1 00:00:00,450 --> 00:00:03,210 Now that we've learned all about loops in Python, 2 00:00:03,540 --> 00:00:06,960 we're finally ready to tackle our final project of the day, 3 00:00:07,290 --> 00:00:09,690 which is the PyPassword generator. 4 00:00:10,440 --> 00:00:14,100 Our program will ask us how many letters would you like in your password? 5 00:00:14,100 --> 00:00:17,640 So I will say I would like a long password, let's say 14. 6 00:00:18,300 --> 00:00:22,290 How many symbols, 3, how many numbers, 4, 7 00:00:22,950 --> 00:00:27,390 and it's going to generate me a password that is almost completely impossible to 8 00:00:27,390 --> 00:00:30,840 crack by any hacker, no matter how talented they are. 9 00:00:31,620 --> 00:00:35,640 So the project of today is to build this password generator. 10 00:00:36,180 --> 00:00:38,670 If you head over to this particular Repl.it, 11 00:00:38,670 --> 00:00:43,320 password-generator-start, then you'll see that here 12 00:00:43,320 --> 00:00:48,320 I've already included for you a list of all the letters in the alphabet from A 13 00:00:48,360 --> 00:00:51,630 to Z, including the uppercase and lowercase letters. 14 00:00:52,200 --> 00:00:56,850 I've got a bunch of numbers and a bunch of symbols that are usually accepted by 15 00:00:56,850 --> 00:00:58,260 websites in the passwords. 16 00:00:59,040 --> 00:01:03,330 And I've also created the inputs that you saw when we did the demo. 17 00:01:03,870 --> 00:01:07,440 So it's going to ask us how many letters, how many symbols, how many numbers, 18 00:01:07,920 --> 00:01:12,270 and then you're going to turn all of that knowledge as well as using these 19 00:01:12,270 --> 00:01:13,080 lists 20 00:01:13,080 --> 00:01:18,060 and what you've learned about loops into the same password generator that you 21 00:01:18,060 --> 00:01:19,890 saw in the final demo. 22 00:01:20,340 --> 00:01:23,160 So have a play around with the final demo yourself, 23 00:01:23,700 --> 00:01:27,900 and then have a think about how you might be able to achieve this goal of 24 00:01:27,900 --> 00:01:32,900 creating a random password for the user based on the number of letters, 25 00:01:33,330 --> 00:01:35,670 symbols, and numbers that they want. 26 00:01:37,050 --> 00:01:40,110 Now there's two levels to this project. 27 00:01:40,200 --> 00:01:45,200 You can either go for the easy version where all you have to do is generate your 28 00:01:46,680 --> 00:01:51,180 password in sequence. So for example, if the user wanted four letters, 29 00:01:51,540 --> 00:01:53,250 two symbols, and two numbers, 30 00:01:53,550 --> 00:01:58,550 then it might just look like this four letters and then two symbols and then two 31 00:02:01,080 --> 00:02:04,650 numbers. So they're in sequence right? First, you've got the letters, 32 00:02:04,950 --> 00:02:07,110 then you've got the number of required symbols, 33 00:02:07,260 --> 00:02:11,490 and then you've got the required numbers. So this is the easy level. 34 00:02:12,060 --> 00:02:17,060 And then there is the hard level. And the hard level requires you to generate the 35 00:02:18,330 --> 00:02:21,810 password in a completely random order. 36 00:02:21,840 --> 00:02:25,500 So instead of having it being, letter symbol number, 37 00:02:25,800 --> 00:02:30,800 it should be maybe letter and then a symbol and then a number, 38 00:02:30,810 --> 00:02:33,930 then a letter, then a symbol and then a number. 39 00:02:34,980 --> 00:02:37,950 But notice how this is completely random. 