diff options
| -rw-r--r-- | website/doc.mdwn | 78 |
1 files changed, 76 insertions, 2 deletions
diff --git a/website/doc.mdwn b/website/doc.mdwn index cd73999..80eca79 100644 --- a/website/doc.mdwn +++ b/website/doc.mdwn @@ -16,5 +16,79 @@ ## Similar Projects ## - * [openssh-gpg](http://www.red-bean.com/~nemo/openssh-gpg/) - * [openssh with network notaries](http://www.cs.cmu.edu/~perspectives/openssh.html) +The monkeysphere isn't the only project intending to implement a PKI +for OpenSSH. We provide links to these other projects because they're +interesting, though we have concerns with their approaches. + +All of the other projects we've found so far require a patched version +of OpenSSH, which makes adoption more difficult. Most people don't +build their own software, and simply overlaying a patched binary is +associated with significant maintenance (and therefore security) +problems. A PKI becomes more useful the more people participate in +it, so widespread adoption is important. + +### `openssh-gpg` ### + +[openssh-gpg](http://www.red-bean.com/~nemo/openssh-gpg/) is a patch +against OpenSSH to support OpenPGP certificates. According to its +documentation, it is intended to support [`pgp-sign-rsa` and +`pgp-sign-dss` public key algorithms, as specified by the +IETF](http://tools.ietf.org/html/rfc4253#section-6.6). + +Some concerns with `openssh-gpg`: + + * This patch is significantly old; it doesn't appear to have been + maintained beyond OpenSSH 3.6p1. As of this writing, OpenSSH is on + version 5.1p1. + + * It requires patching OpenSSH. + +### Perspectives OpenSSH client ### + +[The Perspectives project](http://www.cs.cmu.edu/~perspectives/) at +CMU has released an [openssh client that uses network +notaries](http://www.cs.cmu.edu/~perspectives/openssh.html) to bolster +your confidence in new keys. This offers a defense against a narrow +MITM attack (e.g. by someone who controls your local gateway) by +simply verifying that other machines from around the network see the +same keys for the remote host that you're seeing. + +This is quite useful, but doesn't take the system as far as it could +go, and doesn't tie into the existing web of trust. + +Some concerns with the Perspectives OpenSSH client: + + * This client won't help if you are connecting to machines behind + firewalls, on NAT'ed LANs, with source IP filtering, or otherwise + in a restricted network state. + + * There is still a question of why you should trust these particular + notaries during your verification. Who are the notaries? How + could they be compromised? + + * It requires patching OpenSSH + +### OpenSSH with X.509v3 certificates ### + +Roumen Petrov [maintains a patch to OpenSSH that works with the X.509 +PKI model](http://www.roumenpetrov.info/openssh/). This is the +certificate hierarchy commonly used by TLS (and SSL before that). + +Some concerns about OpenSSH with X.509v3: + + * the X.509 certificate specification itself [encourages corporate + consolidation and centralized global "trust" because of its + single-issuer architectural + limitation](http://lair.fifthhorseman.net/~dkg/tls-centralization/). + This results in an expensive and cumbersome system for smaller + players, and it also doesn't correspond to the true distributed + nature of human-to-human trust. Furthermore, centralized global + "trusted authorities" create a tempting target for attack, and a + single-point-of-failure if an attack is successful. + + Depending on how you declare your trust relationships, OpenPGP is + capable of providing the same hierarchical structure as X.509, but + it is not limited to it. The Web of Trust model is more flexible + and more adaptable than X.509. + + * It requires patching OpenSSH. |