Timeline for Using the same RSA keypair to sign and encrypt
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
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| Sep 3 at 14:40 | comment | added | Paul Crowley | RSA-OAEP and RSA-PSS are "proven safe" in the sense that there is a security reduction in the random oracle from breaking those schemes to breaking the RSA problem itself. If you don't know of a security reduction for using both schemes at once for the same key to the RSA problem, you should not say "it is safe, cryptographically speaking". | |
| May 17, 2019 at 18:12 | history | edited | Gilles 'SO- stop being evil' | CC BY-SA 4.0 |
explain how using the same key for encryption and signature exacerbates weaknesses
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| May 17, 2019 at 17:47 | comment | added | Gilles 'SO- stop being evil' | @arthurmilton Nobody has proved this because nobody has proved that either RSA signature or RSA encryption alone is safe. I'm not aware of a conditional proof assuming that both are safe separately, but they may well exist. PKCS#1 (the standard that codifies RSA) says that it's not recommended to use the same key for both and that doing that “may be [not is] essential to maintain provable security”, but doesn't forbid it and says that there aren't “any known bad interactions”. Which is a bit exaggerated given that using both can worsen attacks, which PKCS#1 does mention and my answer should. | |
| May 17, 2019 at 10:06 | comment | added | arthurmilton | You say: "it is safe, cryptographically speaking, to use the same RSA key pair for signature and encryption". Can you please point to where in the literature this has been proven? I don't believe it to be widely accepted: there may be no known attacks, but I do not believe your claim has been proven as true. | |
| Nov 25, 2016 at 0:01 | comment | added | DepressedDaniel | This is the right answer to this question! I hope it eventually makes it to the top vote-wise, lol. | |
| Dec 5, 2013 at 16:08 | history | answered | Gilles 'SO- stop being evil' | CC BY-SA 3.0 |