# 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 with proper paddings.

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### Who first published the interest of more than two prime factors in RSA?

Multi-prime RSA is now a well known technique (described here): it uses $k>2$ distinct secret prime factors in the public RSA modulus, with the advantage that, using the CRT, we can gain a speed ...
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### Fewest qubits required for the discrete logarithm problem and integer factorization

According to a paper from 2002, the most efficient circuit to factor an $n$-bit integer requires $2n+3$ qubits and $O(n^{3}\lg(n))$ elementary quantum gates, assuming ideal qubits. Later on, according ...
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### 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 ...
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### RSA key such that pi deciphers to your name per RSA-OAEP

Can you efficiently construct an RSA public/private key pair with $8k$-bit public modulus such that $C=\left\lfloor\pi\,2^{8k-2}\right\rfloor$ deciphers per RSA-OAEP to your name as a bytestring in ...
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### RSA factorization with special primes

Suppose that primes for RSA modulus are generated using formula: $P_i(x,y) = \operatorname{next\_prime}(x^{z_i}+y^{z_i}) = x^{z_i}+y^{z_i}+d_i$ where $x,y$ are unknown random numbers with size 128 ...
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### 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 ...
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### Bleichenbacher RSA1024 signature forgery, closed-form solution

Hal Finney's writeup (Bleichenbacher's RSA signature forgery based on implementation error) shows a formula for RSA3072. I tried to replicate the attack for RSA1024 and failed, since the first term of ...
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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 ...
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### RSA like trapdoor permutations in Discrete logarithm

In RSA, given only $(n,e)$, where $n =pq$ and $e$ is the public exponent, it is hard to find $p$ and $q$. It also seems hard to find $d$. So we came up the RSA conjecture that is RSA defines a ...
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### Is there an efficient way to verify the union of two RSA accumulators?

More specifically, say we have one RSA accumulator $A_{S_1}$ accumulating set $S_1$ and another RSA accumulator $A_{S_2}$ accumulating set $S_2$. Does there exist a sublinear method to securely verify ...
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### Can RSA re-encrypt a message without decrypting it?

The goal of this question is to allow a server/proxy to forward an encrypted message without being able to read it with this procedure being transparent to the original sender and receiver. Assume we ...
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### Source of very large prime numbers

The RSA cryptosystem makes use of $n=pq$ where $p, q$ are large prime numbers. With quantum computing, factorization might become easier, so it will probably be useful to use much much bigger $p$, $q$ ...
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### Where is RSA-KEM used as of 2020?

RSA-KEM is introduced by Yuliang Zheng and Jennifer Seberry 1992, Practical Approaches to Attaining Security against Adaptively Chosen Ciphertext Attacks and compared the security against OAEP ...
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### Multi-users RSA problem

Rivest and Kalisky's RSA problem considers various notions on security of the RSA One-Way Trapdoor Permutation. They do it only from the perspective of a single user. What's the state of the art in ...
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### The security of blind RSA signatures with modular exponentiation as padding

It is known that (blind) RSA signature implementations should apply some sort of padding to messages before signing or blinding them. Does blind RSA signature with modular exponentiation as a padding ...
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### Why do one-way accumulators use rigid integers as the modulus?

In the paper that introduced one-way accumulators, the author's justify their use of rigid integers as the modulus with the following: The advantage of using a rigid integer $n = pq$ is that the ...
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### Content Key Encryption for Multi-User data access

I recently worked out a concept for a use-case, but I'm not sure if my approach is good enough. So I would appreciate feedback and things to look out for, as I'm fairly new to this field. A User can ...
Some papers count the number of the fixed points in the RSA encryption algorithm. They're a minimum of 9 and the real number depends on the smoothness of primes $p$ and $q$. It very unlikely that a ...
The classical One-Way Trapdoor Permutation is RSA. The permutation that it implements on a set of $n$ elements¹ is invertible by an adversary knowing only the public key with work $w$ conjecturally² ...