Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.217
1.217 ! djm 1: .\" $OpenBSD: ssh-keygen.1,v 1.216 2021/08/11 08:54:17 djm Exp $
1.1 deraadt 2: .\"
3: .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
4: .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: .\" All rights reserved
6: .\"
1.22 deraadt 7: .\" As far as I am concerned, the code I have written for this software
8: .\" can be used freely for any purpose. Any derived versions of this
9: .\" software must be clearly marked as such, and if the derived work is
10: .\" incompatible with the protocol description in the RFC file, it must be
11: .\" called by a name other than "ssh" or "Secure Shell".
12: .\"
13: .\"
1.33 deraadt 14: .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
15: .\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
16: .\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
1.22 deraadt 17: .\"
18: .\" Redistribution and use in source and binary forms, with or without
19: .\" modification, are permitted provided that the following conditions
20: .\" are met:
21: .\" 1. Redistributions of source code must retain the above copyright
22: .\" notice, this list of conditions and the following disclaimer.
23: .\" 2. Redistributions in binary form must reproduce the above copyright
24: .\" notice, this list of conditions and the following disclaimer in the
25: .\" documentation and/or other materials provided with the distribution.
1.1 deraadt 26: .\"
1.22 deraadt 27: .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28: .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29: .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30: .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31: .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32: .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33: .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34: .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35: .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36: .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.1 deraadt 37: .\"
1.217 ! djm 38: .Dd $Mdocdate: August 11 2021 $
1.2 deraadt 39: .Dt SSH-KEYGEN 1
40: .Os
41: .Sh NAME
42: .Nm ssh-keygen
1.179 jmc 43: .Nd OpenSSH authentication key utility
1.2 deraadt 44: .Sh SYNOPSIS
45: .Nm ssh-keygen
1.25 markus 46: .Op Fl q
1.205 solene 47: .Op Fl a Ar rounds
1.2 deraadt 48: .Op Fl b Ar bits
49: .Op Fl C Ar comment
1.20 markus 50: .Op Fl f Ar output_keyfile
1.155 djm 51: .Op Fl m Ar format
1.171 jmc 52: .Op Fl N Ar new_passphrase
1.191 naddy 53: .Op Fl O Ar option
1.205 solene 54: .Op Fl t Cm dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa
1.173 naddy 55: .Op Fl w Ar provider
1.212 dtucker 56: .Op Fl Z Ar cipher
1.2 deraadt 57: .Nm ssh-keygen
58: .Fl p
1.205 solene 59: .Op Fl a Ar rounds
1.9 markus 60: .Op Fl f Ar keyfile
1.155 djm 61: .Op Fl m Ar format
1.171 jmc 62: .Op Fl N Ar new_passphrase
63: .Op Fl P Ar old_passphrase
1.212 dtucker 64: .Op Fl Z Ar cipher
1.2 deraadt 65: .Nm ssh-keygen
1.37 markus 66: .Fl i
1.171 jmc 67: .Op Fl f Ar input_keyfile
1.95 djm 68: .Op Fl m Ar key_format
1.16 deraadt 69: .Nm ssh-keygen
1.37 markus 70: .Fl e
1.171 jmc 71: .Op Fl f Ar input_keyfile
1.95 djm 72: .Op Fl m Ar key_format
1.16 deraadt 73: .Nm ssh-keygen
1.17 markus 74: .Fl y
1.20 markus 75: .Op Fl f Ar input_keyfile
1.17 markus 76: .Nm ssh-keygen
1.2 deraadt 77: .Fl c
1.205 solene 78: .Op Fl a Ar rounds
1.2 deraadt 79: .Op Fl C Ar comment
1.9 markus 80: .Op Fl f Ar keyfile
1.171 jmc 81: .Op Fl P Ar passphrase
1.9 markus 82: .Nm ssh-keygen
83: .Fl l
1.125 naddy 84: .Op Fl v
1.124 djm 85: .Op Fl E Ar fingerprint_hash
1.35 markus 86: .Op Fl f Ar input_keyfile
87: .Nm ssh-keygen
88: .Fl B
1.20 markus 89: .Op Fl f Ar input_keyfile
1.48 jakob 90: .Nm ssh-keygen
1.82 jmc 91: .Fl D Ar pkcs11
1.48 jakob 92: .Nm ssh-keygen
1.64 djm 93: .Fl F Ar hostname
1.170 jmc 94: .Op Fl lv
1.64 djm 95: .Op Fl f Ar known_hosts_file
96: .Nm ssh-keygen
97: .Fl H
98: .Op Fl f Ar known_hosts_file
99: .Nm ssh-keygen
1.187 djm 100: .Fl K
1.205 solene 101: .Op Fl a Ar rounds
1.187 djm 102: .Op Fl w Ar provider
103: .Nm ssh-keygen
1.64 djm 104: .Fl R Ar hostname
105: .Op Fl f Ar known_hosts_file
1.57 jakob 106: .Nm ssh-keygen
107: .Fl r Ar hostname
1.170 jmc 108: .Op Fl g
1.57 jakob 109: .Op Fl f Ar input_keyfile
1.60 djm 110: .Nm ssh-keygen
1.184 djm 111: .Fl M Cm generate
112: .Op Fl O Ar option
1.191 naddy 113: .Ar output_file
1.60 djm 114: .Nm ssh-keygen
1.184 djm 115: .Fl M Cm screen
1.191 naddy 116: .Op Fl f Ar input_file
1.184 djm 117: .Op Fl O Ar option
1.191 naddy 118: .Ar output_file
