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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Using 32 hexadecimal digits vs ASCII equivalent 16-character password

Assume I'm using a cryptographic algorithm to pseudo-randomly generate a string that is specified to be 16 characters long. The string will be used as a passphrase when encrypting a file. So, for ...
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1answer
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Size of bitwise OR between vectors represented as polynomials

I am using polynomials to represent bit vectors, such that the value of the d-th coefficient is $1$ if the d-th bit in the vector is $1$, and $0$ otherwise. For example, the vector $A = [1, 1, 0, 1, 0]...
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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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Steganography in speech by adding extra “filler” syllables [closed]

PREAMBLE About 20 years ago, when reading a novel (set in late 1800) by some classic Russian writer I came across very curious example of steganography. The two main characters were peasants who got ...
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1answer
319 views

RSA: Given $n$ and $\varphi(n)$, find $e$ such that $e=d$

Say we have chosen $n=pq$, with $p=89,q=97 \implies n=8633$ and $\varphi(n)=88\times96=8448$. Also, if we want the encoding ($e$) and decoding ($d$) exponents to be equal, we need $$(e,8448)=1 \: \: \...
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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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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
659 views

why does TTLV encoding in KMIP require padding?

I study the KMIP in OASIS standard, I need some help. Integers, Enumerations, and Intervals in KMIP length shall be padded with four bytes. the reason for padding in kmip is need to match the right ...
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1answer
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Why is garbled circuit a randomized encoding?

In Garbled Circuit, a circuit C is encoded to C' and input x is encoded to x' such that only C(x) can be computed given C' and x'. Randomized encoding of a function f is another randomized function f'...
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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
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How to decrypt a substitution cipher using a Base64 alphabet [duplicate]

Let us consider a cipher that works like the following: Plaintext is encoded to Base64. The characters in the encoded plaintext are substituted with a randomly shuffled character set (a-z, 0-9, A-Z, /...
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2answers
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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
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Convert plain text as numbers to encrypt using RSA

All mathematical description of encryption functions assume, despite the use of the word plaintext, that the message to be encrypted is a sequence of numbers. For example RSA with $n=pq$ assumes that ...
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1answer
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How to find the encoding of an RSA public key?

What practical methods is there to reconstruct an RSA public key in unknown format? As an illustration, in a database I find this (which doesn't look like ASN to me): ...
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1answer
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Encoding vs. Compression vs. Encryption

In what ways does encryption differ from proprietary/secret compression schemes and codecs?
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Can a Deterministic Signature Algorithm be paired with a Probabilistic Encoding Method?

I'm working with a C++ library and I’m currently investigating the changes needed to accommodate Deterministic DSA and ECDSA Signatures (RFC 6979). While the RFC 6979 changes are specific, I'm trying ...
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1answer
693 views

SHA-1 requires utf-8 and reordering of bytes

Today I implemented SHA-1 in JavaScript. While doing so I stumbled upon two requirements which are not mentioned in the RFC-3174. Text is supposed to be utf-8 encoded / one character should be 8 bit ...
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2answers
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Scalar product of vectors over polynomial rings

I have been studying about homomorphic encryption (HE) lately, and I am trying to perform simple computations over encrypted data. Specifically, I am interested in the scalar product between two ...
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Clarification on Size of an Encryption Key

Given a key with a certain key size (e.g., 64bits). Would I be correct to interpret this as 8 characters (since each character would be 8 bits under ASCII encoding)? Because the ASCII scheme is ...
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1answer
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What are I2OSP & OS2IP in RSA PKCS#1?

I started working with RSA two weeks ago. But I couldn't really understand how exactly I2OSP & OS2IP are working. I am using some open source for signature verification through RSA PSS algorithm. ...
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4answers
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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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1answer
908 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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4answers
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Is this an effective obfuscation technique?

Long ago I created a simple program which obfuscated a file by taking the first byte, then XORing it with the second, taking the (original) 2nd byte and X-ORing with the 3rd, etc, down the line. The ...
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What do the last chunks of the output string of Scrypt contain?