40 00:02:38,310 --> 00:02:40,020 Every single time you generate it, 41 00:02:40,110 --> 00:02:45,110 the order of where the symbols and where the numbers appear in your password are 42 00:02:45,450 --> 00:02:47,430 completely random. So for example, 43 00:02:47,430 --> 00:02:51,210 if you look at the demo version and I do the same thing, 44 00:02:51,210 --> 00:02:53,190 four letters, two symbols, 45 00:02:53,190 --> 00:02:58,110 two numbers, where the numbers and where the symbols occur are completely 46 00:02:58,110 --> 00:03:02,500 unpredictable. And every single time I generate a new password, 47 00:03:02,770 --> 00:03:04,240 it's going to switch it up again. 48 00:03:04,360 --> 00:03:09,220 So that's the hard level. I recommend trying the easy level first 49 00:03:09,430 --> 00:03:13,660 and then once you've managed to do it, then take yourself up to the hard level 50 00:03:13,690 --> 00:03:17,710 if you think you're up to it. But remember that if your doing the hard level, 51 00:03:17,770 --> 00:03:22,450 you might have to do a little quick Google around in order to figure out how to 52 00:03:22,450 --> 00:03:24,850 do something that you might not have seen before. 53 00:03:25,330 --> 00:03:29,560 But it's all part of the challenge and I hope you'll take it on with vigor. 54 00:03:29,710 --> 00:03:33,670 So pause the video now and try to complete the final project. 55 00:03:42,580 --> 00:03:42,870 Alright, 56 00:03:42,870 --> 00:03:47,730 so let's first tackle the easy level where we're just generating a password 57 00:03:48,090 --> 00:03:52,680 with the required number of letters and then the required number of symbols and 58 00:03:52,680 --> 00:03:54,540 then the required number of numbers. 59 00:03:55,050 --> 00:03:57,060 So let's go ahead and tackle this one first. 60 00:03:57,810 --> 00:04:01,680 Now we know that we've got these lists which we can draw from, 61 00:04:01,890 --> 00:04:06,660 and we know that we can use the random module to get hold of a random item from 62 00:04:06,660 --> 00:04:11,190 the list. So all we have to do is first get four random letters. 63 00:04:11,610 --> 00:04:14,010 So let's say that we had a password 64 00:04:14,040 --> 00:04:16,769 which just started out as an empty string. 65 00:04:17,430 --> 00:04:22,430 Then we can use a for loop to loop through all of the characters that we need to 66 00:04:23,580 --> 00:04:27,030 create for our password. For example, 67 00:04:27,030 --> 00:04:32,030 I might say for char, short for character, in the range of, 68 00:04:32,850 --> 00:04:33,360 um, 69 00:04:33,360 --> 00:04:38,100 from 1 to the number of letters that the user wanted. 70 00:04:41,010 --> 00:04:43,380 So in this case, if the user wanted four letters, 71 00:04:43,440 --> 00:04:48,240 then it will be a range from one to four, but not including four. 72 00:04:48,660 --> 00:04:50,820 So it's actually from one to three, 73 00:04:51,180 --> 00:04:54,240 which has only three characters. In order to modify this, 74 00:04:54,270 --> 00:04:56,430 we have to do what we did always before, 75 00:04:56,430 --> 00:04:59,730 which is just to add one to the end of our range. 76 00:05:00,240 --> 00:05:04,620 So now we're going to create a range based on the number of letters that the 77 00:05:04,620 --> 00:05:05,460 user wanted. 78 00:05:05,610 --> 00:05:08,640 And I'm just going to go along with the assumption that the number of letters 79 00:05:08,670 --> 00:05:11,910 equals four. Let's just pretend that's what the user will enter. 80 00:05:12,420 --> 00:05:16,200 So then this range becomes 1, 2, 4 + 1 which is 5. 