1.84 djm 119: .Nm ssh-keygen
1.171 jmc 120: .Fl I Ar certificate_identity
1.84 djm 121: .Fl s Ar ca_key
1.170 jmc 122: .Op Fl hU
1.142 djm 123: .Op Fl D Ar pkcs11_provider
1.84 djm 124: .Op Fl n Ar principals
1.93 djm 125: .Op Fl O Ar option
1.84 djm 126: .Op Fl V Ar validity_interval
1.93 djm 127: .Op Fl z Ar serial_number
1.84 djm 128: .Ar
1.86 djm 129: .Nm ssh-keygen
130: .Fl L
131: .Op Fl f Ar input_keyfile
1.102 stevesk 132: .Nm ssh-keygen
133: .Fl A
1.205 solene 134: .Op Fl a Ar rounds
1.143 djm 135: .Op Fl f Ar prefix_path
1.111 djm 136: .Nm ssh-keygen
137: .Fl k
138: .Fl f Ar krl_file
139: .Op Fl u
1.112 jmc 140: .Op Fl s Ar ca_public
141: .Op Fl z Ar version_number
1.111 djm 142: .Ar
143: .Nm ssh-keygen
144: .Fl Q
1.203 djm 145: .Op Fl l
1.111 djm 146: .Fl f Ar krl_file
147: .Ar
1.163 djm 148: .Nm ssh-keygen
1.196 djm 149: .Fl Y Cm find-principals
1.214 djm 150: .Op Fl O Ar option
1.194 djm 151: .Fl s Ar signature_file
152: .Fl f Ar allowed_signers_file
153: .Nm ssh-keygen
1.217 ! djm 154: .Fl Y Cm match-principals
! 155: .Op Fl O Ar option
! 156: .Fl I Ar signer_identity
! 157: .Fl f Ar allowed_signers_file
! 158: .Nm ssh-keygen
1.171 jmc 159: .Fl Y Cm check-novalidate
1.214 djm 160: .Op Fl O Ar option
1.171 jmc 161: .Fl n Ar namespace
162: .Fl s Ar signature_file
163: .Nm ssh-keygen
1.163 djm 164: .Fl Y Cm sign
165: .Fl f Ar key_file
166: .Fl n Ar namespace
167: .Ar
168: .Nm ssh-keygen
169: .Fl Y Cm verify
1.214 djm 170: .Op Fl O Ar option
1.171 jmc 171: .Fl f Ar allowed_signers_file
1.163 djm 172: .Fl I Ar signer_identity
173: .Fl n Ar namespace
174: .Fl s Ar signature_file
175: .Op Fl r Ar revocation_file
1.13 aaron 176: .Sh DESCRIPTION
1.2 deraadt 177: .Nm
1.37 markus 178: generates, manages and converts authentication keys for
1.2 deraadt 179: .Xr ssh 1 .
1.15 deraadt 180: .Nm
1.140 jmc 181: can create keys for use by SSH protocol version 2.
1.130 jmc 182: .Pp
1.58 jmc 183: The type of key to be generated is specified with the
1.25 markus 184: .Fl t
1.52 djm 185: option.
1.70 djm 186: If invoked without any arguments,
187: .Nm
1.141 naddy 188: will generate an RSA key.
1.15 deraadt 189: .Pp
1.60 djm 190: .Nm
191: is also used to generate groups for use in Diffie-Hellman group
192: exchange (DH-GEX).
193: See the
194: .Sx MODULI GENERATION
195: section for details.
196: .Pp
1.111 djm 197: Finally,
198: .Nm
199: can be used to generate and update Key Revocation Lists, and to test whether
1.112 jmc 200: given keys have been revoked by one.
201: See the
1.111 djm 202: .Sx KEY REVOCATION LISTS
203: section for details.
204: .Pp
1.2 deraadt 205: Normally each user wishing to use SSH
1.99 djm 206: with public key authentication runs this once to create the authentication
1.1 deraadt 207: key in
1.118 naddy 208: .Pa ~/.ssh/id_dsa ,
1.99 djm 209: .Pa ~/.ssh/id_ecdsa ,
1.173 naddy 210: .Pa ~/.ssh/id_ecdsa_sk ,
1.176 naddy 211: .Pa ~/.ssh/id_ed25519 ,
212: .Pa ~/.ssh/id_ed25519_sk
1.15 deraadt 213: or
1.68 djm 214: .Pa ~/.ssh/id_rsa .
1.15 deraadt 215: Additionally, the system administrator may use this to generate host keys,
216: as seen in
217: .Pa /etc/rc .
1.2 deraadt 218: .Pp
1.1 deraadt 219: Normally this program generates the key and asks for a file in which
1.12 aaron 220: to store the private key.
221: The public key is stored in a file with the same name but
1.2 deraadt 222: .Dq .pub
1.12 aaron 223: appended.
224: The program also asks for a passphrase.
225: The passphrase may be empty to indicate no passphrase
1.26 markus 226: (host keys must have an empty passphrase), or it may be a string of
1.12 aaron 227: arbitrary length.
1.51 stevesk 228: A passphrase is similar to a password, except it can be a phrase with a
229: series of words, punctuation, numbers, whitespace, or any string of
230: characters you want.
231: Good passphrases are 10-30 characters long, are
1.1 deraadt 232: not simple sentences or otherwise easily guessable (English
1.42 markus 233: prose has only 1-2 bits of entropy per character, and provides very bad
1.51 stevesk 234: passphrases), and contain a mix of upper and lowercase letters,
235: numbers, and non-alphanumeric characters.
1.12 aaron 236: The passphrase can be changed later by using the
1.2 deraadt 237: .Fl p
1.1 deraadt 238: option.
1.2 deraadt 239: .Pp
1.12 aaron 240: There is no way to recover a lost passphrase.
1.105 djm 241: If the passphrase is lost or forgotten, a new key must be generated
242: and the corresponding public key copied to other machines.
1.2 deraadt 243: .Pp
1.153 djm 244: .Nm
245: will by default write keys in an OpenSSH-specific format.
