Linked Questions

47
votes
3answers
31k views

Definition of textbook RSA

What is the definition of textbook or "raw" RSA? What are some of the properties of textbook RSA? How does it differ from other schemes based on RSA?
16
votes
2answers
7k views

Is RSA encryption with a private key the same as signature generation?

It is often said that RSA encryption of a cryptographic hash with a private key is the same as signing (signature generation). And that verification consists of decryption using a public key. Is RSA ...
12
votes
3answers
2k views

Is RSA padding needed for single recipient, one-time, unique random message?

I want a way to encrypt files using this process: https://crypto.stackexchange.com/a/15 . That is: generate a random password, use that to AES-encrypt a file, and use an RSA public key to encrypt the ...
10
votes
1answer
356 views

Could this “symmetric RSA” scheme provide key compromise resistant communications?

This question, and fkraiem's answer to it, made me wonder about the security and practicality of using "symmetric RSA" to provide a partially compromise-resistant secure channel. Specifically, assume ...
7
votes
2answers
348 views

Which attacks are possible against raw/textbook NTRU encryption?

In the same fashion that these questions about attacks to textbook RSA and ECC, I was wondering what are the immediate drawbacks of applying NTRU Encryption directly, without any padding scheme, such ...
6
votes
1answer
4k views

ECDH or RSA more secure for symmetric key wrapping?

Suppose a message is encrypted with a symmetric block cipher with a random key. RSA is often used to wrap the symmetric key using the recipient's public key. In this case, the size of the message is ...
3
votes
2answers
1k views

Toy public/private key example open to frequency analysis?

I've been looking at an online Public Key Encryption Example (summarized below). It seems to me that choosing cyphertext = plaintext^(key) mod n would produce the ...
3
votes
3answers
219 views

Is RSA in decline across the board?

From what I gather from the internet (source), the recommended practice for 2019 and beyond is to avoid RSA and use ECDH and ECDSA. Is this the general case?
3
votes
1answer
2k views

Why is RSA-2048 max input 245 bytes?

I can see that the message (after padding) should not be 256 bytes because it might be bigger than the modulus of RSA. So I think that the message should be 255 bytes, but I saw posts that says the ...
3
votes
2answers
605 views

Real life systems that use concepts of crypto computing [closed]

Are there any working cloud/internet solutions/products that operates on encrypted data such as systems using homomorphic encryption, secure multiparty computation, electronic voting, private ...
3
votes
0answers
67 views

What type of attacks are practical for this situation?

Here is the details: I found a web api while pentesting for a company which I cannot disclose and while doing so I found a API which signs a request of the users choice, but it adds a tag to the top ...
2
votes
2answers
619 views

Can RSA signing be implemented on top of RSA encryption/decryption?

I need to use RSA-SHA256 signing. Unfortunately not all Microsoft CryptoAPI providers support that. It's possible that I might get a handle to a CryptoAPI provider that can just encrypt/decrypt with ...
2
votes
2answers
293 views

Privacy and Integrity in Public Cryptography

I'm trying to figure out which is the best way to get privacy and integrity together in public cryptography. Alice needs to send multiple files $f$ (may be big) to Bob. I've thought: Alice computes ...
2
votes
1answer
681 views

What use is the signature without the message under RSA?

Using RSA for signing & verification, is there a way to take a valid signature for an unknown message, and for someone else to generate a valid signature using a different key against the valid ...
1
vote
2answers
135 views

Distinguish between cipher-texts of text-book RSA and RSA/OAEP

Is there is a possibility to identify from cipher-text that, this is been encrypted using a text-book RSA or RSA with OAEP padding. (By looking at the cipher-text only) ?

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