81 00:05:16,470 --> 00:05:21,470 So the range is in fact going to be 1 to 4. For every single number in that 82 00:05:22,620 --> 00:05:25,050 range from one to two to three to four, 83 00:05:25,350 --> 00:05:28,200 I'm going to generate them a random letter, 84 00:05:28,260 --> 00:05:32,010 and I'm gonna pick it out of this list of letters. To do that 85 00:05:32,190 --> 00:05:37,190 I can either generate a random number and use it as the index or you might've 86 00:05:37,830 --> 00:05:38,910 seen previously 87 00:05:38,970 --> 00:05:43,970 I showed you the random.choice function. And inside this random.choice, 88 00:05:45,450 --> 00:05:47,610 we can pass a sequence 89 00:05:47,640 --> 00:05:50,760 which in our case is the letters list. 90 00:05:51,450 --> 00:05:56,450 Then it will look through this list of letters and it will give us a random item from 91 00:05:58,490 --> 00:05:59,323 that list. 92 00:05:59,780 --> 00:06:04,340 So now that random letter is going to be something that we're going to need to 93 00:06:04,340 --> 00:06:06,320 add to our password, right? 94 00:06:06,740 --> 00:06:11,210 So we can set this equal to a random character. 95 00:06:12,140 --> 00:06:14,570 And now let's go ahead and just print it out. 96 00:06:15,490 --> 00:06:16,323 Right? 97 00:06:19,690 --> 00:06:24,690 So let's say we want four letters in our password and we can type anything for 98 00:06:24,940 --> 00:06:27,910 the other ones, but notice how when the for loop runs, 99 00:06:28,000 --> 00:06:33,000 it's given us some random characters that it's picked out of our letters list. 100 00:06:34,540 --> 00:06:35,470 So there's an a, 101 00:06:35,500 --> 00:06:40,500 there's a capital P there's a d and there's a capital J. How can we add each of those 102 00:06:41,050 --> 00:06:43,900 letters to our password? Well, 103 00:06:43,900 --> 00:06:48,900 we can use the string concatenation that we learned very early on in Day 1. 104 00:06:49,720 --> 00:06:53,380 We can say password equals the previous password 105 00:06:53,710 --> 00:06:57,460 plus the random character. Of course, 106 00:06:57,460 --> 00:07:01,960 the shortened version of this is just password+= random_char. 107 00:07:02,440 --> 00:07:06,070 And now let's go ahead and instead of printing the random character, 108 00:07:06,400 --> 00:07:09,610 let's print the password at each stage of the loop. 109 00:07:14,050 --> 00:07:14,290 Right? 110 00:07:14,290 --> 00:07:14,830 And again, 111 00:07:14,830 --> 00:07:19,750 I'm going to choose four letters and you can see that the first time the loop 112 00:07:19,750 --> 00:07:24,700 runs I get an M. So password is equal to M. The second time I get a Q 113 00:07:24,700 --> 00:07:29,700 so I add the Q onto the M, I get MQ and so on and so forth until I get these four 114 00:07:30,100 --> 00:07:35,100 characters in the beginning of what seems to be my random password that's going 115 00:07:35,530 --> 00:07:36,490 to be generated. 116 00:07:38,340 --> 00:07:38,540 Right 117 00:07:38,540 --> 00:07:39,680 Now, if you wanted to, 118 00:07:39,680 --> 00:07:43,550 you can actually simplify this down to just one step, 119 00:07:43,850 --> 00:07:46,160 because instead of having this intermediary, 120 00:07:46,160 --> 00:07:48,140 which is the random character variable, 121 00:07:48,410 --> 00:07:53,060 we can simply just replace it with the code, like this. 122 00:07:53,330 --> 00:07:57,470 So in this case, we're getting a random choice from our letters list, 123 00:07:57,560 --> 00:08:01,490 so we get a random letter, and then we add that to our password. 124 00:08:02,330 --> 00:08:04,730 Now that we've done that for the letter, 125 00:08:04,910 --> 00:08:09,020 then it's pretty easy to see how we can continue doing this for the symbol and 126 00:08:09,020 --> 00:08:12,620 the numbers. We just have to keep adding it to the end of our password. 