246: This format is preferred as it offers better protection for
247: keys at rest as well as allowing storage of key comments within
248: the private key file itself.
249: The key comment may be useful to help identify the key.
1.12 aaron 250: The comment is initialized to
1.2 deraadt 251: .Dq user@host
252: when the key is created, but can be changed using the
253: .Fl c
1.1 deraadt 254: option.
1.153 djm 255: .Pp
256: It is still possible for
257: .Nm
258: to write the previously-used PEM format private keys using the
259: .Fl m
260: flag.
261: This may be used when generating new keys, and existing new-format
262: keys may be converted using this option in conjunction with the
263: .Fl p
264: (change passphrase) flag.
1.2 deraadt 265: .Pp
1.205 solene 266: After a key is generated,
267: .Nm
268: will ask where the keys
1.15 deraadt 269: should be placed to be activated.
270: .Pp
1.2 deraadt 271: The options are as follows:
272: .Bl -tag -width Ds
1.102 stevesk 273: .It Fl A
1.175 djm 274: For each of the key types (rsa, dsa, ecdsa and ed25519)
1.118 naddy 275: for which host keys
1.102 stevesk 276: do not exist, generate the host keys with the default key file path,
277: an empty passphrase, default bits for the key type, and default comment.
1.144 jmc 278: If
1.143 djm 279: .Fl f
1.144 jmc 280: has also been specified, its argument is used as a prefix to the
1.143 djm 281: default path for the resulting host key files.
1.104 jmc 282: This is used by
1.102 stevesk 283: .Pa /etc/rc
284: to generate new host keys.
1.117 djm 285: .It Fl a Ar rounds
1.169 jmc 286: When saving a private key, this option specifies the number of KDF
1.211 dtucker 287: (key derivation function, currently
288: .Xr bcrypt_pbkdf 3 )
289: rounds used.
1.117 djm 290: Higher numbers result in slower passphrase verification and increased
291: resistance to brute-force password cracking (should the keys be stolen).
1.204 dtucker 292: The default is 16 rounds.
1.66 jmc 293: .It Fl B
294: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 295: .It Fl b Ar bits
1.12 aaron 296: Specifies the number of bits in the key to create.
1.158 dtucker 297: For RSA keys, the minimum size is 1024 bits and the default is 3072 bits.
298: Generally, 3072 bits is considered sufficient.
1.72 dtucker 299: DSA keys must be exactly 1024 bits as specified by FIPS 186-2.
1.106 djm 300: For ECDSA keys, the
301: .Fl b
1.107 deraadt 302: flag determines the key length by selecting from one of three elliptic
1.106 djm 303: curve sizes: 256, 384 or 521 bits.
304: Attempting to use bit lengths other than these three values for ECDSA keys
305: will fail.
1.176 naddy 306: ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the
1.118 naddy 307: .Fl b
308: flag will be ignored.
1.66 jmc 309: .It Fl C Ar comment
310: Provides a new comment.
1.2 deraadt 311: .It Fl c
1.1 deraadt 312: Requests changing the comment in the private and public key files.
313: The program will prompt for the file containing the private keys, for
1.41 stevesk 314: the passphrase if the key has one, and for the new comment.
1.81 markus 315: .It Fl D Ar pkcs11
1.157 naddy 316: Download the public keys provided by the PKCS#11 shared library
1.83 markus 317: .Ar pkcs11 .
1.98 djm 318: When used in combination with
319: .Fl s ,
320: this option indicates that a CA key resides in a PKCS#11 token (see the
321: .Sx CERTIFICATES
322: section for details).
1.124 djm 323: .It Fl E Ar fingerprint_hash
324: Specifies the hash algorithm used when displaying key fingerprints.
325: Valid options are:
326: .Dq md5
327: and
328: .Dq sha256 .
329: The default is
330: .Dq sha256 .
1.37 markus 331: .It Fl e
1.40 markus 332: This option will read a private or public OpenSSH key file and
1.154 djm 333: print to stdout a public key in one of the formats specified by the
1.95 djm 334: .Fl m
335: option.
336: The default export format is
337: .Dq RFC4716 .
1.96 jmc 338: This option allows exporting OpenSSH keys for use by other programs, including
1.95 djm 339: several commercial SSH implementations.
1.151 djm 340: .It Fl F Ar hostname | [hostname]:port
1.66 jmc 341: Search for the specified
342: .Ar hostname
1.151 djm 343: (with optional port number)
1.66 jmc 344: in a
345: .Pa known_hosts
346: file, listing any occurrences found.
347: This option is useful to find hashed host names or addresses and may also be
348: used in conjunction with the
349: .Fl H
350: option to print found keys in a hashed format.
351: .It Fl f Ar filename
352: Specifies the filename of the key file.
1.57 jakob 353: .It Fl g
1.62 jakob 354: Use generic DNS format when printing fingerprint resource records using the
1.63 jmc 355: .Fl r
1.62 jakob 356: command.
1.66 jmc 357: .It Fl H
358: Hash a
359: .Pa known_hosts
1.67 dtucker 360: file.
361: This replaces all hostnames and addresses with hashed representations
362: within the specified file; the original content is moved to a file with
363: a .old suffix.
1.66 jmc 364: These hashes may be used normally by
365: .Nm ssh
366: and
367: .Nm sshd ,
368: but they do not reveal identifying information should the file's contents
369: be disclosed.
370: This option will not modify existing hashed hostnames and is therefore safe
371: to use on files that mix hashed and non-hashed names.
1.84 djm 372: .It Fl h
373: When signing a key, create a host certificate instead of a user
374: certificate.
375: Please see the
376: .Sx CERTIFICATES
377: section for details.
