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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11
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3answers
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Why triple DES used in EDE mode?

Why is triple DES is calculated in encrypt decrypt encrypt mode? Why a decrypt in the middle? And isn't decrypt = encrypt since DES in a symmetric cipher?
11
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5answers
3k views

Storing private asymmetric key in application binary?

I would like to give a daemon-style process (i.e. no user interaction) access to a shared secret key so that it can access a shared, encrypted data file. User applications accessing the same encrypted ...
8
votes
3answers
7k views

Secure way to transfer public/secret key to second computer

I created a public/secret key using Seahorse (GNOME managing tool for encryption keys). I haven't had issues encrypting and decrypting files from the computer the keys are located in but I'd like to ...
7
votes
1answer
2k views

How do I learn Cryptographic/Mathematical notation

I asked a question earlier where it was recommended that I describe my issue using standard cryptography notation. How do I learn this notation and how to convey my approach? How can I annotate this ...
6
votes
4answers
4k views

Why do you need message authentication in addition to encryption?

I've been reading up on Authenticated Encryption with Associated Data. The linked RFC states: Authenticated encryption is a form of encryption that, in addition to providing confidentiality ...
6
votes
1answer
14k views

How can I tell if a PPTP tunnel is secure?

PPTP has been demonstrated to be broken in many ways, and most installations are insecure. But it is also theoretically not broken if configured correctly. As an end-user, is there a simple way for ...
6
votes
2answers
9k views

How can I recover encrypted files after system reinstallation

I had a file which contains images and videos, I was using the windows 7 ultimate and I had encrypted the file. Now I have copied that file to my hard disk and format that operating system and again. ...
10
votes
1answer
11k views

Are there any known vulnerabilities in PPTP VPNs when configured properly?

PPTP is the only VPN protocol supported by some devices (for example, the Asus RT-AC66U WiFi router). If PPTP is configured to only use the most secure options, does its use present any security ...
9
votes
1answer
847 views

Reversible, recoverable user data encryption scheme

From this earlier question, I have a general need to obfuscate a set of third-party credentials stored in a user account, which are then used in an internal Winforms software client. The scheme from ...
8
votes
7answers
2k views

Is there any asymmetrically encrypted file system?

Is there a file system providing a directory where everybody can write, but only the directory owner can read the files? In theory it could be done by encrypting using the public key while writing, ...
7
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2answers
2k views

How is OTR messaging with Socialist Millionaire Protocol (SMP) protected from Man In The Middle?

So imagine the next situation: Alice wants to initiate OTR instant messaging session with Bob but Joe is Man In The Middle. Alice negotiates a shared secret 'X' with Joe (thinking he is Bob) using ...
7
votes
10answers
6k views

How can I share files with other individuals using the cloud in a secure way?

I would like to use a dropbox because it is easy and convenient. But I want to encrypt the files with the public key of the intended recipient, so he will be the only one who can access the data in ...
7
votes
2answers
3k views

ssh public/private key pair

I am having problems understanding how ssh really works. I know it uses a public key cryptography to encrypt messages. However, I can ssh to a server without first generating a public/private key pair ...
6
votes
2answers
2k views

Considering that SRP is better than SSH and Basic Auth, how can it be implemented in a website?

SRP is short for Secure Remote Password protocol, and provides a better way for passwords to be sent over the internet. I've read the information at it's Stanford University home page, the Wiki ...
6
votes
3answers
14k views

Which type of encryption algorithms android supports, and which would be better?

I read this documentation, and I have written an algo to encrypt and decrypt a string. But I don't know how many types of algorithms android supports. Regarding DES and AES (As wiki documentation) ...
4
votes
1answer
413 views

Has the wedge security flaw been fixed for credit cards?

According to this site http://www.lightbluetouchpaper.org/2009/08/25/defending-against-wedge-attacks/ there is a flaw in EMV. Since then has this flaw been fixed? Is it the same law as the one ...
2
votes
1answer
189 views

What data is not encrypted in iOS 8+ when “locked”

Scenario: iPhone 5+ with iOS 8+ with system encryption enabled. The phone is on and locked. (the user has authenticated (unlocked phone) at least once since power-up, and then relocked). What ...
18
votes
1answer
988 views

Doing a dictionary attack on RSA if you have the public key?

