Cryptography is the practice and study of logical means used to achieve information confidentiality, integrity and authenticity. It covers, among other things, encryption (making some data unreadable except for those who know a given secret element, called a key), data hashing (in particular for ...

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19 views

How would an improved “read receipt” work as an email, Facebook post, or webpage?

I'm exploring various ways to implement cryptographic read receipts, that would be used to tell the content producer that the content was viewed. In addition to feedback reporting, a response might ...
2
votes
2answers
55 views

Checksum Calculation for Source Code tar balls downloads

Http sites like OpenSSL provide checksum for each source code tarball available for download HTTPS sites like GitHub usually do not provide checksum with 'download zip' option. Some sites although ...
1
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1answer
57 views

Am I encrypting and storing an array of user-details correctly?

I came up with a user-details-storing procedure that was, in the beginning, based on actual security-literature – but then I just kept writing without really doing all the cross-checking I should have ...
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0answers
46 views

Designing a web based CTF tournament [on hold]

I'm designing a web based CTF tournament as a information security project.My idea is to build a game which has different tasks in every step.Every step must have some security related stuff like SQL ...
1
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0answers
55 views

Encrypting data before sending to SaaS tool and decrypting on browser view

I'd like to send data to a SaaS tool, where the data is stored in the cloud. I'll use Google Analytics as an example, but it applies to any similar service. Google Analytics does not allow you to ...
0
votes
1answer
108 views

Can this text be figured out?

It seems that as long as a computer is connected to the network, any encryption used by that computer makes it insecure, because the computer can be compromised. I wonder if in this scenario is it ...
677
votes
22answers
136k views

XKCD #936: Short complex password, or long dictionary passphrase?

How accurate is this XKCD comic from August 10, 2011? I've always been an advocate of long rather than complex passwords, but most security people (at least the ones that I've talked to) are ...
0
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0answers
37 views

Are there any paper/human strong crypto systems? [migrated]

Are there any paper/human executed crypto systems that have reasonable strength? I am aware of a few candidates so far Solitare from Cryptonomicon https://en.wikipedia.org/wiki/Solitaire_(cipher) ...
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1answer
42 views

Any audited cryptography library? [on hold]

Is there any open source crypto library (C,C++,Java,whatever) that has been audited by well known cryptographers and which is confirmed to be correctly implemented ? By correctly implemented I mean ...
1
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1answer
46 views

What is the difference between Key Derivation Function and (salted) Hash?

I see in this post that the main difference is that KDF outputs have "certain randomness properties", and I don't understand what does it mean. Suposing that that "certain randomness properties" are ...
1
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2answers
61 views

ECC and RSA 10K stronger claim

There are a lot of websites where it is claimed something akin to this but no explanation on the basis. "ECC key size of 256 bits is equivalent to a 3072-bit RSA key and 10,000 times stronger than a ...
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votes
1answer
36 views

How to verify perfect secrecy of a cryptosystem? [closed]

Playing with an encryption algorithm. how can i prove it's information-theoretically secure?
27
votes
3answers
21k views

Now that it is 2015, what SSL/TLS cipher suites should be used in a high security HTTPS environment?

It has become quite difficult to configure an HTTPS service that maintains "the ideal transport layer". How should an HTTPS service be configured to permit some reasonable level of compatibility while ...
4
votes
1answer
272 views

How to store passwords in database so that they can be retrieved?

I'm developing a password manager web app. It's just for fun: I'm not exposing anybody's passwords. My idea was to use hashing+salting, and that's what I did for the master password. But then I ...
4
votes
0answers
55 views

How to really treat security between peers in WebRTC

Recently I've been implementing WebRTC in my project and would like to add security and privacy to the couple. I then decided to search on and found something if it is really necessary to impose ...
3
votes
2answers
64 views

Where in a TLS connection can I get the signature of the content sent by the server?

I want to be able to prove that a given content returned by a HTTPS server was in fact served. I have looked over the whole TLS protocol and I found I can use ServerKeyExchange to get the server's ...
3
votes
2answers
204 views

Real-world applications of Differential Privacy?

