WebApp Sec mailing list archives
Re: Secret Sharing
From: Nir Izraeli <nirizr () gmail com>
Date: Sat, 03 Aug 2013 21:04:19 +0300
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 8/1/13 7:01 PM, Jamie Riden wrote:
The answer is, I can't think of a better way of doing it. I believe this is how EFS, etc. work - you have a single symmetric encryption key and you encrypt this with the public key of anyone who you want to be able to read the file.
+1. One note though: you should get the PK{A,B} directly from the client and not from the cloud service, if you want to avoid trusting the cloud. the way you described it lets the cloud service hand out it's own public key and then encrypt with B's PK afterwards.
But it's been a while since I read up on this, so I suggest you do a sanity check. cheers, Jamie On 1 August 2013 15:48, saghar estehghari <s.estehghari () gmail com> wrote:Hi, I'm working on a project which involves security of the cloud data. The scenario is as follows: Users A and B have registered to a cloud service (cloud assumed to be semi-trusted). A and B both have secret keys (KA and KB) (for symmetric encryption) and public keys (PKA and PKB) on the cloud server. KA and KB are each encrypted with the passwords of A and B. Now consider A wants to share a file F that is encrypted with key K (K is generate randomly by A). Now K should be shared securely with B over the cloud (we consider that B is not online at the time of sharing). To do this one option would be encrypting K with PKB which should be decrypted by B when he gets online. However this option seems to be complicated for my client. I was wondering whether you have better options in mind that could help me. Please let me know if the explantation is not clear. Thanks This list is sponsored by Cenzic -------------------------------------- Let Us Hack You. Before Hackers Do! It's Finally Here - The Cenzic Website HealthCheck. FREE. Request Yours Now! http://www.cenzic.com/2009HClaunch_Securityfocus --------------------------------------
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Current thread:
- Secret Sharing saghar estehghari (Aug 01)
- Re: Secret Sharing Jamie Riden (Aug 01)
- Re: Secret Sharing Nir Izraeli (Aug 04)
- Re: Secret Sharing Siim Põder (Aug 04)
- <Possible follow-ups>
- RE: Secret Sharing JAntonakos (Aug 04)
- Re: Secret Sharing Jamie Riden (Aug 01)