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22 votes

What are advantages of chaos based image encryption methods over simply treating images as opaque bit strings?

Chaos-based encryption is at worst snake oil, at best of dubious use. The answers you linked to go into this in some detail. Modern encryption algorithms have a very high data rate and are efficient ...
kodlu's user avatar
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18 votes

What are advantages of chaos based image encryption methods over simply treating images as opaque bit strings?

What are advantages of chaos based image encryption methods over simply treating images as opaque bit strings? The principal advantage of the term "image encryption" is that when it is used ...
Image Encryptornator's user avatar
16 votes

Can I change the radio frequency according to my encryption algorithm?

More physical layer security than encryption. Spread spectrum wideband radio using frequency hopping does this. https://en.m.wikipedia.org/wiki/Frequency-hopping_spread_spectrum What is required is a ...
kodlu's user avatar
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14 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

Some facts for you to consider: Brutal-force a cryptographic key is much harder than brutal-force breaking into a house - the former can take as long as for a star to explode, while the latter take ...
DannyNiu's user avatar
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13 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

At least two reasons. 1: security. You want your algorithm to be a good one. One of the best ways we know of ensuring cryptographic algorithms are good is to have as many experts as possible assess ...
ignis volens's user avatar
9 votes

What is meant by software and hardware implementations of cryptograpic schemes? How to do it?

what is mean by software and hardware implementation? I want to know how its been done. Cryptographic Software implementation is coding the cryptographic schemes/algorithms with a programming ...
kelalaka's user avatar
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9 votes
Accepted

How can I understand the gap between CPA and CCA1?

As a general rule most counterexamples will be very contrived. If you don't mind that, it's actually not too hard to come up with a separating example. First consider what power we have in CCA1 that ...
Maeher's user avatar
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8 votes
Accepted

Is AES a group?

See the paper DES is not a group by Campbell and Wiener. TL;DR There are computational proofs that DES is not a group. The point is to carry out the types of computations that established DES is not a ...
kodlu's user avatar
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7 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

I think it most helpful to think of most cryptographic "algorithms" as being not algorithms directly, but rather algorithm factories, which use cryptographic keys as blueprints to produce ...
supercat's user avatar
  • 359
5 votes

Encrypt different inputs with different keys to obtain the same output

Is there a standardized way to achieve this? That's actually a fairly common request - here's the problem - there's no way to do it without making the ciphertext as long as the two plaintext messages ...
poncho's user avatar
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5 votes
Accepted

What is simple asymmetric encryption that use arbitrary key?

With the standard definition of public key encryption (or signature), it's not possible to make the public key arbitrary†. If it was, the method to find a matching private key from public key would ...
fgrieu's user avatar
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5 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

Because anyone can create a good secure key. Very few people can create create cryptographically secure encryption methods. Most likely, your 'secure encryption' is breakable, possibly by me, because ...
Questor's user avatar
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5 votes
Accepted

Is there any way to measure entropy of encryption algorithms in python?

Ciphers are deterministic. As such there is no such thing as "ciphertext entropy". Given a certain key, IV, and plaintext you should always get the same ciphertext. If neither of those ...
Maarten Bodewes's user avatar
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5 votes

Is it faster to decrypt than to encrypt in all cryptography systems?

In CBC and CFB modes, decryption can be parallelized, but encryption cannot. That's the most common reason for decryption being faster than encryption. But no, it is not faster to decrypt than to ...
fgrieu's user avatar
  • 142k
5 votes
Accepted

Can I change the radio frequency according to my encryption algorithm?

The answer to this is actually "yes", but it's generally not done due to encryption, it's done for the practicalities of RF. When you change frequencies, you often change the channel ...
b degnan's user avatar
  • 4,880
5 votes

Is it possible to create a mix of predefined and generated shares for Shamir's Secret Sharing?

This is certainly possible. Given a threshold of $k$, we can set $k-1$ shares to be arbitrary and then determine the remaining shares. This is a natural consequence of all possible secrets being ...
Daniel S's user avatar
  • 24.1k
5 votes

What are advantages of chaos based image encryption methods over simply treating images as opaque bit strings?

This is a compression problem, not a security problem. As other answers point out, it's not a different problem from redundant text, and modern crypto is secure even in that case. If file size is a ...
Peter Cordes's user avatar
4 votes

How do encrypted radios perform key exchange?

P25 AFAIK does not include a radio to radio key exchange protocol. Keys are loaded onto the radio by a key fill device or over the air rekeying which relies on a long term per device key protects the ...
Richard Thiessen's user avatar
4 votes

If I encrypt a plaintext with different keys for each block, will I have the same security as a one-time pad?

No, not necessarily. That depends heavily on the underlying algorithm (AES). Suppose that AES leaks information about one bit (of the input block) with negligible probability $\epsilon $. Then there ...
canary's user avatar
  • 124
4 votes
Accepted

Why the Modulus and Exponent of the public key and the private key are the same?

the Module and Exponent of the public key must be different from the Module and Exponent of the private key. Most commonly, public key is $(n,e)$, and private key is either $(n,d)$ or $(n,e,d,p,q,d_p,...
fgrieu's user avatar
  • 142k
4 votes

Is there still a place for obfuscation (secret algorithms) in encryption?

Since about 1883 when Kerckhoffs published his principles, there is no serious contest that the security of a cryptosystem should not require secrecy of it's design; that it should not be a problem if ...
fgrieu's user avatar
  • 142k
4 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

Brute force means trying possibilities until one works. If you use a single algorithm with a 128-bit key, there are $2^{128}$ possibilities for the attacker to test. If you choose between 16 different ...
benrg's user avatar
  • 776
4 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

The existing answers are good. Here's a way of looking at it that might fit your intuition better: I just read for a key length being around 128 bits of length results in 340,282,366,920,938,463,463,...
Ray Morris's user avatar
4 votes

Is this self algorithm made private key for Diffie-Hellman key exchange secure

Is this algorithm secure ? No, it is not. As kelalaka pointed out, the $a$ values you get are always less than 111 bits long; we know private exponents that small can be recovered. However, it's ...
poncho's user avatar
  • 148k
4 votes

What best to put in unused nonce bytes when using AES-GCM-SIV

In short yes, nonces just need to be unique. Just zeroing "leftover" bytes is fine if your protocol can guarantee uniqueness with fewer bytes. In protocols the zero bytes are often ...
Maarten Bodewes's user avatar
  • 93.2k
4 votes
Accepted

equivalence between entropic perfect secrecy and single probability

Yes it is. The conditional entropy $H(Y|X)$ is equal to $H(Y)$ if and only if $X$ and $Y$ are independent random variables. Hence $H(M|C)=H(M)$ implies that $M$ and $C$ are independent random ...
Daniel S's user avatar
  • 24.1k
4 votes

Confusion in the security level offered by KYBER

I think you are looking at the wrong metric. You need to look at the number of classical gates (second row from the bottom). NIST in https://csrc.nist.gov/CSRC/media/Projects/Post-Quantum-Cryptography/...
honzaik's user avatar
  • 452
4 votes

What is the purpose of making salted passwords public?

The difference is how the brute force attack scales: Without salt, the hacker can just hash the most likely passwords and then scan the whole database for the corresponding hashes. One succesful brute ...
rkw's user avatar
  • 41
4 votes
Accepted

Can the RSA public key be used for both encryption and decryption?

The standard convention in asymmetric cryptography (thus RSA), is that key generation generates a key pair comprising a public key and a private key, and unless otherwise stated the public key is ...
fgrieu's user avatar
  • 142k
4 votes

Why is the ciphertext output 32 bytes long when i encrypt a 16 bytes long plaintext by using AES-128-CBC

CBC mode requires A nonce ( it was stated as IV for CBC but it is nonce - number used once); so that we can have probabilistic encryption, i.e. even if we have the same plaintext and ciphertext we ...
kelalaka's user avatar
  • 49k

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