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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424 views

breaking down RSA/ECB/OAEPWITHSHA-256ANDMGF1PADDING

So Java has a mode called RSA/ECB/OAEPWITHSHA-256ANDMGF1PADDING. What does that even mean? RFC3447, Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1, section 7....
-1
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1answer
141 views

Why not create your own encryption? [duplicate]

I am wondering if AES-128 and the likes were once broken and if they were broken because people knew they were trying to break AES then why don't we create our own personal algorithm to encrypt the ...
0
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0answers
109 views

Triple-DES DUKPT CBC PIN variant vs Data variant

Does any know the difference between triple des dukpt decryption algorithm with PIN variant and Data variant? I have done Triple DES DUKPT PIN variant, which generate session key from KSN and BDK. ...
1
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0answers
362 views

Storing Social Security Numbers in a Database

I'm developing an online application that needs the user's social security number. The application won't be processed on the web server so I'll be using an asymmetric key. So a compromised web server ...
1
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0answers
41 views

Let users sign in with eIDs - do I need government authorisation? (scope: all nation-states) [closed]

I've decided to launch a crypto-basic income system. Crypto UBIs are pretty popular now. For me, it seems like an open nation-state ID should exist by now (2015). However, Mike Hearn, Bitcoin core-...
2
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1answer
301 views

Does CryptoWall needs a internet connection to encrypt my files?

Does CryptoWall 3.0 use some resource on the internet to encrypt my files? I watched this video on YouTube - in this video a tool is used to sniff network traffic and find information about ...
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3answers
67 views

Hashing Algorithms Costs vs Sleep

I understand most of the concepts behind hashing password but this one still escapes me. I understand that you want the hash to take some time ( a couple milliseconds) so the attacker can't ...
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0answers
120 views

OpenPGP smartcards compromised by blackhat 2015 simcard hack?

This blackhat was a new sidechannel attack in the SIM-card AES encryption announced. I am currently using the OpenPGP smart/SIM-card version 2.1 to store my PGP-private keys, which is the same model ...
3
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1answer
186 views

“MAC function must resist existential forgery under chosen-plaintext attacks”, what does that mean?

While reading about MAC (Message Authentication Code) I have faced this sentence: MAC function must resist existential forgery under chosen-plaintext attacks but I got confused. What does ...
4
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2answers
2k views

How do session keys in public key cryptography work? [duplicate]

I have read that a session key is symmetric, and it is encrypted by recipient's public key; When "Bob" receives a message, does he decrypt it with his private key and he's then in possession of an ...
6
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2answers
212 views

Is RSA useless when my app is fully decompiled?

I've programmed an Android game with Unity Engine. As you know in Unity, scripts compiled into one file named "Assembly-CSharp.dll". I wrote my scripts in C#. After I compiled whole game into .apk, I ...
3
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2answers
139 views

Securely saving credentials for later plain-text authentication

I am developing a Django application where a user logs in with Kerberos, and then has accesses to a number of internal applications. One of these is a file application that connects to a server over ...
2
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1answer
211 views

GnuPG - Problems with large RSA keys

I have read that GnuPG limits the size of RSA keys to 4096-bits because this could lead to problems with running out of secure memory. But in which operation is this the case? Generating the keys? ...
2
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1answer
151 views

What is the most secure way to digitally communicate between the U.S. and China?

What is the most secure way for two people to communicate digitally when one person is in the U.S. and the other is in China (likely being monitored)? Updated: Here's some additional info: The ...
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1answer
2k views

Secure Client-Initiated Renegotiation - DoS DANGER

I tested my server against cryptographic attacks and I have a few major and minor issues. However I would like to know how can I mitigate and protect against such vulnerability warning: Secure Client-...
2
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0answers
96 views

A fledgling idea: Relational Encryption [closed]

I've been spending my spare time coming up with the basis for an encryption algorithm. I am completely unfamiliar with computer programming, but my time as a Network Technician left me incredibly ...
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5answers
957 views

Asymmetric encryption: Is it possible to share private key and hide public key?

I know that normally it's the public key to be shared and the private key to be kept secret (hence the names) in asymmetric encryption. I have a special case that I want to encrypt some files and let ...
1
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0answers
87 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 ...
3
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2answers
242 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 ...
2
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1answer
241 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
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1answer
119 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 ...
1
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2answers
118 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 ...
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1answer
243 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 ...
3
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2answers
234 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 ...
6
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2answers
666 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 ...
5
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2answers
83 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 ...
6
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2answers
301 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
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1answer
173 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 ...
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2answers
90 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 ...
3
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3answers
241 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 ...
2
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2answers
119 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
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1answer
70 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 ...
9
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1answer
331 views

Attacks on keys generated with low entropy

If I were to give someone a two 4096 bits keys, and say one was generated in a Linux OS with very very low entropy available, and one was generated in a Linux OS with more than enough entropy. Would ...
6
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2answers
396 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 ...
5
votes
1answer
236 views

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

I've heard that encryption 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 ...
1
vote
1answer
138 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 ...
3
votes
1answer
143 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 ...
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8answers
2k 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 ...
1
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1answer
61 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, ...
1
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1answer
120 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. ...
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4answers
1k 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 ...
2
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1answer
215 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 %...
12
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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
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1answer
35 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 ...
33
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2answers
2k views

How to start writing crypto software [closed]

This is just an academic question, I do not intend to write my own crypto software. Every time someone asks the question “How do I write my own Crypto?” the answer is don't. I'm currently studying ...
3
votes
1answer
107 views

What is the output length of CBC with zero input?

Given this formula for CBC encryption from 6.2 The Cipher Block Chaining Mode what is the output length of CBC if plaintext P is of length 0?
10
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2answers
282 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 ...
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1answer
340 views

Is RC2-CBC at all secure?

(And more generally, is there a site listing which various algorithms are still considered secure, so I wouldn't have to ask that here? Wikipedia's "known best attack" is not particularly clear.) I ...
9
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5answers
3k views

Is this RSA/AES combination good?

The team of developers I am part of is trying to develop a safe way to exchange sensitive data between a server and mobile devices. We have come up with the following algorithm: Device generates ...
2
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1answer
118 views

Is a Fernet token's timestamp a security risk?

A Fernet token has the following format: Version ‖ Timestamp ‖ IV ‖ Ciphertext ‖ HMAC As the above shows, the timestamp is not part of the ciphertext, so anyone can read the time the token was made....