[freenet-dev] Fast *and* secure Freenet: Secure bursting and long term requests was Re: Planned changes to keys and UI
or nothing and hope the redundancy is enough. 2) Establish alternate routes in advance. Use them but if they fail give up. 3) Reroute on demand, possibly after using pre-established alternate routes. We can specify behaviour in the bundle: FAST: Reroute on demand using limited broadcasts. SECURE: Establish multiple alternate routes in advance. Use them but if they fail give up (or wait for nodes to come back online). MIXED: Secure then fast. TRANSIENT: Do not establish alternate routes. Fail or wait when our original routes go down. The catch with backup routes is of course that they tend to be longer than the original data return route. It would be nice if we could avoid triggering the backup routes until we actually need them: In a popular splitfile for example, the redundancy in the returned data may allow us to reconstruct even if many of the pathways downstream fail. One way to implement this would be for A to wait a while before contacting C. However, C is committed to receiving the data, because there is no abort. If an alternative route to A is found, then C will have less reason to penalise B if (when!) it reconnects. Should there be an abort option? The problem is that being able to start a transfer and then abort it facilitates censorship attacks. Classically Freenet resists censorship because if you fetch a key and take out the node that returned it, the data will have been cached downstream. We should check fairly urgently whether the current code allows for aborting transfers all the way down, I think it did but I fixed it. Another interesting point with all this is it requires quite a lot of disk space - the maximum in-flight data for each peer. -- next part -- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 197 bytes Desc: This is a digitally signed message part. URL: <https://emu.freenetproject.org/pipermail/devl/attachments/20100624/23adbc10/attachment.pgp>
[freenet-dev] Fast *and* secure Freenet: Secure bursting and long term requests was Re: Planned changes to keys and UI
problem with this scheme: If you > get any nontrivial trust from announcing, you can announce, connect to nodes, > use that capacity to DoS them and then disconnect and talk to another node. > However, if everyone has fast links, it could return data very quickly on > opennet... > 10. If our capacity limits are low then we will have to send requests (or > inserts) for big files in a series of separate bundles. We warn the user that > we cannot guarantee full security, and get a confirmation. Unless seclevel = > LOW, in which case we just proceed anyway without asking. One interesting > point is that this allows us to quantify the loss of security on opennet, > although arguably that will just result in more people getting connections to > random strangers out of band, many of whom will turn out to be NSA... > > Of course there are security risks with bursting, in that if an attacker has > access to traffic analysis as well as nodes close to the originator, he may > be able to tie the two together. But the above is not limited to bursting: > The principle is we burst the routing phase and then return the data as fast > or as slow as possible. It is compatible with sneakernet, it is compatible > with CBR links. > > Ideas? Challenges? Suggestions for how to deal with opennet in this framework? > Another point: We should declare bundles explicitly. 1. Attackers can identify them anyway, by the timestamp being the same (or very close, but that might allow some window for progression for attackers), or by correlated keys (for requests). 2. We can then round-robin between them. So we send a bundle asking for a freesite, and we expect it to complete more quickly than the bundle we sent requesting a (gnu/hurd!) DVD ISO. 3. We can send the requests more efficiently, we don't need one message for each request, we can send a bulk transfer with all the keys, the first block or even a separate message specifies the HTL, etc. Okay it might be possible to compress requests anyway ... but it makes more sense if it's a bundle ... -- next part -- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 197 bytes Desc: This is a digitally signed message part. URL: <https://emu.freenetproject.org/pipermail/devl/attachments/20100624/8b3ae1fb/attachment.pgp>
[freenet-dev] Fast *and* secure Freenet: Secure bursting and long term requests was Re: Planned changes to keys and UI
problem with this scheme: If you > get any nontrivial trust from announcing, you can announce, connect to nodes, > use that capacity to DoS them and then disconnect and talk to another node. > However, if everyone has fast links, it could return data very quickly on > opennet... > 10. If our capacity limits are low then we will have to send requests (or > inserts) for big files in a series of separate bundles. We warn the user that > we cannot guarantee full security, and get a confirmation. Unless seclevel = > LOW, in which case we just proceed anyway without asking. One interesting > point is that this allows us to quantify the loss of security on opennet, > although arguably that will just result in more people getting connections to > random strangers out of band, many of whom will turn out to be NSA... > > Of course there are security risks with bursting, in that if an attacker has > access to traffic analysis as well as nodes close to the originator, he may > be able to tie the two together. But the above is not limited to bursting: > The principle is we burst the routing phase and then return the data as fast > or as slow as possible. It is compatible with sneakernet, it is compatible > with CBR links. > > Ideas? Challenges? Suggestions for how to deal with opennet in this framework? > One important security challenge is each time you request the same splitfile you are vulnerable. So either: 1) We route once, and reroute downstream. I.e. full passive requests. Which would combine very neatly with passive requests - when a peer comes online, check its bloom filters for anything that you or any of your pending requests want. However, this is a big step beyond the above, because it means freezing requests *that have not found a path to the data*. 