text stringlengths 1 81 | start float64 0 10.1k | duration float64 0 24.9 |
|---|---|---|
SPEAKER 3: As far back
as you can remember. | 5,079.292 | 3.013 |
SPEAKER 2: All right. | 5,082.305 | 0.875 |
Well, let me tell you. | 5,083.18 | 2.64 |
The first time I met David Malan,
I knew he was nothing but trouble. | 5,085.82 | 4.06 |
SPEAKER 4: There's a David
J. Malan here for you. | 5,097.779 | 2.041 |
SPEAKER 5: Who? | 5,099.82 | 1.534 |
SPEAKER 4: He says he's in
your Computer Science 50 class. | 5,101.354 | 2.416 |
Wants to talk about his grade. | 5,103.77 | 2.04 |
SPEAKER 5: Are you kidding me? | 5,105.81 | 1.44 |
I mean, who does he
think he is, Bill Gates? | 5,107.25 | 3.67 |
All right. | 5,110.92 | 0.82 |
send him in. | 5,111.74 | 2.02 |
[MUSIC PLAYING] | 0 | 2.952 |
DAVID MALAN: This is CS50's
introduction to cybersecurity. | 18.21 | 3.18 |
My name is David Malan. | 21.39 | 1.08 |
And this week, let's focus
on securing accounts. | 22.47 | 2.67 |
You and I have so many
accounts nowadays, | 25.14 | 2.04 |
be it for websites or apps or the like. | 27.18 | 2.25 |
And we'll focus today on
exactly what the threats are | 29.43 | 2.7 |
to all of those accounts but more
importantly, what some of the defenses | 32.13 | 3.21 |
are so that you can keep
those accounts secure. | 35.34 | 2.25 |
But let's first consider what we mean
by security in the physical world, | 37.59 | 3.22 |
for instance. | 40.81 | 0.66 |
Whether you live in a home, an
apartment, a dormitory or the like, | 41.47 | 3.29 |
odds are you have a key that
lets you into that building. | 44.76 | 3.18 |
Now, that key, of course, lets
you in through that locked door, | 47.94 | 3.48 |
and then you have access
to the entire habitat. | 51.42 | 3.51 |
But the catch is that if someone
else gets that key, of course, | 54.93 | 3 |
they, too, can let themselves into
that system or into that same building. | 57.93 | 5.077 |
So let's consider now in the
digital world, though, what | 63.007 | 2.333 |
some of the building
blocks are of security so | 65.34 | 2.508 |
that we can focus exactly what those
threats and what those defenses are. | 67.848 | 3.042 |
So first, allow me to
propose that we think | 70.89 | 2.34 |
about the security of our accounts
in terms of authentication. | 73.23 | 3.24 |
So authentication
refers to this process, | 76.47 | 2.8 |
digitally, of proving who you are,
that I, for instance, am David. | 79.27 | 4.89 |
But that alone isn't
necessarily enough to keep | 84.16 | 2.94 |
a system secure because just because
I'm David doesn't necessarily mean | 87.1 | 3.66 |
I should have access
to your entire home. | 90.76 | 2.61 |
Perhaps I should not have access at all. | 93.37 | 2.038 |
Perhaps I should just have
access to the entryway | 95.408 | 2.042 |
or some narrower form of access. | 97.45 | 2.62 |
And so there's this
related topic when it | 100.07 | 1.76 |
comes to the security of locations
or systems known as authorization. | 101.83 | 4.29 |
So authorization speaks
to whether or not | 106.12 | 3.18 |
you should have access to something,
once you have proven that you are, | 109.3 | 4.96 |
that I am David and that I should,
in fact, have access to the door | 114.26 | 3.8 |
that I just walked through. | 118.06 | 1.47 |
Now, when it comes to our
accounts in the digital world, | 119.53 | 3.81 |
we, of course, don't use physical
keys, but very frequently nowadays we | 123.34 | 3.63 |
use usernames, which, of
course, can be public. | 126.97 | 2.37 |
It might be a username like David. | 129.34 | 2.22 |
It might be a username like Malan. | 131.56 | 1.53 |
Or it might be more commonly, even an
entire email address that presumably | 133.09 | 4.59 |
uniquely identifies you in the world. | 137.68 | 2.23 |
But even though that's public, the thing
that you and I ideally keep private | 139.91 | 4.01 |
is, of course, our password. | 143.92 | 1.53 |
And nowadays, you and I
must have dozens, maybe even | 145.45 | 3.27 |
hundreds of passwords that
are hopefully distinct | 148.72 | 3.81 |
and not reused across all
of those different websites, | 152.53 | 2.25 |
but more on that in a moment. | 154.78 | 1.3 |
And so it's really this
password that ultimately | 156.08 | 2.75 |
allows you to authenticate
yourself, demonstrate | 158.83 | 3.09 |
who you are because presumably I am
the only one in the world that knows, | 161.92 | 4.21 |
not only my username or email
address, which all of us can know, | 166.13 | 3.338 |
but presumably I'm the only
one in the world that knows | 169.468 | 2.292 |
my username and this here password. | 171.76 | 2.91 |
And so the presumption is if
I type in both of those values | 174.67 | 2.73 |
to some app or some website that I must,
in fact, be David Malan, in that case. | 177.4 | 5.4 |
Of course, it's not good
enough to just have a password. | 182.8 | 3.78 |
You need to have a good password. | 186.58 | 1.447 |
Now, what do we mean by good password? | 188.027 | 1.583 |
Well, ideally, this password is
not going to be in a dictionary, | 189.61 | 3.24 |
like, literally a
dictionary of English words | 192.85 | 2.46 |
or whatever your human
language might be. | 195.31 | 2.14 |
Why? | 197.45 | 0.5 |
Well, there's this threat
known as a dictionary attack. | 197.95 | 2.86 |
And by this I mean an
adversary, a hacker that | 200.81 | 2.78 |
wants to get into your
account, they could just | 203.59 | 2.25 |
start typing randomly to try to
figure out what your password is. | 205.84 | 2.73 |
But they're a little smarter. | 208.57 | 1.29 |
They'll actually use
a dictionary attack. | 209.86 | 2.31 |
That is they'll open a
physical book of words, | 212.17 | 2.55 |
or more likely they'll open a
file on their computer containing | 214.72 | 3.57 |
a whole lot of actual English words or
in some other human language, and then | 218.29 | 4.29 |
just one at a time, try
this word as your password, | 222.58 | 2.52 |
this word as your password, this
word as your password and so forth. | 225.1 | 3.06 |
Because if you and I have chosen
a pretty guessable password, one | 228.16 | 3.87 |
that is an actual word in a dictionary,
they're going to get into your account | 232.03 | 3.3 |
much faster. | 235.33 | 1.38 |
But even if you and I are clever-- | 236.71 | 1.8 |
and odds are by this point in life
you know that you shouldn't just | 238.51 | 3.24 |
choose a simple English or
some other language word, | 241.75 | 2.76 |
but rather you should probably
have some numbers, some letters, | 244.51 | 3.12 |
some punctuation, or the
like-- you're still vulnerable, | 247.63 | 2.61 |
as am I, to what we would
call a brute force attack. | 250.24 | 4.02 |
Brute force sort of evokes
the memories of yesteryear | 254.26 | 5.4 |
where someone might have had
a big branch of a tree using | 259.66 | 2.94 |
as a battering ram trying to get
into the castles from past times. | 262.6 | 3.33 |
But brute force attacks
in the digital world | 265.93 | 2.07 |
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