HardenedBSD/crypto/openssh/PROTOCOL.key
Ed Maste 38a52bd3b5 ssh: update to OpenSSH 9.1p1
Release notes are available at https://www.openssh.com/txt/release-9.1

9.1 contains fixes for three minor memory safety problems; these have
lready been merged to the copy of OpenSSH 9.0 that is in the FreeBSD base
system.

Some highlights copied from the release notes:

Potentially-incompatible changes
--------------------------------

 * ssh(1), sshd(8): SetEnv directives in ssh_config and sshd_config
   are now first-match-wins to match other directives. Previously
   if an environment variable was multiply specified the last set
   value would have been used. bz3438

 * ssh-keygen(8): ssh-keygen -A (generate all default host key types)
   will no longer generate DSA keys, as these are insecure and have
   not been used by default for some years.

New features
------------

 * ssh(1), sshd(8): add a RequiredRSASize directive to set a minimum
   RSA key length. Keys below this length will be ignored for user
   authentication and for host authentication in sshd(8).

 * sftp-server(8): add a "users-groups-by-id@openssh.com" extension
   request that allows the client to obtain user/group names that
   correspond to a set of uids/gids.

 * sftp(1): use "users-groups-by-id@openssh.com" sftp-server
   extension (when available) to fill in user/group names for
   directory listings.

 * sftp-server(8): support the "home-directory" extension request
   defined in draft-ietf-secsh-filexfer-extensions-00. This overlaps
   a bit with the existing "expand-path@openssh.com", but some other
   clients support it.

 * ssh-keygen(1), sshd(8): allow certificate validity intervals,
   sshsig verification times and authorized_keys expiry-time options
   to accept dates in the UTC time zone in addition to the default
   of interpreting them in the system time zone. YYYYMMDD and
   YYMMDDHHMM[SS] dates/times will be interpreted as UTC if suffixed
   with a 'Z' character.

   Also allow certificate validity intervals to be specified in raw
   seconds-since-epoch as hex value, e.g. -V 0x1234:0x4567890. This
   is intended for use by regress tests and other tools that call
   ssh-keygen as part of a CA workflow. bz3468

 * sftp(1): allow arguments to the sftp -D option, e.g. sftp -D
   "/usr/libexec/sftp-server -el debug3"

 * ssh-keygen(1): allow the existing -U (use agent) flag to work
   with "-Y sign" operations, where it will be interpreted to require
   that the private keys is hosted in an agent; bz3429

MFC after:	2 weeks
Relnotes:	Yes
Sponsored by:	The FreeBSD Foundation
2022-10-19 10:27:11 -04:00

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This document describes the private key format for OpenSSH.
1. Overall format
The key consists of a header, a list of public keys, and
an encrypted list of matching private keys.
#define AUTH_MAGIC "openssh-key-v1"
byte[] AUTH_MAGIC
string ciphername
string kdfname
string kdfoptions
uint32 number of keys N
string publickey1
string publickey2
...
string publickeyN
string encrypted, padded list of private keys
2. KDF options for kdfname "bcrypt"
The options:
string salt
uint32 rounds
are concatenated and represented as a string.
3. Unencrypted list of N private keys
The list of privatekey/comment pairs is padded with the
bytes 1, 2, 3, ... until the total length is a multiple
of the cipher block size.
uint32 checkint
uint32 checkint
byte[] privatekey1
string comment1
byte[] privatekey2
string comment2
...
string privatekeyN
string commentN
byte 1
byte 2
byte 3
...
byte padlen % 255
where each private key is encoded using the same rules as used for
SSH agent.
Before the key is encrypted, a random integer is assigned
to both checkint fields so successful decryption can be
quickly checked by verifying that both checkint fields
hold the same value.
4. Encryption
The KDF is used to derive a key, IV (and other values required by
the cipher) from the passphrase. These values are then used to
encrypt the unencrypted list of private keys.
5. No encryption
For unencrypted keys the cipher "none" and the KDF "none"
are used with empty passphrases. The options if the KDF "none"
are the empty string.
$OpenBSD: PROTOCOL.key,v 1.3 2022/07/01 04:45:50 djm Exp $