AW: question about rsa encryption

[Kuehn, Ulrich]

> Von: Scott G. Kelly [mailto:scott at bstormnetworks.com]
> 
> Does anyone know of any issue 
> with using
> RSA encryption to encrypt a symmetric key under the target's 
> public key
> if the encrypted value is public (e.g. sent over a network)?
> 
You have to be very careful in designing and implementing your _de_cryption
routines. There have been some attacks when the decryption is not done
correctly. 

References are:
- Daniel Bleichbacher, Chosen Ciphertext Attacks Against Protocols Based on
the RSA Encryption Standard PKCS #1. CRYPTO 1998: 1-12. 
- James Manger, A Chosen Ciphertext Attack on RSA Optimal Asymmetric
Encryption Padding (OAEP) as Standardized in PKCS #1 v2.0. CRYPTO 2001:
230-238

These attacks are against PKCS#1 padding, and for the method you describe
(direct encryption of a symmetric key with zero padding) I had a paper at
this year's PKC conference describing some attacks.

I hope this helps,
Ulrich Kuehn

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