# All Questions

135 views

### XOR = Best encryption? [duplicate]

If you have a TRULY random key (in binary) and you have a text (in binary) that you want to encrypt. Can you simple XOR the key and the text? Is that secure? How secure?
92 views

### Definition of the term “key”

I've looked in many places (NIST, text books, online resources) and I cannot find an answer to the definition of the term "key" from a semantic point of view. Is it the "key" to cipher-texts (i.e. ...
120 views

### Turning data into seemingly random noise

I am currently working on a python script that does image steganography, altering the least significant bit on each channel of the image. Now imagine encrypting a file with a bunch of null bytes, or ...
323 views

### How to create a PEM file for storing an RSA key?

I have an RSA private key $\{d,n\}$ and a public key $\{e,n\}$, where $n$ is the modulus, and I also have the prime factors $p$ and $q$ of $n$. I want to create a PEM file containing this information,...
137 views

### Understanding Diffie-Hellman Key Exchange [closed]

Help me understand the Diffie-Hellman Key Exchange From what I understand: Agreed upon numbers: Both parties agree on the value of a large prime number $p$ and a generator $g$. The users each ...
539 views

### At what point can you you implement crypto algorithms?

First off, this feels like it should be a common question, so I'm sorry if I've missed an older thread. Note that in my question, I'm talking about "implementing AES" rather than "designing AES2" or ...
82 views

### If someone had a list of all primes, would it be possible for them to factor any integer in polynomial time? [duplicate]

For example, if they somehow got a function that would churn out any arbitrary amount of primes in a row. Could they break the RSA problem then?
59 views

### “Strict” software for playing and learning with private and public key

my question is just for teaching/learning practice and I think it's not meaningful for the real world. I've played with openssl a lot but from my understanding it's somehow not strict in the format ...
76 views

### Missing public exponent

Using LUC RSA, I have a list of 8 public keys $(R_1,n_1)$ through $(R_8,n_8)$, and a list of $8$ messages $M_1\dots M_8$. The messages have all been double encrypted. However, one of the public key ...
339 views

### Brute-force attack given small search-space and hash prefix

Suppose we have a value $secret which is a random 56-bit (7-byte) string. Suppose an adversary wishes to discover$secret. The ...
157 views

### Does the Paillier system remain secure if it is used to encrypt only binary values, i.e. {0, 1}?

Is there any security compromises if the Paillier system was used to encrypt only binary message in {0, 1}? i.e., plaintexts are either 0 or 1.
95 views

81 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 trasform a message in a curve point? To sign a transaction (message) in Bitcoin system, you need to encode ...
183 views

146 views

### What does signed fixed window method mean in ECC?

I am studying (sliding) window method in Elliptic Curve Cryptography (ECC) but I am confused by the term, signed fixed window method. By the way term is used in a research paper and not in the book ...
22k views

### How much would it cost in U.S. dollars to brute force a 256 bit key in a year?

I am often told that any key can be broken and that it is only a matter of time and resources for any key to be broken. I know that this it technically true. However, I think that there is probably a ...
2k views

### Is ECB mode safe to use with RSA encryption? [duplicate]

Firstly, bear with me, I'm relatively new to cryptography. In a recent static analysis scan of our application, one of the findings complained that we are using ECB: A mode of operation of a block ...
381 views

### How to verify a shared secret using only AES?

I have two devices that need to verify that they both are in possesion of the same secret key. One of the devices is a very limited embedded device that only has AES128 available, no SHA or other hash ...
232 views

### Are well designed crypographic codes unbreakable? (NOT ciphers)

Codes are not to be confused with ciphers. It is known that all known ciphers are theoretically breakable except the one-time pad and this isn't what the question is about. Some cryptographic codes ...
647 views

### PGP digital signature vs SHA256 HMAC Comparison

First let me admit that I am not a mathematician or a cryptographer. I am responsible for assisting in making a recommendation on a project that is consolidating payment processes within a company's ...
42 views

### trying to get calculator and RSA calculatin does not make sense [duplicate]

got two question, I am novice in the area of crypto and currently in big learning curve. From crypto book I am going over with, I see the RSA algorithm example as follows: it chose two rand #-s: p=...
132 views

### Format preserving encryption FFX

In FFX mode the format of the ciphertext is same as plaintext. How does it ensure data integrity and authentication? Is there any bit flip attack in FFX mode? Is it malleable?

15 30 50 per page