Encryption is the process of transforming plaintext using a cipher to make it unreadable to anyone except those possessing the key.

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214
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13answers
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How is it possible that people observing an HTTPS connection being established wouldn't know how to decrypt it?

I've often heard it said that if you're logging in to a website - a bank, GMail, whatever - via HTTPS, that the information you transmit is safe from snooping by 3rd parties. I've always been a little ...
211
votes
7answers
155k views

RSA vs. DSA for SSH authentication keys

When generating SSH authentication keys on a Unix/Linux system with ssh-keygen, you're given the choice of creating a RSA or DSA key pair (using -t type). What is the difference between RSA and DSA ...
114
votes
11answers
30k views

Why are hash functions one way? If I know the algorithm, why can't I calculate the input from it?

Why can't a password hash be reverse engineered? I've looked into this ages ago and have read lots on it, but I can't find the explanation of why it can't be done. An example will make it easier to ...
97
votes
2answers
56k views

What is the difference between https://google.com and https://encrypted.google.com?

Is it there any difference between the encrypted Google search (at https://encrypted.google.com) and the ordinary HTTPS Google search (at https://google.com)? In terms of security what were the ...
67
votes
5answers
7k views

How can my employer be a man-in-the-middle when I connect to Gmail? [duplicate]

I'm trying to understand SSL/TLS. What follows are a description of a scenario and a few assumptions which I hope you can confirm or refute. Question How can my employer be a man-in-the-middle when ...
63
votes
12answers
21k views

Is Google overreaching by forcing me to use TLS?

Gmail was recently changed to require HTTPS for everyone, whether they want to use it or not. While I realize that HTTPS is more secure, what if one doesn't care about security for certain accounts? ...
63
votes
11answers
14k views

Is there any technical security reason not to buy the cheapest SSL certificate you can find?

While shopping for a basic SSL cert for my blog, I found that many of the more well known Certificat Authorities have an entry-level certificate (with less stringent validation of the purchaser's ...
58
votes
8answers
123k views

How to determine what type of encoding/encryption has been used?

Is there a way to find what type of encryption/encoding is being used? For example, I am testing a web application which stores the password in the database in an encrypted format ...
56
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5answers
16k views

Is sending password to user email secure?

How secure is sending passwords through email to a user, since email isn't secured by HTTPS. What is the best way to secure it? Should i use encryption?
49
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6answers
17k views

Can my IT department read my Google Hangouts chats while at work?

Is Google hangouts encrypted? Would my work's IT guys be able see pictures and text I send while on a work computer? Yes I know I shouldn't be sending stuff I don't want them to see while at work, but ...
46
votes
8answers
5k views

Online backup : how could encryption and de-duplication be compatible?

A "soon to enter beta" online backup service, Bitcasa, claims to have both de-duplication (you don't backup something already in the cloud) and client side encryption. ...
45
votes
17answers
3k views

Can we still provide confidentiality when cryptography is outlawed?

In certain jurisdictions, use of cryptography by the private sector is limited: e.g. there are reports that in the UAE and other countries not all of the encryption capabilities of the BlackBerry are ...
45
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3answers
4k views

What kinds of encryption are _not_ breakable via Quantum Computers?

There's the recent article NSA seeks to build quantum computer that could crack most types of encryption. Now I'm not surprised by the NSA trying anything1, but what slightly baffles me is the word ...
44
votes
5answers
4k views

How does a country block its citizens from accessing a site?

Following Turkey's recent social site blocks, I am wondering how can you efficiently accomplish that as a country. Similar for a big company. Blocking IPs → easy to circumvent, (proxys, tunnels, ...
44
votes
4answers
10k views

Why should one not use the same asymmetric key for encryption as they do for signing?

In an answer to a question about RSA and PGP, PulpSpy noted this: It is possible to generate an RSA key pair using GPG (for both encryption and signing -- you should not use the same key for ...
41
votes
12answers
6k views

Why should I care if a site uses encryption or not if I'm not exchanging any sensitive data? [duplicate]

Lots of sites these days, that don't deal with sensitive data, enable encryption. I think it's mostly to make (paranoid?) users feel safer. In cases where there is a user's account being logged in, ...
39
votes
6answers
11k views

How hard is it to intercept SMS (two-factor authentication)?

