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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Can Cryptolocker (Or Other Ransomware) Encrypt Files That Are Already Encrypted?

If you have already encrypted files, are they still vulnerable to being encrypted a second time by a program like Cryptolocker, or would this protect them?
17
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5answers
1k views

Why is security through obscurity not a good option for encryption? [duplicate]

I feel like there must be a simple explanation, but I've been looking around haven't found any wholesome answers. Take for example my name is Alice and my best friend Bob and we want to communicate ...
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3answers
78 views

Encrypting a huffman encoded file

I wrote a huffman encoding program that can compress and decompress files. The file contains a header which contains information that allows me to retrieve the huffman tree. I wanted to add a simple ...
2
votes
1answer
114 views

Is it possible to design a system where the client doesn't have to trust the server?

When you are using services like chat, file sending, exchanging etc., you always have to trust server providing these services. The only way to use services without having to trust third party is to ...
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1answer
28 views

Which encryption technique should be used for users name and passwords in my notebook [duplicate]

i writing all my passwords and users names on my notebook emails,amazons,facebook. and i have really Nosy little's brothers that will probably look at my notebook when i am not around, which ...
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0answers
36 views

What type of encoding/encryption is this? [on hold]

Im new to encoding and this realm, and I know this is not Base64. Could anyone tell me what this is? ·H AGHü§“-GYÖÍ=cp:S´’u@Ô∂ıAº¨¿mÇ…VÙ®ù¯˘JÂK‚“][ÿ ∞4‹ ...
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vote
2answers
74 views

Which encryption technique should be used for cloud computing data transfer?

I want to setup my application for cloud computing for Software as a Service. There is going to be a lot of data transfer between my server and client, to and fro. The technique I have envisaged is: ...
6
votes
1answer
191 views

How could a system be zero-knowledge?

I'm actually interested about zero-knowledge storage system. Those system where the storage provider claims he can't have any access to the data stored. As far I know, the data are encrypted using a ...
0
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1answer
31 views

Forward Secrecy not supported with referenced browsers?

I am running a scan against one of our servers from the Qualys SSL tester site and it says that my server "does not support forward secrecy with the referenced browsers". What exactly does that mean? ...
2
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2answers
129 views

How can I secure the secret key?

I am a bit confused about securing the secret encyption key. Here is the scenario: I need to encrypt some data (file) This data will be read by a program (say written in C/C++). Both the program ...
2
votes
1answer
59 views

How does Mylar ensure encrypted data remains secure even if the live app code is compromised

Because Mylar does the decryption in the browser, the key is never stored on the server. Nice. This moves the threat to the browser, where, if the attacker is able to get a malicious script to be ...
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0answers
54 views

text messages you cant delete [closed]

why is there an anonymous text on my phone that will not delete?
1
vote
1answer
22 views

updatedb and encrypted home folders: Does it store unencrypted file and folder names somewhere?

When you encrypt your home folder in Ubuntu and Debian, it protects not only the file contents but also the file and folder names. Yet I see that updatedb and locate works in Debian. When I run ...
0
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0answers
20 views

Possible CPA or CCA attack when using AES-CBC mode under the following situation?

Both client and server know a shared key in advance. Both sides us EVP_BytesToKey() derive a pair of same key and same IV. Then, client and server start transferring data encrypted by AES-CBC mode ...
0
votes
1answer
26 views

encrypted lookup-keys for key-value store

I'd like to use a key-value store (cassandra, redis, ...), but I don't trust the server. The clients have a shared secret, and I'm using that to encrypt the stored values. But what is the proper way ...
0
votes
1answer
38 views

iOS Security/Encryption techniques for REST webservice [closed]

Say there's a banking app with a lots of web-service calls involved. How do you store secure data (such as sessions, fund transfer validation keys etc) encrypted locally which can be retrieved back ...
1
vote
3answers
339 views

Protect database data from everyone, including sys admins, etc

One of the things that has always bothered me about simple database data encryption: If the server is compromised, the database is effectively compromised. The attacker can use the same code as the ...
0
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1answer
56 views

Encrypting folders with flash drive key?

