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diff --git a/doc/servers.mdwn b/doc/servers.mdwn new file mode 100644 index 0000000..3e82c7e --- /dev/null +++ b/doc/servers.mdwn @@ -0,0 +1,194 @@ +There are currently not enough keysafe servers. We need at least 3 for +keysafe to work. Please contact <id@joeyh.name> if you would like to run a +keysafe server. + +## Server categories + +Keysafe's server list puts servers in three categories: + +1. **Recommended**: Servers that meet all best practices for security and + are run by a well-known, trusted entity. + + Keysafe prefers to store data only on Recommended servers when possible. + +2. **Alternate**: Servers that are not secured well enough to be + Recommended. + + Keysafe will store data on Alternate servers if it has to, but will + avoid storing enough data to allow the key to be recovered using only + the data stored on Alternate servers. + + For example, with 2 of 3 shares needed to restore a key, keysafe can + store 1 share on an Alternate server, and the other 2 shares on two + Recommended servers. + +3. **Untrusted**: Servers that are not secured well or are run by an untrusted + entity. + + Keysafe will never store data on Untrusted servers. + + If a server becomes untrusted and keysafe stored data on it in the past, + keysafe will warn the user about this problem. + + The only time keysafe will use untrusted servers is if it's restoring a + key, and cannot find enough shares on Recommended/Alternate + servers, and has to fall back to downloading from an Untrusted server. + +## Server list + +### Recommended + +#### hlmjmeth356s5ekm.onion + + -----BEGIN PGP SIGNED MESSAGE----- + Hash: SHA1 + + The keysafe server hlmjmeth356s5ekm.onion is provided and administered by + Purism. It is located in the EU (Cyprus). + + We intend to run this server for at least 10 years (through 2027), + or failing that, to transition any data stored on it to another + server that is of similar or higher security. + + Our warrant canary is <https://puri.sm/warrant-canary/>, + and is updated quarterly. + -----BEGIN PGP SIGNATURE----- + Version: GnuPG v1 + + iQIcBAEBAgAGBQJYF8U4AAoJECPPLj0lRRT30CkP/Rn2TAeriNWO9wZcr0OHyX7B + TJcgLy3pZXbGn6T6qmJqg3K22fTKJ7CX0dfIM+WLI9FfBtnT95q1rnzywhBGPXzj + eD3g7r3QinIfMLBQTKyc9Ik5132uenD5h72ggVl3D+kuWv622IhaAaiVkuHc5KoR + 3/S+ImkcS/gz83UNTXnWdMs0V8+eqAjpWeYQS8Ih28AECI9f+xUUH//V9Ii/4Usv + E3Y0hbqj8kSi4/Q6IwmFiJTKZ1FpccKhl6GIYUSLwJMJDHoI46M/AaZy0Xx9pLcU + niSELai/7/0fY4N0TY2CbZUgH7FEhi0k8cCsGF7yTA6dqya8deKQKdUdDllcHayv + +GOAqijiSTPrRox4TPMMdurPXTsJxeJuxVdS75Lw2cFk+JaaIVS/3XEyeuGpaVKW + wSTltyFkMx9ur5cCPT2rxoRN78HuqgiHda/Jd4c2pny7GwpUEYAznQQaBYEl2jlQ + /Go3ZudpnWfBRRe7znazhA6mIatPY61GrNIebVlET6/NCw9sZFRjHXY3pMw1u/TY + 4eP0UQpBUed4/sot5vsZVwbn8e6eFh0S4HTdl5x1G8jN8nUZVdJJjOtACrONW+TG + CLSNDkMgQ5slBmtZm+MzL2VYkFHCMmPerNXY1DhHjMyfLpQEIN+bho+mIyc5h/W/ + Br5jFZujcQ0u7GzqvaDB + =RmK4 + -----END PGP SIGNATURE----- + +### Alternate + +#### keysafe.joeyh.name + + -----BEGIN PGP SIGNED MESSAGE----- + Hash: SHA256 + + keysafe.joeyh.name is provided by me, Joey Hess. + + I intend to run this server for at least 10 years (through 2027), + or failing that, to transition any data stored on it to another + server that is of similar or higher security. + + It is a Digital Ocean VPS, located in Indonesia. I can't tell if the + hosting provider is accessing the contents of the server, and so + this server is not securely hosted enough to be Recommended. + -----BEGIN PGP SIGNATURE----- + + iQIcBAEBCAAGBQJXx0qFAAoJEMkQ2SIlEuPHyGMQALSLL7LZEpTi+zf2kPYGoBMQ + 3z3FDB9B6SaF4uN3r+XlAw2Vzas2KVLCbNkO+np7tLzC0qdY5dBLDI7+ZJXiKi2v + iqxKICl0E8+ih8JOe0JWfoysO974I1DesEI7X6VUewwNpd35OgCuIL5RmknKrX4I + x7gUfsONiojUKgOT0yMErUfw3VNYB0Kbzw4Xic66eIkFl5z6APMknjqvOC1196v9 + BW0rSM+OsthB9xkj7ULKQv+1LrxmwNu0+FL62qNKGObbXHayfLBGm8TT9Y7etQYD + 3zRDiUfa0m2aYu7ZRx5HSIgExVVd3YosDUFA4xsIb6N4wBbP1zS2TG2Zo5o/+3gt + BerkQL/xkMWhIMVCYp1hWc47MenHk1MJU5EhS+duL/fnlqW2HcFanM+fOv+/ZWt6 + da2mdjSR95Ekq22BXN9eHO54AFJKLWYNdT9E5W2rlwqUoC4dqsqYGT3XWnAaKHC/ + he9+B/wdEf7165Qy+MKo/36Ib7pfhPQv4hip2cuMP9w0E6JoKZusBV5AdxRvGAGf + GvUhvNog6v9/t+cqUp6dSTT2WVllkXJ/5deGJYLzZMJjZS3cZ75ZKr8OD5oQxr+m + 7oL6BDvxha7Q4qHo/RZgxyd/qZ7zWHTT6Tn6qNCBGUi4b6Etb0kEd5Os66WoLCSK + lhmhvShr0WRqB8fWYPkc + =SNGN + -----END PGP SIGNATURE----- +</pre> + +#### thirdserver + + Provided by Marek Isalski at [Faelix](http://www.faelix.net/). + Currently located in UK, but planned move to CH. + Vetting to Recommended level in progress. + +## Detailed requirements + +### Alternate + +* Keysafe port only exposed via tor hidden service. +* Dedicated to only running keysafe, no other services. (Other than tor and + ssh for admin) +* The set of people who administer the server, and procedures for giving + others access is well-defined. +* Noone who has access to the server also has access to any Recommended + server. +* Commitment to either keep the server running long-term (ie, 10+ years), + or transition the data to a replacement server that meets these + requirements and that must not contain any related shards. +* No other open ports (other than ssh). +* Ssh authentication only by ssh key, not password. +* Either off-server backup, or replication of shards to additional disks. + (rsync to additional local disks would work perfectly well and avoids + the complications of RAID) +* Any off-server backup is strongly encrypted. + (There's a trade-off here; any backup widens the attack surface. + It may be better to run some servers without backups and adjust the + number of shards needed to recover keys; a server losing its data + need not be catastrophic.) +* Any backup should take care to not leak information about what objects + were present on the server at multiple times in the past. That would + let an attacker who can access the backups make guesses about shares + belong with other shares stored on other servers in the same time period. + See [[details]] for how that makes it somewhat easier for an attacker. + + keysafe --backup-server can be used to generate encrypted files to back up, + in a way that is designed to avoid these problems. + +* Similarly, the filesystem and storage system should not allow rolling back + to old snapshots. + +### Recommended + +* Everything in Alternate, to start with. +* Run by a well known and trustworthy entity. +* Noone who has access to the server also has access to any other + Recommended or Alternate server. +* Warrant canary. +* Hardware is hosted in-house. A VM at a cloud provider is right out + because the provider could be made to give access to it without the + server operator knowing about it. Which would bypass the warrant canary. +* The keysafe data store and any swap partitions are encrypted, + and have to be manually unlocked when the server is booted. + +## Server scaling + +Each key takes a minimum of 64 KiB to store, perhaps more for gpg keys +with lots of signatures. So 10 GiB of disk is sufficient for 160 thousand +users, which is enough for a small keysafe server. + +The keysafe server uses very little memory and CPU. It does rate limiting +with client-side proof-of-work to prevent it being abused for +general-purpose data storage. + +There is some disk IO overhead, because keysafe updates the mtime and ctime +of all shards stored on the server, as frequently as every 30 minutes. +Once a large number of shards are stored, this could become a significant +source of disk IO. + +## Server setup + +It's early days still, but keysafe's server code works well enough. + +* `git clone git://keysafe.branchable.com/ keysafe` +* Be sure to verify the gpg signature of the git repository! +* You will need to install keysafe from source; see its INSTALL file. + Use `make install` to install it, including a systemd service file. +* `systemctl enable keysafe.service` +* Install tor and set up a tor hidden service. Keysafe listens on port 4242 + by default, so use that port. +* Configure the server to meet all the requirements for Alternate or + Required. +* Once ready, email id@joeyh.name to get added to keysafe's server list. + +Here's a the [[code/propellor]] config for my own keysafe server: +<http://source.propellor.branchable.com/?p=source.git;a=blob;f=joeyconfig.hs;h=15a00f7c2dffa15ed275fdd44e84e2edcc226559;hb=b9f87f0c08d94c5d43224a2c6bbacb332ebfc1b6#l460> +--[[Joey]] |