A lot of two-factor authentication mechanisms use SMS to deliver single-use passphrase to the user. So how secure is it? Is it hard to intercept the SMS message containing the passphrase? Do mobile ...
37
votes
2answers
19k views

How secure is Ubuntu's default full-disk encryption?

How secure is the encryption offered by ubuntu (using the disk utility)? What algorithm is used underneath it? If someone could at least provide a link to some documentation or article regarding that ...
37
votes
5answers
3k views

Client-side encryption, but cloud service can still decrypt data in the event of a death? Is this possible?

I've been worried about this password manager, PasswordBox that seems to be gathering quite a bit of steam lately. They seem to have raised VC funding and are offering a free password management and ...
35
votes
5answers
3k views

Pattern to allow multiple persons to decrypt a document, without sharing the encryption key?

Current setup We have a service that allows users to upload documents through a website and stores the uploaded documents encrypted on disk. The documents on disk are encrypted with a per-user key, ...
34
votes
5answers
4k views

HTTPS still NSA-safe? [closed]

There are exerpts, that say that using https can be broken by the NSA by now. So is https still a solution for secure web-browsing? source: ...
34
votes
9answers
15k views

Are powerline ethernet adapters inherently secure?

I have 2 Zyxel PLA407 powerline adapters. Router is downstairs connected to one adapter, other adapter is upstairs about 30 feet away connected to a desktop. I have a house, not an apartment or ...
33
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7answers
4k views

How dangerous might be publishing a public key?

Maybe this question sounds obvious, but I wonder how dangerous might be publishing a public key for an asymmetric encryption system? I know public keys are meant for encrypting messages by anyone ...
33
votes
3answers
2k views

Am I wrong to believe that passwords should never be recoverable (one way hash)?

I recently forgot my password for our cable provider online account, only to discover that they sent it to us via plain text in an email. I quickly sent an email to customer support asking them if ...
32
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1answer
3k views

Why does AES encryption take more time than decryption?

While I was studying the time consumed by some methods I found that encryption take more time than decryption. Is this right? I am using AES (the same steps will be taken during the enc and dec)
32
votes
5answers
41k views

Advantages and disadvantages of Stream versus Block Ciphers

Encryption algorithms such as Blowfish,AES,RC4,DES and Seal are implemented in one of two categories of ciphers. What are the advantages/disadvantages to the type of ciphers?
31
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7answers
6k views

Why isn't open WiFi encrypted?

As far as I understand, WiFi networks that require no password send traffic through the air unencrypted. Those that require a password encrypt each connection uniquely, even if they're all using the ...
31
votes
5answers
2k views

Password Storage - Self Encryption vs Hashing?

Self Encryption: Encrypting a password using the password itself (as a symmetric key). Basically, by doing this, I'll get random data as an output. Now, in order to retrieve the password from this ...
31
votes
2answers
7k views

Web Application encryption key management

In a nutshell, let's consider a web application which stores some information in a database as encrypted data. While I'm purposely trying to keep this some what generic, here are some assumptions: ...
30
votes
2answers
39k views

How to estimate the time needed to crack RSA encryption?

How to estimate the time needed to crack RSA encryption? I mean the time needed to crack Rsa encryption with key length of 1024, 2048, 3072, 4096, 5120, 6144, 5120, 7168, 8192, 9216, 10240, 11264, ...
30
votes
5answers
52k views

Why most people use 256 bit encryption instead of 128 bit?

Isn't 128 bit security enough for most practical applications?
30
votes
3answers
1k views

Why do WordPress installations retrieve the crypto secrets remotely on installation?

It seems that WordPress retrieves all the crypto constants remotely (via HTTPS): // setup-config.php $secret_keys = wp_remote_get( 'https://api.wordpress.org/secret-key/1.1/salt/' ); Are there ...
30
votes
3answers
27k views

Is 7-Zip's AES encryption just as secure as TrueCrypt's version?

