1
00:00:00,009 --> 00:00:05,070
Welcome back. So in the previous video, we successfully created the encryption key

2
00:00:05,389 --> 00:00:09,279
and we give it the file path of encryption underscore key dot key.

3
00:00:09,460 --> 00:00:14,590
And we also wrote a simple function to load the key. So now

4
00:00:14,739 --> 00:00:17,670
let us write the functions which we're going to use

5
00:00:17,860 --> 00:00:19,389
to actually

6
00:00:19,760 --> 00:00:24,309
encrypt our files but also decrypt them.

7
00:00:24,620 --> 00:00:25,450
And by the way,

8
00:00:25,459 --> 00:00:31,190
I just noticed over here on line nine that I did not add my colon at the end.

9
00:00:31,200 --> 00:00:32,729
So please, if you haven't done that,

10
00:00:33,009 --> 00:00:34,889
I'll be sure to do that as well.

11
00:00:34,900 --> 00:00:41,360
And then also on line five, I missed another column as well. So please

12
00:00:41,709 --> 00:00:47,680
do add the columns to line five and line nine as well. OK. So

13
00:00:48,150 --> 00:00:53,360
we are going to write a function to encrypt our file.

14
00:00:53,779 --> 00:00:56,930
So I'm gonna come down here and let's say, define and

15
00:00:57,310 --> 00:00:59,880
let's call the function encrypt,

16
00:01:00,500 --> 00:01:02,139
encrypt

17
00:01:02,470 --> 00:01:03,909
underscore file.

18
00:01:04,050 --> 00:01:04,559
OK.

19
00:01:04,839 --> 00:01:05,599
Now

20
00:01:05,830 --> 00:01:07,199
think about this. OK.

21
00:01:07,830 --> 00:01:10,069
Our function because we're going to encrypt the file,

22
00:01:10,080 --> 00:01:12,930
we're going to require three different parameters.

23
00:01:12,940 --> 00:01:13,319
OK?

24
00:01:13,669 --> 00:01:16,379
The first parameter will be the actual file itself,

25
00:01:16,389 --> 00:01:18,029
which we're going to be encrypted.

26
00:01:18,040 --> 00:01:19,870
So let's call that file

27
00:01:20,160 --> 00:01:21,699
the input

28
00:01:22,300 --> 00:01:23,790
underscore file

29
00:01:24,000 --> 00:01:28,059
OK. Now, we're also going to need to create a file

30
00:01:28,160 --> 00:01:33,760
that will contain the encrypted version. So let's call that file the output

31
00:01:35,110 --> 00:01:38,000
underscore file. OK? And then finally,

32
00:01:38,169 --> 00:01:40,550
we're going to need the actual key,

33
00:01:40,559 --> 00:01:44,889
which we're going to use to encrypt the input file, right?

34
00:01:45,169 --> 00:01:47,120
So let me add my colon at the end.

35
00:01:47,620 --> 00:01:49,629
So the first thing we're going to do right now is

36
00:01:49,639 --> 00:01:53,089
we're going to create our fret object with the provided key.

37
00:01:53,099 --> 00:01:53,839
So I'm gonna say fer

38
00:01:55,190 --> 00:01:56,720
now equals

39
00:01:56,830 --> 00:01:57,889
capital

40
00:01:58,500 --> 00:01:59,180
F

41
00:01:59,379 --> 00:01:59,910
fret.

42
00:02:01,099 --> 00:02:02,680
And now in brackets,

43
00:02:03,650 --> 00:02:05,239
we're going to add our key.

44
00:02:05,610 --> 00:02:10,869
OK? So from here we want to read the input file.

45
00:02:10,970 --> 00:02:11,369
OK?

46
00:02:11,380 --> 00:02:12,199
That will be obviously,

47
00:02:12,210 --> 00:02:15,740
the next step will be to actually open up the input file that we want to encrypt.

48
00:02:15,750 --> 00:02:15,990
So

49
00:02:16,330 --> 00:02:19,789
I'm gonna say with open and now in brackets,

50
00:02:20,160 --> 00:02:23,339
I'm gonna say the inputs underscore file

51
00:02:23,759 --> 00:02:24,990
and now what mode

52
00:02:25,160 --> 00:02:28,710
we're gonna go with the read, binary mode. So RB,

53
00:02:29,029 --> 00:02:29,589
OK?

54
00:02:30,380 --> 00:02:33,199
And now I'm going to say as file

55
00:02:33,779 --> 00:02:34,779
and now

56
00:02:35,070 --> 00:02:37,559
what we're gonna do is we're going to read the contents of

57
00:02:37,570 --> 00:02:41,679
the file and we're going to pass those contents to another variable.

58
00:02:41,690 --> 00:02:45,229
So let's say let's call the variable original because I'm

59
00:02:45,240 --> 00:02:48,179
gonna say original right now will be equal to what

60
00:02:48,410 --> 00:02:53,070
the file dot read because we want to read the contents of the file

61
00:02:53,259 --> 00:02:55,479
and let's add our buckets right there.

