Introduce signing guile-ssh functions.

[nicolas-graves]

This is corresponding to the current https://gitlab.com/libssh/libssh-mirror/-/merge_requests/536 (not merged yet, but I expect that to be soon enough).

Here's a usage example :

(use-modules (ssh key)
             (srfi srfi-26)
             (ice-9 textual-ports))

(define (public-keys-equal? pub1 pub2)
  (string=? (public-key->string pub1)
            (public-key->string pub2)))

(define rsakey (private-key-from-file "tests/keys/rsakey"))
(define test-string "Test input\0string")

(call-with-output-file "/tmp/message.sig"
  (cut format <> (sign test-string rsakey)))

(and=>
 (verify
  "Test input\0string"
  ;; "not a signature"
  (call-with-input-file "/tmp/message.sig" get-string-all))
 (cut public-keys-equal? rsakey <>))

[nicolas-graves]

@artyom-poptsov The first commit can already be reviewed/merged, see https://codeberg.org/guix/guix/issues/113 for the reason why it's required.

[nicolas-graves]

@artyom-poptsov It's been merged upstream! Next steps here?

[artyom-poptsov]

Thanks for your contribution! Sorry, I was busy with other tasks so forgot about you pull request.

I checked your changes locally and saw some compilation errors. I'm building this with libssh 0.10, so I suppose the new functionality shouldn't work anyway. However, we need to make sure that Guile-SSH builds with older libssh verisons as well. So, in case of your changes, we need to issue a warning from configure script about lack of signing functionality when older libssh version is used, but other parts of Guile-SSH must work nevertheless.

