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# Questions tagged [rsa]

an asymmetric (e.g. public-key) cryptosystem, based on modular exponentiation with big exponents and modulus. RSA can be used both for signature and encryption.

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### Chosen plaintext attack on textbook RSA decryption

Let $(n,d)$ be an RSA private key and $(n,e)$ the corresponding public key. Generate a secret random $r$ from $(\mathbb{Z}/n\mathbb{Z})^*$ Compute $C’ = C (r^e) \bmod n$ Submit $C’$ as a chosen ...
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### RSA PCKS1 v2.1 RSAES-OAEP algorithm

Using RSA public key (n,e) the encryption of a message is c= (m^e) mod n and the corresponding message is decrypted as ...
256 views

### RSA private exponent primality

I know that the public exponent is always a prime, but what about the private exponent? Is it always a prime too?
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### Can you recognize a low private exponent from a public key?

In the RSA cryptosystem, Wiener, Boneh and Durfee showed that low private exponents can be efficiently recovered. Is it possible to see from a public key alone whether the private exponent (d) is ...
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### How does OAEP improve the security of RSA?

The heart of OAEP algorithm used for RSA encryption are the cryptographic hash functions $H$ and $G$. Does everybody (so also an adversary) know these functions? If YES: How does it help the ...
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### What will happen if I use RSA encryption for plaintext larger than RSA bit size?

I have often read that using RSA for encrypting bigger size plaintext is not good solution. What I understand is that using RSA encrytion is best for small plaintext and most effective if it is ...
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### Does it make sense to have a 4000 bit long key?

My question is about the key length of a asymetric algorithm. How is it possible to memorize or remember a key that is about 4000 bits long?
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### Is this RSA signing and verification process secure?

I need to verify that messages in a communications program are from valid senders. Below is a highlevel outline of how I think the process would work. The connections themselves are done over TLS. The ...
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### Primality test in GPG/RSA or extract numbers of private key

I cannot find if the two numbers for RSA are tested against an elliptic curve primality test. If not, is there a way to extract the two integers of my private key in order to test it by myself? If ...
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### 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 ...
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### Picking 'e' for RSA encryption

What is the reason behind picking either $3$ or $2^{16}+1$ for generating the public key in RSA?
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### 1024 RSA Hash Signature attack. Forge a valid signature

I have an RSA signature of 1024 bit where i know the following: Public modulus N Public exponent (0x03) Cypher message Summary: An MD5 hash is calculated from a collection of byte and is used as ...
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### How to sign with RSA safely?

what should I do to make my RSA signatures secure? If "plaintext RSA" is not secure, is there some sort of "RSA on steroids" I am not aware of? Could anybody tell me what is it? I read a Wikipedia ...
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### In RSA, given $n=100$ and $e=13$ ,Encrypt and Decrypt the plain Text “SECRET”

Is this question valid as $n=100$ is not a product of two primes, but can be expressed as $100=2^2 5^2$, if valid is there any criteria for choosing $d$ and other values?
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### What's the best way to pad a message?

Currently my padding is adding a string of random characters $l(N)/3 - (l(M) + 1)$ Long and just adding it to the messages, is this sufficient? $l(x)$ = length of a variable
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### Certificate Authority RSA key expiration?

My understanding about SSL/TLS for HTTPS is that servers send their certificates to browsers and browser attempt to decrypt them using trusted CA public keys that are already presented in their store. ...