Re: [Bitcoin-development] Safe auto-updating
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Gregory Maxwell had some good ideas along these lines at the san jose conference. Extending gitian with these kinds of features would be a good approach. But I think its worth thinking about attack models. A huge danger with auto-updating is that it is easy to target individuals; if I leave auto-updates on I am essentially trusting the developers capable of signing an update not to specifically try to attack me in the future, a much more risky thing to do than simply trusting them not to release a malicious release. Sure you can try to implement anonymous downloads and similar mechanisms, but they all tend to be fragile with regard to deanonymization attacks. A better way is to ensure that the act of making a release available for download must be public, even if you can control what binaries are made available to a particular target. You can do this by putting a commitment in the blockchain itself. Each person on the signing list creates a transaction with a special form from a specific pubkey that commits to the digest of the binaries, and the auto-update code refuses to update unless it sees that special transaction with a sufficient number of confirmations. The developers now can't make a special release for a specific target without letting the world know they did so, even under coercion. They developers could of course still make a release with code inside targeting a specific individual, but in theory at least the public can check if their builds are reproducible, and start asking questions why not? Alan Reiner wrote: >Indeed. You can hardcode a "distributor" public key in the software, >and client software will only trust signed data from that key. Of >course, the private key for that data is not kept on the server >distributing the signed checksums. Ideally it would be kept offline, >and the couple-times-per-year that you actually execute an upgrade, you >sign the new checksums offline and upload the signed checksum to the >distribution server. Then even if the server is compromised, the >client-side software will not accept a bogus checksum because it won't >bear the right signature. > >If you do this, it would be good to also have some kind of revocation >process that can be used in the event of the offline key being >compromised. You won't be able to "switch" keys, as that would defeat >the purpose (the attacker who compromises the offline key could just >issue a replacement with his own). Instead, it would be an >irreversible >broadcast that would force clients to start rejecting updates from that >key. If the key is compromised (and find out), you broadcast the >revocation and the users will stop auto-updating, and be given a >warning >that they should manually upgrade the software through trusted >channels. It's not failproof, but it's a decent way to minimize damage >if you discover compromise early enough. > >-Alan > > > > > > >On 08/05/2013 11:54 AM, Daniel F wrote: >> If you want package authentication, you should at least throw in some >> digital signing, not just a checksum. With a compromised host, both >the >> checksum and binaries can be changed undetectably, but if there's a >> signature made by a key that is not kept on the host, there's no way >to >> fake a valid binary. >> >> There may be other issues people would want to bring up, but surely >just >> a checksum is not sufficient. >> >> on 08/05/2013 10:39 AM Wendell said the following: >>> For usability purposes, we at Hive would like to have an >>> auto-updater >> in our wallet app. >>> What is a safe way to do this? I understand that Bitcoin-QT lacks >>> such >> an updater for security reasons... Has been thought out in more >detail >> since that decision was made? >>> We have been toying around with the idea of placing one server >>> behind >> a Tor hidden service, whose only function is to output a checksum of >the >> update package. The theory is that if it is well-secured, it will at >> least be immune to tampering at the physical hosting level. >>> Any thoughts or advice about any of this? >>> -wendell >>> >>> grabhive.com | twitter.com/grabhive | gpg: 6C0C9411 >>> >>> >>> >>> >-- >>> Get your SQL database under version control now! >>> Version control is standard for application code, but databases >havent >>> caught up. So what steps can you take to put your SQL databases >under >>> version control? Why should you start doing it? Read more to find >out. >>> >http://pubads.g.doubleclick.net/gampad/clk?id=49501711&iu=/4140/ostg.clktrk >>> >>> >>> >>> ___ >>> Bitcoin-development mailing list >>> Bitcoin-development@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/bitcoin-development >>> >> >> >-- >> Get your SQL database under v
Re: [Bitcoin-development] Safe auto-updating
