, siglen); //CONVERT sig TO BASE64
 
     //DEALLOCATION
     why2_deallocate(sig);
@@ -157,6 +165,30 @@ char *why2_chat_ecc_sign(char *message)
     return encoded_sig;
 }
 
+why2_bool why2_chat_ecc_verify_signature(char *message, char *signature, EVP_PKEY *key)
+{
+    //VARIABLES
+    size_t length;
+    char *decoded_signature = base64_decode(signature, &length); //DECODE SIGNATURE
+    why2_bool returning;
+
+    //INIT CONTEXT
+    EVP_MD_CTX* ctx = EVP_MD_CTX_new();
+
+    //INIT VERIFICATION CONTEXT
+    EVP_DigestVerifyInit(ctx, NULL, EVP_sha256(), NULL, key);
+
+    //VERIFY MESSAGE
+    EVP_DigestVerifyUpdate(ctx, message, strlen(message));
+    returning = EVP_DigestVerifyFinal(ctx, (unsigned char*) decoded_signature, length) == 1;
+
+    //DEALLOCATION
+    EVP_MD_CTX_free(ctx);
+    why2_deallocate(decoded_signature);
+
+    return returning;
+}
+
 void why2_chat_deallocate_keys(void)
 {
     //DEALLOCATE THE pkey