Questions tagged [encoding]

Encoding is the act of transforming information from one form to another. In cryptography, encoding is typically used to refer to an unkeyed process that does not provide any security in itself, but just changes the representation of information into a more convenient form.

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Can Reed Solomon parity blocks be used as an all-or-nothing transform?

Consider the following scheme: Perform an (N,N) Reed-Solomon encoding (i.e. N data blocks, N parity blocks) Drop the N data blocks and keep only the N parity blocks. Are these N parity blocks an all-...
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421 views

How to calculate secret key size of a CP-ABE scheme

How can I calculate the real size of key in a CP-ABE scheme. For example, I have this GSWV scheme: Fuchun Guo, Willy Susilo, Duncan Wong, Vijay Varadharajan: CP-ABE with constant-size keys for ...
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74 views

What are coding schemes for timing channels

I know we can hide information in the inter-packet delays, e.g. we can generate a code-book that each code-word corresponds to a message and is generated by realization of a specific random process. ...
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How to encode and decode 14-character codes with 20 specifically allowed characters as integers within the smallest range possible? [closed]

I am attempting to do phase space analysis on Coke Reward Codes that are 14 characters long and composed of only the following 20 characters: Letters: B F H J K L M N P R T V W X Numbers: 4 5 6 7 9 ...
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Constructing Low-Density Parity-Check Codes of length $n$ and minimum distance = $\delta n$ over $GF(q)$? [closed]

I am looking for a way to construct an LDPC (Low-Density Parity-Check) Code $C$ of length $n$ and minimum distance $d_C$ that scales linearly to $n$, meaning $d_C = \delta n$ for $\delta \in (0,1)$. ...
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Weird base64-like (?) encoding [closed]

I have some encoded strings which are probably encoded in a base64-variant - except that there aren't only 64 chars, but all the (printable) ASCII chars between 33 and 126 (0x21 to 0x7E). I've ...
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704 views

Is there specific name for simple XOR with ADD/SUB encoding?

Several years ago a group of malware authors began using code like this: for (j = 0; j < length; j++) ptr[j] = (ptr[j] ^ VALUEA) - VALUEB; for encoding, and ...
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How to securely map an element from an smaller domain to the other element in a large domain

Problem: I have a small sized domain, say s-bit. It's clear that the probability for an adversary to guess an element is $ \frac{1}{2^s}$. I need to make the probability negligible. However, I need to ...
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Is XORing a random stream of bytes a secure way to obscure a file?

Long ago I created a very simple program that used the C library's rand method to generate bytes to XOR with the bytes of a file. This was a reversible (just run it through again) method to make a ...
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What is the opposite of embed?

We often embed items from one space into another space, e.g. embedding plaintext items from $\{0, 1\}^m$ into some ring $R_q/\langle x^N + 1 \rangle$ for RingLWE. What is the inverse of this action ...
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Does encoding a secret affect security?

My question is simple. I have a secret that is generated with a 10 byte long pseudorandom generator library (e.g. Java's SecureRandom), that in theory provides a security equivalent to $2^{40}$ (...
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496 views

What kind of ECDSA signature encoding is this?

I am trying to generate an ECDSA signature using ARM's CryptoCell 310 (hardware cryptography module) and verify the signature using mbedTLS software library. The harware module documentation says ...
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understanding NTLM authentication

The flow is like this. Client sends GET to Server Server responds with 401 UNAUTHORIZED and the authentication protocol: NTLM Client re-sends the request including authentication information. I don'...
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128 views

Keys and mixed encoding - security implications

Let's say we generate a 256-bit key like: secret = base64(csprng(32)). Assume someone using the secret ascii-decodes the base64-encoded string and uses the output ...
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615 views

Is “6 bit packed ASCII” an effective encoding to obscure text data?

I wrote a routine for a former employer that took the low six bits of ASCII text and "compressed" by cramming the bits together, so that 4 bytes reduced to 3. This had the advantage of automatically ...
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271 views

How to encode a message to MD5?

I have faced a problem to understand MD5 algorithm.My question is weather the original input message is converted to binary value in MD5 before using the input message as parameter in four Feistel ...
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1answer
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How to solve encryption with ASCII output

There are lots of text files which have unknown data packets with ASCII output (no available plaintext exists with regard to any ciphertext, I have only encrypted outputs). The input data is known to ...
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1answer
794 views

Do RSA keys contain a checksum mechanism? [duplicate]

I'm new to cryptography, and I was making an experiment a few minutes ago, but I want to have some deeper knowledge about RSA public and private keys. I have a set of keys One begins with ...
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Compact encoding of an elliptic curve point

I'm working on a project with elliptic curve cryptography (ECC), I'm using the secp256k1 library (the one that's used in bitcoin). My goal is to create the most compact platform-independent ...
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finding encoding based collision

For example, If I enter as a sample "hello world" in English, then the hashing protocol by encoding the text to binary strings makes the hash. What if I find a word in other languages like Hindi or ...
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2answers
474 views

Is MD5 neither encryption nor encoding? [duplicate]

Article saying it used as hash function producing a 128-bit hash value. It can still be used as a checksum to verify data integrity, but only against unintentional corruption. So when it's neither ...
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1answer
863 views

Base64 for a hash algorithm [closed]

May be a silly question, but I am really curious. If a hash algorithm uses Base64 in the process of hashing a string for example, it is still considered a hash algorithm, even though it uses an ...
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1answer
153 views

Is it safe to encode an entropy this way?

I have been analyzing the source code of a software, and I came across this encoding snippet, I would like to know if it's safe to encode an entropy source this way. So the entropy source is a 132bit ...
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1answer
354 views

Reversing a Psuedo Crytographic Hash [closed]

I'm trying to get a better understanding of cryptographic hashing. Take the example transformation function below, is it possible to reverse this formula to solve/isolate for message[i]? ...
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1answer
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What type of data encoding could it be? [closed]

It's an answer to RPC call to program written in delphi. ...
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Are HTML entities considered a form of cryptography?

For example, I could use these html entities to encode purchase data, ...
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Would fragmenting data into several independent secured files would make a system Quantum-Resistant?

In 2018 IBM is making available the first quantum computers. This can be a disaster for most security systems based on computing power. Could this type of scheme bring a solution to this problem ? ...
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Is it worth using custom encoding on top of standard encryption?

I am using standard encryption AES/CBC. I wonder if I can invest some time adding my own custom encoding/decoding after the encryption just as an extra security layer. Does it really add any value ...