I have a ciphertext $c$ encrypted with RSA algorithm that needs to decrypt. I have the public key $(n,e)$.
Is it possible to decrypt with this amount of information?
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$\begingroup$ The public key of RSA is exactly $(n,e)$, so are you asking how to attack RSA? $\endgroup$ – xskxzr Sep 29 '18 at 15:45
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$\begingroup$ crypto.stanford.edu/~dabo/papers/RSA-survey.pdf $\endgroup$ – kelalaka Oct 7 '18 at 10:52
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$\begingroup$ members.tripod.com/irish_ronan/rsa/attacks.html $\endgroup$ – kelalaka Oct 7 '18 at 10:52
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$\begingroup$ Question is do you have single ciphertext or multiple encrypted under the same key. $\endgroup$ – kelalaka Oct 7 '18 at 10:54
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You have the public key. The whole point about public key cryptography is that the message is encrypted with the public key and must be decrypted with the private key, which you don't have.
The public key is not a secret: it is distributed publically so that people can encrypt messages for its owner. If you could decrypt the message knowing the cyphertext and the public key, RSA would be completely broken, because then anybody could decrypt any message. If anybody knows how to do this, they're keeping it a secret.
answered Oct 7 '18 at 15:52
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$\begingroup$ If he has more ciphertexts encrypted under the same key, there are some attacks. $\endgroup$ – kelalaka Oct 7 '18 at 15:54
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$\begingroup$ The question says "a ciphertext" not "some ciphertexts". $\endgroup$ – David Richerby Oct 7 '18 at 15:57
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$\begingroup$ Well, there was a similar question in crypto.StackExchange with 'a' and the accepted answer was based on multiple ciphertexts $\endgroup$ – kelalaka Oct 7 '18 at 18:15
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1$\begingroup$ @kelalaka OK, but I'm answering this question on Computer Science SE and I've chosen to answer the question that's been asked, rather than some other question that might have been asked instead. If you'd like to post an answer that deals with the case of having multiple cyphertexts, please go right ahead. $\endgroup$ – David Richerby Oct 7 '18 at 18:19
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1$\begingroup$ No, actually, I totally agree with you. I've already supplied the document links as comments at the beginning. thanks. $\endgroup$ – kelalaka Oct 7 '18 at 18:23