1.85 jmc 378: .It Fl I Ar certificate_identity
1.84 djm 379: Specify the key identity when signing a public key.
380: Please see the
381: .Sx CERTIFICATES
382: section for details.
1.37 markus 383: .It Fl i
384: This option will read an unencrypted private (or public) key file
1.95 djm 385: in the format specified by the
386: .Fl m
387: option and print an OpenSSH compatible private
1.37 markus 388: (or public) key to stdout.
1.122 jmc 389: This option allows importing keys from other software, including several
390: commercial SSH implementations.
391: The default import format is
392: .Dq RFC4716 .
1.188 jmc 393: .It Fl K
1.187 djm 394: Download resident keys from a FIDO authenticator.
395: Public and private key files will be written to the current directory for
396: each downloaded key.
1.207 djm 397: If multiple FIDO authenticators are attached, keys will be downloaded from
398: the first touched authenticator.
1.111 djm 399: .It Fl k
400: Generate a KRL file.
401: In this mode,
402: .Nm
403: will generate a KRL file at the location specified via the
404: .Fl f
1.114 jmc 405: flag that revokes every key or certificate presented on the command line.
1.111 djm 406: Keys/certificates to be revoked may be specified by public key file or
407: using the format described in the
408: .Sx KEY REVOCATION LISTS
409: section.
1.86 djm 410: .It Fl L
1.129 djm 411: Prints the contents of one or more certificates.
1.9 markus 412: .It Fl l
1.77 grunk 413: Show fingerprint of specified public key file.
1.50 markus 414: For RSA and DSA keys
415: .Nm
1.78 jmc 416: tries to find the matching public key file and prints its fingerprint.
417: If combined with
418: .Fl v ,
1.132 jmc 419: a visual ASCII art representation of the key is supplied with the
1.131 djm 420: fingerprint.
1.184 djm 421: .It Fl M Cm generate
422: Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for
423: eventual use by the
424: .Sq diffie-hellman-group-exchange-*
425: key exchange methods.
426: The numbers generated by this operation must be further screened before
427: use.
428: See the
429: .Sx MODULI GENERATION
430: section for more information.
431: .It Fl M Cm screen
432: Screen candidate parameters for Diffie-Hellman Group Exchange.
433: This will accept a list of candidate numbers and test that they are
434: safe (Sophie Germain) primes with acceptable group generators.
435: The results of this operation may be added to the
436: .Pa /etc/moduli
437: file.
438: See the
439: .Sx MODULI GENERATION
440: section for more information.
1.95 djm 441: .It Fl m Ar key_format
1.155 djm 442: Specify a key format for key generation, the
1.95 djm 443: .Fl i
1.155 djm 444: (import),
1.95 djm 445: .Fl e
1.155 djm 446: (export) conversion options, and the
447: .Fl p
448: change passphrase operation.
449: The latter may be used to convert between OpenSSH private key and PEM
450: private key formats.
1.95 djm 451: The supported key formats are:
452: .Dq RFC4716
1.96 jmc 453: (RFC 4716/SSH2 public or private key),
1.95 djm 454: .Dq PKCS8
1.161 djm 455: (PKCS8 public or private key)
1.95 djm 456: or
457: .Dq PEM
458: (PEM public key).
1.161 djm 459: By default OpenSSH will write newly-generated private keys in its own
460: format, but when converting public keys for export the default format is
1.95 djm 461: .Dq RFC4716 .
1.148 djm 462: Setting a format of
463: .Dq PEM
464: when generating or updating a supported private key type will cause the
465: key to be stored in the legacy PEM private key format.
1.66 jmc 466: .It Fl N Ar new_passphrase
467: Provides the new passphrase.
1.84 djm 468: .It Fl n Ar principals
469: Specify one or more principals (user or host names) to be included in
470: a certificate when signing a key.
471: Multiple principals may be specified, separated by commas.
472: Please see the
473: .Sx CERTIFICATES
474: section for details.
1.93 djm 475: .It Fl O Ar option
1.184 djm 476: Specify a key/value option.
477: These are specific to the operation that
478: .Nm
479: has been requested to perform.
480: .Pp
481: When signing certificates, one of the options listed in the
1.183 djm 482: .Sx CERTIFICATES
1.184 djm 483: section may be specified here.
484: .Pp
485: When performing moduli generation or screening, one of the options
486: listed in the
487: .Sx MODULI GENERATION
488: section may be specified.
489: .Pp
1.190 jmc 490: When generating a key that will be hosted on a FIDO authenticator,
491: this flag may be used to specify key-specific options.
492: Those supported at present are:
493: .Bl -tag -width Ds
494: .It Cm application
495: Override the default FIDO application/origin string of
1.189 djm 496: .Dq ssh: .
1.190 jmc 497: This may be useful when generating host or domain-specific resident keys.
1.200 djm 498: The specified application string must begin with
499: .Dq ssh: .
1.199 jmc 500: .It Cm challenge Ns = Ns Ar path
1.198 jmc 501: Specifies a path to a challenge string that will be passed to the
502: FIDO token during key generation.
1.199 jmc 503: The challenge string may be used as part of an out-of-band
504: protocol for key enrollment
505: (a random challenge is used by default).
1.190 jmc 506: .It Cm device
507: Explicitly specify a
1.189 djm 508: .Xr fido 4
509: device to use, rather than letting the token middleware select one.
1.190 jmc 510: .It Cm no-touch-required
511: Indicate that the generated private key should not require touch
1.185 djm 512: events (user presence) when making signatures.
513: Note that
514: .Xr sshd 8
515: will refuse such signatures by default, unless overridden via
516: an authorized_keys option.
1.190 jmc 517: .It Cm resident
518: Indicate that the key should be stored on the FIDO authenticator itself.
1.185 djm 519: Resident keys may be supported on FIDO2 tokens and typically require that
520: a PIN be set on the token prior to generation.