62
00:02:55,660 --> 00:03:00,190
OK? We're doing great. We're doing great. Now, we need to encrypt the file.

63
00:03:00,770 --> 00:03:02,500
Ok? And by the way, I forgot to add

64
00:03:02,850 --> 00:03:06,270
the column in here on line 16. So let's add a column right there.

65
00:03:06,899 --> 00:03:11,490
Ok. So now that we've opened up the file, ok, we now want to encrypt it.

66
00:03:11,500 --> 00:03:12,350
So I'm gonna say,

67
00:03:13,059 --> 00:03:14,910
let's call this one encrypted. Ok.

68
00:03:14,919 --> 00:03:17,279
This will be the variable to store the actual encrypted version.

69
00:03:17,289 --> 00:03:18,919
So I'm gonna say encrypted will be equal to.

70
00:03:19,419 --> 00:03:20,070
And now fer

71
00:03:20,960 --> 00:03:23,490
dot encrypt

72
00:03:23,750 --> 00:03:28,770
and now in brackets because we've passed file dot readd into the variable original.

73
00:03:28,779 --> 00:03:29,960
So I'm gonna come in here right now

74
00:03:30,279 --> 00:03:31,429
and simply say, or

75
00:03:31,830 --> 00:03:32,199
region.

76
00:03:33,529 --> 00:03:34,160
OK?

77
00:03:34,520 --> 00:03:37,149
And then what is the last thing we're going to do?

78
00:03:37,350 --> 00:03:41,649
We would have to write the encrypted content to a file.

79
00:03:41,830 --> 00:03:42,419
So

80
00:03:42,630 --> 00:03:44,220
I'm gonna say with

81
00:03:44,679 --> 00:03:45,500
open

82
00:03:46,729 --> 00:03:49,550
and now in brackets the output

83
00:03:50,899 --> 00:03:52,190
underscore file

84
00:03:53,399 --> 00:03:57,850
and now the mode will be wide binary. So WB

85
00:03:58,750 --> 00:04:01,169
and now I'm gonna see as file

86
00:04:01,270 --> 00:04:01,300
at

87
00:04:01,740 --> 00:04:01,759
our

88
00:04:01,880 --> 00:04:03,130
colon right there.

89
00:04:04,259 --> 00:04:08,399
And all we have to do right now is to say file dot Right,

90
00:04:08,559 --> 00:04:11,410
because we're creating our file and now in brackets, what's it going to be,

91
00:04:11,419 --> 00:04:13,600
it's going to be encrypted.

92
00:04:13,610 --> 00:04:14,940
So I'm gonna say encrypted.

93
00:04:16,108 --> 00:04:18,170
So this will write the encrypted content of the file.

94
00:04:18,488 --> 00:04:22,690
And of course, we can simply add a print statement, we can say print

95
00:04:23,339 --> 00:04:28,049
and uh yep, we can go with this one, prints f file, encrypted and saved to

96
00:04:28,149 --> 00:04:30,040
the output file.

97
00:04:30,329 --> 00:04:31,480
So from here,

98
00:04:31,489 --> 00:04:37,209
what we have to do right now will be to create the function that we can use to decrypt

99
00:04:37,600 --> 00:04:41,109
the file. So it's basically going to be like a reverse of what we've we've just done.

100
00:04:41,119 --> 00:04:43,209
So check this out. Like I'm gonna come over here

101
00:04:43,670 --> 00:04:47,279
and let's call our function decrypt

102
00:04:48,179 --> 00:04:49,640
underscore file.

103
00:04:49,809 --> 00:04:52,369
And then just like with encryption, we're going to need three parameters,

104
00:04:52,380 --> 00:04:55,670
the input file, the output file as well as the key.

105
00:04:55,679 --> 00:04:56,119
So

106
00:04:56,480 --> 00:05:00,739
I'm going to add those as you can see, input file, output file and then key.

107
00:05:01,149 --> 00:05:03,350
And now, as usual, I'm gonna say fer

108
00:05:03,700 --> 00:05:03,980
net

109
00:05:04,859 --> 00:05:09,059
equals and then capital fernet and then in brackets key.

110
00:05:09,329 --> 00:05:12,670
So this will be the key that we're gonna use to decrypt our file.

111
00:05:12,769 --> 00:05:14,489
So now what we want to do,

112
00:05:14,630 --> 00:05:19,869
we want to read the contents of the encrypted file. So

113
00:05:20,269 --> 00:05:22,070
I'm gonna come in here on a new line,

114
00:05:22,350 --> 00:05:24,029
I'm gonna say with open

115
00:05:24,500 --> 00:05:27,399
and now what are we opening, we're opening up the input on the

116
00:05:27,500 --> 00:05:28,420
core file.

