From: Harishankar <v.harishankar@gmail.com>
Date: Tue, 12 May 2020 09:13:40 +0000 (+0530)
Subject: Implemented encryption to obfuscate the grid in puzzle file
X-Git-Tag: 0.3a
X-Git-Url: https://harishankar.org/repos/?a=commitdiff_plain;h=efe3df7ba8a310849b15b1247addfb6908cc33cf;p=wordblah.git

Implemented encryption to obfuscate the grid in puzzle file
Implemented encryption while saving the puzzle file for the puzzle
grid characters using the master password for key generation.
---

diff --git a/wordblah.h b/wordblah.h
index 13874dc..f818a7e 100644
--- a/wordblah.h
+++ b/wordblah.h
@@ -50,7 +50,7 @@ typedef char String[MAX_CLUE_LENGTH];
 
 /* The main puzzle struct type */
 typedef struct {
-	char chars[MAX_PUZZLE_SIZE][MAX_PUZZLE_SIZE];
+	char chars[MAX_PUZZLE_SIZE+1][MAX_PUZZLE_SIZE+1];
 	int start_across_word[MAX_PUZZLE_SIZE][MAX_PUZZLE_SIZE];
 	int start_down_word[MAX_PUZZLE_SIZE][MAX_PUZZLE_SIZE];
 	String clue_across[MAX_PUZZLE_SIZE][MAX_PUZZLE_SIZE];
@@ -66,7 +66,7 @@ typedef struct {
 	Puzzle puzzle;
 	char filename[65535];
 	bool is_loaded;
-	char char_ans[MAX_PUZZLE_SIZE][MAX_PUZZLE_SIZE];
+	char char_ans[MAX_PUZZLE_SIZE+1][MAX_PUZZLE_SIZE+1];
 	int cur_row;
 	int cur_col;
 	bool solution_revealed;
@@ -103,13 +103,113 @@ err:
 	exit (2);
 }
 
-/* encode the binary data to readable text format using OpenSSL */
-void encode_binary (char *encoded, unsigned char *binary_data, unsigned int len)
+/* encode the binary data to readable text format using OpenSSL - also call
+   OPENSSL_free if the binary data was allocated by OpenSSL */
+void encode_binary (char *encoded, unsigned char *binary_data, unsigned int len,
+						bool free_openssl_data)
 {
 
 	EVP_EncodeBlock ((unsigned char*)encoded, 
 							(const unsigned char*)binary_data, len);
-	OPENSSL_free (binary_data);
+	if (free_openssl_data)
+		OPENSSL_free (binary_data);
+}
+
+/* decode the binary data from the textual representation using OpenSSL */
+void decode_binary (char *bin_data, char *encoded)
+{
+	EVP_DecodeBlock ((unsigned char*)bin_data, 
+							(const unsigned char*)encoded, strlen (encoded));
+}
+
+/* encrypt a block of text using password/passphrase with OpenSSL and 
+   also encode it to textual representation */
+void encrypt_data (char *enc_data, const char *data, const char *password)
+{
+	EVP_CIPHER_CTX *ctx;
+	int len, cipher_len; 
+	ctx = EVP_CIPHER_CTX_new ();
+	if (! ctx) goto err;
+	
+	unsigned char encrypted[256] = { '\0' };
+	
+	unsigned char key[EVP_MAX_KEY_LENGTH] = { '\0'};
+	unsigned char iv[EVP_MAX_IV_LENGTH] = { '\0' };
+	
+	if (! EVP_BytesToKey (EVP_aes_256_cbc(), EVP_md5(), NULL, 
+									(unsigned char*)password, strlen(password),
+										10, key, iv))
+		goto err;
+	
+	if (1 != EVP_EncryptInit_ex (ctx, EVP_aes_256_cbc(), NULL, key, iv))
+		goto err;
+	
+	if (1 != EVP_EncryptUpdate (ctx, (unsigned char*) encrypted, &len, 
+								(unsigned char*) data, strlen (data) ))
+		goto err;
+	cipher_len = len;
+	
+	if (1 != EVP_EncryptFinal_ex (ctx, encrypted + len, &len))
+		goto err;
+	
+	cipher_len += len;
+	EVP_CIPHER_CTX_free (ctx);
+	
+	EVP_EncodeBlock ((unsigned char*) enc_data, (unsigned char*) encrypted, 
+						cipher_len);
+	return;
+ err:
+ 	ERR_print_errors_fp (stderr);
+ 	EVP_CIPHER_CTX_free (ctx);
+ 	exit (2);
+}
+
+/* decrypt a block of text using password/passphrase with OpenSSL */
+void decrypt_data (char *dec_data, const char *data, const char *password)
+{
+	EVP_CIPHER_CTX *ctx;
+	int len, text_len; 
+	ctx = EVP_CIPHER_CTX_new ();
+	if (! ctx) goto err;
+	
+	char enc_data[256] = { '\0' };
+	
+	unsigned char key[EVP_MAX_KEY_LENGTH] = { '\0'};
+	unsigned char iv[EVP_MAX_IV_LENGTH] = { '\0' };
+
+	
+	if (! EVP_BytesToKey (EVP_aes_256_cbc(), EVP_md5(), NULL, 
+									(unsigned char*)password, strlen(password),
+										10, key, iv))
+		goto err;
+	
+	int r = EVP_DecodeBlock ((unsigned char*)enc_data, 
+								(const unsigned char*) data, strlen (data));
+	if (-1 == r)
+		goto err;
+	
+	
+	if (1 != EVP_DecryptInit_ex (ctx, EVP_aes_256_cbc(), NULL, key, iv))
+		goto err;
+	
+	if (1 != EVP_DecryptUpdate (ctx, (unsigned char*) dec_data, &len, 
+								(unsigned char*) enc_data, r - (r % 16) ))
+		goto err;
+	text_len = len;
+	
+	if (1 != EVP_DecryptFinal_ex (ctx, (unsigned char *)dec_data + len, &len))
+		goto err;
+	
+	text_len += len;
+	EVP_CIPHER_CTX_free (ctx);
+	
+	dec_data[text_len] = '\0';
+		
+	return;
+ err:
+ 	ERR_print_errors_fp (stderr);
+ 	EVP_CIPHER_CTX_free (ctx);
+ 	exit (2);
 }
 
