60
votes
Why do we need full-fledged workstations running massive OSes with massive software?
You are conflating a number of issues here.
Why does my software have all these features to begin with?
Because other computers' software has those features, and network effects punish any software ...
- 3,473
26
votes
Why do we rely on computers in critical fields?
Computer hardware almost always does exactly what software tells it to do.
It's useful to distinguish software bugs from unreliable hardware.
Cosmic rays can randomly flip a bit in memory, though; ...
- 841
24
votes
Accepted
Why do we rely on computers in critical fields?
If computers really make many errors (as I assumed earlier)...
Your assumption is wrong. Firstly, computers do not (except in extreme cases) "make many errors", humans do. Computers simply ...
- 356
22
votes
Do passwords need a max length?
No. There is no* limit on the length of the input to for most* good cryptographic hash functions. As a result, password hashing can support passwords of unlimited length and do not need to impose a ...
D.W.♦
- 156k
15
votes
Why do we rely on computers in critical fields?
Most errors in computer systems are caused by humans directly through design and programming errors.
Almost all questions on Stack Overflow concern programming problems and most errors that make it to ...
- 746
14
votes
Why do we rely on computers in critical fields?
Because there's no practical alternative. Modern life is too complex for ordinary humans to keep track of all the details. And critical systems often require reaction times far quicker than humans or ...
- 443
13
votes
Why do we need full-fledged workstations running massive OSes with massive software?
Since the other answers go pretty well into why companies just buy general purpose computers, I wanted to give an answer about security. In a lot of ways, it's easier to secure a system you know is ...
- 231
10
votes
Accepted
Can you prevent a man in the middle from reading the message?
Can the man in the middle not just take the keys swapped by the opponents, change the keys and then decrypt and encrypt the message again?
Yes, they can.
A key exchange protocol like (the "textbook" ...
- 4,979
9
votes
Running an algorithm on data remotely and ensuring answer has not been tampered with
In the crypto community, this task is known as delegated computation, or verifiable delegation. You wish to let the server (the "cloud") to do the work for you, but you also want the cloud to give you ...
- 20.6k
9
votes
Do passwords need a max length?
Yes, passwords need maximum length, but not because of collision risk (see other answers regarding collisions).
Reason for setting maximum length - possibility of denial of service attack.
Someone ...
- 191
8
votes
Do passwords need a max length?
As hashes are fixed length, does that mean that even if not specified when creating the password, all login systems would need to have some sort of maximum input length (although probably very high)?
...
- 191
7
votes
Zero-knowledge proof: Abstract example
I believe this is done to illustrate two things.
(i)
The small probability, that $P$eggy ($P$rover) might be lying. If she really does not know the magic word and $V$ictor ($V$erifier) sees her ...
- 138
7
votes
Accepted
Can software itself be encrypted?
If you want a practical answer: with Intel SGX, the answer seems to be a qualified yes, but software development is likely to be more painful. (Similar with a TPM, though that will be even more ...
D.W.♦
- 156k
5
votes
Accepted
Computer Security versions of the Halting Problem
What you're looking for is Rice's Theorem, which is a generalized version of Halting Undecidability.
It basically says that any property of a Turing Machine (i.e. any computer program) is undecidable,...
- 29.7k
5
votes
Can you prevent a man in the middle from reading the message?
In a man-in-the-middle attack, you ask Bob for his key but Eve intercepts the message and sends you her key instead. She asks Bob for his key and then passes messages between you and Bob, decrypting ...
- 81.4k
5
votes
Why do we need full-fledged workstations running massive OSes with massive software?
"If I were running a company ... the employee would see only the "sections" that are relevant for them, coded by me."
You are not prescient. You cannot predict the future requirements of all your ...
- 51
5
votes
Why do we need full-fledged workstations running massive OSes with massive software?
I'd use a simple username/password system, with no password resets or two-factor auth
Password resets are required somewhere because people forget passwords. 2FA is required sometimes because they ...
- 411
5
votes
Why did the concept of "write-protecting" not carry over from floppy disks to USB memsticks and especially external USB HDDs?
I'm not entirely sure that this question is on topic, but nonetheless, I suspect it has a simple answer.
Physical write protection mechanisms predate floppy disks. At my school holiday job in the ...
- 21.6k
4
votes
Why do we need full-fledged workstations running massive OSes with massive software?
I would argue that the premise of the question makes a wrong assumption:
There is an enormous amount of people that use computers set up to perform a single task.
Behind the scenes, they're generic ...
- 141
4
votes
Accepted
How large is the seed in an encryption algorithm such as stream cipher?
The seed of a pseudorandom generator that is used as a stream cipher is called a key.
The most common key sizes are 128 bits and 256 bits. (That's symmetric keys, where there's no cheaper way to break ...
4
votes
Accepted
Sharing a requested secret number not knowing which
This is known as the oblivious transfer problem. You can find about it online if you are looking for zero-knowledge interactive proofs for it.
- 11.5k
4
votes
Why are computers so fundamentally insecure?
The point of a general-purpose computer is that it can do almost anything. It's an extremely flexible tool.
The point of a secure system is that it can't do most things. It can only do the things that ...
- 1,720
3
votes
Zero-knowledge proof: Abstract example
The article tries to illustrate the property that a zero knowledge proof is only convincing to the observer. In other words, the observer would not be able to convince someone else later.
It does so ...
- 213
3
votes
How long does it take to crack a password by brute force
Perhaps your teacher was talking about some system where the format of passwords is restricted (e.g., where they can't be longer than whatever number of characters allows a typical computer to try all ...
- 81.4k
3
votes
Can Eve impersonate Alice or Bob by using a replay attack?
well, you don't really explain what happens in each step, and how the authentication procedure works, but your first suggestion is at the right direction. However, the impersonator wishes to ...
- 20.6k
3
votes
Accepted
What exactly would stop me from registering a domain from my own nameserver?
Nothing stops you from setting up such a nameserver. However, this wouldn't be of any use to you, because no one is going to contact your nameserver to ask whether domainexample.com exists: they're ...
D.W.♦
- 156k
3
votes
Why don't most websites I visit seem to use TLS with Ephemeral Diffie-Hellman?
The typical process to establish a secure channel uses asymmetric cryptography for two purposes: to allow the parties to authenticate each other, and to establish a shared symmetric key (in TLS, that'...
3
votes
Why do we need full-fledged workstations running massive OSes with massive software?
TL;DR: Modern computers are general purpose tools. They have a huge diversity of capabilities which will never be used simultaneously. All of these capabilities integrate with each other which creates ...
- 131
3
votes
Decryption of RSA
You'll need to factor the base of the RSA public key to be able to decrypt. That is the whole point: cracking RSA is equivalent to factoring, and factoring is (presumed to be) very hard.
- 13.9k
3
votes
How large is the seed in an encryption algorithm such as stream cipher?
The seed is called the key and to be secure it really depends on the usage and known computing powers. The most powerful collective power (known) is currently the bitcoin miners that they have reached ...
- 1,151
Only top scored, non community-wiki answers of a minimum length are eligible