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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6 views

Java Keystore best practice for large scale application

I'm new to JCE/cryptography in general but I'm working on demo where we are going to create a public/private key combination for each users of the site. All the examples I have seen so far stores ...
8
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3answers
1k views

Does the entire AES encrypted dataset have to be present to be 'cracked'?

I am implementing an AES 256 algorithm on credit cards and I am wondering if I would be strengthening or weakening the encrypted dataset if I split the dataset and persisted it in two locations. I ...
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0answers
27 views

KakaoTalk message encryption [on hold]

I am trying to write a tool to decode the KakaoTalk chat application and the messages are encrypted with this pretty bizarre looking base64 'Lx7ZczQJ/sdOAw8DdFcauw==', That might possibly be a base64 ...
7
votes
1answer
91 views
+50

What concrete parameters can I change to make my passphrase-protected private gpg key more secure

There are several questions which discuss the resistance of passphrase-protected private gpg keys against brute force attacks. It seems, this kind of discussion could go on forever. Rather than ...
39
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3answers
4k views

Is Git crowdsourcing cryptographic attacks?

A strong cryptographic hash makes collisions unlikely. Many cryptographic protocols build on that fact. But Git is using SHA-1 hashes as object identifiers. So there are a lot of already computed ...
0
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0answers
35 views

Suggestion of encrypt method for short fixed size result

I'm searching for a encrypt method that receives an int variable and outputs exactly 11 hexadecimal digits. I'm starting on a existing application, that already has a database of more than 130.000 ...
0
votes
1answer
54 views

Integrity-Based Execution

Intrusion Detection Systems (IDS) rely on binary signatures or known-bad-behavior of malware in order to detect threats. It has become very clear that this approach has limited success due to the fact ...
9
votes
4answers
4k views

Is Changing a File Type and Name an Effective Security Solution?

Is renaming folders & files and changing file types an effective solution for file security of a PC? I am an application programmer and have an extensive background in it. I have written a ...
1
vote
1answer
63 views

Calculating D-Wave's integer factorization capabilties

D-Wave has teased the ability to perform integer factorization previously, but if you jump to ~10:00 in this presentation they actually appear to outline how they can perform integer factorization ...
2
votes
2answers
65 views

Why is GPG encrypted message size not proportional to number of recipients & file size?

I have noticed that when I am using GnuPG to encrypt a file for multiple recipients, the size of the encrypted message does not seem to be directly proportional to the number of recipients. For ...
7
votes
1answer
472 views

Is there a method to get plain-text from cipher-text in HMAC SHA-1, given that the key is known?

This is technically not even an attack. We have all the resources at hand, except for the original plain-text. We have the cipher-text (to be converted back to plain-text), as well as the key. The ...
4
votes
2answers
295 views

Including and storing the order of character entry in a password as an enhanced security measure

I'm sure I will be quickly corrected if this is a stupid idea, or if it has already been tried. My question is: has this idea been tried before? If not, are there good reasons it would not work, or ...
1
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0answers
47 views

Public keys Quality

Is there any way to test the quality of generated keys from a public key cryptosystem? I've read about the common RSA attacks, but attacking the algorithm may not mean checking if the generated keys ...
2
votes
3answers
134 views

Are there any flaws in this two way cryptographic function?

I created a simple two way cryptographic function which allows you to encrypt a message and decrypt it with the same key. Here's how it works. Split the message into an array of 32-bit (or something ...
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votes
0answers
15 views

How to compare security parameters of different schemes (Sign-Encrypt, Encrypt-Sign, etc)? [migrated]

How can one compare the security parameters (confidentiality, integrity, non repudiation, etc.) for different schemes (Sign-Encrypt, Encrypt-Sign, Sign-Encrypt-Sign, Encrypt-Sign-Encrypt)? Are there ...
2
votes
2answers
81 views

how to find a cryptography scheme (either authentication or encryption) for which some formal analysis of security has not been done yet

I have a project in Cryptography where I have to discuss the provable security of any proposed scheme (encryption or authentication) which has not been discussed yet. Any pointers on how and where to ...
0
votes
3answers
177 views

How strong is a simple XOR encryption with random IV?