2) We accept the security penalty and warn users before they enable poll-forever. And of course, it is yet another reason to improve persistence radically. We have several options for that: - Chase up why triple inserts are *drastically* better at long term persistence, and probably modify inserts to capture this behaviour at a lower security and performance cost. - Implement bloom filter sharing. - Client layer persistence improvements. -- next part -- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 197 bytes Desc: This is a digitally signed message part. URL: <https://emu.freenetproject.org/pipermail/devl/attachments/20100624/fb6a5a3a/attachment.pgp>
[freenet-dev] Fast *and* secure Freenet: Secure bursting and long term requests was Re: Planned changes to keys and UI
ity risks with bursting, in that if an attacker has access to traffic analysis as well as nodes close to the originator, he may be able to tie the two together. But the above is not limited to bursting: The principle is we burst the routing phase and then return the data as fast or as slow as possible. It is compatible with sneakernet, it is compatible with CBR links. Ideas? Challenges? Suggestions for how to deal with opennet in this framework? -- next part -- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 197 bytes Desc: This is a digitally signed message part. URL: <https://emu.freenetproject.org/pipermail/devl/attachments/20100624/0339c74a/attachment.pgp>
Re: [freenet-dev] Fast *and* secure Freenet: Secure bursting and long term requests was Re: Planned changes to keys and UI
On Thursday 24 June 2010 18:28:42 Matthew Toseland wrote: > On Thursday 24 June 2010 04:05:48 Evan Daniel wrote: > > On Wed, Jun 23, 2010 at 5:43 PM, Matthew Toseland > > wrote: > > > On Wednesday 23 June 2010 20:33:50 Sich wrote: > > >> Le 23/06/2010 21:01, Matthew Toseland a écrit : > > >> > Insert a random, safe key > > >> > This is much safer than the first option, but the key will be > > >> > different every time you or somebody else inserts the key. Use this if > > >> > you are the original source of some sensitive data. > > >> > > > >> > > > >> Very interesting for filesharing if we split the file. > > >> When some chunk are lost, you have only to reinsert those who are > > >> lost... But then we use much datastore... But it's more secure... > > >> Loosing datastore space is a big problem no ? > > > > > > If some people use the new key and some use the old then it's a problem. > > > If everyone uses one or the other it isn't. I guess this is another > > > reason to use par files etc (ugh). > > > > > > The next round of major changes (probably in 1255) will introduce > > > cross-segment redundancy which should improve the reliability of really > > > big files. > > > > > > Long term we may have selective reinsert support, but of course that > > > would be nearly as unsafe as reinserting the whole file to the same key > > > ... > > > > > > If you're building a reinsert-on-demand based filesharing system let me > > > know if you need any specific functionality... > > > > The obvious intermediate is to reinsert a small portion of a file. > > The normal case is (and will continue to be) that when a file becomes > > unretrievable, it's because one or more segments is only a couple > > blocks short of being retrievable. If you reinsert say 8 blocks out > > of each segment (1/32 of the file), you'll be reinserting on average 4 > > unretrievable blocks from each segment. That should be enough in a > > lot of cases. This is probably better than selective reinsert (the > > attacker doesn't get to choose which blocks you reinsert as easily), > > though it does mean reinserting more blocks (8 per segment when merely > > reinserting the correct 3 blocks might suffice). > > > > The simple defense against a mobile opennet attacker that has been > > proposed before would be particularly well suited to partial > > randomized reinserts. The insert comes with a time (randomized per > > block, to some time a bit before the reinsert started), and is only > > routed along connections that were established before that time, until > > it reaches some relatively low HTL (10?). This prevents the attacker > > from moving during the insert. On a large file that takes a long time > > to insert, this is problematic, because there aren't enough > > connections that are old enough to route along. For a partial > > reinsert, this is less of a concern, simply because it doesn't take as > > long. > > This is a very good point. What if we can improve on this further? > > By implementing long-term requests, we could have *all* the requests for a > splitfile go out *at once*, be routed immediately, and then return the data > over a long period. This means that: > 1) The data needs to be trickled back even if nodes go offline - either via > rerouting (but consider carefully how to make this safe, e.g. establishing > backup routes at the time, or using a node identifier for the next hop so we > can reroute via FOAFs without involving the originator so not giving a data > point away), or by waiting for the nodes to come back online. > 2) Load management needs to be able to deal with the fact that we have > thousands of requests in flight. This means it may not work on opennet, > because there is no underlying trust; although we could maybe have a > reputation system to build up some amount of trust. Trust can be translated > into capacity limits. > 3) The mobile attacker defence holds: If all the requests get routed inside a > few minutes, and then return data along fixed paths, the attacker has no > chance of moving towards the originator. And this works even for fairly big > files, without the overhead of tunnels, for requests and inserts of > predictable data. > 4) Overheads should be reasonable, because we can bundle a large number of > requests together efficiently. > 5) We get "burst" behaviour. If we have a fast connection, the data will be > returned fast. > 6) We get slow-return behaviour. In many cases it will take a long time for > the data to trickle back. At each hop it will make sense to send one key at a > time, if we happen to have multiple keys fully available. > 7) The node needs to be able to cope with a large number of requests pending: > We can keep the current code for routing them but once we have a route, the > requests as well as the transfers need to be threadless. > 8) We need to be able to specify that we want a fast response on a request > and that it should not get queu
Re: [freenet-dev] Fast *and* secure Freenet: Secure bursting and long term requests was Re: Planned changes to keys and UI
On Thursday 24 June 2010 18:28:42 Matthew Toseland wrote: > On Thursday 24 June 2010 04:05:48 Evan Daniel wrote: > > On Wed, Jun 23, 2010 at 5:43 PM, Matthew Toseland > > wrote: > > > On Wednesday 23 June 2010 20:33:50 Sich wrote: > > >> Le 23/06/2010 21:01, Matthew Toseland a écrit : > > >> > Insert a random, safe key > > >> > This is much safer than the first option, but the key will be > > >> > different every time you or somebody else inserts the key. Use this if > > >> > you are the original source of some sensitive data. > > >> > > > >> > > > >> Very interesting for filesharing if we split the file. > > >> When some chunk are lost, you have only to reinsert those who are > > >> lost... But then we use much datastore... But it's more secure... > > >> Loosing datastore space is a big problem no ? > > > > > > If some people use the new key and some use the old then it's a problem. > > > If everyone uses one or the other it isn't. I guess this is another > > > reason to use par files etc (ugh). > > > > > > The next round of major changes (probably in 1255) will introduce > > > cross-segment redundancy which should improve the reliability of really > > > big files. > > > > > > Long term we may have selective reinsert support, but of course that > > > would be nearly as unsafe as reinserting the whole file to the same key > > > ... > > > > > > If you're building a reinsert-on-demand based filesharing system let me > > > know if you need any specific functionality... > > > > The obvious intermediate is to reinsert a small portion of a file. > > The normal case is (and will continue to be) that when a file becomes > > unretrievable, it's because one or more segments is only a couple > > blocks short of being retrievable. If you reinsert say 8 blocks out > > of each segment (1/32 of the file), you'll be reinserting on average 4 > > unretrievable blocks from each segment. That should be enough in a > > lot of cases. This is probably better than selective reinsert (the > > attacker doesn't get to choose which blocks you reinsert as easily), > > though it does mean reinserting more blocks (8 per segment when merely > > reinserting the correct 3 blocks might suffice). > > > > The simple defense against a mobile opennet attacker that has been > > proposed before would be particularly well suited to partial > > randomized reinserts. The insert comes with a time (randomized per > > block, to some time a bit before the reinsert started), and is only > > routed along connections that were established before that time, until > > it reaches some relatively low HTL (10?). This prevents the attacker > > from moving during the insert. On a large file that takes a long time > > to insert, this is problematic, because there aren't enough > > connections that are old enough to route along. For a partial > > reinsert, this is less of a concern, simply because it doesn't take as > > long. > > This is a very good point. What if we can improve on this further? > > By implementing long-term requests, we could have *all* the requests for a > splitfile go out *at once*, be routed immediately, and then return the data > over a long period. This means that: > 1) The data needs to be trickled back even if nodes go offline - either via > rerouting (but consider carefully how to make this safe, e.g. establishing > backup routes at the time, or using a node identifier for the next hop so we > can reroute via FOAFs without involving the originator so not giving a data > point away), or by waiting for the nodes to come back online. > 2) Load management needs to be able to deal with the fact that we have > thousands of requests in flight. This means it may not work on opennet, > because there is no underlying trust; although we could maybe have a > reputation system to build up some amount of trust. Trust can be translated > into capacity