One approach you could use would be to use bitcoin signing on a list of the build artifacts together with their SHA256 hashes. If you have a look at the MultiBit release notes you get the overall idea: https://multibit.org/releases/multibit-0.5.13/release.txt Currently these aren't machine readable but you can imagine having a machine readable statement with: + a list of the files in the build + their SHA256 hashes + the above bitcoin signed by multiple signatures e.g. 2 of 3 The client can then download the file, check the signature, check the hashes and knows which files to download. The acceptable Bitcoin addresses for signatures would be a whitelist in the client code. On Mon, Aug 5, 2013, at 05:47 PM, Alan Reiner wrote: > Indeed. You can hardcode a "distributor" public key in the software, > and client software will only trust signed data from that key. Of > course, the private key for that data is not kept on the server > distributing the signed checksums. Ideally it would be kept offline, > and the couple-times-per-year that you actually execute an upgrade, you > sign the new checksums offline and upload the signed checksum to the > distribution server. Then even if the server is compromised, the > client-side software will not accept a bogus checksum because it won't > bear the right signature. > > If you do this, it would be good to also have some kind of revocation > process that can be used in the event of the offline key being > compromised. You won't be able to "switch" keys, as that would defeat > the purpose (the attacker who compromises the offline key could just > issue a replacement with his own). Instead, it would be an irreversible > broadcast that would force clients to start rejecting updates from that > key. If the key is compromised (and find out), you broadcast the > revocation and the users will stop auto-updating, and be given a warning > that they should manually upgrade the software through trusted > channels. It's not failproof, but it's a decent way to minimize damage > if you discover compromise early enough. > > -Alan > > > > > > > On 08/05/2013 11:54 AM, Daniel F wrote: > > If you want package authentication, you should at least throw in some > > digital signing, not just a checksum. With a compromised host, both the > > checksum and binaries can be changed undetectably, but if there's a > > signature made by a key that is not kept on the host, there's no way to > > fake a valid binary. > > > > There may be other issues people would want to bring up, but surely just > > a checksum is not sufficient. > > > > on 08/05/2013 10:39 AM Wendell said the following: > >> For usability purposes, we at Hive would like to have an > >> auto-updater > > in our wallet app. > >> What is a safe way to do this? I understand that Bitcoin-QT lacks > >> such > > an updater for security reasons... Has been thought out in more detail > > since that decision was made? > >> We have been toying around with the idea of placing one server > >> behind > > a Tor hidden service, whose only function is to output a checksum of the > > update package. The theory is that if it is well-secured, it will at > > least be immune to tampering at the physical hosting level. > >> Any thoughts or advice about any of this? > >> -wendell > >> > >> grabhive.com | twitter.com/grabhive | gpg: 6C0C9411 > >> > >> > >> > >> -- > >> Get your SQL database under version control now! > >> Version control is standard for application code, but databases havent > >> caught up. So what steps can you take to put your SQL databases under > >> version control? Why should you start doing it? Read more to find out. > >> http://pubads.g.doubleclick.net/gampad/clk?id=49501711&iu=/4140/ostg.clktrk > >> > >> > >> > >> ___ > >> Bitcoin-development mailing list > >> Bitcoin-development@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/bitcoin-development > >> > > > > -- > > Get your SQL database under version control now! > > Version control is standard for application code, but databases havent > > caught up. So what steps can you take to put your SQL databases under > > version control? Why should you start doing it? Read more to find out. > > http://pubads.g.doubleclick.net/gampad/clk?id=49501711&iu=/4140/ostg.clktrk > > ___ > > Bitcoin-development mailing list > > Bitcoin-development@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > -- > Get your SQL database under version control now! > Version control is standard for application code, but databases havent > caught up. So what steps can you take to put your SQL databases under
Re: [Bitcoin-development] Safe auto-updating
Indeed. You can hardcode a "distributor" public key in the software, and client software will only trust signed data from that key. Of course, the private key for that data is not kept on the server distributing the signed checksums. Ideally it would be kept offline, and the couple-times-per-year that you actually execute an upgrade, you sign the new checksums offline and upload the signed checksum to the distribution server. Then even if the server is compromised, the client-side software will not accept a bogus checksum because it won't bear the right signature. If you do this, it would be good to also have some kind of revocation process that can be used in the event of the offline key being compromised. You won't be able to "switch" keys, as that would defeat the purpose (the attacker who compromises the offline key could just issue a replacement with his own). Instead, it would be an irreversible broadcast that would force clients to start rejecting updates from that key. If the key is compromised (and find out), you broadcast the revocation and the users will stop auto-updating, and be given a warning that they should manually upgrade the software through trusted channels. It's not failproof, but it's a decent way to minimize damage if you discover compromise early enough. -Alan On 08/05/2013 11:54 AM, Daniel F wrote: > If you want package authentication, you should at least throw in some > digital signing, not just a checksum. With a compromised host, both the > checksum and binaries can be changed undetectably, but if there's a > signature made by a key that is not kept on the host, there's no way to > fake a valid binary. > > There may be other issues people would want to bring up, but surely just > a checksum is not sufficient. > > on 08/05/2013 10:39 AM