127 00:08:12,980 --> 00:08:15,140 So let me quickly write out the code for this. 128 00:08:23,510 --> 00:08:23,770 Right? 129 00:08:23,770 --> 00:08:27,880 So now when the user requests that they want four letters in their password, 130 00:08:28,240 --> 00:08:31,510 then we generate a range from one to five. 131 00:08:31,900 --> 00:08:34,570 And then for each of those positions, 132 00:08:34,600 --> 00:08:38,650 we generate a random letter in order to fill the password. 133 00:08:39,190 --> 00:08:42,730 And then we add on the required number of symbols and the required number of 134 00:08:42,730 --> 00:08:46,600 numbers. And finally, we print out the final password. 135 00:08:47,110 --> 00:08:50,830 Let's go ahead and run this code. And again, 136 00:08:50,830 --> 00:08:54,310 I'm going to choose four letters, two numbers, and two symbols. 137 00:08:54,990 --> 00:08:57,780 And I end up with my final password, 138 00:08:58,050 --> 00:09:01,920 which fits exactly that criteria and it looks pretty random. 139 00:09:02,670 --> 00:09:07,670 But the only problem is that if a hacker knew that you always have two symbols 140 00:09:08,190 --> 00:09:11,310 at this position, and two number at this position, 141 00:09:11,640 --> 00:09:16,640 then it's very easy to crack that password because in order to get the last 142 00:09:16,650 --> 00:09:20,940 digit, for example, they only have to try nine different variations, 12 143 00:09:20,940 --> 00:09:22,920 3456789. 144 00:09:23,400 --> 00:09:28,400 And this just limits the strength of your password. In order to tackle that you 145 00:09:29,460 --> 00:09:31,620 would have to tackle it at the hard level, 146 00:09:31,890 --> 00:09:36,660 which is how do you get a password that has all of these letters and numbers in 147 00:09:36,660 --> 00:09:40,500 a completely random order. To do that 148 00:09:40,650 --> 00:09:43,680 we mentioned that you have to do a bit of googling because it might require 149 00:09:43,680 --> 00:09:46,950 something that you haven't done before. But in essence, 150 00:09:47,010 --> 00:09:50,940 you've got access to everything you need to perform the logic. 151 00:09:51,480 --> 00:09:53,280 So if you haven't given that a go, 152 00:09:53,520 --> 00:09:57,210 then this might be a good time to pause and have a think about how you might 153 00:09:57,210 --> 00:10:02,210 structure the logic or how you might create a flow chart to express this logic 154 00:10:03,060 --> 00:10:05,730 that you would want. And once you've done that, 155 00:10:05,820 --> 00:10:08,490 and if you want to see the solution and walk through it with me, 156 00:10:08,670 --> 00:10:13,230 then come back here and I'll show you how to do it, but first give it a go. 157 00:10:15,870 --> 00:10:16,703 Right? 158 00:10:17,110 --> 00:10:19,720 All right. In order to tackle the hard level, 159 00:10:20,050 --> 00:10:25,050 what we essentially need to do is instead of adding each of these letters into a 160 00:10:25,300 --> 00:10:29,050 string, we actually want to add it into a list. 161 00:10:30,040 --> 00:10:32,410 So I'm going to copy all of this that's here, 162 00:10:32,500 --> 00:10:37,500 and I'm just gonna comment it out and I'm going to paste it under my hard level and 163 00:10:37,720 --> 00:10:42,250 work on it here. So instead of using a password string, 164 00:10:42,430 --> 00:10:45,280 I'm going to create a list and to better describe it 165 00:10:45,730 --> 00:10:49,660 I'll change my variable name, the password list. So now, 166 00:10:49,660 --> 00:10:54,660 instead of using password to add each of these letters