521: Resident keys may be loaded off the token using
522: .Xr ssh-add 1 .
1.190 jmc 523: .It Cm user
524: A username to be associated with a resident key,
1.189 djm 525: overriding the empty default username.
526: Specifying a username may be useful when generating multiple resident keys
527: for the same application name.
1.206 djm 528: .It Cm verify-required
529: Indicate that this private key should require user verification for
530: each signature.
1.208 jmc 531: Not all FIDO tokens support this option.
1.206 djm 532: Currently PIN authentication is the only supported verification method,
533: but other methods may be supported in the future.
1.199 jmc 534: .It Cm write-attestation Ns = Ns Ar path
1.209 djm 535: May be used at key generation time to record the attestation data
1.197 djm 536: returned from FIDO tokens during key generation.
1.209 djm 537: Please note that this information is potentially sensitive.
538: By default, this information is discarded.
1.190 jmc 539: .El
1.185 djm 540: .Pp
1.214 djm 541: When performing signature-related options using the
542: .Fl Y
543: flag, the following options are accepted:
544: .Bl -tag -width Ds
1.216 djm 545: .It Cm print-pubkey
546: Print the full public key to standard output after signature verification.
1.214 djm 547: .It Cm verify-time Ns = Ns Ar timestamp
548: Specifies a time to use when validating signatures instead of the current
549: time.
550: The time may be specified as a date in YYYYMMDD format or a time
551: in YYYYMMDDHHMM[SS] format.
552: .El
553: .Pp
1.185 djm 554: The
555: .Fl O
556: option may be specified multiple times.
1.66 jmc 557: .It Fl P Ar passphrase
558: Provides the (old) passphrase.
1.2 deraadt 559: .It Fl p
1.1 deraadt 560: Requests changing the passphrase of a private key file instead of
1.12 aaron 561: creating a new private key.
562: The program will prompt for the file
1.1 deraadt 563: containing the private key, for the old passphrase, and twice for the
564: new passphrase.
1.113 jmc 565: .It Fl Q
566: Test whether keys have been revoked in a KRL.
1.203 djm 567: If the
568: .Fl l
569: option is also specified then the contents of the KRL will be printed.
1.5 aaron 570: .It Fl q
571: Silence
572: .Nm ssh-keygen .
1.152 djm 573: .It Fl R Ar hostname | [hostname]:port
1.151 djm 574: Removes all keys belonging to the specified
1.64 djm 575: .Ar hostname
1.151 djm 576: (with optional port number)
1.65 jmc 577: from a
1.64 djm 578: .Pa known_hosts
579: file.
1.65 jmc 580: This option is useful to delete hashed hosts (see the
1.64 djm 581: .Fl H
582: option above).
1.66 jmc 583: .It Fl r Ar hostname
584: Print the SSHFP fingerprint resource record named
585: .Ar hostname
586: for the specified public key file.
1.84 djm 587: .It Fl s Ar ca_key
588: Certify (sign) a public key using the specified CA key.
589: Please see the
590: .Sx CERTIFICATES
591: section for details.
1.111 djm 592: .Pp
593: When generating a KRL,
594: .Fl s
1.112 jmc 595: specifies a path to a CA public key file used to revoke certificates directly
1.111 djm 596: by key ID or serial number.
597: See the
598: .Sx KEY REVOCATION LISTS
599: section for details.
1.175 djm 600: .It Fl t Cm dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa
1.66 jmc 601: Specifies the type of key to create.
602: The possible values are
1.100 naddy 603: .Dq dsa ,
1.118 naddy 604: .Dq ecdsa ,
1.173 naddy 605: .Dq ecdsa-sk ,
1.118 naddy 606: .Dq ed25519 ,
1.175 djm 607: .Dq ed25519-sk ,
1.100 naddy 608: or
1.139 jmc 609: .Dq rsa .
1.159 djm 610: .Pp
611: This flag may also be used to specify the desired signature type when
1.160 jmc 612: signing certificates using an RSA CA key.
1.159 djm 613: The available RSA signature variants are
614: .Dq ssh-rsa
615: (SHA1 signatures, not recommended),
1.160 jmc 616: .Dq rsa-sha2-256 ,
617: and
1.159 djm 618: .Dq rsa-sha2-512
619: (the default).
1.142 djm 620: .It Fl U
621: When used in combination with
622: .Fl s ,
623: this option indicates that a CA key resides in a
624: .Xr ssh-agent 1 .
625: See the
626: .Sx CERTIFICATES
627: section for more information.
1.112 jmc 628: .It Fl u
629: Update a KRL.
630: When specified with
631: .Fl k ,
1.114 jmc 632: keys listed via the command line are added to the existing KRL rather than
1.112 jmc 633: a new KRL being created.
1.84 djm 634: .It Fl V Ar validity_interval
635: Specify a validity interval when signing a certificate.
636: A validity interval may consist of a single time, indicating that the
637: certificate is valid beginning now and expiring at that time, or may consist
638: of two times separated by a colon to indicate an explicit time interval.
1.145 djm 639: .Pp
640: The start time may be specified as the string
641: .Dq always
642: to indicate the certificate has no specified start time,
1.147 djm 643: a date in YYYYMMDD format, a time in YYYYMMDDHHMM[SS] format,
1.145 djm 644: a relative time (to the current time) consisting of a minus sign followed by
645: an interval in the format described in the
1.116 jmc 646: TIME FORMATS section of
1.90 jmc 647: .Xr sshd_config 5 .
1.145 djm 648: .Pp
1.147 djm 649: The end time may be specified as a YYYYMMDD date, a YYYYMMDDHHMM[SS] time,
1.145 djm 650: a relative time starting with a plus character or the string
651: .Dq forever
1.202 dtucker 652: to indicate that the certificate has no expiry date.