limits. > 3) The mobile attacker defence holds: If all the requests get routed inside a > few minutes, and then return data along fixed paths, the attacker has no > chance of moving towards the originator. And this works even for fairly big > files, without the overhead of tunnels, for requests and inserts of > predictable data. > 4) Overheads should be reasonable, because we can bundle a large number of > requests together efficiently. > 5) We get "burst" behaviour. If we have a fast connection, the data will be > returned fast. > 6) We get slow-return behaviour. In many cases it will take a long time for > the data to trickle back. At each hop it will make sense to send one key at a > time, if we happen to have multiple keys fully available. > 7) The node needs to be able to cope with a large number of requests pending: > We can keep the current code for routing them but once we have a route, the > requests as well as the transfers need to be threadless. > 8) We need to be able to specify that we want a fast response on a request > and that it should not get queu
Re: [freenet-dev] Fast *and* secure Freenet: Secure bursting and long term requests was Re: Planned changes to keys and UI
On Thursday 24 June 2010 18:28:42 Matthew Toseland wrote: > On Thursday 24 June 2010 04:05:48 Evan Daniel wrote: > > On Wed, Jun 23, 2010 at 5:43 PM, Matthew Toseland > > wrote: > > > On Wednesday 23 June 2010 20:33:50 Sich wrote: > > >> Le 23/06/2010 21:01, Matthew Toseland a écrit : > > >> > Insert a random, safe key > > >> > This is much safer than the first option, but the key will be > > >> > different every time you or somebody else inserts the key. Use this if > > >> > you are the original source of some sensitive data. > > >> > > > >> > > > >> Very interesting for filesharing if we split the file. > > >> When some chunk are lost, you have only to reinsert those who are > > >> lost... But then we use much datastore... But it's more secure... > > >> Loosing datastore space is a big problem no ? > > > > > > If some people use the new key and some use the old then it's a problem. > > > If everyone uses one or the other it isn't. I guess this is another > > > reason to use par files etc (ugh). > > > > > > The next round of major changes (probably in 1255) will introduce > > > cross-segment redundancy which should improve the reliability of really > > > big files. > > > > > > Long term we may have selective reinsert support, but of course that > > > would be nearly as unsafe as reinserting the whole file to the same key > > > ... > > > > > > If you're building a reinsert-on-demand based filesharing system let me > > > know if you need any specific functionality... > > > > The obvious intermediate is to reinsert a small portion of a file. > > The normal case is (and will continue to be) that when a file becomes > > unretrievable, it's because one or more segments is only a couple > > blocks short of being retrievable. If you reinsert say 8 blocks out > > of each segment (1/32 of the file), you'll be reinserting on average 4 > > unretrievable blocks from each segment. That should be enough in a > > lot of cases. This is probably better than selective reinsert (the > > attacker doesn't get to choose which blocks you reinsert as easily), > > though it does mean reinserting more blocks (8 per segment when merely > > reinserting the correct 3 blocks might suffice). > > > > The simple defense against a mobile opennet attacker that has been > > proposed before would be particularly well suited to partial > > randomized reinserts. The insert comes with a time (randomized per > > block, to some time a bit before the reinsert started), and is only > > routed along connections that were established before that time, until > > it reaches some relatively low HTL (10?). This prevents the attacker > > from moving during the insert. On a large file that takes a long time > > to insert, this is problematic, because there aren't enough > > connections that are old enough to route along. For a partial > > reinsert, this is less of a concern, simply because it doesn't take as > > long. > > This is a very good point. What if we can improve on this further? > > By implementing long-term requests, we could have *all* the requests for a > splitfile go out *at once*, be routed immediately, and then return the data > over a long period. This means that: > 1) The data needs to be trickled back even if nodes go offline - either via > rerouting (but consider carefully how to make this safe, e.g. establishing > backup routes at the time, or using a node identifier for the next hop so we > can reroute via FOAFs without involving the originator so not giving a data > point away), or by waiting for the nodes to come back online. > 2) Load management needs to be able to deal with the fact that we have > thousands of requests in flight. This means it may not work on opennet, > because there is no underlying trust; although we could maybe have a > reputation system to build up some amount of trust. Trust can be translated > into capacity limits. > 3) The mobile attacker defence holds: If all the requests get routed inside a > few minutes, and then return data along fixed paths, the attacker has no > chance of moving towards the originator. And this works even for fairly big > files, without the overhead of tunnels, for requests and inserts of > predictable data. > 4) Overheads should be reasonable, because we can bundle a large number of > requests together efficiently. > 5) We get "burst" behaviour. If we have a fast connection, the data will be > returned fast. > 6) We get slow-return behaviour. In many cases it will take a long time for > the data to trickle back. At each hop it will make sense to send one key at a > time, if we happen to have multiple keys fully available. > 7) The node needs to be able to cope with a large number of requests pending: > We can keep the current code for routing them but once we have a route, the > requests as well as the transfers need to be threadless. > 8) We need to be able to specify that we want a fast response on a request > and that it should not get queu
