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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1answer
209 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
118 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
114 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
vote
1answer
134 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
votes
2answers
206 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
votes
2answers
589 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
votes
2answers
80 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
votes
2answers
253 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
1answer
140 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 ...
1
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2answers
88 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
votes
3answers
167 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
votes
2answers
100 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
68 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
votes
1answer
267 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
votes
2answers
357 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
125 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
140 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 ...
1
vote
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
vote
1answer
112 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. ...
7
votes
4answers
903 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
votes
1answer
174 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
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
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
votes
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
96 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
votes
2answers
261 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 ...
0
votes
1answer
244 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
votes
5answers
2k 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
votes
1answer
104 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 ...
3
votes
2answers
262 views

Is it possible to construct a specific AES collision?

Suppose I have a plaintext message P, and I encrypt it using key K to get ciphertext C. It's trivial to find a different plaintext message P' and a key K' so that the encryption results in C: just ...
4
votes
1answer
310 views

Can't get rid of “Your connection to website is encrypted with obsolete cryptography”

In my Nginx config I have: ssl_protocols TLSv1 TLSv1.1 TLSv1.2; ssl_ciphers ...
-3
votes
1answer
101 views

For which time-frame should we assume quantum computers? [closed]

It is generally known that we choose our key-lengths, so they are unbreakable in a specific time frame. For example we choose 112 bit keys (=2048-bit RSA) to protect data for the next few years and we ...
37
votes
2answers
4k views

How can it be easy to write but “impossible” to extract the private key from a crypto token?

A number of crypto-dongles make the claim that it is impossible to extract the stored private key once written. Yubico: The YubiKey AES Key information can never be extracted from a YubiKey ...
2
votes
2answers
128 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 ...
3
votes
2answers
107 views

Requirements Placed on a User of a FIPS 140-2 Validated System

Per customer requirements, I am working with a FIPS 140-2 validated network switch that is actually running in FIPS mode. This guarantees that any cryptographic operations the device performs will be ...
2
votes
1answer
965 views

Understanding Key Serial Numbers (KSN) in Derived Unique Key Per Transaction (DUKPT)

I have a number of questions regarding Key Serial Numbers (KSNs) in DUKPT: KSNs are 8 - 10 bytes long. Older implementation are 8 bytes whereas newer ones are 10 bytes. Do I risk being incompatible ...
1
vote
0answers
45 views

Blinding to mask private key operations

Blinding is often used to mask private key operations when the underlying problem is integer factorization. For example, its used in both RSA and Rabin-Williams signature schemes. This presumes ...
2
votes
2answers
2k views

Why is there a “des-ede3-cbc” in my rsa private key?

I have created an OpenSSL RSA private key and certificate request with 4096 bit with the following command: openssl req -newkey 4096 When I view the private key with openssl asn1parse -in privkey ...
4
votes
2answers
726 views

How do cryptographic algorithms help hackers to bypass Antivirus software?

I was wondering how do hackers use cryptography for bypassing antivirus software. I don't have some deep understanding on how antivirus software works, but I know that every antivirus has base of ...
0
votes
2answers
556 views

Encryption Laws in India

Is cryptography legal in India? If yes, then what type of encryption is not allowed?
1
vote
1answer
100 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 ...
1
vote
1answer
228 views

Getting multiple key matches on plaintext/ciphertext pairs in double DES

I'm trying to implement a Meet-in-the-Middle attack and just to test it out I've done some hardcoding of values, which is simply this block of simple code: byte[] key1 = new byte[] { 0x20, 0x00, ...
1
vote
1answer
196 views

CryptoAPI to CommonCrypto with RC4

I have cryptographic code used in the Windows platform, which uses the Crypto API functions and need to convert this to using Common Crypto on OS X. Essentially the original code is this, with error ...
0
votes
0answers
48 views

Is there an encryption scheme that allows an auditor to view some, not all data?

I want to create an online chat room allows for privacy, freedom of speech, and for law enforcement to protect citizens from violent behavior. I think the best approach is to use Shamir secret ...
7
votes
1answer
934 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 ...
3
votes
1answer
177 views

Can TPM “Storage Keys” be created outside the 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 ...
0
votes
0answers
112 views

Would it take long to brute force a md5 hash like this?

1be8917510-36.51929856278002 10bce1af27-99.18403192423284 103fa11cc6-87.21158325206488 Few examples above and as you can see the pattern is: 1xxxxxxxxx-{a percentage (0-100) to 14 decimal places} ...
1
vote
0answers
42 views

Checklist for Data Communication Review in ERP Solution

I am looking out for a checklist for data communication review within ERP application. I understand some of the checks would be related to digital signature, TLS/SSL use, Key Life Cycle management ...