Linked Questions

27 votes
2 answers
20k views

Using the same RSA keypair to sign and encrypt

The RSA signature operation is basically the same as encrypting with the private key. In particular, both operations use the same kind of keys. Is it safe to use the same RSA keypair both for ...
user avatar
16 votes
2 answers
26k views

Using ECB as RSA encryption mode when encrypted messages are unique?

As I understand, ECB should not be used as encryption mode unless you are encrypting single blocks of data which are always unique and only are encrypted once. I have a collection of ids represented ...
user avatar
9 votes
2 answers
3k views

How does PKCS 1.5 solve the insecureness of Textbook RSA?

As we know, Textbook RSA is not enough safe to use because of the following issues; Guessable plaintext problem Small $e$ issue I want to know how PKCS 1.5 solved these problems.
user avatar
  • 93
7 votes
4 answers
2k views

Finding flaw in cryptographic protocol

If you find a flaw or bug for example in Linux kernel you can create an issue in GitHub, or if you can solve it you can contribute. How about Finding a flaw in cryptographic protocol?! How can you ...
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  • 1,854
4 votes
1 answer
9k views

What's the point of OAEP?

I can't seem to wrap my head around what benefit OAEP provides (specifically with RSA). Lets consider really small numbers for a moment. If the random source in the padding algorithm gave a random ...
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8 votes
2 answers
10k views

How to verify the integrity of RSA encrypted messages?

I need to encrypt messages using PublicKeyCrypto and send it to the server, where the message should be decrypted. I'm aware of the Padding Oracle Attack and want to apply a server side integrity ...
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3 votes
3 answers
4k views

How can a system be non-deterministic?

Newbie here, so forgive me if this is a stupid question. In math class we learned about RSA encryption (as a practical application of what we learned about the Euler phi function and Fermats little ...
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6 votes
1 answer
3k views

How can I securely encrypt the same message multiple times?

I want to encrypt the same message multiple times. I want to store the encrypted messages together. I've heard if you do this with RSA, an attacker could decrypt the message with the Chinese Remainder ...
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5 votes
1 answer
3k views

Do I need to use a MAC with asymmetric encryption?

The internet has drilled into me that when I delivery any symmetrically encrypted data, I should also deliver a MAC to authenticate it before any decryption occurs. Do I also need to do this if I use ...
user avatar
  • 153
14 votes
1 answer
4k views

Bleichenbacher 1998 "Million message attack" on RSA

I have been reading Bleichenbacher's 1998 paper on a forged message attack on RSA. The paper assumes access to an Oracle that takes a ciphertext $c$ and will check the decrypted text for valid PKCS #1 ...
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  • 563
3 votes
2 answers
1k views

Why is this a fix to Bleichenbacher's attack?

Looking at this excellent explaination of the attack, I have one additional question: It says that: ""To prevent this attack, SSL servers do not inform the client about padding woes. If decryption ...
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  • 33
5 votes
2 answers
1k views

Timing attacks against RSA, DH and AES

I have been reading about “Timing Attacks on RSA: Revealing Your Secrets through the Fourth Dimension” by Wing H. Wong. I was wondering if this attack is feasible while signing with RSA and, if yes, ...
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  • 51
3 votes
2 answers
328 views

Is this toy RSA demonstration flawed?

I want to present the basics of how RSA works to an audience of beginners in cryptography. The problem is that I am lightyears from being an expert. After reading about how RSA works in wikipedia, ...
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  • 141
1 vote
1 answer
3k views

Strength of RSA with OAEP

In our current system we use an encryption solution based on RSA with OAEP padding. Key size is optional but default 2048. What is the general strength of RSA with OAEP? Are there know attacks that ...
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  • 145
4 votes
1 answer
1k views

Is RSA vulnerable to the padding oracle attack?

I know that AES in combination with CBC mode is vulnerable against the Padding Oracle Attack. RSA also uses some kind of padding, hence can this attack be apply to RSA encrypted messages too?
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