 /* get a number from the user */
@@ -134,7 +234,7 @@ bool verify_solution_password (Puzzle *p, const char* password)
 	digest_message ((const unsigned char *)password, strlen(password),
 						&hashed_sol_password, &len);
 	char hashed_hex_pwd[256] = { '\0' };
-	encode_binary (hashed_hex_pwd, hashed_sol_password, len);
+	encode_binary (hashed_hex_pwd, hashed_sol_password, len, true);
 	
 	if (strcmp (p->hashed_solution_password, hashed_hex_pwd) == 0)
 		return true;
@@ -156,7 +256,7 @@ bool verify_master_password (Puzzle *p, const char* password)
 	digest_message ((const unsigned char *)password, strlen(password),
 						&hashed_mas_password, &len);
 	char hashed_hex_pwd[256] = { '\0' };
-	encode_binary (hashed_hex_pwd, hashed_mas_password, len);
+	encode_binary (hashed_hex_pwd, hashed_mas_password, len, true);
 	
 	if (strcmp (p->hashed_master_password, hashed_hex_pwd) == 0)
 		return true;
@@ -180,7 +280,7 @@ void set_solution_password (Puzzle *p, const char *password)
 		/* the hashedpwd contains binary data - we will convert it to 
 		   hexadecimal data and store in file */
 
-		encode_binary (p->hashed_solution_password, hashedpwd, len);
+		encode_binary (p->hashed_solution_password, hashedpwd, len, true);
 	}
 }
 
@@ -200,7 +300,7 @@ void set_master_password (Puzzle *p, const char *password)
 		/* the hashedpwd contains binary data - we will convert it to 
 		   hexadecimal data and store in file */
 
-		encode_binary (p->hashed_master_password, hashedpwd, len);
+		encode_binary (p->hashed_master_password, hashedpwd, len, true);
 	}
 }
 
@@ -517,11 +617,14 @@ void save_puzzle (Puzzle *puzzle, const char* file)
 	/* the hashed_solution_password */
 	fprintf (outfile, "%s\n", puzzle->hashed_solution_password);
 	
-	/* First output the grid characters columns/rows */
+	/* First output the grid characters columns/rows as encrypted */
 	for (int i = 0; i < puzzle->grid_size; i ++)
 	{
-		for (int j = 0; j < puzzle->grid_size; j ++)
-			fprintf (outfile, "%c", puzzle->chars[i][j]);
+		char encrypted[256] = { '\0' };
+		encrypt_data (encrypted, puzzle->chars[i], 
+								puzzle->hashed_master_password);
+
+		fprintf (outfile, "%s", encrypted);
 		fprintf (outfile, "\n");
 	}
 	
@@ -670,9 +773,12 @@ Puzzle load_puzzle (const char* file)
 	/* read each character of the grid */
 	for (int i = 0; i < p.grid_size; i ++ )
 	{
-		fgets (line, MAX_CLUE_LENGTH + 10, infile);
+		char encoded[256];
+		fgets (encoded, MAX_CLUE_LENGTH + 10, infile);
+		decrypt_data (line, encoded, p.hashed_master_password);
 		for (int j = 0; j < p.grid_size; j ++)
 			p.chars[i][j] = line[j];
+
 	}
 	/* read the word numbers */
 	for (int i = 0; i < p.grid_size; i ++)
diff --git a/wordblah_player.c b/wordblah_player.c
index 9ca4938..50a1c57 100644
--- a/wordblah_player.c
+++ b/wordblah_player.c
@@ -57,7 +57,7 @@ gboolean on_down_list_selection_changed (GtkTreeSelection *sel,
 	GtkTreeIter iter;
 	GtkTreeModel* mod;
 	
-	if (gtk_tree_selection_get_selected (sel, &mod, &iter))
+	if (gtk_tree_selection_get_selected (sel, &mod, &iter) == TRUE) 
 	{
 		guint sel_word_index;
 		gtk_tree_model_get (mod, &iter, 0, &sel_word_index, -1);
@@ -78,7 +78,7 @@ gboolean on_across_list_selection_changed (GtkTreeSelection *sel,
 	GtkTreeIter iter;
 	GtkTreeModel* mod;
 	
-	if (gtk_tree_selection_get_selected (sel, &mod, &iter))
+	if (gtk_tree_selection_get_selected (sel, &mod, &iter) == TRUE)
 	{
 		guint sel_word_index;
 		gtk_tree_model_get (mod, &iter, 0, &sel_word_index, -1);