Encryption is the process of transforming plaintext using a cipher into ciphertext to make it unreadable to anyone except those possessing the key. Decryption is the process of transforming that ciphertext back into plaintext, using the key.

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Cryptographic key with editing safeguard [on hold]

I need to encrypt a number in a file, say 142345. It encrypts to EfsFjs or something else. I need a method that safeguards ...
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18 views

Determining an encryption key when ciphertext and algorithm are known

I would like to know how I can tell that I have successfully performed an exhaustive search attack on an encrypted message. Here are the conditions: key is 40 bit I am aware of the cipher text and ...
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13 views

Dynamic Password Making [on hold]

I want to make a dynamic password for my server, the password should changeable with different algorithms, for example: password can be attached with the minutes of the clock. Then password may be ...
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1answer
27 views

CPA on theoretical OTP with CBC mode

Body of question Note: this is THEORETICAL exercise. I understand OTP and CBC does not get along. I have to find a CPA on CBC enc-mode using OTP as the encryption algorithm, s.t a new key is ...
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0answers
25 views

Unknown Hash or Cipher [on hold]

I'm trying to identify what method was used to hash or encrypt a string of text, I have the plain text and the output, however, I have been unable to identify the method used to produce the output. ...
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0answers
32 views

improve of cryptography algorithm [on hold]

This is my algorithm.. ...
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4answers
157 views

To what extent is WhatsApp's statement on secure messaging realistic?

As those of you who use WhatsApp Messenger probably know, with their recent update chats and calls are now encrypted. Here's what WhatsApp claims: Messages you send to this chat and calls are now ...
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1answer
83 views

Is this cascading encryption, and is my security weakened as a result?

I'm trying to understand what is, and what is not, considered cascading encryption. All of the posts and conversations I've read over the past few days discourage the practice, including this article. ...
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0answers
11 views

Are there any free to use video and audio chat programs that offer end-to-end encryption that do not let the service know of the content? [migrated]

Skype is compromised, FaceTime is compromised, and I believe Ovoo is compromised. Does anyone know of any genuinely free (not free-to-try or in-app purchase-type applications) that offer end-to-end ...
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1answer
51 views

How secure is the OTR protocol?

I am using Adium and wondering how secure it is. I believe it uses AES-256 (I do not understand what that means) by default. It also requests that users exchange fingerprints with each other before ...
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0answers
59 views

Shamir secret sharing and homomorphism [on hold]

Problem: Implement Shamir’s (k, n) Secret Sharing (SSS) scheme, with $k = 3, n = 5$, to (a) Find shares of a given set of numbers. (b) Compute average from shares (c) Choose any ...
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0answers
46 views

How solid is this method of encryption? [on hold]

Let's say your message is "This is a message." Now translate it into numbers. a=1 b=2 c=3 so on and so forth. Now take those numbers and turn them into three digits based on a randomly generated ...
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13 views

Can someone please decrypt “NUZGIEJX” using Vigenére [on hold]

The key is "FUN". I just want to make sure I am doing it correctly.
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0answers
8 views

Deciphering and encrypting using Vigenére square for kids?

Is Vigenére cipher the most basic form of enrypting or is there another simpler way? I'd like to expose my niece to it.
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0answers
13 views

Autokey Cipher Question [on hold]

you receive the message DQIXFQETXPPZZR Given that the ciphertext has been encrypted using an Autokey cipher with key k in the range 16 to 18, decipher the meassage. Thanks,
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0answers
31 views

How to use OpenSSL command line utility to encrypt data with encrypted key from public key?

I may not be asking the right question. I am fairly new to data encryption. I am currently being sent encrypted data that's stored as follows: [ [keysize] [key encrypted with public key] [ivsize] ...
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1answer
43 views

Tackling encryption problems with “Zipf's law”?

I am new to cryptography and was wondering if it would be possible to semi-reliably "decrypt" an encrypted message by using the statistical distribution of symbols (/letters/numbers) in the encrypted ...
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0answers
24 views

MAC is constructed by hashing and then encrypting

Suppose the MAC is constructed by hashing and then encrypting, that is $MAC(m, k2)=E_{k2}(H(m))$ where H is a public hash function. There can be several alternatives in how the transmitted message is ...
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0answers
10 views

Using Openssl Libarary to convert .key encoded to .pem [migrated]

So i created a c program that takes in an encrypted (encrypted.key) file and a public key to decrypt the private encrypted encrypted.key. However, my program only works when taking in two files that ...
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0answers
59 views

What are applications of math in cryptology that can be explored by a high-school student? [closed]

I was interested in knowing applications that would be comprehensible to a high school senior with a strong mathematical background
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3answers
124 views

Searchable Encryption with Substring Search

I want to search substrings in encrypted string. To do that I have read “Implement Rabin-Karp Algorithm” and “Substring-Searchable Symmetric Encryption”. After that, I completed the Rabin-Karp ...
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1answer
77 views

RSA when n= 2360221 and encryption = 5 find decryption key d, when M =1234

when n= 2360221 and encryption = 5 find decryption key d,and Cipher text C when M =1234
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1answer
60 views

How to detect what crypto-method is used by Filecoder.Q?

I have 2 different images, one original, and one locked by a malware detected by eset as "Win32/Filecoder.Q". How to detect the encryption method that is used and the key, that is not using any ...
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0answers
28 views

How to vary bit length of prime numbers in RSA by using MATLAB? [closed]

Please Can any one Tell me how to vary bit length of prime numbers of RSA cryptography algorithm in MATLAB.When i am considering more then 16 bit length of prime numbers Its not working. So can any ...
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0answers
24 views

What is transaction capacity of a POS using 3DES DUKPT?