The main difference being TrueCrypt creates containers and 7-Zip encrypts the file itself, so file sizes can be guessed. Now let's just talk about the strength and breakability of the encryption. ...
28
votes
5answers
19k views

Should RSA public exponent be only in {3, 5, 17, 257 or 65537} due to security considerations?

In my project I'm using the value of public exponent of 4451h. I thought it's safe and ok until I started to use one commercial RSA encryption library. If I use this exponent with this library, it ...
28
votes
3answers
53k views

Understanding 2048 bit SSL and 256 bit encryption

On DigiCert's page, they advertise a 2048 bit SSL with a 256 bit encryption: http://www.digicert.com/256-bit-ssl-certificates.htm What exactly is the difference here and why are two encryption bits ...
27
votes
3answers
3k views

Is there any advantage to splitting a password?

I've been reading about the LANMAN (LM) hash and I'm curious about a particular part of the algorithm. The LM hash is computed as follows: The user’s ASCII password is converted to uppercase. ...
27
votes
3answers
3k views

Why can a Tor exit node decrypt data, but not the entry node?

Me -> Node A -> Node B -> Node C -> destination The documentation on Tor always states that only the exit node C can see plain text data. How is this possible without me talking to Node C ...
27
votes
4answers
17k views

How does PGP differ from S/MIME?

Is S/MIME an abstracted system for general MIME type encryption, whereas PGP is more for email? Why would I want to choose one over the other, or can I use both at the same time?
27
votes
3answers
3k views

Tell people that I can encrypt emails

I know that it is still not very easy to use PGP for an average user. However, the situation is improving (there are some easy plugins that can even nicely integrate into your GMail webmail). In ...
27
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1answer
6k views

iOS Encryption Details

Following on from this question Does anyone have any details/resources on the technical specifics of how apple implement encryption on their iOS 4.x series devices? The Apple marketing material here, ...
26
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5answers
10k views

Why AES is not used for secure hashing, instead of SHA-x?

As far as I understand, AES is believed to be extremely secure. (I have read somewhere that it would certainly not be broken in the next 20 years, but I am still not sure if the author was serious.) ...
26
votes
1answer
3k views

Is all data sent over SSH encrypted?

When you are connected to another computer over SSH, is all data transferred between the two computers encrypted? Or is any data sent in plaintext or any other "easy to intercept" format?
26
votes
8answers
2k views

Share certain information only after death

After your death, you want to make sure that a special someone gets a vital piece of information (like the password to your bank account), but: You don't want anyone else to be able to get that ...
26
votes
2answers
1k views

Does versioning an encrypted file make it less secure?

Suppose I use KeePassX as a password manager, and I store the kdb file in Sparkleshare folder as a way for backing up and syncing with multiple devices. The kdb file in itself would be encrypted, but ...
26
votes
4answers
11k views

Standards for encrypting passwords in configuration files?

My workplace has a standard that plaintext passwords are not allowed in application configuration files. This makes enough sense on its face, in case someone gets access to the config files they ...
26
votes
4answers
4k views

How secure are my passwords in the hands of Firefox using a Master Password?

I'm relying on Firefox to remember my passwords, using a Master Password of more than 25 characters. How secure is this set-up?
25
votes
2answers
3k views

Break the popularity contest crypto

There is a very interesting puzzle on the Programming Puzzles and Code Golf site to Rearrange pixels in an image so it can't be recognized and then get it back. I understand that this is not ...
25
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2answers
20k views

How can I check that my cookies are only sent over encrypted https and not http?

I read a blog post GitHub moves to SSL, but remains Firesheepable that claimed that cookies can be sent unencrypted over http even if the site is only using https. They write that a cookie should be ...
24
votes
4answers
14k views

What steps do Gmail, Yahoo! Mail, and Hotmail take to prevent eavesdropping on email?

I would like to ask what happens when an email is sent from gmail, yahoo or hotmail public web email services? I don't understand email protocols in details, but as far as I know email traffic is ...
24
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6answers
25k views

Asymmetric vs Symmetric Encryption

I am currently taking a principles of information security class. While talking about different encryption methods a large number of my classmates seem to believe that Asymmetric Encryption is better ...