Is there any way to have a flash drive encrypted and it will only open with one computer that has the key in it?
2
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2answers
117 views

How can I secure my api to avoid copying?

Im building an app which should receive data from my server. The Api should be a PHP based script which provides the data as JSON. However I want to keep the data private and it should only be ...
0
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0answers
42 views

Are temporary files an issue when opening and editing an encrypted 7z file?

I am new to security and encryption. I want to store important information like passwords and pin codes so I don't forget them. So far I have been using LastPass but I would prefer a solution I ...
0
votes
1answer
46 views

How are TLSv1.0 ciphers negotiated as TLSv1.2?

I'm a little confused about something I am reading in Bulletproof SSL. "TLS 1.2 is the only protocol that allows suites to define their PRFs. This means that for the suites defined before TLS 1.2 ...
0
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0answers
21 views

Encryption test failed [migrated]

I am facing a problem when attempting to send an encrypted email via Enigmail (Thunderbird) in Ubuntu 14.04. I was following the Email Self-Defense guide https://emailselfdefense.fsf.org/en/ ...
1
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2answers
68 views

Are digital signature algorithms subject to the same types of attack as public-key encryption algorithms?

I understand that digital signatures are usually implemented by encrypting a message digest with a private key, decrypting the resulting signature with a public key, and verifying that the message ...
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2answers
50 views

ECDSA ciphers and forward secrecy question about key exchange

I have heard that with forward secrecy that the ECDSA ciphers generate different keys for "each session" because they are not dependent on the private key of the server. My question is how is "each ...
48
votes
6answers
13k 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 ...
2
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1answer
39 views

Possibility of using CA as an attack point by governmental organizations under their pressure

I was always concerned about the model of trust behind CA stuff we use . Well, for most of us, it is OK to trust them, since they are reliable organizations with a bunch of solid experience. ...
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1answer
94 views

Security margin of a winzip, Winrar password of 64 characters against GPU cracking

what s the longterm security margin of of a winzip or Winrar file encrypted with aes-256 and a password consisting of 64 completely random characters set a-z 0-9 and other printable special ...
2
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1answer
142 views

Is encrypting something more than once safer than hashing more than once?

I am aware of the implications that hashing something more than once correctly will increase the security of a system, but doing it incorrectly will decrease it, as noted here and on various other ...
3
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0answers
51 views

How are secure hashing and encryption algorithms proven? [migrated]

Given that: You should always use proven secure hashing and encryption algorithms, rather than attempting to write your own. What's the process for criteria for an algorithm being proven? Is ...
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2answers
41 views

Identifying/decrypting hashed/encrypted data [closed]

This weekend I took part in an security challenge. I had great fun doing it but i found a huge gap in my knowledge that I'm really keen to fill and hope someone here can help get me pointing in the ...
4
votes
2answers
963 views

Extract AES key by comparing plaintext and encrypted data

Is there a kind of analysis which would enable me to get AES key which was used for encrypting arbitrary data while I have both original and encrypted version of data ? The problem is that the AES ...
2
votes
1answer
47 views

Drawbacks to only using TLS 1.2 ciphers in OpenSSL

I understand you would not want to do this as it would limit compatibility for older devices and platforms. However if someone were in an all TLS1.2 environment, say a very well managed internal ...
0
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3answers
82 views

Why do we use such a redundant language (English) for network communication? [closed]

I have heard throughout the internet that English is incredibly redundant. So why do we turn English messages in to a cipher which is then, from my understanding more vulnerable to letter frequency ...
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1answer
20 views

Choosing right way to secure access to server access via socket

I have an application running on a server, that has an exposed socket to the Internet to communicate with client that is/are application(s) on a phone. How would one go about properly securing the ...
0
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0answers
117 views

Why can't you decrypt an encrypted message with just the public key? [migrated]

How does asymmetric crypto work? For example, if you use PGP in emails, you generate a private key that is known only to you and a public key, which is available to everyone. Is there a simple way ...
1
vote
3answers
68 views

How are HSMs used in payment processing on the server?