When you use scrypt to hash a string, it will generate something like: ...
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1answer
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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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Encryption-then-encode or encode-then-encryption?

I have this question in which I m struggling. I have read in many sites about encrypt-then-mac etc. If the confidentiality for transmission is needed, discuss the feature for the order of encryption ...
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1answer
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Numeric base conversion in cryptosystems?

I have been wondering if numeric base conversion has ever found an application in cryptography. By base conversion, an example that is probably familiar is Base64 encoding. This is an example of ...
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Do I need to worry about timing attacks in Base64 encoding/decoding of private keys?

Do I need to worry about timing attacks in Base64 encoding/decoding of private keys? This is a common operation (ex. PEM keys) and is variable time in typical implementations.
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1answer
226 views

Huffman coding is a prefix code, proof [closed]

How would you prove that Huffman coding $C$ is a prefix code, i.e $$\forall x,y \in C,\ \forall z \in \lbrace 0,1\rbrace^*,\ x\not=y||z$$ Using induction according to the number of items to code? ...
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1answer
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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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1answer
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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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853 views

Algorithms for Cyrillic encryption

I am working on a cryptography application which is to be used in my country. I tried looking up to see if there are any algorithms that support the Cyrillic alphabet, but I found none. Do you know of ...
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1answer
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Decoding base64 encoded message with a key

I am pentesting a database that where I found data which was base64 encoded. I tried the usual method of decoding base64, which didn't work. Later, I found in ...
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Would it be better to split a file and then encrypt, or vice versa?

Assuming that you are paranoid before storing your file (distributed across a shared location), which will be the best case scenario: splitting the file first and then encrypting or encrypting first ...
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Is there an existing cryptography algorithm / method that both encrypts AND compresses text?

So I'm trying to find a method of encryption that not only obfuscates text, but also compresses the result. For example, if I encrypted ninechars, the ideal result ...
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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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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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1answer
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How to determine the RSA Private key size from the Public.key file?

Question: How to determine the RSA Private key size from the Public.key file? Just roughly, how big it could be? ...
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1answer
76 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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2answers
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Is there a practical security difference between OTP with letters and OTP with numbers?

Is there a practical security difference between “OTP with letters” and “OTP with numbers”? If, for example, I encrypt a letter message using Tabula Recta with a random letter key, I would get: <...
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Are specially designed fonts sometimes used in cryptography?

As a font designer, I was thinking that it would be very easy to design a special font that could either jumble characters of a language (or of a code) or simply (with the features offered by the OTF ...
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1answer
620 views

Huffman encoding of hashes

I have a huge list of MD5 hashes, which takes up quite some space. I wonder whether I would achieve (some) compression by encoding the characters (which are A-F 0-9), with Huffman coding. I made a ...
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1answer
226 views

Encoding a message to a point of curve y^2=x^3+7 and Bitcoin Core

Where should I look at in Bitcoin Core source code to figure out how the signature process transform a message in a curve point? To sign a transaction (message) in the Bitcoin system, you need to ...
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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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1answer
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Koblitz encoding a message to a point, what is the “associated auxiliary base parameter”?

I am looking at the Koblitz method for encoding a message as an elliptic curve point. The first step given in the paper I'm reading is: "Choose an elliptic curve and its associated auxiliary base ...
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2answers
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Solving Quadratic equations in Galois Field (2^163)

Hello I am working on implementing a message to elliptic curve point mapping hardware circuit I have done some research and found out the koblitz mapping method: I will be using a field of binary ...
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1answer
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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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3answers
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How to perform frequency analysis of a substitution cipher using a Base64 alphabet

Let's imagine a cipher that works like the following: Plaintext is encoded to Base64. The characters in the encoded plaintext are substituted with a randomly shuffled character set(A-z, 0-9, -, _, =)....
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0answers
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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 ...
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1answer
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Can I remove newlines in a public key?

Can I remove new lines from the RSA public key file to get a one line string? So the question is if the key looks like this AAA BBB CCC or ...