Differentially private techniques guarantee privacy while often permitting accurate answers ...this is something I have been reading up on lately as a means of preserving user ...
2
votes
1answer
61 views

Are TLS session keys cached in a browser?

For example, when authenticating to a TLS protected service, and then closing the tab, you can sometimes reconnect to the service afterwards without re-authenticating. In preservation of perfect ...
2
votes
2answers
54 views

Authenticated encryption (Symmetric encryption) for .NET applications [closed]

Is there an implementation of Authenticated encryption for .NET applications? The AES API from .NET does not include mode such as GCM. In the documentation, I can only see insecure modes (ECB, CBC, ...
1
vote
1answer
62 views

Which stream ciphers are supported in am335x cryptographic accelerator?

I want to use cryptographic accelerator in aes cfb mode [or any other stream cipher]. According to http://e2e.ti.com/support/arm/sitara_arm/f/791/p/156983/658334 link cfb is supported in am335x. I ...
20
votes
1answer
634 views

How to encrypt in PHP, properly?

How do I encrypt data in PHP, properly, using symmetric-key encryption? I have a message M and a secret S. I'm looking for a solution that uses cryptography properly without making any of the usual ...
3
votes
2answers
272 views

Using OAuth 2.0 without token storage

I am building a system for a product which requires authentication and authorization. Naturally I have chosen using OAuth 2.0 as it is a commonly used protocol and has proven to be useful. I am ...
0
votes
2answers
74 views

Do modern cryptographers / cryptoanalytics need the knowledge of historical cryptography

It makes a lot of sense for people to know the history of their profession from various points of view and I suppose especially in cryptography because people can still use old ciphers and no one ...
1
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1answer
55 views

Does WebCrypto also mandate the crypto algorithms be implemented in Javascript?

I am trying to understand what WebCrypto means. From what I understand it is - A Javascript Crypto API spec that all browsers must (hopefully) support. Am I correct? If so are the crypto algorithms ...
2
votes
3answers
38 views

Chaining multiple PGP keys

I would like to know the practical limitations to contact chaining multiple peoples pgp key's in order to protect a file. In normal public key cryptography, four keys are required, public and private ...
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votes
2answers
172 views

Cryptowall encryption files

This is a question concerning the way the Cryptowall ransomware encrypts files on the victim's computer. Someone knows if it is possible to recover the encryption key comparing the encrypted file and ...
0
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0answers
49 views

Why is Rabin encryption equivalent to factoring? [migrated]

I don't understand the proof of equivalence I've read everywhere (e.g., in Rabin's paper or on Wikipedia). Here's my objection: let's say you have a Rabin decryption oracle that takes n and c and ...
0
votes
1answer
57 views

Using the index of characters in a security question [duplicate]

I'm seeing many sites offering one or two "security questions" that have to be answered by choosing characters at specific indexes, in addition to username + password. For example: "What is your ...
3
votes
2answers
198 views

How to store derby database encryption key in HSM?

The Derby Database supports encryption with a key or password. Traditionally this key is stored in the file systems, now I am looking to store and protect this key in the HSM instead, but I couldn't ...
1
vote
0answers
24 views

Explanation of part of a visual cryptography algorithm [migrated]

I have been working on a project involving visual cryptography and I am stuck with the following problem. My question is related to this paper, AN IMPROVED VISUAL CRYPTOGRAPHY SCHEME FOR SECRET ...
6
votes
2answers
278 views

How much entropy is good enough for seeding a CSPRNG?

I have some fundamental questions on using Cryptographically Secure Pseudorandom Number Generators (CSPRNGs). What should be the size of the seed that I initialize a CSPRNG with? How often should I ...
3
votes
1answer
93 views

Are there any passwords managers that use a second hidden encryption drive to hide passwords?

I've heard that encyption program, Truecrypt can create a hidden encrypted drive within an encrypted drive; and even if an attacker accesses the first encrypted drive he/she cannot prove the hidden ...
3
votes
1answer
114 views

Can applying second cipher (including home brew) reduce security

I have asked a question regarding the benefits (if any) of the following scheme: AES(HomeBrew(plaintext)). There are many good answers for that, but many people say that it's theoretically possible ...
10
votes
8answers
1k views

Double encryption with home brew algorithm

Everyone says that home brew encryption is not a good idea because one day the algorithm will be known to attacker which sounds reasonable. So that seems it's main problem, on the other hand known ...
14
votes
2answers
2k views

How would I implement “Broadcast Encryption”?