1.84 djm 653: .Pp
654: For example:
655: .Dq +52w1d
656: (valid from now to 52 weeks and one day from now),
657: .Dq -4w:+4w
658: (valid from four weeks ago to four weeks from now),
659: .Dq 20100101123000:20110101123000
660: (valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011),
661: .Dq -1d:20110101
1.210 dtucker 662: (valid from yesterday to midnight, January 1st, 2011),
1.145 djm 663: .Dq -1m:forever
664: (valid from one minute ago and never expiring).
1.61 djm 665: .It Fl v
666: Verbose mode.
667: Causes
668: .Nm
669: to print debugging messages about its progress.
670: This is helpful for debugging moduli generation.
671: Multiple
672: .Fl v
673: options increase the verbosity.
674: The maximum is 3.
1.173 naddy 675: .It Fl w Ar provider
1.180 naddy 676: Specifies a path to a library that will be used when creating
677: FIDO authenticator-hosted keys, overriding the default of using
678: the internal USB HID support.
1.196 djm 679: .It Fl Y Cm find-principals
680: Find the principal(s) associated with the public key of a signature,
1.194 djm 681: provided using the
682: .Fl s
683: flag in an authorized signers file provided using the
684: .Fl f
685: flag.
686: The format of the allowed signers file is documented in the
687: .Sx ALLOWED SIGNERS
1.195 jmc 688: section below.
1.217 ! djm 689: If one or more matching principals are found, they are returned on
! 690: standard output.
! 691: .It Fl Y Cm match-principals
! 692: Find principal matching the principal name provided using the
! 693: .Fl I
! 694: flag in the authorized signers file specified using the
! 695: .Fl f
! 696: flag.
1.196 djm 697: If one or more matching principals are found, they are returned on
698: standard output.
1.182 jmc 699: .It Fl Y Cm check-novalidate
700: Checks that a signature generated using
701: .Nm
702: .Fl Y Cm sign
703: has a valid structure.
704: This does not validate if a signature comes from an authorized signer.
705: When testing a signature,
706: .Nm
707: accepts a message on standard input and a signature namespace using
708: .Fl n .
709: A file containing the corresponding signature must also be supplied using the
710: .Fl s
711: flag.
712: Successful testing of the signature is signalled by
713: .Nm
714: returning a zero exit status.
1.166 jmc 715: .It Fl Y Cm sign
1.163 djm 716: Cryptographically sign a file or some data using a SSH key.
717: When signing,
718: .Nm
719: accepts zero or more files to sign on the command-line - if no files
720: are specified then
721: .Nm
722: will sign data presented on standard input.
723: Signatures are written to the path of the input file with
724: .Dq .sig
725: appended, or to standard output if the message to be signed was read from
726: standard input.
727: .Pp
728: The key used for signing is specified using the
729: .Fl f
730: option and may refer to either a private key, or a public key with the private
731: half available via
732: .Xr ssh-agent 1 .
733: An additional signature namespace, used to prevent signature confusion across
734: different domains of use (e.g. file signing vs email signing) must be provided
735: via the
736: .Fl n
737: flag.
738: Namespaces are arbitrary strings, and may include:
739: .Dq file
740: for file signing,
741: .Dq email
742: for email signing.
743: For custom uses, it is recommended to use names following a
744: NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces.
1.166 jmc 745: .It Fl Y Cm verify
1.163 djm 746: Request to verify a signature generated using
747: .Nm
1.166 jmc 748: .Fl Y Cm sign
1.163 djm 749: as described above.
750: When verifying a signature,
751: .Nm
752: accepts a message on standard input and a signature namespace using
753: .Fl n .
754: A file containing the corresponding signature must also be supplied using the
755: .Fl s
756: flag, along with the identity of the signer using
757: .Fl I
758: and a list of allowed signers via the
759: .Fl f
760: flag.
761: The format of the allowed signers file is documented in the
762: .Sx ALLOWED SIGNERS
763: section below.
764: A file containing revoked keys can be passed using the
765: .Fl r
1.165 jmc 766: flag.
767: The revocation file may be a KRL or a one-per-line list of public keys.
1.163 djm 768: Successful verification by an authorized signer is signalled by
769: .Nm
770: returning a zero exit status.
1.181 jmc 771: .It Fl y
772: This option will read a private
773: OpenSSH format file and print an OpenSSH public key to stdout.
1.212 dtucker 774: .It Fl Z Ar cipher
775: Specifies the cipher to use for encryption when writing an OpenSSH-format
776: private key file.
777: The list of available ciphers may be obtained using
778: .Qq ssh -Q cipher .
779: The default is
780: .Dq aes256-ctr .
1.93 djm 781: .It Fl z Ar serial_number
782: Specifies a serial number to be embedded in the certificate to distinguish
783: this certificate from others from the same CA.
1.156 djm 784: If the
785: .Ar serial_number
786: is prefixed with a
787: .Sq +
788: character, then the serial number will be incremented for each certificate
789: signed on a single command-line.
1.93 djm 790: The default serial number is zero.
1.111 djm 791: .Pp
792: When generating a KRL, the
793: .Fl z
794: flag is used to specify a KRL version number.
1.2 deraadt 795: .El
1.60 djm 796: .Sh MODULI GENERATION
797: .Nm
798: may be used to generate groups for the Diffie-Hellman Group Exchange
799: (DH-GEX) protocol.
800: Generating these groups is a two-step process: first, candidate
801: primes are generated using a fast, but memory intensive process.
802: These candidate primes are then tested for suitability (a CPU-intensive
803: process).
804: .Pp
805: Generation of primes is performed using the
1.184 djm 806: .Fl M Cm generate
1.60 djm 807: option.