and numbers and symbols, 167 00:10:55,990 --> 00:10:58,240 I'm going to be adding it to my list. 168 00:10:59,650 --> 00:11:00,420 Right, 169 00:11:00,420 --> 00:11:01,253 Right, 170 00:11:02,210 --> 00:11:03,000 Right 171 00:11:03,000 --> 00:11:05,130 Now, to add things to a list, 172 00:11:05,340 --> 00:11:09,240 you can use the same syntax that you did with strings, 173 00:11:09,660 --> 00:11:14,660 which is to add the new item into the list and to update the old list. 174 00:11:17,430 --> 00:11:20,340 You might be more familiar though with the syntax 175 00:11:20,340 --> 00:11:23,850 which is append and both of these work. 176 00:11:23,940 --> 00:11:28,110 You can use either of them if you want, but they'll end up doing the same thing, 177 00:11:28,170 --> 00:11:32,580 which is to add each of those things you've generated in the order that you've 178 00:11:32,580 --> 00:11:34,560 generated to your password. 179 00:11:34,800 --> 00:11:39,120 So we end up now with a list with four letters, 180 00:11:39,510 --> 00:11:42,030 two symbols, and two numbers, 181 00:11:42,210 --> 00:11:46,650 all stored as strings because of the quotation marks around them. 182 00:11:47,460 --> 00:11:51,360 So now that we've got a list, well, then we have to think about, well, 183 00:11:51,570 --> 00:11:53,800 how can we shuffle our list, 184 00:11:53,800 --> 00:11:56,890 how can we mess up the order of the items in our list? 185 00:11:57,730 --> 00:12:01,420 And that might take you to Google and you might search for something like how to 186 00:12:01,420 --> 00:12:05,410 change the order of items in a list. 187 00:12:05,680 --> 00:12:09,160 And then we also have to add our keyword, which is Python, 188 00:12:09,190 --> 00:12:12,490 because there's obviously a lot of other programming languages. 189 00:12:12,910 --> 00:12:15,910 And we come up against our first Stack Overflow question, 190 00:12:15,910 --> 00:12:19,930 how can I reorder a list? Well, that sounds kind of like what I want to do, 191 00:12:19,930 --> 00:12:22,450 right? So if we scroll down, 192 00:12:22,510 --> 00:12:27,510 you can see that the way to do it is either using a for loop, 193 00:12:27,910 --> 00:12:30,430 like so, or 194 00:12:30,700 --> 00:12:33,520 to simply use the shuffle function. 195 00:12:34,630 --> 00:12:39,630 This is a much simpler way because it allows us to update the existing list just 196 00:12:41,740 --> 00:12:43,990 by calling the shuffle function on it. 197 00:12:44,650 --> 00:12:49,510 And this one actually requires us to create a new list and we have to create a 198 00:12:49,510 --> 00:12:52,270 bunch of random numbers for the order, 199 00:12:52,600 --> 00:12:54,910 and then to reorder them using a four loop. 200 00:12:55,300 --> 00:12:58,840 So I'm going to go with this version and let's try it out. 201 00:12:59,350 --> 00:13:01,420 Instead of printing password_list, 202 00:13:01,480 --> 00:13:04,270 let's print the password_list before the shuffle, 203 00:13:04,600 --> 00:13:09,600 and then let's use the random.shuffle and pass in the password_list. 204 00:13:10,150 --> 00:13:13,480 And then let's print the outcome of that shuffle, 205 00:13:13,480 --> 00:13:15,640 so let's print the password_list again. 206 00:13:17,740 --> 00:13:20,380 So now you can see that we've got a version before, 207 00:13:20,590 --> 00:13:22,210 and then we've got a version after. 208 00:13:22,420 --> 00:13:26,920 So if I run my code and I write again, four letters, 209 00:13:26,980 --> 00:13:29,020 two symbols, two numbers, 210 00:13:29,590 --> 00:13:34,210 you can see that previously it was ordered in the order that we added each of 211 00:13:34,210 --> 00:13:36,580 the characters. After the shuffle 212 00:13:36,610 --> 00:13:40,570 they're now pretty much random. There's letters in random places, 213 00:13:40,600 --> 00:13:42,160 there's symbols in random places. 