I came to know recently that HSMs are used in credit card processing on the server side but since I don't work in that space and stumped as to why its needed. I can see it used in an ATM machine - ...
0
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0answers
22 views

Truecrypt Password Problem, Have Recovery Disk [migrated]

I am trying to log in to a laptop that has not been used since the end of last year. The laptop has Truecrypt 7.1 along with Windows 7. I am 99% sure i am using the correct password. On entering the ...
4
votes
1answer
75 views

Is there a secure way to create and distribute Shamir Secrets?

This Shamir Secret sharing utility consumes the secret key, and then generates N keys that must be manually distributed to each person. This is probably fine for most low-security situations, but not ...
2
votes
2answers
222 views

Easiest solution for automatic encryption of files on Dropbox?

I don't trust Dropbox to keep my files secure. In fact, the same goes for all the other file clouds. What I'd like is a easy and cross platform means of encrypting files that I add and read from ...
0
votes
1answer
54 views

Using different algorithms to slow down GPU password cracking

I have some job related files I have already compressed with 7Z. I have protected each with good 10 character passwords consisting of upper, and lower cases, numbers and special characters. And I ...
1
vote
1answer
162 views

Using AES as a Stream Cipher

I need to send a lot of small messages that are usually between 128 bits and 256 bits long, and each message is encrypted with a separate 128 bit AES key. Therefore, to send each message with the key ...
0
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2answers
34 views

Entering payment information in Android Apps

I'm concerned how android apps that integrate payment processing deal with secure financial information.When purchasing through these apps the apps show the Webpage of the bank asking for credentials. ...
2
votes
1answer
77 views

Are all TCP connection protected by IPsec?

I hope this question fits this stackexchange: From what I understand, IPSec takes care of encrypting everything above the IP layer (transport, application). Does that mean that if I open a socket ...
2
votes
0answers
114 views

Some http requests are not send encrypted by vpn! Why?

I subscribed to a VPN service recently, and installed wireshark to take a look at the traffic sent from my computer. Practically all of it goes through UDP protocol, encrypted. But there are two HTTP ...
0
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0answers
30 views

Payment Application Integration - Encryption or HMAC

Doing an integration with an online payment provider. Payment provider will be making a web request to my server to provide some information about the basket content. On my end there's no payment ...
1
vote
2answers
44 views

How to identify Encryption algorithm for data coming in field/attribute values of an xml

I have data coming in the form of XML with certain XML attributes being encrypted. I am very new to encryption/decryption. So I would like a detailed explanation on how to find the encryption ...
4
votes
2answers
96 views

How does an insecure RNG affect cryptography, and how do I measure the corresponding loss of security?

Suppose a given random number generator has poor entropy, and is compressible by any compression algorithm (zlib, bzip2, lzma, etc). Specifically the issues with this RNG are: Bad entropy Bad seed ...
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3answers
91 views

What's the most secure way to send information from one device to another?

I need to send sensitive information from one piece of hardware to another. I was thinking wifi, but if someone obtains the password, it wouldn't be encrypted. I don't think you can use ssl unless ...
4
votes
1answer
158 views

How is ZixCorp able to provide email encryption without a password?

I am trying to understand how/if an email I received is being encrypted. A financial institution sent me a verifiable email (i.e. not phising) asking me to fill out a pdf form to complete a ...
2
votes
3answers
109 views

Adding photos to Truecrypted, gapless laptop from camera safely

I have a Truecrypted, airgapped (no internet connectivity at all) laptop that I use as a completely secure computer for sensitive files. I want to add images from my iPhone (I know), camera or other ...