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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45 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
101 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 ...
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) ...
2
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1answer
33 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
40 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
43 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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1answer
36 views

How to verify perfect secrecy of a cryptosystem? [on hold]

Playing with an encryption algorithm. how can i prove it's information-theoretically secure?
4
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1answer
270 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 ...
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 ...
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 ...
2
votes
1answer
60 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 ...
0
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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 ...
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 ...
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, ...
0
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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 ...
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 ...
1
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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
92 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 ...
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 ...
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 ...
1
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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, ...
1
vote
1answer
68 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. ...
8
votes
4answers
524 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
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 ...
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
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 ...
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votes
0answers
49 views

How to determine what type of hash algorithm is used [duplicate]

My friend gave me a hashed/ encrypted ciphertext and I want to determine which hash algorithm is used. 3_HA{_[Kg742ea6zy.CT30:b:SX@:T]vf{2A<Mk9ab:@oU[VCOA_B5BI.9CqZ3tl I don't think this is a ...
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 ...
2
votes
1answer
48 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?
6
votes
1answer
76 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
52 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 ...
8
votes
4answers
1k 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
48 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
70 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
149 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
41 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 ...
1
vote
0answers
21 views

bytes to be converted into PrivateKey Object [migrated]

I have a symmetric Key in my JKS (Java Key Store) file, I want to wrap my private key with a symmetric key. Again I am using wrappedBytes to PrivateKey Object. And finally I want the KeyPair Object. ...
35
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
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 ...
3
votes
2answers
48 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 ...
1
vote
1answer
75 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
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0answers
17 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
263 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
205 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
131 views

Encryption Laws in India

Is cryptography legal in India? If yes, then what type of encryption is not allowed?
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 ...
0
votes
1answer
33 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, ...