214 00:13:42,550 --> 00:13:45,970 So if only we could turn this back into a string, 215 00:13:46,450 --> 00:13:49,870 then we've got our password that's nicely shuffled. 216 00:13:50,260 --> 00:13:53,290 So how can we turn it back into a string? Well, 217 00:13:53,290 --> 00:13:55,720 we could simply use a for loop, right? 218 00:13:55,810 --> 00:13:59,080 We could say for each, um, 219 00:13:59,440 --> 00:14:03,910 character in the password_list, 220 00:14:04,690 --> 00:14:08,980 we're going to add it to a variable called a password, 221 00:14:09,370 --> 00:14:12,610 which is going to start off again as a empty string 222 00:14:13,240 --> 00:14:15,430 and then we're going to add to it. 223 00:14:15,460 --> 00:14:20,440 So we're going to say password += char in our password_list. 224 00:14:21,040 --> 00:14:24,790 And now if I go ahead and just print my final password, 225 00:14:25,180 --> 00:14:27,070 I'm going to add a fstring as well. 226 00:14:27,550 --> 00:14:30,310 Let's say your password is, 227 00:14:31,360 --> 00:14:33,460 and then let's insert the password. 228 00:14:34,840 --> 00:14:38,230 And now if I run my code and let's say, 229 00:14:38,230 --> 00:14:40,900 I want 12 letters, uh, 230 00:14:40,930 --> 00:14:43,330 three symbols and four numbers, 231 00:14:43,870 --> 00:14:47,530 then it's going to generate me a entire password 232 00:14:47,740 --> 00:14:52,550 that's completely randomized in terms of the orders of the symbols and the 233 00:14:52,550 --> 00:14:53,383 numbers. 234 00:14:53,660 --> 00:14:58,660 And I've now solved the hard part of this challenge project. 235 00:15:00,080 --> 00:15:03,530 Did that make sense to you? Did you manage to get it 236 00:15:03,530 --> 00:15:04,940 to do what you want it to do? 237 00:15:06,800 --> 00:15:10,070 If you're at all confused about the code that we've covered here, 238 00:15:10,370 --> 00:15:14,510 then be sure to check out the final project that I've got here, 239 00:15:14,510 --> 00:15:16,700 which is the App generator end, 240 00:15:17,150 --> 00:15:20,600 and take a look at how the easy level is implemented, 241 00:15:20,630 --> 00:15:25,160 how the hard level is implemented and try switching it around so that you really 242 00:15:25,160 --> 00:15:26,390 get to understand it. 243 00:15:26,720 --> 00:15:31,070 Try instead of maybe getting the user to tell you how many letters, 244 00:15:31,070 --> 00:15:34,970 how many symbols, how many numbers, instead just define those yourself 245 00:15:35,000 --> 00:15:37,790 or use a random number of letters, numbers, 246 00:15:37,790 --> 00:15:42,440 and symbols. Play around with the code until it starts doing what you want it to 247 00:15:42,440 --> 00:15:44,240 do and it starts making sense. 248 00:15:44,840 --> 00:15:48,770 But I hope you had fun building this project with me today and learning all 249 00:15:48,770 --> 00:15:51,440 about loops. On the next lesson 250 00:15:51,440 --> 00:15:54,800 we're going to be learning more about these things that we've been using a lot, 251 00:15:55,160 --> 00:16:00,110 which is Python functions. So I'm going to bid you goodnight for today, 252 00:16:00,200 --> 00:16:03,200 and hopefully I'll see you bright and early tomorrow, 253 00:16:03,680 --> 00:16:06,860 and we'll learn some new skills and work on some new projects. 254 00:16:07,070 --> 00:16:09,710 So that's all from me, goodnight from Angela.