Provided by: libopaque-bin_0.99.3-1_amd64
NAME
opaque - simple command-line frontend for libopaque
SYNOPSIS
Create new OPAQUE records Create new opaque record - offline echo -n password | opaque init idU idS 3>export_key [4<skS] >record Initiate new online registration echo -n password | opaque register >msg 3>ctx Respond to new online registration request opaque respond <msg >rpub 3>rsec [4<skS] Finalize online registration opaque finalize idU idS <ctx 4<rpub 3>export_key >record Complete online record opaque store <rec 3<rsec >record Server portion of online registration socat | opaque server-reg 3>record [4<skS] User portion of online registration socat | opaque user-reg idU idS 3< <(echo -n password) 4>export_key Run OPAQUE Server portion of OPAQUE session socat | opaque server idU idS context 3<record 4>shared_key User portion of OPAQUE session socat | opaque user idU idS context 3< <(echo -n password) 4>export_key 5>shared_key [6<pkS]
DESCRIPTION
The OPAQUE protocol is an asymmetric password-authenticated key-exchange. Essentially it allows a client to establish a shared secret with a server based on only having a password. The client doesn’t need to store any state. The protocol has two phases: • In the initialization phase a client registers with the server. • In the AKE phase the client and server establish a shared secret. The initialization only needs to be executed once, the key-exchange can be executed as many times as necessary. Initialization Initializing OPAQUE (registration) can be done either online or offline. The online variant has the benefit that the server never learns anything about the users password, with the drawback that this requires 3 messages to be exchanged by the client and the server. The offline initialization is much easier, however either the user learns the servers secret, or the server learns the users password. The latter might be useful if some organisation wants to enforce some password quality rules and check those upon registration. The drawback is that either way, some sensitive information leaks to the other party. Offline Registration echo -n password | ./opaque init user server >record 3>export_key Online Registration socat style On the server: socat tcp-l:23523,reuseaddr,fork system:"bash -c \'opaque server-reg user server 3>record\'" On the client: socat tcp:127.0.0.1:23523 exec:'bash -c \"opaque user-reg user server 3< <(echo -n password) 4>export_key\"' tcpserver style On the server: s6-tcpserver 127.0.0.1 23523 bash -c 'opaque server-reg user server 3>record' On the client: s6-tcpclient 127.0.0.1 23523 bash -c "opaque user-reg user server <&6 >&7 3< <(echo -n password) 4>export_key" Manually It’s possible to do all 4 steps seperately, in case you cannot connect to the server directly, then: The user initiates with: echo -n password | opaque register >msg 3>ctx The server gets msg and responds with rpub, while keeping rsec secret: cat msg | opaque respond >rpub 3>rsec The user receives rpub and creates stub record and optionally uses the export key to encrypt more data: cat ctx | opaque finalize user server 4<rpub >record 3>export_key the server finalizes the record by completing the stub record from the client: cat rec | opaque store user server >record 3<rsec Running OPAQUE tcpserver style On the server: s6-tcpserver 127.0.0.1 23523 bash -c './opaque server user server context 3<record 4>shared_secret' On the client: s6-tcpclient 127.0.0.1 23523 bash -c "./opaque user user server context <&6 >&7 3< <(echo -n password) 4>export_key 5>shared_secret" socat style On the server: socat tcp-l:23523,reuseaddr,fork system:"bash -c \'./opaque server user server context 3<record 4>shared_secret\'" On the client: socat tcp:127.0.0.1:23523 exec:'bash -c \"./opaque user user server context 3< <(echo -n password) 4>export_key 5>shared_secret\"'
REPORTING BUGS
https://github.com/stef/libopaque/issues/
AUTHOR
Written by Stefan Marsiske.
COPYRIGHT
Copyright © 2023 Stefan Marsiske. License LGPLv3+: GNU Lesser GPL version 3 or later <https://gnu.org/licenses/lgpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
https://ctrlc.hu/~stef/blog/tags/opaque/ socat(1), tcpserver(1) opaque(1)