I'm trying to learn exactly how RSA works. Currently I have a very, very simplictic overview that goes like this. Having the public key allows you to encrypt things. Encrypting the same message ...
15
votes
2answers
969 views

Does the haystack theory work

The haystack theory is the recommendation to put repeated characters in your password in order to make it harder for brute force to reveal. Does this have any mathematical basis? Or is it snake oil?
14
votes
4answers
2k views

Is Steganography considered encryption and subject to USA export restrictions?

I have written an application for Apple's iOS which embeds messages in JPEG files using steganography (see http://en.wikipedia.org/wiki/Steganography). For the purposes of this question lets assume ...
11
votes
4answers
9k views

What's the standard way to encrypt a file with a public key in Java?

I'm writing a client app in Java that sends encrypted data back to the server. All clients have my RSA public key. Is there a standard way to encrypt a given file with it to send it back to the ...
8
votes
1answer
554 views

Protecting emails in your database

It's common to encrypt passwords in the database, but I'm wondering what solutions are out there to protect emails in your database. Not just from hacking, but from disgruntled employees or engineers ...
6
votes
2answers
195 views

Decrypting arbitrary offset of encrypted file

I want to store encrypted files on some storage backend that allows me to fetch bytes X through Y of the encrypted file. I can obviously decrypt the entire file locally and send it back to the client. ...
6
votes
1answer
744 views

Database encryption or filesystem encryption?

Recently I've been working on some data which, although not directly governed by any infosec laws, is sensitive enough to warrant being encrypted. I'm interested in finding out about best practises ...
4
votes
2answers
534 views

TLS reliance on System Time

I'm interested to know if there is any reliance on system time (as defined by Linux or windows) when initiating a secure handshake. I'm aware that TCP typically uses a random number (RFC 1323) to ...
3
votes
1answer
453 views

Is it bad practice to add an encrypted private key to source control?

I understand that it is bad practice to add passwords and secret tokens to source control, with obvious implications arising if you are working on an open-source or related project. Rather, you ...
3
votes
1answer
2k views

What are the Netscape Cert Type attributes? Why/when are they needed?

What are the Netscape Cert Type attributes in a X.509 Certificate and how are they different with the X509v3 extensions? Example: There is the Client/Server Extended Key Usage (X.509) but there is ...
3
votes
4answers
6k views

What Are The Best Practices (Application Security Policy) For Modifying Rijndael Salt, IV, Pass Phrase

(Note: originally posted in SO - advised to post on SSE) With regards to Rijndael encryption, what (if any) are the best practices (and consequences) regarding the periodic modification of one or ...
3
votes
3answers
3k views

Is encrypting data with a private key dangerous?

I have been reviewing code for various internal apps that handle secure transmission of data with external systems. These follow the following process: RSA encrypt data with 3rd party public key RSA ...
2
votes
1answer
945 views

Vulnerabilities in Host Proof Hosting

I've recently been doing some research on Host-Proof Hosting, specifically in a web app environment. It seems like a pretty rock solid method of security, but I'm certainly not a security expert and ...
2
votes
3answers
4k views

Why different key exhange techniques for ssl key exchange?

During ssl key exchange, I have read that sending the symmetric key to the server encrypted with the server's public key is an old technique. Now for key echange Diffie hellman and other techniques ...
1
vote
2answers
2k views

What's the limit on the size of the data that public-key cryptos can handle?

Someone mentioned here that asymmetric encryption might not be appropriate for bulk data and gave an example of RSA with 100 bytes. Of course, I understand that it was a rough example. But it made me ...
1
vote
1answer
241 views

Implementation review - Independent key, admin side and user side

The admin of the website needs to read user data. So, if the key is derived from the user pass, then the admin has to know the user pass, not exactly a good idea. The following encryption scheme was ...
1
vote
2answers
1k views

encryption method against man in the middle attack

Let's say there are 3 computers: Alice, Bob, Carol. Carol is network provider, so everything from Alice to Bob and vice versa passes through Carol. Carol can modify messages between Alice and Bob. Is ...
0
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1answer
78 views

Bridge mode question [closed]

İ have an outdoor in my shop and distributing my network to customers using mac filtering opition.. one of my neighboor got a weak signal....so, he bought a wirelss repeater to recieve a better ...
0
votes
1answer
396 views

Can eavesdropping be facilitated by injecting content that will be transmitted?