$ make -j25
Making all in build-aux
make[1]: Entering directory '/home/avp/src/projects/guile-ssh/build-aux'
Making all in am
make[2]: Entering directory '/home/avp/src/projects/guile-ssh/build-aux/am'
make[2]: Nothing to be done for 'all'.
make[2]: Leaving directory '/home/avp/src/projects/guile-ssh/build-aux/am'
Making all in m4
make[2]: Entering directory '/home/avp/src/projects/guile-ssh/build-aux/m4'
make[2]: Nothing to be done for 'all'.
make[2]: Leaving directory '/home/avp/src/projects/guile-ssh/build-aux/m4'
make[2]: Entering directory '/home/avp/src/projects/guile-ssh/build-aux'
make[2]: Nothing to be done for 'all-am'.
make[2]: Leaving directory '/home/avp/src/projects/guile-ssh/build-aux'
make[1]: Leaving directory '/home/avp/src/projects/guile-ssh/build-aux'
Making all in libguile-ssh
make[1]: Entering directory '/home/avp/src/projects/guile-ssh/libguile-ssh'
  GEN      auth.x
  GEN      channel-func.x
  GEN      channel-type.x
  GEN      error.x
  GEN      key-func.x
  GEN      key-type.x
  GEN      log.x
  GEN      message-func.x
  GEN      message-type.x
  GEN      server-func.x
  GEN      server-type.x
  GEN      session-func.x
  GEN      session-type.x
  GEN      sftp-file-type.x
  GEN      sftp-dir-type.x
  GEN      sftp-dir-func.x
  GEN      sftp-session-func.x
  GEN      sftp-session-type.x
  GEN      version.x
make  all-am
make[2]: Entering directory '/home/avp/src/projects/guile-ssh/libguile-ssh'
  CC       libguile_ssh_la-callbacks.lo
  CC       libguile_ssh_la-auth.lo
  CC       libguile_ssh_la-channel-func.lo
  CC       libguile_ssh_la-channel-type.lo
  CC       libguile_ssh_la-channel-main.lo
  CC       libguile_ssh_la-error.lo
  CC       libguile_ssh_la-key-func.lo
  CC       libguile_ssh_la-key-main.lo
  CC       libguile_ssh_la-key-type.lo
  CC       libguile_ssh_la-session-func.lo
  CC       libguile_ssh_la-session-type.lo
  CC       libguile_ssh_la-server-main.lo
  CC       libguile_ssh_la-session-main.lo
  CC       libguile_ssh_la-server-func.lo
  CC       libguile_ssh_la-server-type.lo
  CC       libguile_ssh_la-message-type.lo
  CC       libguile_ssh_la-message-func.lo
  CC       libguile_ssh_la-message-main.lo
  CC       libguile_ssh_la-version.lo
  CC       libguile_ssh_la-threads.lo
  CC       libguile_ssh_la-common.lo
  CC       libguile_ssh_la-log.lo
  CC       libguile_ssh_la-sftp-session-type.lo
  CC       libguile_ssh_la-sftp-session-main.lo
  CC       libguile_ssh_la-sftp-session-func.lo
  CC       libguile_ssh_la-sftp-file-type.lo
  CC       libguile_ssh_la-sftp-file-main.lo
channel-func.c: In function 'guile_ssh_channel_listen_forward':
channel-func.c:420:3: warning: 'ssh_forward_listen' is deprecated [-Wdeprecated-declarations]
  420 |   res = ssh_forward_listen (sd->ssh_session,
      |   ^~~
In file included from channel-func.c:24:
/home/avp/.guix-profile/include/libssh/libssh.h:553:31: note: declared here
  553 | SSH_DEPRECATED LIBSSH_API int ssh_forward_listen(ssh_session session, const char *address, int port, int *bound_port);
      |                               ^~~~~~~~~~~~~~~~~~
channel-func.c: In function 'guile_ssh_channel_accept_forward':
channel-func.c:450:3: warning: 'ssh_channel_accept_forward' is deprecated [-Wdeprecated-declarations]
  450 |   c_channel = ssh_channel_accept_forward (sd->ssh_session,
      |   ^~~~~~~~~
/home/avp/.guix-profile/include/libssh/libssh.h:517:39: note: declared here
  517 | SSH_DEPRECATED LIBSSH_API ssh_channel ssh_channel_accept_forward(ssh_session session,
      |                                       ^~~~~~~~~~~~~~~~~~~~~~~~~~
message-func.c: In function 'get_auth_req':
message-func.c:298:3: warning: 'ssh_message_auth_password' is deprecated [-Wdeprecated-declarations]
  298 |   const char *password = ssh_message_auth_password (msg);
      |   ^~~~~
In file included from message-func.c:25:
/home/avp/.guix-profile/include/libssh/server.h:302:39: note: declared here
  302 | SSH_DEPRECATED LIBSSH_API const char *ssh_message_auth_password(ssh_message msg);
      |                                       ^~~~~~~~~~~~~~~~~~~~~~~~~
message-func.c:299:3: warning: 'ssh_message_auth_pubkey' is deprecated [-Wdeprecated-declarations]
  299 |   ssh_key public_key   = ssh_message_auth_pubkey (msg);
      |   ^~~~~~~
/home/avp/.guix-profile/include/libssh/server.h:320:35: note: declared here
  320 | SSH_DEPRECATED LIBSSH_API ssh_key ssh_message_auth_pubkey(ssh_message msg);
      |                                   ^~~~~~~~~~~~~~~~~~~~~~~
channel-func.c: In function 'guile_ssh_channel_cancel_forward':
