Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [padding]

Padding has two primary uses in cryptography, ensuring messages are the proper length necessary for certain ciphers (e.g., block ciphers) or to provide assurances not built into the core cipher (e.g., semantic security)

8
votes
1answer
149 views

Adding parameters to sponge's capacity

Is it safe to XOR parameters like domain, length of the message or block counter into sponge's capacity or that gives attacker control over capacity? For example NORX XORs domain into capacity. Does ...
-1
votes
1answer
1k views

How to perform the padding oracle attack on AES CBC?

Assume I am the attacker. I want to break the plaintext by performing the padding oracle attack on AES CBC mode. I know the following information: ...
13
votes
0answers
215 views

Name of an archaic type of RSA padding (0BBBBBBB…)

In some legacy code, I encountered RSA signature padding in the following format (hexadecimal): 0B BB BB BB BB BB BB ... BB BB <hash> Is there a name for ...
10
votes
0answers
586 views

Are there attacks against broken RSA signature pad checking with $e = 65537$?

Let's say that an RSA implementation of PKCS #1 signatures fails to validate that the 00 01 FF FF FF ... FF 00 portion of the decrypted signature is exactly as long ...
3
votes
0answers
154 views

IND-CCA1 RSA padding?

I've found a way to complete a task which I'd solve with passwords or by sending keys over the wire (otherwise) by using RSA's homomorphic property. I'm restricted to RSA (any padding; for hardware ...
2
votes
0answers
37 views

OAEP Hash function truncation

I am using OAEP in a project and I want the resulting number of bits (n) to be 288 bits. Most of the implementations online seem to be for 1024 bits and using SHA-256 and I was wondering if truncating ...
2
votes
0answers
298 views

RSA signatures that allow hash to move around in block

I'm looking at a broken RSA signature padding implementation in a real device. It's a very-badly implemented version of PKCS #1-like encoding, but before PKCS added the DER-encoded hash identifier. ...
2
votes
0answers
119 views

Estonian e-voting, vote verification system

I believe I do understand basics of how Estonian e-voting system work, but I'm stuck at their vote verification system. In order to get the vote verified, client needs to encrypt all of the possible ...
2
votes
0answers
158 views

Security of right-zero padded signatures with $e=3$

I am facing this question about RSA signatures and I understand that a hash encode is secure, but I was asked this: Given the scheme based on RSA assumption. Consider the RSA function f with some ...
2
votes
0answers
607 views

TLS padding format

My question is about how the padding is formated in TLS1.0, 1.1, 1.2, 1.3 I came across the PKCS7 format for the padding: ...
2
votes
0answers
422 views

RSA encryption and signature padding flaw

This is Oxford's computer security exam question: Suppose that Bob has published an RSA encryption key $ke$ (retaining in secret the corresponding decryption key $kd$), and Alice has published a ...
1
vote
0answers
81 views

RSA low exponent with padded plain-text

Considering a case, when modulus is large and hard to factor, exponent e=3 and there is a cipher-text which is created by padding plain-text with ...
1
vote
0answers
54 views

Discrepancy in padding order between NORX specification and reference code

I have been working on implementing the NORX V3.0 authenticated encryption algorithm and I have run into a very confusing contradiction regarding the order in which padding and permutation are ...
1
vote
0answers
75 views

CCA attack on RSA padded with random oracle

I'm trying to do the ex 11.15 of the Katz-Lindell book. Consider the RSA-based encryption scheme in which a user encrypts a message $m ∈ $ {$0, 1$}$^l$ with respect to the public key $(N, e)$ by ...
1
vote
0answers
224 views

Textbook RSA Signature attacks (without message padding)

I have been reading as much as possible, but I haven't so far found anything exactly like what I'm looking for. I have a couple of questions (given what I know below): One, is it possible to find d? ...
1
vote
0answers
58 views

Security implications of plaintext-padding in an AEAD-scheme

Let's say I have a secure AEAD-scheme like ChaCha20/HMAC and my encrypted blobs need to match a fixed size: Is it OK to apply some padding to my plaintext to match the block-size? Can I use any ...
1
vote
0answers
55 views

When we use a PRF to pad a message, do we need to worry about the PRF's output range and/or probability of collision?

My question is related to: How to contruct a pseudorandom with a specific property Collision in pseudorandom function when two different keys are used Question: When we use a pseudorandom function ...
1
vote
0answers
138 views

How to produce a message digest?

I've been trying this problem: Use the prototype function to hash message bit string into a length 16 message digest. Append (at the right end) the shortest nonce to the string (the spaces are ...
1
vote
0answers
351 views

Padding in hash functions

What are the consequences, in terms of security, of using a padding rule at the beginning of the message? Instead of the end? For instance, in most hash functions, we are using the following padding ...
1
vote
0answers
106 views

Padding for blinded messages?

I have a message $m$ that I wish to send as a blinded message for approval (a signature) to then unbind and use as authority. Should I preform the procedure like so: pad $m$ using EMSA-PSS (...
1
vote
0answers
577 views

How to use OpenSSL command line utility to encrypt data with encrypted key from public key?

I may not be asking the right question. I am fairly new to data encryption. I am currently being sent encrypted data that's stored as follows: [ [keysize] [key encrypted with public key] [ivsize] [...
1
vote
0answers
83 views

Does not using padding mean a lack of security?

I've read several texts which say that if the entire plaintext is a multiple of the block-size padding is not required (and not using padding would not mean a loss of security). I generally disagree ...
0
votes
0answers
33 views

Mitigating leakage of asymmetric encryption scheme leaking the length of plaintext

Asymmetric encryption schemes do leak something about the encrypted plaintext: the length of the plaintext. How can this be mitigated? My solution: Padding the plaintext with some string of the ...
0
votes
0answers
164 views

Symmetric encryption with compression for MySQL DB data

I would like to compress data before encrypting and storing it in a MySQL DB to reduce especially bandwith requirements (compression reduces bandwith by 70-80%). At present, all is handled by a server-...
0
votes
0answers
160 views

NRPAD and FPAD padding schemes (Korean Seed?)

I've got an API spec that specifies NRPAD and FPAD as possible padding schemes. I see these being used together with the Korean SEED algorithm. The SEED specification however is void of any padding ...