C language to implement a password manager (under update)

  As a computer enthusiast , Will often register various website accounts , But considering the possible leakage of privacy , Don't like hosting passwords to browsers , So often forget all kinds of passwords . After suffering , I decided to learn a little c Language knowledge to write a password manager .

  Before writing, I hope it can realize the following functions ：

  1. Be able to write a new password , And save the time and date when writing the password .

  2. Can find the password , When you can't find an account that fully matches the characteristics , Can remind me of the most similar account .  

  3. Be able to change the password of a certain account type , When modifying , Synchronize the time of modification .、

  4. The stored data is divided into four parts , The first is the account type , Such as ：wechat, The second is account , The third is the account and password , The fourth is the last storage , Or the standard time of modification .

  5. Be able to list all account types , For me to read .

  6. All stored data should be randomly encrypted , When reading, it can decrypt according to the random key .

After figuring out the function , We need to imagine using the process , first , You must log in , If you haven't logged in before , Then you need to register .

Part of the code is as follows ：

int jianchadengru()
{ 
	char arr1[100] = { 0 };
	char arr2[100] = { 0 };
	char count[100] = { 0 };
	char pass[100] = { 0 };
	char date[100] = { 0 };
	char type[100] = { 0 };
	char mystring[400] = { 0 };
	FILE* pf = fopen("test.txt", "r");
	fgets(mystring, 400, pf);
	fclose(pf);
	jiemi(type, arr1, arr2, date, mystring);
	//printf("%s", type);
	printf(" Enter your account number :");
	scanf("%s", &count);
	printf(" Enter your password :");
	scanf("%s", &pass);
	if (strcmp(count, arr1) == 0 && strcmp(pass, arr2) == 0 && strcmp(type, "admin") == 0)
		return 1;
	return 0;
}

After go in , Need to write a simple menu .

void onlymenu()
{
	printf("---------------------------------------\n");
	printf("-----           Password trustee         ------\n");
	printf("-----          1. Write new password       ------\n");
	printf("-----          2. Find a password     ------\n");
	printf("-----          3. Modify an account     ------\n");
	printf("-----          4. See all accounts     ------\n");
	printf("-----          0. Exit procedure         ------\n");
	printf("---------------------------------------\n");
	printf("---------------------------------------\n");
	printf("---------------------------------------\n");
}
void menu()
{
	onlymenu();
	int i = 0;
	do
	{
		printf("\n Please select :");
		scanf("%d", &i);
		int k = 0;
		switch (i)
		{
		case 1:
			add_count();
			break;
		case 2:
			chazhao();
			break;
		case 3:
			xiugai();
			break;
		case 4:
			check_all();
			break;
		case 0:
			return;
		default:
			printf(" Wrong choice \n");
			break;
		}
	} while (i);
}

Writing a new password is relatively simple , Just add write ok.

void add_count()
{
	while (1)
	{
		char flag[20] = { 0 };
		char count[100] = { 0 };
		char pass[100] = { 0 };
		char type[100] = { 0 };
		printf(" Enter the account type you want to add ( Do not include spaces , Not more than 100 Characters ):");
		scanf("%s", &type);
		printf(" Enter the account you want to add ( Do not include spaces , Not more than 100 Characters ):");
		scanf("%s", &count);
		printf(" Enter the password of the account you want to add ( Do not include spaces , Not more than 100 Characters ):");
		scanf("%s", &pass);
		printf(" The account type you added is :%s, Account No :%s, The password for :%s\n Are you sure (YES):",type, count, pass);
		scanf("%s", &flag);
		if (strcmp(flag, "YES") == 0)
		{
			xieru(type, count, pass);
			printf(" Write successfully !");
			break;
		}
	}
}

