# Tag Info

1 vote
Accepted

### Is it appropriate to prohibit an adversary from querying a specific input in an algorithm in some situation?

You can certainly define a security model that prohibits certain inputs. For example the adaptive chosen ciphertext attack model (e.g. IND-CCA2) only allows an adversary to submit inputs to the ...
• 18.3k

### Textbook RSA security for fully random message

Your description of the algorithm looks a lot like RSA-KEM, which is considered secure. However, note that the (b) argument of the security proof indicates that "the input is independent of the ...
• 89.2k
1 vote
Accepted

### Self-contained digital certification device

I believe that when you can hypothetically give the adversary a signature engine, even under the assumption that the engine is physically protected and the adversary could not access the internal keys ...
Accepted

### How does the public key cryptography algorithm generate a public key based on the private key?

The question gets some facts wrong about RSA; refer to PKCS#1 for a reference. 1, 5, 6, 7, 8, 9, 10, 12, 13 are show-stoppers. The answer to the question is in 11 and 12. The correct condition for $p$...
• 132k
1 vote

### How is asymmetric encryption possible if you need a passcode in order to encrypt something?

In asymmetric encryption, knowledge of the encryption key allows to encrypt, not to decrypt. That's even with full knowledge of the encryption and decryption algorithms†. Contrary to the question's ...
• 132k
Accepted

### How is asymmetric encryption possible if you need a passcode in order to encrypt something?

Cant you look at the algorithm used to encrypt and find the private key from the public key that way? Welcome to the wonderful (and nonintuitive) world of public key cryptography. In this world, we ...
• 139k

### How can you verify private key ownership using a public key and message signature?

The answer without lengthy mathematical formulas to the essential part of your question which is about reverse engineering a private key from a public key is presented here: A private key cannot be (...
• 1

### Understanding RLWE Encryption

These vectors represent the elements of $R_q$ given by $a,aX,\ldots aX^{n-1}$. Specifically if we write $a=a_1X^{n-1}+a_2X^{n-2}+\cdots a_{n-1}X+a_n$, where the $a_j$ are elements pf \$\mathbb Z/q\...
• 18.3k

### Can Quantum Computers crack RSA and AES?

In general in Internet cryptography there is a key establishment mechanism separate from a bulk encryption mechanism. Where Diffie-Hellman (including elliptic curve Diffie-Hellman) is used, it is as a ...
• 18.3k

### Can Quantum Computers crack RSA and AES?

It's almost public knowledge by now. Quantum Computing (QC) does break existing asymmetric-key algorithms - those based on integer factorization and discrete-logarithm such as RSA, DH, ECDSA, etc. ...
• 8,015