I am looking for the transaction capacity of a Point-Of-Sale device using 3DES DUKPT. Once all keys derived from the future key set are exhausted (1M or 500K?), how will the POS be reloaded with a new ...
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0answers
31 views

Encrypt file using pycrypto RSA from python [closed]

Basically I am writing a program that needs to have basic encryption for storing some program parameters in a config file. The program is run under linux debian. Since sudoers can modify the config ...
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33 views

Squaring and multiply function in encryption algorithm [closed]

Could any one explain the square and multiply function in AES, Elgamal or RSA algorithm.
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1answer
27 views

Steps to encrypt endorsements to a petition

I plan to circulate a petition, asking people to support it. This petition will reach a senior government official. In regular circumstances, people would support such petitions by writing their ...
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1answer
63 views

How secure is this logarithmic encryption algorithm?

How secure would the following logarithmic encryption algorithm be when tested under the same conditions as high end encryption algorithms (AES, RSA etc...). Note: For smaller text the text will be ...
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0answers
31 views

AES-CMAC in Java Card

Hello I am new to the world of Java card programming. Is there a proper way of doing an AES CMAC encryption? After researching I've hit a roadblock wherein I cannot find any example or samples of Java ...
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1answer
63 views

Analysis of DGHV Security

I want to know how security of DGHV can be breached using oracle and Binary GCD. As I study this paper : Fully Homomorphic Encryption over the Integers But I am not able to understand Section 4.1: ...
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10 views

ACM 2004 World Finals, problem D: how can I solve this using a brute force method? [migrated]

https://icpcarchive.ecs.baylor.edu/external/29/2996.pdf How can I solve this using a brute force method in Python? I want to use a nested for-loop for the parameters I'm just not sure where to go ...
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1answer
43 views

Key Hierarchy and key Encryption

If i have two 56-bit DES keys, and I use these two key to encrypt a 256-bit AES key. Like this $K_{AT}$ encrypts $K_{BT}$ and $K_{BT}$ encrypts $K$ What is the effective security of key $K$? Is it ...
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2answers
83 views

Verifying Without Knowing Key

Say user Bob sends an encrypted message to a server. People can download the message from this server and later get the key directly from Bob. Is it possible for the server to somehow verify that ...
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34 views

Which are similar encryption techniques as honey encryption?

I was reading about this technique called "Honey Encryption." Can someone suggest encryption techniques similar to honey encryption? To know more about honey encryption please refer the link ...
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0answers
45 views

Meaning of “random n/2 bit prime length prime p”

iam trying to solve a homework for the subject "system security" at university. For my question iam referring to this document: Solution to the Millionaire's Problem Could you please tell me why in ...
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1answer
44 views

Security of DGHV Encryption

In DGHV Security How to get reliable oracle for least significant bit and then uses binary GCD algorothm that uses reliable oracle to find secret key p.Also what is oracle. Is this a turing ...
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44 views

Format Preserving Encryption FF1 Samples

NIST published methods for Format-Preserving Encryption and there is a link in the document giving examples for FF1 methods. I am confused by the value of R given in the examples. $R$ is the output ...
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1answer
98 views

Time taken for a brute force attack on a key size of 64-bits

You can do $2^{30}$ encryptions per second and the key size is 64 bits. $2^{64}/2^{30}$ should give me the time taken for a brute force attack? What if you double the key size? How can I calculate ...
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29 views

WPA-PSK authentication without password [closed]

Suppose I have a service in which I allow users to share their WiFi connection. When sharing their connection, users provide their WPA PSK password to my service. Now if somebody wants to use this ...
0
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1answer
34 views

Calculating characters from the sum of ASCII pairs

I have a series of messages (limited to only a-z and A-Z) that are encoded such that the sum is taken of every two ASCII values and concatenated. For instance, the message ...
5
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1answer
196 views

How does Microsoft's BitLocker Recovery Code work?

I don't trust Microsoft BitLocker because it is closed source, which makes it so people can't audit it. But now I'm really interested in how its recovery code works. In my own knowledge, encrypted ...
14
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2answers
221 views

Is GCM still recommended?

I stumbled across a forum thread where a security researcher seemed to have negative feelings towards GCM. I had always thought from prior readings that GCM was the current gold standard for ...
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2answers
73 views

Brute force knowing a part of the password

So here is the problem, my brother forgot about the eight digit numeric part of his password, he is using Ubuntu 15.04 default whole disk encryption To make it clear, this was his password (example) ...
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1answer
98 views

Large Volumes of Asymmetric Encryption

First of all, I apologize in advance if I use any incorrect terminology. I am just getting my feet wet when it comes to cryptography and there is a lot to learn. For the past 12 months we have been ...
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8 views

How AES/GCM deals with data smaller than block size? [migrated]

I am using bouncy castle library for encryption and decryption in c# and I was wondering how to deal with plain text smaller than block size? here is what I have done so far: ...
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3answers
94 views

Will the contents of a password protected Zip 2.0 file be safe for a week

I will need to distribute a file to people for a challenge and I need them to open the file at the same time. The file will be provided a couple of days before the challenge. For maximum compatibility ...
0
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1answer
49 views

File using same key on XOR cipher. Using CBC [closed]

I have some files that are encrypted using an unknown key and it's using the CBC method to encrypt the files. When I XOR two files together the first two bytes are always the same, but different for ...
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0answers
22 views

Concatenated Key Question - Poly-alphabetic Substitution and Columnar Transposition

I am working on a degree module, and have been tasked with designing an Encryption/Decryption algorithm. I hope to receive some help with a couple of questions, if possible. Apologies if terminology ...
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1answer
36 views

RC6 Key Size Understanding

I need help to understand how RC6 works. Many sites show that the maximum key size of RC6 is 2040 bits (255 Bytes). I can also have 0..255 rounds and 4 times 32bits words in the 128bit block variant ...