Re: [GENERAL] Postgresql + digital signature
Hi Marko, Actually I have it, However I was thinking the problem in a wrong way. In my particular case, the fact of the private key in memory is a good reason for discard the electronic signature, I mean, in order to have a real protection against the data modification I need a TSA (time stamping service) or something like that and my problem grow. Thanks a lot for your advice (and your time). They were really helpful. Best Regards, On Jan 23, 2008 1:59 PM, Marko Kreen <[EMAIL PROTECTED]> wrote: > On 1/23/08, Luis Alberto Pérez Paz <[EMAIL PROTECTED]> wrote: > > Very interesting point of view. > > Yes, you're right about the manage key problem. > > > > The grant database access looks like a real solution. > > Eh, for some reason I imagined you have have some good reason > why simple solutions are not enough... > > > Btw, if you try to simply rrestrict access to your data, one good > way for that is to make all data access and modification go via > SECURITY DEFINER functions, so that user have no access to > underlying data tables. > > This gives both more flexible access handling than simple GRANTs > can give you and also give ability to do smooth schema upgrades > without applications noticing. > > -- > marko > -- paz, amor y comprensión (1967-1994)
Re: [GENERAL] Postgresql + digital signature
On 1/23/08, Luis Alberto Pérez Paz <[EMAIL PROTECTED]> wrote: > Very interesting point of view. > Yes, you're right about the manage key problem. > > The grant database access looks like a real solution. Eh, for some reason I imagined you have have some good reason why simple solutions are not enough... Btw, if you try to simply rrestrict access to your data, one good way for that is to make all data access and modification go via SECURITY DEFINER functions, so that user have no access to underlying data tables. This gives both more flexible access handling than simple GRANTs can give you and also give ability to do smooth schema upgrades without applications noticing. -- marko ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
Re: [GENERAL] Postgresql + digital signature
Very interesting point of view. Yes, you're right about the manage key problem. The grant database access looks like a real solution. Thanks a lot for your advice. Best Regards, Luis Alberto Perez Paz On Jan 23, 2008 11:20 AM, David Wall <[EMAIL PROTECTED]> wrote: > > > We're in a stage where I need to implement a mechanism to prevent the > > data modification. > > > > I'm thinking on 'Digital Signatures' (maybe RSA) in each row. If > > there's a modification, the signature doesn't verify. > Like all such solutions, the key (lame pun intended) is how to do you > manage the keys? Obviously, when the digitally signed data is inserted, > the private key must be accessible. If you then do an update and also > have access to the keys, then new digitally signed data would be there. > > Is there no way for your application to ensure that once data is > inserted, it cannot be changed? > > You can also grant database access with just SELECT,INSERT permissions > so that an UPDATE and DELETE are not allowed. > > We store lots of digitally signed data as BLOBs in PG, but control this > at the application level since it's the one that has access to the > private key, and our application has no UPDATE/DELETE calls. > > Good luck, > David > > ---(end of broadcast)--- > TIP 4: Have you searched our list archives? > > http://archives.postgresql.org/ > -- paz, amor y comprensión (1967-1994)
Re: [GENERAL] Postgresql + digital signature
We're in a stage where I need to implement a mechanism to prevent the data modification. I'm thinking on 'Digital Signatures' (maybe RSA) in each row. If there's a modification, the signature doesn't verify. Like all such solutions, the key (lame pun intended) is how to do you manage the keys? Obviously, when the digitally signed data is inserted, the private key must be accessible. If you then do an update and also have access to the keys, then new digitally signed data would be there. Is there no way for your application to ensure that once data is inserted, it cannot be changed? You can also grant database access with just SELECT,INSERT permissions so that an UPDATE and DELETE are not allowed. We store lots of digitally signed data as BLOBs in PG, but control this at the application level since it's the one that has access to the private key, and our application has no UPDATE/DELETE calls. Good luck, David ---(end of broadcast)--- TIP 4: Have you searched our list archives? http://archives.postgresql.org/
Re: [GENERAL] Postgresql + digital signature
On 1/23/08, Luis Alberto Pérez Paz <[EMAIL PROTECTED]> wrote: > I'm working in a project which is using postgres (great database!, I love > it) > > We're in a stage where I need to implement a mechanism to prevent the data > modification. > > I'm thinking on 'Digital Signatures' (maybe RSA) in each row. If there's a > modification, the signature doesn't verify. > > > However before start I need your help to know: > > Is there in postgres something functionality like this? > Does any know if there's something similar another database system? There is hmac() in pgcrypto, basically digest() with key. It should be enough if you are ok with symmeric keys. For public keys there is also pgp_pub_encrypt/decrypt but not sign/verify. You emulate them with digest() + pub_encrypt, but that would be ugly, you are better off doing proper sign/verity in client. Another path would be to look for PLs that have module for sign+verify - I'd guess that both plpythonu and plperlu should have those. -- marko ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