808: The desired length of the primes may be specified by the
1.184 djm 809: .Fl O Cm bits
1.60 djm 810: option.
811: For example:
812: .Pp
1.184 djm 813: .Dl # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates
1.60 djm 814: .Pp
815: By default, the search for primes begins at a random point in the
816: desired length range.
817: This may be overridden using the
1.184 djm 818: .Fl O Cm start
1.60 djm 819: option, which specifies a different start point (in hex).
820: .Pp
1.109 dtucker 821: Once a set of candidates have been generated, they must be screened for
1.60 djm 822: suitability.
823: This may be performed using the
1.184 djm 824: .Fl M Cm screen
1.60 djm 825: option.
826: In this mode
827: .Nm
828: will read candidates from standard input (or a file specified using the
829: .Fl f
830: option).
831: For example:
832: .Pp
1.184 djm 833: .Dl # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048
1.60 djm 834: .Pp
835: By default, each candidate will be subjected to 100 primality tests.
836: This may be overridden using the
1.184 djm 837: .Fl O Cm prime-tests
1.60 djm 838: option.
839: The DH generator value will be chosen automatically for the
840: prime under consideration.
841: If a specific generator is desired, it may be requested using the
1.184 djm 842: .Fl O Cm generator
1.60 djm 843: option.
1.66 jmc 844: Valid generator values are 2, 3, and 5.
1.60 djm 845: .Pp
846: Screened DH groups may be installed in
847: .Pa /etc/moduli .
1.213 dtucker 848: It is important that this file contains moduli of a range of bit lengths.
1.184 djm 849: .Pp
850: A number of options are available for moduli generation and screening via the
851: .Fl O
852: flag:
1.186 jmc 853: .Bl -tag -width Ds
1.184 djm 854: .It Ic lines Ns = Ns Ar number
855: Exit after screening the specified number of lines while performing DH
856: candidate screening.
857: .It Ic start-line Ns = Ns Ar line-number
858: Start screening at the specified line number while performing DH candidate
859: screening.
860: .It Ic checkpoint Ns = Ns Ar filename
861: Write the last line processed to the specified file while performing DH
862: candidate screening.
863: This will be used to skip lines in the input file that have already been
864: processed if the job is restarted.
865: .It Ic memory Ns = Ns Ar mbytes
866: Specify the amount of memory to use (in megabytes) when generating
867: candidate moduli for DH-GEX.
868: .It Ic start Ns = Ns Ar hex-value
869: Specify start point (in hex) when generating candidate moduli for DH-GEX.
870: .It Ic generator Ns = Ns Ar value
871: Specify desired generator (in decimal) when testing candidate moduli for DH-GEX.
872: .El
1.84 djm 873: .Sh CERTIFICATES
874: .Nm
875: supports signing of keys to produce certificates that may be used for
876: user or host authentication.
877: Certificates consist of a public key, some identity information, zero or
1.94 jmc 878: more principal (user or host) names and a set of options that
1.84 djm 879: are signed by a Certification Authority (CA) key.
880: Clients or servers may then trust only the CA key and verify its signature
881: on a certificate rather than trusting many user/host keys.
882: Note that OpenSSH certificates are a different, and much simpler, format to
883: the X.509 certificates used in
884: .Xr ssl 8 .
885: .Pp
886: .Nm
887: supports two types of certificates: user and host.
888: User certificates authenticate users to servers, whereas host certificates
1.85 jmc 889: authenticate server hosts to users.
890: To generate a user certificate:
1.84 djm 891: .Pp
892: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub
893: .Pp
894: The resultant certificate will be placed in
1.91 djm 895: .Pa /path/to/user_key-cert.pub .
1.84 djm 896: A host certificate requires the
897: .Fl h
898: option:
899: .Pp
900: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub
901: .Pp
902: The host certificate will be output to
1.91 djm 903: .Pa /path/to/host_key-cert.pub .
1.98 djm 904: .Pp
905: It is possible to sign using a CA key stored in a PKCS#11 token by
906: providing the token library using
907: .Fl D
908: and identifying the CA key by providing its public half as an argument
909: to
910: .Fl s :
911: .Pp
1.127 naddy 912: .Dl $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub
1.142 djm 913: .Pp
914: Similarly, it is possible for the CA key to be hosted in a
915: .Xr ssh-agent 1 .
916: This is indicated by the
917: .Fl U
918: flag and, again, the CA key must be identified by its public half.
919: .Pp
920: .Dl $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub
1.98 djm 921: .Pp
922: In all cases,
1.84 djm 923: .Ar key_id
924: is a "key identifier" that is logged by the server when the certificate
925: is used for authentication.
926: .Pp
927: Certificates may be limited to be valid for a set of principal (user/host)
928: names.
929: By default, generated certificates are valid for all users or hosts.
930: To generate a certificate for a specified set of principals:
931: .Pp
932: .Dl $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub
1.127 naddy 933: .Dl "$ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub"
1.84 djm 934: .Pp
935: Additional limitations on the validity and use of user certificates may
1.94 jmc 936: be specified through certificate options.
1.93 djm 937: A certificate option may disable features of the SSH session, may be
1.84 djm 938: valid only when presented from particular source addresses or may
939: force the use of a specific command.
1.183 djm 940: .Pp
941: The options that are valid for user certificates are:
942: .Pp
943: .Bl -tag -width Ds -compact
944: .It Ic clear
945: Clear all enabled permissions.
946: This is useful for clearing the default set of permissions so permissions may
947: be added individually.
948: .Pp
949: .It Ic critical : Ns Ar name Ns Op Ns = Ns Ar contents
950: .It Ic extension : Ns Ar name Ns Op Ns = Ns Ar contents
951: Includes an arbitrary certificate critical option or extension.