I'd like to implement some kind of simple (yet as strong as possible) encryption for my client-server application network traffic. Data to be encrypted can be both textual, and binary. Now I'm ...
0
votes
1answer
65 views

Can a botnet be used to effectively break encryption keys?

Can a botnet amass and coordinate enough computing power to break encryption keys that are typically considered to be secure (through brute force)? If this is the case, do we need to make our ...
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votes
1answer
43 views

Calculating the breakability of a given encryption method

I will soon be doing a very important project for school. The main goal of my project is to find a mathematical way to calculate the breakability of a given encryption method of ciphertext. Is there ...
1
vote
1answer
98 views

How are SHA1 and MD5 considered to not protect against collisions?

SHA1 and MD5 hash functions are considered to not protect against collisions while SHA2 is. Is it the size of the message digest that makes this or the algorithm itself? If it is based on the message ...
0
votes
1answer
55 views

Why do we encrypt ephemeral Public key in Encrypted Key Exchange

Encrypted Key Exchange can resist off-line dictionary attack Protocol : A ---> B : Ep (PK) B ---> A : Ep(Epk(K)) K is Session Key generated by B PK is an ephemeral public key ...
1
vote
1answer
87 views

How can you check if a private key and certificate match in OpenSSL with ECDSA?

I know how to do this with RSA keys (see this article: Determine if private key belongs to certificate?) however I do not know how to do this for ECDSA certificate / key pairs. With RSA keys, the ...
0
votes
1answer
138 views

AES 128bit decryption using a key longer than 16 bytes

I got a little problem regarding AES decryption. I have to decrypt some text that has been encrypted using 128bit AES / ECB with PHP mcrypt. The thing is, the key that is being used to encrypt/decrypt ...
0
votes
1answer
63 views

Does encrypting the message protect it against length extension attacks

Assuming the following HMAC is used : HMACK(M) = Hash(K||M) = H which is "secret-prefix" hashed function. M is the plaintext message , K is the secret key used The ciphertext is generated as follow : ...
2
votes
0answers
80 views

Which keys does a bank typically exchange with a card scheme?

I'm trying to understand the different EMV-related keys that are shared between a bank who issues EMV cards and a card scheme, such as Visa or MasterCard. I understand the bank would typically ...
1
vote
1answer
325 views

Minimal HTTPS SSL client in C [closed]

I want to implement an HTTPS client using pure C. I have implemented an HTTP client, and it works just fine. My question is: I know the HTTPS protocol does some kind of negotiation to announce what ...
2
votes
4answers
377 views

How to prove to friend I have solution to puzzle (without revealing it)? [closed]

My friend Paul set me this arithmetic puzzle: To make 21 from the numbers 1, 5, 6, 7. You can use the operations add, subtract, multiply, divide as well as brackets. You must use each number once. ...
3
votes
2answers
240 views

Continued Use of Kerberos

I posted this question over on Crypto.SE, but didn't get any takers and thought it might be more suited for this site as it were, so I'm cross posting it here. I was recently looking through the Mac ...
1
vote
1answer
60 views

Multi hash security [duplicate]

Is md5(sha1(pass)) more secure than md5(pass)? For example in case of sqli when attacker cant get our hashing schema, brute force or dictionary attack would be much less efficient. Am i right or is it ...
1
vote
2answers
101 views

POODLE and REST APIs

Are non-browser applications which do not contain an embedded browser, and merely make REST API calls over HTTPS, vulnerable to POODLE? And if not, is it unnecessary to disable SSL in such ...
0
votes
4answers
190 views

How safe is it to use older/unknown Encryption methods for plaintext?

When mailing or chatting with people, it had crossed my mind, what if, for simple communication, someone would use an older encryption method (i.e., ENIGMA), to encrypt their message? Would because ...
0
votes
1answer
109 views

Why is not safe to use the same public key in RSA?

