Linked Questions

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ECDH, x25519 and limitations for securing client-certificates on the server

g'day Crypto.SE I'm working on a practical application of sharing a static key to better-identify a user, between the recipient (server) and the initiator (client ie. user's machine). My core ...
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83 views

Why can´t an attacker find the key if he has the plain text, the IV and the ciphertext? [duplicate]

I am reading a book about web security and they are now talking about AES CBC. After reading the chapter I was wondering, can an attacker compute my secret key if he has access to the IV, the plain ...
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1answer
711 views

Padding on RSA signature and RSA encryption

Why use a random padding on RSA encryption and not on RSA signature?
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161 views

Is there any theory to measures and determine the strength of an encryption protocol?

To determine the strength of an encryption protocol, there are elements like key size, Strength of an algorithm, Performance of an algorithm or etc, I have studied these topics but I could not find ...
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276 views

When do I need to use hybrid cryptography?

I need to provide confidentiality for a protocol. The protocol message size is between 100 bytes to 500 bytes. Do I need to use asymmetric encryption or hybrid cryptography?
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307 views

Proof that a modified public-key encryption scheme is not CCA secure

Let $\mathcal{E} = (G, E, D)$ be a CCA-secure public-key encryption scheme defined over $(\mathcal{M, C})$ where $\mathcal{C} := \{0, 1\}^\ell$. Let $\mathcal{E'} = (G, E', D')$ be a scheme (over $(\...
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149 views

algorithmic scheme to compare these two number encrypted using paillier cryptosystem

I have been going through https://eprint.iacr.org/2006/287.pdf (Conjunctive, Subset, and Range Queries on Encrypted Data by Dan boneh) I am trying to implement the paillier system to create a secure ...
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1answer
281 views

Use of OAEP in RSA Encryption

I am working on creating an RSA Algorithm and learned that OAEP is a padding scheme that is commonly used before encrypting using RSA. Is this step necessary? Will it harm the integrity/security of ...
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1answer
93 views

What is the advantage of a probabilistic PKC over a traditional PKC?

While reading through a textbook, I came across the idea of a probabilistic public key cryptosystem, which uses a probabilistic TM to generate the public encryption and private decryption algorithm; ...
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416 views

Message Expansion / Encryption Blowup Factor / Ciphertext Expansion of ECC

In order to complete the following table with asymptotic times and message expansions, $\quad \quad \quad \quad \quad \quad \quad \quad \quad$ RSA $\quad$ McEliece $\quad$ ECC Encryption Speed $\...
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1answer
153 views

Is this a good communication scheme?

I'm writing a wrapper for a chat program to allow for end-to-end encryption. I'm using Python and PyCrypto to accomplish this. I'd like to use a well known library to do this, but to my knowledge, ...
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67 views

Asymmetric encryption property required in an authentication protocol

We want to choose an asymmetric encryption scheme for use as follows: A device holds its private key, with the corresponding public key known and trusted by all. The device also holds a small $b$-bit ...
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360 views

What do you mean by Ciphertext indistinguishability [duplicate]

Wiki definition : A cryptosystem is considered secure in terms of indistinguishability if no adversary, given an encryption of a message randomly chosen from a two-element message space ...
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691 views

Understanding CPA and CCA Secure [duplicate]

CPA attack means the attacker can send in his own plaintext to the oracle and receives some sort of ciphertext back. CCA attack means the attacker can send in his own ciphertext to the oracle and ...
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117 views

Formal security-definition reference

Is there a reference where all common formal security-definitions are summarized (such as OW-CPA, IND-CPA, IND-CCA1, IND-CCA2, EUF-CMA and so on)? I need a PUBLISHED reference (paper, book) which ...

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