I was asked during a job interview the following question, to which I couldn't find an answer then, and this thing is still bothering me. I was hoping someone might know the answer here: Consider ...
0
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2answers
176 views

Monitoring user use VPN

If there is an employee uses the internet through an internal proxy in his company, and he use a paid VPN service to browse safely, can IT side be able to monitor his behavior?
11
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1answer
1k views

Any risk in using the same salt for several hashes on a user?

Right now I'm storing a salt and password_hash on the users table (pretty standard stuff). The need arose to get a secure hash of another field for a user. Is there any risk in reusing the same salt ...
8
votes
2answers
5k views

WPA2 Enterprise AES encryption key size?

I have recently set up a RADIUS server with EAP for my wireless router, however, I have some questions about the key size and how WPA2 enterprise (AES) works in general. I have read that in ...
8
votes
3answers
2k views

Is it safe to store a single symmetric key encrypted with several different RSA public keys?

For the field-based encryption of a database containing sensitive information, I was thinking of the following design: Every user has a smartcard used for client certificate login. After login the ...
7
votes
3answers
15k views

What does these warnings mean on an SSL connection by firefox (only)

I am connecting to a secure site and firefox mentions about identity: Owner: This website does not supply ownership information Verified by: Not specified Technical Details: Connection ...
5
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2answers
240 views

Does adding a non-entropic part to a password makes it less secure?

Suppose I'm encrypting a file via AES using a password of my choice, or creating a TrueCrypt volume using a password and no keyfiles. Which of the following two passwords would be more secure: ...
5
votes
1answer
280 views

What issues might exist with TLS-OBC's emulation of Browser Certificates?

TLS-OBC is an RFC proposal that increases SSL/TLS security by using certificates on both ends of the TLS connection. What's special here is that the client is permitted to dynamically create a local, ...
5
votes
4answers
2k views

AES ECB Mode for single block/random data encryption

I need to save random 16 byte keys to a database. To encrypt these keys I currently use AES 128 with ECB Mode (because of smaller data to store, no IV needed), but now I read a lot about ECB being ...
4
votes
4answers
365 views

Is using Tor and VPN combination more secure?

I have been reading more about Tor and its risks to personal data leakage to the exit nodes in the chain. This last node can snatch encryption keys or log in information of websites I may have ...
4
votes
3answers
927 views

Determine hashing algorithm only with known input and output

Given the input: test A system generates the following output hash: 0x001F41B6A0534D3B851D69EFE6237F550100000010D5F4FC65E64BCFDBF2590212E4411C44942C6C734C00ACFE13B958DCAB3614 I do not know ...
4
votes
3answers
1k views

How are possible uses for X.509 (SSL) certificates denoted?

X.509 certificates can be used for servers, clients, email, code signing and more applications. http://twitpic.com/6gdxaq indicates that a certificate can have different of these 'capabilities' on it ...
3
votes
3answers
179 views

Should traffic between two hosts in the same data center be encrypted?

We have two hosts, theoretically in the same data center. The two machines are hosted at Online.net. We're having a bit of a debate: should the traffic between the two hosts be encrypted. The traffic ...
3
votes
2answers
231 views

How does my bank knows my second and forth chars of my password [duplicate]

I see that the new login mechanism used by some banks in UK and also used by visa debit authentication is to ask for three random characters from your password at login (for example second, ninth and ...
3
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2answers
5k views

How effectively can ISPs detect illegal file sharing?

Recently the USA passed a law requiring ISPs to spy on their customers' internet connections to check for illegal file sharing. I assume that they would do this by sniffing packets, but doesn't this ...