I am new to cryptography, i know essential part of asymmetric cryptography but is it possible to decrypt 617 decimal digits (2,048 bits) with RSA ? How it can be factored?

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    $\begingroup$ It's a bit of a pet peeve of mine, but asymmetric cryptography (and especially RSA) is almost never safe if used for encryption or decryption. It's used for signatures, cryptographic accumulators, and KEMs (key encapsulation modes), but direct encryption of messages with RSA is extremely error prone. So anything that has you thinking it's a good idea to decrypt (or encrypt) using RSA is probably wrong. $\endgroup$ Commented May 29, 2020 at 14:10
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    $\begingroup$ @SAIPeregrinus: actually, using a good padding method (e.g. OAEP), RSA can be used as a public key encryption method. $\endgroup$
    – poncho
    Commented May 29, 2020 at 15:32
  • $\begingroup$ Can be. But rarely is, since performance is terrible, and still tends to be difficult to get right. Thus all the hedging in my language. It's not a hard never do this, just a you should have very good reasons why this is needed. $\endgroup$ Commented May 30, 2020 at 15:30
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    $\begingroup$ Library support / compatibility are two good reasons, but let's not stray too far off topic guys. $\endgroup$
    – Maarten Bodewes
    Commented May 31, 2020 at 19:18

1 Answer 1


There is no known classical algorithm that can factor a 2048-bit modulus in feasible time.

Shor's algorithm could do it in feasible time but this algorithm needs to be run on a large-scale quantum computer and as of now there are too many obstacles to create a large-scale quantum computer.

  • $\begingroup$ and actually we almost believe that we are close to the lower bound $\endgroup$
    – kelalaka
    Commented May 29, 2020 at 16:03

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