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Yubico / python-yubihsm

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How to obtain 512 bits with PKCS1v15? #9

Closed evaristesome closed 3 years ago

evaristesome commented 4 years ago

I have been trying to hash and sign 512 bits using PKCS1v15, but the result is more than 512. RSA offers 2048, 3072, and 4096 bits key for PKCSv15. How may I play around to obtain 512 bits?

However, with the same program, hashing and signing for 512 using ECDSA works perfectly.

Can Yubico PKCS1v15 provide exactly 512 bit?

Thank you.

Eva

joernheissler commented 3 years ago

Hi evso9816, RSA signatures are as large as the RSA modulus. If you want a 512 bit signature, you need to use an RSA 512 key. According to https://developers.yubico.com/YubiHSM2/Concepts/Algorithms.html and your own comment, RSA 512 is not supported. So it's not possible. RSA 512 is insecure anyway, so there's no good reason to support it.

Your issue is a year old. Did you figure things out by now, can the ticket be resolved?

evaristesome commented 3 years ago

Yes, keep the case closed. I solved it. Thanks!

On Sat, Nov 21, 2020 at 2:42 AM Jörn Heissler notifications@github.com wrote:

Hi evso9816, RSA signatures are as large as the RSA modulus. If you want a 512 bit signature, you need to use an RSA 512 key. According to https://developers.yubico.com/YubiHSM2/Concepts/Algorithms.html and your own comment, RSA 512 is not supported. So it's not possible. RSA 512 is insecure anyway, so there's no good reason to support it.

Your issue is a year old. Did you figure things out by now, can the ticket be resolved?

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/Yubico/python-yubihsm/issues/9#issuecomment-731555067, or unsubscribe https://github.com/notifications/unsubscribe-auth/AISQHT73B4L6ADW64WQMTG3SQ6DQRANCNFSM4J5PACGQ .

nevun commented 3 years ago

thanks :+1: