# Tagged Questions

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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### Is RSA with SHA1 broken?

I am using CryptSignMessage to sign a string/file. Is using RSASha1 insecure? I know Sha1 is broken as a hashing algorithm, but does that also mean that using it for signing with RSA is broken?
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### Find private exponent in RSA [duplicate]

The other answers for this confuse me, I know the principle of d in terms of the equation it has to satisfy. However I'm not sure how I would go about finding the private exponent without trial and ...
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### What is proper size of window Using RSA Window method?

I want to Use Window method for RSA modular Exponentiation. because of SCA. But I don`t know what is proper window size.
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### How do you work out the private key in a RSA cryptosystem knowing a certain public key?

The public key: n = 85 and e = 19 I know that n is the product of two prime numbers, now is it right of me to figure them out by process of elimination which I got p or q equals 17 and 5. Or is ...
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### How to decrypt an RSA ciphertext given an oracle providing the lower 8 bits of decryptions?

I have access to an oracle that can encrypt and partially decrypt a number with RSA-1024 algorithm. For encryption: $$C = M^e\bmod n$$ But for decryption, result will ...
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### CCA on PKCS#5 using error feedback

My question is about attacking PKCS#5 with CCA using the error feedback. What we learnt in class about PKCS#5: CBC requires padding to whole block boundary PKCS#5: standard padding If ...
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### Storing RSA private key

Currently I'm developing an application where users generate their own pair RSA keys in order to achieve a secure communication with my server. Also clients are able to communicate directly, sending ...
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### Cube-Root attack - RSA with low exponent

I have this RSA public key ...
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### How to decrypt RSA if ciphertext is less than the modulus and e=3?

I'm given a public key. Using openssl rsa ..... I got the public key has the exponent as 3. When I calculated the size of the ciphertext, it is 8 bits smaller than the 2048-bit modulus. How can I ...
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### Doubts about Authenticated Data Structures logic

I am studying the theory of authenticated data structure, like Merkle Tree and I have a doubt: why use them? I explain better: why to be sure, for example, that a cloud provider didn't modify my files ...
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### Random Coin Flip

Quoting an old question: Consider the following protocol for two parties A and B to flip a fair coin (more complicated versions of this might be used for Internet gambling): A trusted ...