channel-func.c:481:3: warning: 'ssh_forward_cancel' is deprecated [-Wdeprecated-declarations]
  481 |   res = ssh_forward_cancel (sd->ssh_session,
      |   ^~~
/home/avp/.guix-profile/include/libssh/libssh.h:552:31: note: declared here
  552 | SSH_DEPRECATED LIBSSH_API int ssh_forward_cancel(ssh_session session, const char *address, int port);
      |                               ^~~~~~~~~~~~~~~~~~
message-func.c:315:35: warning: 'ssh_message_auth_publickey_state' is deprecated [-Wdeprecated-declarations]
  315 |                                   (int) ssh_message_auth_publickey_state (msg));
      |                                   ^
/home/avp/.guix-profile/include/libssh/server.h:325:54: note: declared here
  325 | SSH_DEPRECATED LIBSSH_API enum ssh_publickey_state_e ssh_message_auth_publickey_state(ssh_message msg);
      |                                                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
message-func.c: In function 'get_pty_req':
message-func.c:327:3: warning: 'ssh_message_channel_request_pty_term' is deprecated [-Wdeprecated-declarations]
  327 |   const char *term = ssh_message_channel_request_pty_term (msg);
      |   ^~~~~
/home/avp/.guix-profile/include/libssh/server.h:356:39: note: declared here
  356 | SSH_DEPRECATED LIBSSH_API const char *ssh_message_channel_request_pty_term(ssh_message msg);
      |                                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
message-func.c:328:3: warning: 'ssh_message_channel_request_pty_width' is deprecated [-Wdeprecated-declarations]
  328 |   int w   = ssh_message_channel_request_pty_width (msg);
      |   ^~~
/home/avp/.guix-profile/include/libssh/server.h:357:31: note: declared here
  357 | SSH_DEPRECATED LIBSSH_API int ssh_message_channel_request_pty_width(ssh_message msg);
      |                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
message-func.c:329:3: warning: 'ssh_message_channel_request_pty_height' is deprecated [-Wdeprecated-declarations]
  329 |   int h   = ssh_message_channel_request_pty_height (msg);
      |   ^~~
/home/avp/.guix-profile/include/libssh/server.h:358:31: note: declared here
  358 | SSH_DEPRECATED LIBSSH_API int ssh_message_channel_request_pty_height(ssh_message msg);
      |                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
message-func.c:330:3: warning: 'ssh_message_channel_request_pty_pxwidth' is deprecated [-Wdeprecated-declarations]
  330 |   int pxw = ssh_message_channel_request_pty_pxwidth (msg);
      |   ^~~
/home/avp/.guix-profile/include/libssh/server.h:359:31: note: declared here
  359 | SSH_DEPRECATED LIBSSH_API int ssh_message_channel_request_pty_pxwidth(ssh_message msg);
      |                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
message-func.c:331:3: warning: 'ssh_message_channel_request_pty_pxheight' is deprecated [-Wdeprecated-declarations]
  331 |   int pxh = ssh_message_channel_request_pty_pxheight (msg);
      |   ^~~
/home/avp/.guix-profile/include/libssh/server.h:360:31: note: declared here
  360 | SSH_DEPRECATED LIBSSH_API int ssh_message_channel_request_pty_pxheight(ssh_message msg);
      |                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
key-func.c:490:15: error: 'SSHSIG_DIGEST_SHA2_256' undeclared here (not in a function)
  490 |   { "sha256", SSHSIG_DIGEST_SHA2_256 },
      |               ^~~~~~~~~~~~~~~~~~~~~~
  CC       libguile_ssh_la-sftp-dir-type.lo
key-func.c:491:15: error: 'SSHSIG_DIGEST_SHA2_512' undeclared here (not in a function)
  491 |   { "sha512", SSHSIG_DIGEST_SHA2_512 },
      |               ^~~~~~~~~~~~~~~~~~~~~~
  CC       libguile_ssh_la-sftp-dir-func.lo
  CC       libguile_ssh_la-sftp-dir-main.lo
key-func.c: In function 'guile_ssh_sign':
key-func.c:530:9: error: implicit declaration of function 'sshsig_sign' [-Wimplicit-function-declaration]
  530 |   res = sshsig_sign (data, data_len, kd->ssh_key, c_sig_namespace,
      |         ^~~~~~~~~~~
key-func.c: In function 'guile_ssh_verify':
key-func.c:578:9: error: implicit declaration of function 'sshsig_verify' [-Wimplicit-function-declaration]
  578 |   res = sshsig_verify (data, data_len, c_signature, c_sig_namespace, &sign_key);
      |         ^~~~~~~~~~~~~
make[2]: *** [Makefile:701: libguile_ssh_la-key-func.lo] Error 1
make[2]: *** Waiting for unfinished jobs....
make[2]: Leaving directory '/home/avp/src/projects/guile-ssh/libguile-ssh'
make[1]: *** [Makefile:509: all] Error 2
make[1]: Leaving directory '/home/avp/src/projects/guile-ssh/libguile-ssh'
make: *** [Makefile:437: all-recursive] Error 1