I have a stream that I want to encrypt for broadcast to 10,000 subscribers. I know I should encrypt this data using a symmetric key; and also intend that this symmetric key will be rotated every 30 ...
2
votes
1answer
397 views

How does signing work with Elliptic Curve Crypto?

So I have read up and have a decent understanding of how the crypto works with Elliptic Curve Cryptography. I also think I have an understanding of how signing works with things like Elliptic Curve ...
0
votes
1answer
80 views

Is this data encryption process secure?

I have created the following encryption process which I will be using to store CD keys inside my database. Before I use it, however, I need to make sure that this is as secure as possible. From what ...
22
votes
2answers
44k views

Security comparsion of 3DES and AES

Which one is more secure and least possible to be broken through cryptanalysis AES or 3DES (no matter performance)? I need to use encryption for my projects to store and secure sensitive information ...
2
votes
1answer
128 views

if a public key cannot decrypt the cipher text, then how can a private key?

I understand the "public" part of public key cryptography. Not the "private" part. For example, let's say our public key is %7 (modulo 7). And the message to be encrypted is 22. And we know that 22 ...
2
votes
1answer
61 views

Can TPM Storage Keys be Created Outside TPM?

I am interested in 'adding' preexisting keys to a TPM's storage hierarchy. An example of a desired key hierarchy can be shown as: (SRK)----->(User Storage Key)-------> User Working Key 1 ...
12
votes
5answers
2k views

Guessing random bit with 100% accuracy [closed]

I am soon to start my compulsory military service. I applied to the Cyber Warfare Unit of Finnish army. There was a test for applicants. Since the test is done the questions have now been published ...
1
vote
1answer
69 views

Basic XOR cipher for longer messages

How much effective strength is the following adding to a basic 512 bit XOR cipher? Private Key = Key0 consists of 512 randomly generated bits. This key is never used to encrypt or decrypt anything. ...
1
vote
1answer
57 views

Are encryption algorithms designed to hinder parallelization?

Are things like large memory requirements and constantly mutable state typically added to encryption alogrithms to hinder the ability of attackers to try multiple candidate keys simultaneously? Also, ...
8
votes
4answers
525 views

What Country, State and City should I choose when requesting an SSL certificate?

I am really confused about the country, state and city I should select when submitting an SSL certificate. Should I provide the location of my servers or my current home address?I can always reissue a ...
7
votes
1answer
157 views

Using RSA-SHA as/instead HMAC in OpenVPN?

While reading the manual of OpenVPN 2.3, I came across the --auth alg option. The manual says: Authenticate packets with HMAC using message digest algorithm alg. (The default is SHA1 ). HMAC is a ...
2
votes
2answers
65 views

Secure communication in SHTF

I am a prepper. I am preparing for a situation where there will be no rule of law and where I can't rely on the government for all my needs. This naturally involves storing food, water, and items for ...
1
vote
1answer
29 views

Is there a cryptosystem that allows a set of auditors to confirm that they have valid Shamir or Group signatures?

Suppose I have a client that generates and sends a Shamir key (or group signature) to a set of Auditors. This key is essentially an unverified set of bytes. Each auditor wants to somehow verify that ...
2
votes
3answers
278 views

Asymmetric vs symmetric encryption benchmarks

I have found these benchmarks in Crypto++'s site. http://www.cryptopp.com/benchmarks.html But I am, quite honestly, not entirely sure how to interpret them. I am really looking for a set of ...
1
vote
1answer
60 views

How to encrypt or store data so that only a pool of processes can share it on Windows?

I am writing an application T1 which is using SQLite database to store some sensitive data and i am trying to encrypt it securely. The issue i am facing is that i don't want my symmetric key to be ...
6
votes
1answer
77 views

What real life scenarios require separate end user certificates for Signing and Identity?

Based on this question, I'm interested in any rational argument that would support the idea of maintaining separate signing and authentication certificates. Conventional logic & wisdom says there ...