New
Stack Overflow Jobs powered by Indeed: A job site that puts thousands of tech jobs at your fingertips (U.S. only). Search jobs

# Tag Info

Accepted

### How does PKCS 1.5 solve the insecureness of Textbook RSA?

PKCS#1 v1.5 describes a method (formally known as RSAES-PKCS1-v1_5) that turns textbook RSA into a (heuristically) secure encryption scheme for small messages (PKCS#...
• 142k
Accepted

TL;DR: Padding is part of the specification of the mode and thus doesn't need to be done by the user of the primitive. Internally GCM really is CTR mode along with a polynomial hashing function ...
• 46.1k
Accepted

### How much safer is RSA-OAEP compared to RSA with PKCS#1 v1.5 padding?

RSA PKCS#1 is still secure if padding oracles do not apply. If padding oracles apply, for instance when a server verifies the padding after decryption and somehow leaks the result (through an error ...
• 92.9k

### How to encrypt the number one using RSA?

The algorithm you quote is usually called textbook RSA and is not used in practice for numerous security reasons (the problem you pointed out, is just one of them). In practice, you have to pad (or ...
• 2,528
Accepted

### The 9 lives of Bleichenbacher's CAT, it puts another scratch again

How does the new attack work at top level? In short They used BEAST-like Man in the Browser attack by using Cache-like attacks to perform a downgrade attack against any TLS connection to a ...
• 48.7k

### Random data CBC padding scheme?

Padding is dangerous. CBC mode with padding is secure against chosen-plaintext attacks, where the adversary can convince the legitimate party to encrypt messages and obtain the ciphertexts. But it is ...

### How does PKCS 1.5 solve the insecureness of Textbook RSA?

The Structure of PKCS#1 v1.5 as follows; The message $m$ is padded to x = 0x00 || 0x02 || r || 0x00 || m and the ciphertext calculated as $c=x^e\bmod N$ not ...
• 48.7k
Accepted

• 234

### Which attacks are possible against raw/textbook NTRU encryption?

I am a cryptographic researcher at Security Innovation, which acquired NTRU. Apart from the aforementioned attack, there are two significant attacks, namely a chosen plaintext attack (CPA) and a ...

### Which attacks are possible against raw/textbook NTRU encryption?

Without a well-designed padding system it may be possible to craft a ciphertext that the decryptor may or may not be able to decrypt properly. Whether the decryptor is able to do so will depend on the ...
• 148k
Accepted

### Why are hashes padded only at the end of the block?

Is it somehow connected with sequentially reading in files /data of unknown length? Yes, indeed. It is part of a requirement to perform online message processing, or, in other words, the ability to ...
• 92.9k
Accepted

When you use textbook RSA, the public key is $(e,N)$ and the ciphertext of a message $m$ is $c = m^e\bmod N$. The encryption process of textbook RSA involves no randomness; this causes the problem. It ...
• 4,178
Accepted

You are talking about the PKCS#7 padding. There is a simple reason; assume that when the last block is full and you don't apply the padding before encryption and then send the message. When ...
• 48.7k
Accepted

### Does EAX require padding to be secure?

The EAX mode of operation is defined for 128 bit block ciphers. It consists of a combination of CTR mode for confidentiality and OMAC for authentication and nonce derivation. CTR mode does not require ...
• 10.4k
Accepted

### Padding RSA with random number

The system proposed has no practical interest. If $r$ is public, then it is easy to check a guess $\overline m$ of $m$ (compute $\overline m'=\overline m+r$, feed it to the RSA function, and compare ...
• 142k
Accepted

### Security of RSA for padding $\texttt{0x00|message|random_bytes}$

Your message format is; $$\texttt{padded_message} =\texttt{|0x00|message|random_bytes|}$$ You did not specify what will happen if the message is short. If we assume that it is filled with zero then ...
• 48.7k
Accepted

• 142k