In the RSA context, why is not safe to use the same n (public key)for different people?
0
votes
2answers
35 views

encryption using two keys

The use case is analogous to accessing a safe box in a bank. There is a per-user key, unique for each user, either generated by the system or hashed from the user's password. And there is a ...
2
votes
2answers
83 views

Encrypted container on top of a copy-on-write filesystem

The way I understand it, when you write to a copy-on-write filesystem, data never gets overwritten in place, instead new data is written to a new location, and the old data will only be overwritten ...
3
votes
1answer
84 views

Encryption and HMAC with the same password

I need to send authenticated ciphered messages by using a single password. Reusing the same (derived) key for the block cipher and the HMAC is not a good practice, I know. My initial idea is to ...
0
votes
1answer
107 views

Is (WEP) shared key authentication secure?

I've been reading up on wireless authentication and shared key authentication sounds completely bonkers. I know WEP is very insecure and breaking it with aircrack-ng takes 5-15 minutes but this sounds ...
0
votes
0answers
19 views

Infer encoding mechanism from n-grams distance

I have a series of obfuscated strings which across the set of strings have regions of high variance and regions of low variance (implying some encoding mechanism as opposed to an encryption procedure ...
18
votes
3answers
1k views

What is the difference between “key length” and “bit strength”?

On occasion, I hear the terms "key length" and "bit strength" used interchangeably. Are these the same things? Or are they different?
1
vote
2answers
66 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 ...
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votes
1answer
46 views

Permutation based file secure

I have a thought. 1. Take a file. 2. Read number of bytes. If its less than 2048, padd it till 2048 3. Read each byte. And create a single file which contains the particular byte. Give a random name ...
0
votes
1answer
86 views

How negative are virtual machines (vms) to /dev/urandom?

I looked at the questions here and here. This then piqued my interest as I've recently been involved with looking into FIPS compliance, and in my vm environment /dev/urandom compliance testing ...
7
votes
1answer
54 views

Unlock codes for a mobile app

This is for an Android (via Cordova/Phonegap) game project. My goal is to be able to provide a "promo code" that will allow anyone to unlock the game for free, but I want to limit each code to only ...
1
vote
1answer
85 views

Hardware Implementation of Encryption Algorithm

In the abstract of the AES-GCM RFC, the following passage is prominently included: [AES-GCM] can be efficiently implemented in hardware for speeds of 10 gigabits per second and above... Is the ...
8
votes
4answers
744 views

Why the symmetric key is added to the message?

Yesterday in my class we learnt how to send a message from Alice to Bob with the achieved goals of confidentiality, integrity and authenticity. In order to have a better performance we use a hybrid ...
5
votes
2answers
634 views

Authentication: Username (email) and password hashed together in one database field

I am currently developping a platform with a PHP framework for our client. The head of the client's IT department wants us to handle authentication with one database field containing ...
4
votes
2answers
156 views

Encrypt with private and decrypt with public

Above picture is captured from iOS Security overview at page 25. The path encrypt with public and decrypt with private makes sense. But the other path, encrypt with private and decrypt with public ...
2
votes
2answers
98 views

Difference between Second Pre-image Resistance and Collision Resistance in Cryptographic Hash Functions

I am studying the subject from these notes. However it is not clear what is the difference between "Second Pre-image Resistance" and "Collision Resistance" properties of Cryptographic Hash Functions. ...
29
votes
2answers
3k views

What actually happens in “low voltage fault attacks”

I understand they are an attack on crypto algorithms as implemented on various processors, but how do they work? The online papers are too complex for me to understand.
6
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1answer
407 views

Two takes on PHP two way encryption - which one is preferable?

I need to encrypt some data and have it decrypted on a later point in time. The data is tied to specific users. I've gathered two possible solutions... 1: The first one is derived from the official ...
1
vote
1answer
68 views

Can a known MD5 hash limit the search space for SHA1 collisions?

For a course in game theory, we are dealing with BitTorrent and alternative strategies (roughly alternative clients) we can employ to maximize our download speed. One strategy is to over-report the ...