openssh/sshsig.h
djm@openbsd.org 2a9c9f7272 upstream: sshsig: lightweight signature and verification ability
for OpenSSH

This adds a simple manual signature scheme to OpenSSH.
Signatures can be made and verified using ssh-keygen -Y sign|verify

Signatures embed the key used to make them. At verification time, this
is matched via principal name against an authorized_keys-like list
of allowed signers.

Mostly by Sebastian Kinne w/ some tweaks by me

ok markus@

OpenBSD-Commit-ID: 2ab568e7114c933346616392579d72be65a4b8fb
2019-09-03 18:40:23 +10:00

79 lines
2.8 KiB
C

/*
* Copyright (c) 2019 Google LLC
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef SSHSIG_H
#define SSHSIG_H
struct sshbuf;
struct sshkey;
typedef int sshsig_signer(struct sshkey *, u_char **, size_t *,
const u_char *, size_t, const char *, u_int, void *);
/*
* Creates a detached SSH signature for a given message.
* Returns 0 on success or a negative SSH_ERR_* error code on failure.
* out is populated with the detached signature, or NULL on failure.
*/
int sshsig_sign_message(struct sshkey *key, const char *hashalg,
const struct sshbuf *message, const char *sig_namespace,
struct sshbuf **out, sshsig_signer *signer, void *signer_ctx);
/*
* Creates a detached SSH signature for a given file.
* Returns 0 on success or a negative SSH_ERR_* error code on failure.
* out is populated with the detached signature, or NULL on failure.
*/
int sshsig_sign_fd(struct sshkey *key, const char *hashalg,
int fd, const char *sig_namespace, struct sshbuf **out,
sshsig_signer *signer, void *signer_ctx);
/*
* Verifies that a detached signature is valid and optionally returns key
* used to sign via argument.
* Returns 0 on success or a negative SSH_ERR_* error code on failure.
*/
int sshsig_verify_message(struct sshbuf *signature,
const struct sshbuf *message, const char *sig_namespace,
struct sshkey **sign_keyp);
/*
* Verifies that a detached signature over a file is valid and optionally
* returns key used to sign via argument.
* Returns 0 on success or a negative SSH_ERR_* error code on failure.
*/
int sshsig_verify_fd(struct sshbuf *signature, int fd,
const char *sig_namespace, struct sshkey **sign_keyp);
/*
* Return a base64 encoded "ASCII armoured" version of a raw signature.
*/
int sshsig_armor(const struct sshbuf *blob, struct sshbuf **out);
/*
* Decode a base64 encoded armoured signature to a raw signature.
*/
int sshsig_dearmor(struct sshbuf *sig, struct sshbuf **out);
/*
* Checks whether a particular key/principal/namespace is permitted by
* an allowed_keys file. Returns 0 on success.
*/
int sshsig_check_allowed_keys(const char *path, const struct sshkey *sign_key,
const char *principal, const char *ns);
#endif /* SSHSIG_H */