117
00:05:28,799 --> 00:05:32,149
And now what mode are B

118
00:05:32,630 --> 00:05:33,470
I'm gonna say

119
00:05:34,540 --> 00:05:35,839
uh as file

120
00:05:36,170 --> 00:05:37,290
and a colon.

121
00:05:37,529 --> 00:05:42,519
So now what do we want to do? We want to decrypt. So I'm gonna say the encrypted

122
00:05:44,429 --> 00:05:45,609
encrypted here

123
00:05:45,809 --> 00:05:47,170
equals to file

124
00:05:47,309 --> 00:05:48,570
dot read. OK.

125
00:05:48,869 --> 00:05:53,250
So we're passing the contents of the encrypted file to a variable called encrypted

126
00:05:53,559 --> 00:05:56,190
because now what we're gonna do is we're

127
00:05:56,200 --> 00:05:59,890
going to create another variable called decrypted.

128
00:06:00,660 --> 00:06:02,640
And now this will be equal to fernet

129
00:06:03,700 --> 00:06:06,279
and now I'm going to pass the crypt

130
00:06:07,820 --> 00:06:08,980
in brackets

131
00:06:09,480 --> 00:06:10,429
encrypted.

132
00:06:10,760 --> 00:06:15,529
So this right here is how we're going to decrypt the contents of our file.

133
00:06:15,799 --> 00:06:22,130
And now what is the last step we want to save the decrypted information to a new file.

134
00:06:22,220 --> 00:06:24,920
So now I'm simply going to say with open

135
00:06:25,269 --> 00:06:27,880
and now in brackets the output

136
00:06:28,859 --> 00:06:30,109
underscore file

137
00:06:31,239 --> 00:06:33,149
and now WB

138
00:06:34,369 --> 00:06:35,579
as file

139
00:06:35,709 --> 00:06:36,720
colon

140
00:06:37,160 --> 00:06:40,149
and now simply file dot Right.

141
00:06:41,350 --> 00:06:42,609
And now decrypted.

142
00:06:44,040 --> 00:06:44,970
So we're gonna write the

143
00:06:45,149 --> 00:06:46,450
code to the file.

144
00:06:46,660 --> 00:06:50,279
And then finally, we can just add the usual print statement.

145
00:06:50,290 --> 00:06:51,779
So we can say something like print

146
00:06:52,440 --> 00:06:55,619
our brackets F colon.

147
00:06:56,339 --> 00:06:58,140
And let us say

148
00:06:58,429 --> 00:07:01,019
file, decrypted and save to the

149
00:07:01,209 --> 00:07:03,440
output file. I think, I think this is fine.

150
00:07:04,359 --> 00:07:06,940
And there it is

151
00:07:08,130 --> 00:07:11,850
actually let me improve on this one. I can say

152
00:07:12,269 --> 00:07:13,859
a file,

153
00:07:15,200 --> 00:07:15,790
OK?

154
00:07:16,660 --> 00:07:19,190
And now call braces and the input file.

155
00:07:21,410 --> 00:07:24,109
OK? And now

156
00:07:25,290 --> 00:07:26,720
I would say decrypted

157
00:07:27,690 --> 00:07:31,329
and saved to the output file. I think this is better

158
00:07:31,730 --> 00:07:33,959
and there it is. So

159
00:07:34,100 --> 00:07:38,299
once again, we created functions to both encrypt and decrypt our files.

160
00:07:38,309 --> 00:07:41,470
For the encryption function. We need three parameters,

161
00:07:41,769 --> 00:07:43,869
the input file, which we're going to encrypt

162
00:07:44,130 --> 00:07:47,609
the file that we're going to create that will store the encrypted information,

163
00:07:47,619 --> 00:07:48,750
which is output file

164
00:07:48,880 --> 00:07:50,829
and then the key for the actual encryption.

165
00:07:51,079 --> 00:07:54,799
So we created a key right here by infinite equals finite and then brackets key.

166
00:07:55,000 --> 00:07:57,500
And now we opened up the original file

167
00:07:57,950 --> 00:08:00,519
and we store the contents of the file into our

168
00:08:00,529 --> 00:08:03,890
verbal called original by saying file dot read equals original.

169
00:08:04,239 --> 00:08:08,769
And now to do the actual encryption itself, we set encrypted equals F

170
00:08:08,910 --> 00:08:10,809
dot encrypt. And now in brackets original

171
00:08:11,140 --> 00:08:13,410
and now with open because we want to store

172
00:08:13,579 --> 00:08:16,730
the encrypted information on the new file, the output file,

173
00:08:16,940 --> 00:08:20,809
we created the file right here, lines 1920 21.

174
00:08:21,130 --> 00:08:23,470
And then we did pretty much the exact opposite with

175
00:08:23,730 --> 00:08:24,779
the decryption

176
00:08:24,880 --> 00:08:25,950
function. So

177
00:08:26,149 --> 00:08:28,309
join me in the very next video where

178
00:08:28,839 --> 00:08:33,750
we're gonna go ahead and now create the main function for the user interaction.