README.md

   1 # ucert
   2
   3 ucert is a signature-chaining wrapper around usign using blob and blobmsg.
   4 It's meant to be used for OpenWrt routers and uses libubox for most things, to allow dumping certificates in JSON format libjson-c and libblobmsg-json are used as well.
   5
   6 ## a few words about security
   7 ucert inherits all its cryptographic properties from the underlying usign implementation which as such wasn't meant to be used in such a way.
   8 To maintain a high cryptographic standard, it is likely that further optimization of the signed payload format (reduce known-plaintext by normalization, add salts in case usign doesn't, ...) has to be carried out.
   9
  10 ## usage
  11 ```shell
  12 Usage: ucert <command> <options>
  13 Commands:
  14   -A:                   append signature (needs -c and -x)
  15   -D:                   dump (needs -c)
  16   -I:                   issue cert and revoker (needs -c and -p and -s)
  17   -R:                   process revoker certificate (needs -c and -P)
  18   -V:                   verify (needs -c and -p|-P, may have -m)
  19 Options:
  20   -c <file>:            certificate file
  21   -m <file>:            message file (verify only)
  22   -p <file>:            public key file
  23   -P <path>:            public key directory (verify only)
  24   -q:                   quiet (do not print verification result, use return code only)
  25   -s <file>:            secret key file (issue only)
  26   -x <file>:            signature file
  27 ```
  28
  29 ### examples
  30 ```shell
  31 # on airgap system
  32 # create root keypair (which never leaves airgap)
  33 usign -G -p capubkey -s caseckey
  34 # create delegate keypair
  35 usign -G -p pubkey -s seckey
  36 # create ca-signed delegate cert (and revoker)
  37 ucert -I -p pubkey -s caseckey -c newcert
  38
  39 # eg. on buildbot worker
  40 # got newcert and seckey from airgap
  41 # sign content
  42 usign -S -m message.bin -s seckey -x message.bin.sig
  43 # create cert for message
  44 cp newcert message.bin.ucrt
  45 ucert -A -c message.bin.ucrt -x message.bin.sig
  46
  47 # on client
  48 ucert -V -P /etc/opkg/keys -m message.bin -c message.bin.ucrt && echo message.bin verified successfully
  49 ```