Implementing a cipher or protocol is the process of taking it from its mathematical or algorithmic description and producing a working version, often in computer software or hardware. This tag should be used for any question discussing the various potential considerations and pitfalls of this ...
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How to properly format a PGP Message Block?
As sort of a follow up to my (currently) unanswered question, if it is correct, how do i properly calculate and format the packet that actually stores the data being encrypted? I thought I knew what I ...
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8answers
460 views
Does a public key absolutely need to be used to initiate an encrypted session?
I am a software developer working on an application with the .NET platform. This application needs to provide a secure connection and encrypt all data between the client and the server. It is a ...
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2answers
730 views
How to perform file encryption using 128-Bit AES?
I am confused, how can I encrypt a file using 128 Bit Advanced Encryption Standard?
Do I need only to encrypt the file name and it's content or is there something that I need to do to encrypt it? Is ...
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3answers
201 views
Getting started [closed]
I'm looking for a good place to start in cryptography and places to go to get free books etc on the topic.
I have been looking online but I always get stuck at some point or another. I need something ...
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2answers
437 views
Why do all hash functions use big-endian data?
I've looked at several hash function specifications, and they all emphasize the need for big-endian byte ordering. Is there a reason for this that has to do with security, or is it simply convention?
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1answer
145 views
What does modular inversion mean?
I'm trying to implement an e-voting algorithm, which is described at the paper "Internet Voting Protocol Based on Improved Implicit Security" by Abhishek Parakh & Subhash Kak.
At the Example 1 ...
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2answers
108 views
What cipher mode is suitable for independantly decryptable short messages?
I'm building a small VoIP client which transmits encrypted audio data via UDP, and some packet loss is expected, so each packet will need to be decrypted separately even if others in the stream don't ...
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1answer
117 views
Why does .NET's ECB mode implementation append a constant block to my ciphertext?
Consider the following code and output:
...
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1answer
381 views
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3answers
310 views
Learnt cryptography and python. What do I do next? [closed]
OK, so I have spent the last 3 months learning cryptography through the Coursera-Stanford crypto course. I also learnt Python thoroughly.
Now I am eager to use this new-found knowledge. But neither ...
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1answer
88 views
Polynomial multiplication and division in 2^128
I want to multiply and divide polynomials, and implement the extended Euclidean
algorithm for polynomial greatest common divisors, over a Galois Field of size $2^{128}$. Moreover, I want to use the ...
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1answer
67 views
How to compare two datasets „anonymously”?
Ok, I hope this question makes some sense because I am not so sure how to word it any differently… Imagine the following situation:
There are 10 defined colors (blue, orange, yellow etc.)
There are ...
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2answers
247 views
Where i can find an AES implementation in python?
Where i can find a "reviewed" version of AES implementation in python. Not an API like PyCrypto whereby you can call AES algorithms in a single line.
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2answers
165 views
How do I demonstrate that a PRNG not designed for cryptography is not suitable for generating passwords?
This is a replication of this question on Stack Overflow. There's class Random in .NET runtime which is designed for use as a cheap fast source of pseudo-random ...
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1answer
118 views
synchronization of counters in HOTP
How is synchronization of counter values achieved in the HOTP protocol?
As I understand it, the server increments its counter value only if a match (of the OTP value) is found. What happens at ...
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2answers
135 views
Zero-Knowledge Challenge-Responce Protocol
Good day to everyone.
I am trying to implement an e voting system (just for reference -it is not important though-it is described at the Internet Voting Protocol Based on Improved Implicit Security ...
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1answer
57 views
What is the most secure way to let Alice “input” her private key, transfer it to the server and decrypt the message?
What is the most secure way to let Alice "input" her private key, transfer it to the server and decrypt the message? (Then destroy the private key on the server)
Every connection is using SSL.
...
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1answer
297 views
How can I implement the “Multiplication Modulo” and “Addition Modulo” operations in IDEA?
I am currently working on IDEA (International Data Encryption Algorithm), and I don't know how to perform Multiplication Modulo and Addition Modulo.
This is how IDEA operates:
IDEA operates on ...
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1answer
183 views
OpenPGP Public-Key Encrypted Session Key Packet Key ID generation
Im probably just not reading something again, but:
RFC 4880 says that a OpenPGP Public-Key Encrypted Session Key Packet (tag 1) is made up of
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0answers
150 views
Proper formatting of symmetric algorithm secret key
Given this description from RFC 4880 sec 5.1:
The value "m" in the above formulas is derived from the session key as
follows. First, the session key is prefixed with a one-octet algorithm
...
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0answers
92 views
Setting protocol parameters to achieve concrete security
Background
One issue with modern security proofs is that they are usually asymptotic. In other words, such proofs are usually formulated as follows: For any polynomial-time adversary $\mathcal A$, we ...
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0answers
77 views
Storing counter value of HOTP at client side [closed]
How can we store counter value on the client side in HOTP??
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2answers
212 views
Custom crypto library in C
I will be making (in the near future) an app that will contain some pretty heavy crypto. As it is possible that my app will be ported to different devices (initially it will be iOs only, but Mac, ...
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3answers
173 views
Implementing secret reconstruction in Shamir's Secret Sharing
I am trying to implement Shamir's secret sharing in C++.
I have got the generation of shares working.
However, I am very confused with the reconstruction of shares. I get the part on how three users ...
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3answers
74 views
MISTY1 Implementation error
I am trying to implement MISTY1. It's RFC, RFC2994, contains psuedocode that I basically copy and pasted into Code::Blocks. However, I managed to mess that up somehow. After 2 days, I still have not ...
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1answer
60 views
Encrypting a broadcast channel
We're building a data service that is expected to go out through a single "fat pipe" channel. The design requirement says that the data in the channel must be protected by authentication and ...
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1answer
80 views
Trapdoor implementation
Please refer to this secure index paper. On page#6, a trapdoor is defined as
...
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1answer
155 views
RSA 1024bit decryption performance
i want to know how many RSA 1024 bit long key decryption can a regular pentium4 computer do per second ? how to calculate RSA performance and determine its remaining time ?
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1answer
180 views
Why does my implementation of CBC mode only decrypt the first block correctly? [closed]
I have the following code that uses a CBC mode to encrypt a text by dividing it to 3-elements block. But it only works correctly on the first block which is xored with the IV.
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0answers
32 views
Security of .net AES implementation and security of a hash MAC
Hello I wanted to ask if there is any review about the security of the AES implementation of the .net Framework?
I found nothing concrete to that question, searching the Internet.
And, but this is a ...
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0answers
30 views
How to create a public-key certificate for RSA Web of trust?
How to create a public-key certificate for RSA Web of trust?
I have (for exemple) two public / private key pair (obviously).
They all need to sign each other certificate.
How to create the ...
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0answers
242 views
Matlab vs mathematica vs python [closed]
I just want to know that which is better for cryptography implementation ie in dealing with huge numbers.
-1
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1answer
182 views
Recommended Books for Cryptography : Theory and Implementation [closed]
It is a great idea if experts in Cryptography from mathematicians to security engineers introduce books and textbooks which they think is helpful or instructive for all people interested in the ...