Wendell said the following: >> For usability purposes, we at Hive would like to have an >> auto-updater > in our wallet app. >> What is a safe way to do this? I understand that Bitcoin-QT lacks >> such > an updater for security reasons... Has been thought out in more detail > since that decision was made? >> We have been toying around with the idea of placing one server >> behind > a Tor hidden service, whose only function is to output a checksum of the > update package. The theory is that if it is well-secured, it will at > least be immune to tampering at the physical hosting level. >> Any thoughts or advice about any of this? >> -wendell >> >> grabhive.com | twitter.com/grabhive | gpg: 6C0C9411 >> >> >> >> -- >> Get your SQL database under version control now! >> Version control is standard for application code, but databases havent >> caught up. So what steps can you take to put your SQL databases under >> version control? Why should you start doing it? Read more to find out. >> http://pubads.g.doubleclick.net/gampad/clk?id=49501711&iu=/4140/ostg.clktrk >> >> >> >> ___ >> Bitcoin-development mailing list >> Bitcoin-development@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/bitcoin-development >> > > -- > Get your SQL database under version control now! > Version control is standard for application code, but databases havent > caught up. So what steps can you take to put your SQL databases under > version control? Why should you start doing it? Read more to find out. > http://pubads.g.doubleclick.net/gampad/clk?id=49501711&iu=/4140/ostg.clktrk > ___ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- Get your SQL database under version control now! Version control is standard for application code, but databases havent caught up. So what steps can you take to put your SQL databases under version control? Why should you start doing it? Read more to find out. http://pubads.g.doubleclick.net/gampad/clk?id=49501711&iu=/4140/ostg.clktrk ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Safe auto-updating
If you want package authentication, you should at least throw in some digital signing, not just a checksum. With a compromised host, both the checksum and binaries can be changed undetectably, but if there's a signature made by a key that is not kept on the host, there's no way to fake a valid binary. There may be other issues people would want to bring up, but surely just a checksum is not sufficient. on 08/05/2013 10:39 AM Wendell said the following: > For usability purposes, we at Hive would like to have an > auto-updater in our wallet app. > > What is a safe way to do this? I understand that Bitcoin-QT lacks > such an updater for security reasons... Has been thought out in more detail since that decision was made? > > We have been toying around with the idea of placing one server > behind a Tor hidden service, whose only function is to output a checksum of the update package. The theory is that if it is well-secured, it will at least be immune to tampering at the physical hosting level. > > Any thoughts or advice about any of this? > -wendell > > grabhive.com | twitter.com/grabhive | gpg: 6C0C9411 > > > > -- > Get your SQL database under version control now! > Version control is standard for application code, but databases havent > caught up. So what steps can you take to put your SQL databases under > version control? Why should you start doing it? Read more to find out. > http://pubads.g.doubleclick.net/gampad/clk?id=49501711&iu=/4140/ostg.clktrk > > > > ___ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > -- Get your SQL database under version control now! Version control is standard for application code, but databases havent caught up. So what steps can you take to put your SQL databases under version control? Why should you start doing it? Read more to find out. http://pubads.g.doubleclick.net/gampad/clk?id=49501711&iu=/4140/ostg.clktrk ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Preparing for the Cryptopocalypse
Interesting! I will refrain from digging into QC right now, per Alan's suggestion. :) -- Get your SQL database under version control now! Version control is standard for application code, but databases havent caught up. So what steps can you take to put your SQL databases under version control? Why should you start doing it? Read more to find out. http://pubads.g.doubleclick.net/gampad/clk?id=49501711&iu=/4140/ostg.clktrk___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
[Bitcoin-development] Safe auto-updating
For usability purposes, we at Hive would like to have an auto-updater in our wallet app. What is a safe way to do this? I understand that Bitcoin-QT lacks such an updater for security reasons... Has been thought out in more detail since that decision was made? We have been toying around with the idea of placing one server behind a Tor hidden service, whose only function is to output a checksum of the update package. The theory is that if it is well-secured, it will at least be immune to tampering at the physical hosting level. Any thoughts or advice about any of this? -wendell grabhive.com | twitter.com/grabhive | gpg: 6C0C9411 signature.asc Description: Message signed with OpenPGP using GPGMail -- Get your SQL database under version control now! Version control is standard for application code, but databases havent caught up. So what steps can you take to put your SQL databases under version control? Why should you start doing it? Read more to find out. http://pubads.g.doubleclick.net/gampad/clk?id=49501711&iu=/4140/ostg.clktrk___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
