Window CryptoAPI: Can I choose the public exponent when generating an RSA key pair?

Question

Using the Windows CryptoAPI, is there any way to specify which public exponent to use when generating a new key-pair (ie. 3 instead of 65537)?

As a bonus question: how would I access this functionality using .NET RSACryptoServiceProvider?

EDIT: My guess is that the answer is "No", but I would like to get confirmation.

blowdart · Accepted Answer · 2009-11-18T14:10:52.837

3

No - there we go :) More seriously CryptGenKey The only parameters you can send to CryptGenKey are set in CryptSetKeyParam. You can see from the documentation you can only set a limited number of properties for each key type, and only one for RSA keys.

(Plus, as I'm sure you're aware, small exponents are dangerous anyway)

edited Nov 18 '09 at 14:10

answered Nov 18 '09 at 11:12

blowdart

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Prime? Generator? If you are talking about KP_G and KP_P, those are for DSA. – Rasmus Faber Nov 18 '09 at 13:52
Errr doh. Slows how asleep I am :) Still, the parameters structure still applies, it's the only way to effect key generation, and there's nothing there for RSA except for KP_OAEP_PARAMS – blowdart Nov 18 '09 at 14:10

score 1 · Answer 2 · answered Nov 20 '09 at 16:10

1

I think this answers your second question:

EncryptTo/DecryptTo: Encryption in .NET with CryptoAPI Certificate Stores

answered Nov 20 '09 at 16:10

Window CryptoAPI: Can I choose the public exponent when generating an RSA key pair?

2 Answers2