[freenet-dev] Fast *and* secure Freenet: Secure bursting and long term requests was Re: Planned changes to keys and UI
On Thursday 24 June 2010 04:05:48 Evan Daniel wrote: > On Wed, Jun 23, 2010 at 5:43 PM, Matthew Toseland > wrote: > > On Wednesday 23 June 2010 20:33:50 Sich wrote: > >> Le 23/06/2010 21:01, Matthew Toseland a écrit : > >> > Insert a random, safe key > >> > This is much safer than the first option, but the key will be different > >> > every time you or somebody else inserts the key. Use this if you are the > >> > original source of some sensitive data. > >> > > >> > > >> Very interesting for filesharing if we split the file. > >> When some chunk are lost, you have only to reinsert those who are > >> lost... But then we use much datastore... But it's more secure... > >> Loosing datastore space is a big problem no ? > > > > If some people use the new key and some use the old then it's a problem. If > > everyone uses one or the other it isn't. I guess this is another reason to > > use par files etc (ugh). > > > > The next round of major changes (probably in 1255) will introduce > > cross-segment redundancy which should improve the reliability of really > > big files. > > > > Long term we may have selective reinsert support, but of course that would > > be nearly as unsafe as reinserting the whole file to the same key ... > > > > If you're building a reinsert-on-demand based filesharing system let me > > know if you need any specific functionality... > > The obvious intermediate is to reinsert a small portion of a file. > The normal case is (and will continue to be) that when a file becomes > unretrievable, it's because one or more segments is only a couple > blocks short of being retrievable. If you reinsert say 8 blocks out > of each segment (1/32 of the file), you'll be reinserting on average 4 > unretrievable blocks from each segment. That should be enough in a > lot of cases. This is probably better than selective reinsert (the > attacker doesn't get to choose which blocks you reinsert as easily), > though it does mean reinserting more blocks (8 per segment when merely > reinserting the correct 3 blocks might suffice). > > The simple defense against a mobile opennet attacker that has been > proposed before would be particularly well suited to partial > randomized reinserts. The insert comes with a time (randomized per > block, to some time a bit before the reinsert started), and is only > routed along connections that were established before that time, until > it reaches some relatively low HTL (10?). This prevents the attacker > from moving during the insert. On a large file that takes a long time > to insert, this is problematic, because there aren't enough > connections that are old enough to route along. For a partial > reinsert, this is less of a concern, simply because it doesn't take as > long. This is a very good point. What if we can improve on this further? By implementing long-term requests, we could have *all* the requests for a splitfile go out *at once*, be routed immediately, and then return the data over a long period. This means that: 1) The data needs to be trickled back even if nodes go offline - either via rerouting (but consider carefully how to make this safe, e.g. establishing backup routes at the time, or using a node identifier for the next hop so we can reroute via FOAFs without involving the originator so not giving a data point away), or by waiting for the nodes to come back online. 2) Load management needs to be able to deal with the fact that we have thousands of requests in flight. This means it may not work on opennet, because there is no underlying trust; although we could maybe have a reputation system to build up some amount of trust. Trust can be translated into capacity limits. 3) The mobile attacker defence holds: If all the requests get routed inside a few minutes, and then return data along fixed paths, the attacker has no chance of moving towards the originator. And this works even for fairly big files, without the overhead of tunnels, for requests and inserts of predictable data. 4) Overheads should be reasonable, because we can bundle a large number of requests together efficiently. 5) We get "burst" behaviour. If we have a fast connection, the data will be returned fast. 6) We get slow-return behaviour. In many cases it will take a long time for the data to trickle back. At each hop it will make sense to send one key at a time, if we happen to have multiple keys fully available. 7) The node needs to be able to cope with a large number of requests pending: We can keep the current code for routing them but once we have a route, the requests as well as the transfers need to be threadless. 8) We need to be able to specify that we want a fast response on a request and that it should not get queued and trickled through/around offline nodes. 9) We need a different way to handle timeouts. At the moment we detect when a node is busted by not getting the data within X period. If the node has a backlog of thousands of blocks then t