void put_time(char ltime[100], int* i, int time_flag)
{
	ltime[*i] = time_flag / 10 + '0';
	(*i)++;
	ltime[*i] = time_flag % 10 + '0';
	(*i) += 3;
}
void get_time(char ltime[100])
{
	time_t timep;
	struct tm* p;
	time(&timep);
	p = gmtime(&timep);
	int i = 0;
	int year = 1900 + p->tm_year;
	while (year > 0)
	{
		ltime[i] = (year % (int)pow(10, 4 - i)) / (int)pow(10, 3 - i) + '0';
		i++;
		year = year % (int)pow(10, 4 - i);
	}
	strcat(ltime, " year ");
	i += 2;
	char* week[7] = { " Monday "," Tuesday "," Wednesday "," Thursday "," Friday "," Saturday "," Sunday " };
	put_time(ltime, &i, 1 + p->tm_mon);
	strcat(ltime, " month ");
	put_time(ltime, &i, p->tm_mday);
	strcat(ltime, " Japan ");
	i += 6;
	strcat(ltime, week[p->tm_wday]);
	put_time(ltime, &i, p->tm_hour + 8);
	strcat(ltime, " when ");
	put_time(ltime, &i, p->tm_min);
	strcat(ltime, " branch ");
	put_time(ltime, &i, p->tm_sec);
	strcat(ltime, " second ");
}
void xieru(char type[100],char count[100],char pass[100])
{
	FILE* pf = fopen("test.txt", "a");
	int code1 = readom();
	char ltime[100] = { 0 };
	get_time(ltime);
	jiami(ltime, (int)strlen(ltime), code1);
	jiami(count, (int)strlen(count), code1);
	jiami(pass, (int)strlen(pass), code1);
	jiami(type, (int)strlen(type), code1);
	char code = code1 + '0';
	fputc(code, pf);
	fputc(';', pf);
	fputs(type, pf);
	fputc(';', pf);
	fputs(count, pf);
	fputc(';', pf);
	fputs(pass, pf);
	fputc(';', pf);
	fputs(ltime, pf);
	fputc('\n', pf);
	fclose(pf);
}

In this way, the writing automatically adds the system time .

Then there is the lookup function .

Lookup function , My idea is this , If you can find an account that fully matches the characteristics , Then there is no need to look down , If you don't find a perfect match , Then create an array , Record the overlapping size of each account and search account , Take the maximum to prompt .

int findmax(int arr[100])
{
	int i = 0;
	int max = 0;
	int max_i = 0;
	for (i = 0; i < 100; i++)
	{
		if (arr[i] > max)
		{
			max_i = i;
			max = arr[i];
		}
	}
	return max_i;
}
void chazhao()
{
	char count[30][100] = { 0 };
	char pass[30][100] = { 0 };
	char type[30][100] = { 0 };
	char date[30][100] = { 0 };
	FILE* pf = fopen("test.txt", "r");
	char mystring[400] = {0};
	int i = 0;
	int j = 0;
	int tmp = 0;
	if (pf == NULL)
	{
		printf(" Missing key files , Program error , Please contact the developer .\n");
		system("pause");
		return;
	}
	else
	{
		while (fgets(mystring, 400, pf) != NULL)
		{
			jiemi(type[i],count[i], pass[i],date[i], mystring);		
			i++;
		}
		fclose(pf);
	}
	int flag[100] = { 0 };
	while (1)
	{
		printf(" Please enter the account type you want to find :");
		char count1[100] = {0};
		scanf("%s", &count1);
		tmp = i;
		int coin = 0;
		for (i = 0; i < tmp; i++)
		{
			if (strcmp(count1, type[i]) == 0)
			{
				coin = 1;
				printf(" Account No :%s\n The password for :%s\n",count[i], pass[i]);
				return;
			}
			else
			{
				for (j = 0; j < 100; j++)
				{
					if (type[i][j] == count1[j] && j < strlen(count1) && j < strlen(type[i]))
					{
						flag[i]++;
					}
				}
			}		
		}
		if (coin != 1)
		{
			printf(" The account that fully matches the characteristics is not found \n The program guesses that you are looking for :%s Type account \n", type[findmax(flag)]);
		}
	}
}

Then modify the function , We can modify it like this , First write the modified value to the original file , Then find the location of the account number to be modified in the original file , Then create a new file , Copy the original file , But when it comes to modifying the location of the account , Just skip. .

void xiugai()
{
	int i = 0;
	while (1)
	{
		char type[100] = { 0 };
		char count[100] = { 0 };
		char pass[100] = { 0 };
		char date[100] = { 0 };
		int notice = 0;
		char arr[100] = { 0 };
		printf(" Please enter the account type to be modified :");
		scanf("%s", &arr);
		if (strcmp("admin",arr) == 0)
		{
			printf(" Modification of login account is not supported for the time being \n");
			return;
		}
		i = 0;
		int tmp = 0;
		int j = 0;
		FILE* pf = fopen("test.txt", "r");
		if (pf == NULL)
		{
			printf(" Missing key files , Please contact the developer .");
			return;
		}
		char mystring[400] = { 0 };
		while (fgets(mystring, 400, pf) != NULL)
		{
			char count_tmp[100] = { 0 };
			int key = mystring[0] - '0';
			for (j = 2, tmp = 0; mystring[j] != ';'; j++, tmp++)
				count_tmp[tmp] = mystring[j] + key;
			if (strcmp(count_tmp, arr) == 0)
			{
				notice = 1;
				fclose(pf);
				jiemi(type, count, pass, date, mystring);
				break;
			}
			else
				i++;
		}
		fclose(pf);
		if (notice == 0)
		{
			printf(" No fully matching account was found \n Please check this account first , Then enter the exact name !\n");
			return;
		}
		else
		{
			char typetmp[100] = { 0 };
			char counttmp[100] = { 0 };
			char passtmp[100] = { 0 };
			printf(" Please enter why you want to change the account type ( If it is not modified, enter quit):");
			scanf("%s", &typetmp);
			if (strcmp(typetmp, "quit") == 0)
				strcpy(typetmp, type);
			printf(" Please enter the reason for modifying the account ( If it is not modified, enter quit):");
			scanf("%s", &counttmp);
			if (strcmp(counttmp, "quit") == 0)
				strcpy(counttmp, count);
			printf(" Please enter the reason for changing the password ( If it is not modified, enter quit):");
			scanf("%s", &passtmp);
			if (strcmp(passtmp, "quit") == 0)
				strcpy(passtmp, pass);
			xieru(typetmp,counttmp,passtmp);
			break;
		}
	}
	move(i);
	printf(" Modification successful ！\n2s After the return \n");
	Sleep(2000);
	system("cls");
	onlymenu();
}
void move(int i)
{
	FILE* pf = fopen("test.txt", "r");
	FILE* pf1 = fopen("tmp.txt", "w");
	char mystring[400] = { 0 };
	int j = 0;
	int flag = i;
	for (i = 0; fgets(mystring, 400, pf) != NULL; i++)
		if (i != flag)
			fputs(mystring, pf1);
	fclose(pf);
	fclose(pf1);
	//fclose("test.txt");
	remove("test.txt");
	rename("tmp.txt","test.txt");
}

Then there is the function that displays all accounts , This is the simplest .

void check_all()
{
	char type[30][100] = { 0 };
	char date[30][100] = { 0 };
	char pass[30][100] = { 0 };
	char count[30][100] = { 0 };
	FILE* pf = fopen("test.txt", "r");
	char mystring[400] = { 0 };
	int i = 0;
	int tmp = 0;
	if (pf == NULL)
	{
		printf(" Missing key files , Program error , Please contact the developer .(qq:2898239515)\n");
		system("pause");
		return;
	}
	else
	{
		while (fgets(mystring, 400, pf) != NULL)
		{
			jiemi(type[i], count[i], pass[i], date[i], mystring);
			i++;
		}
		fclose(pf);
	}
	printf(" The account you are hosting here has the following :\n");
	printf(" Account type ---- The last time the account was saved or modified \n");
	for (tmp = 0; tmp < i; tmp++)
	{
		printf("%s", type[tmp]);
		printf("    ");
		printf("%s\n", date[tmp]);
	}
}

Next is the most critical random encryption and decryption function , My current idea is to generate 10 A random number within is used as the random key , Then subtract the random number from all the characters , Get a new character , The whole data is encrypted . When decrypting , Read this key , Then add it back , It's solved .（ Of course, I think this encryption method is very simple , I may use a more complicated encryption method later ）

If the audience wants to experience , You can ask me for exe Oh .