952: The specified
953: .Ar name
954: should include a domain suffix, e.g.\&
955: .Dq name@example.com .
956: If
957: .Ar contents
958: is specified then it is included as the contents of the extension/option
959: encoded as a string, otherwise the extension/option is created with no
960: contents (usually indicating a flag).
961: Extensions may be ignored by a client or server that does not recognise them,
962: whereas unknown critical options will cause the certificate to be refused.
963: .Pp
964: .It Ic force-command Ns = Ns Ar command
965: Forces the execution of
966: .Ar command
967: instead of any shell or command specified by the user when
968: the certificate is used for authentication.
969: .Pp
970: .It Ic no-agent-forwarding
971: Disable
972: .Xr ssh-agent 1
973: forwarding (permitted by default).
974: .Pp
975: .It Ic no-port-forwarding
976: Disable port forwarding (permitted by default).
977: .Pp
978: .It Ic no-pty
979: Disable PTY allocation (permitted by default).
980: .Pp
981: .It Ic no-user-rc
982: Disable execution of
983: .Pa ~/.ssh/rc
984: by
985: .Xr sshd 8
986: (permitted by default).
987: .Pp
988: .It Ic no-x11-forwarding
989: Disable X11 forwarding (permitted by default).
990: .Pp
991: .It Ic permit-agent-forwarding
992: Allows
993: .Xr ssh-agent 1
994: forwarding.
995: .Pp
996: .It Ic permit-port-forwarding
997: Allows port forwarding.
998: .Pp
999: .It Ic permit-pty
1000: Allows PTY allocation.
1001: .Pp
1002: .It Ic permit-user-rc
1003: Allows execution of
1004: .Pa ~/.ssh/rc
1005: by
1006: .Xr sshd 8 .
1007: .Pp
1008: .It Ic permit-X11-forwarding
1009: Allows X11 forwarding.
1010: .Pp
1011: .It Ic no-touch-required
1.206 djm 1012: Do not require signatures made using this key include demonstration
1.193 naddy 1013: of user presence (e.g. by having the user touch the authenticator).
1.192 naddy 1014: This option only makes sense for the FIDO authenticator algorithms
1.183 djm 1015: .Cm ecdsa-sk
1016: and
1017: .Cm ed25519-sk .
1018: .Pp
1019: .It Ic source-address Ns = Ns Ar address_list
1020: Restrict the source addresses from which the certificate is considered valid.
1021: The
1022: .Ar address_list
1023: is a comma-separated list of one or more address/netmask pairs in CIDR
1024: format.
1.206 djm 1025: .Pp
1026: .It Ic verify-required
1027: Require signatures made using this key indicate that the user was first
1028: verified.
1029: This option only makes sense for the FIDO authenticator algorithms
1030: .Cm ecdsa-sk
1031: and
1032: .Cm ed25519-sk .
1033: Currently PIN authentication is the only supported verification method,
1034: but other methods may be supported in the future.
1.183 djm 1035: .El
1036: .Pp
1037: At present, no standard options are valid for host keys.
1.84 djm 1038: .Pp
1039: Finally, certificates may be defined with a validity lifetime.
1040: The
1041: .Fl V
1042: option allows specification of certificate start and end times.
1043: A certificate that is presented at a time outside this range will not be
1044: considered valid.
1.210 dtucker 1045: By default, certificates are valid from the
1.110 jmc 1046: .Ux
1047: Epoch to the distant future.
1.84 djm 1048: .Pp
1049: For certificates to be used for user or host authentication, the CA
1050: public key must be trusted by
1051: .Xr sshd 8
1052: or
1053: .Xr ssh 1 .
1054: Please refer to those manual pages for details.
1.111 djm 1055: .Sh KEY REVOCATION LISTS
1056: .Nm
1057: is able to manage OpenSSH format Key Revocation Lists (KRLs).
1058: These binary files specify keys or certificates to be revoked using a
1.119 tedu 1059: compact format, taking as little as one bit per certificate if they are being
1.111 djm 1060: revoked by serial number.
1061: .Pp
1062: KRLs may be generated using the
1063: .Fl k
1064: flag.
1.114 jmc 1065: This option reads one or more files from the command line and generates a new
1.111 djm 1066: KRL.
1067: The files may either contain a KRL specification (see below) or public keys,
1068: listed one per line.
1069: Plain public keys are revoked by listing their hash or contents in the KRL and
1070: certificates revoked by serial number or key ID (if the serial is zero or
1071: not available).
1072: .Pp
1073: Revoking keys using a KRL specification offers explicit control over the
1074: types of record used to revoke keys and may be used to directly revoke
1075: certificates by serial number or key ID without having the complete original
1076: certificate on hand.
1077: A KRL specification consists of lines containing one of the following directives
1078: followed by a colon and some directive-specific information.
1079: .Bl -tag -width Ds
1.115 jmc 1080: .It Cm serial : Ar serial_number Ns Op - Ns Ar serial_number
1.111 djm 1081: Revokes a certificate with the specified serial number.
1.112 jmc 1082: Serial numbers are 64-bit values, not including zero and may be expressed
1.111 djm 1083: in decimal, hex or octal.
1084: If two serial numbers are specified separated by a hyphen, then the range
1085: of serial numbers including and between each is revoked.
1086: The CA key must have been specified on the
1087: .Nm
1.114 jmc 1088: command line using the
1.111 djm 1089: .Fl s
1090: option.
1091: .It Cm id : Ar key_id
1092: Revokes a certificate with the specified key ID string.
1093: The CA key must have been specified on the
1094: .Nm
1.114 jmc 1095: command line using the
1.111 djm 1096: .Fl s
1097: option.
1098: .It Cm key : Ar public_key
1099: Revokes the specified key.
1.112 jmc 1100: If a certificate is listed, then it is revoked as a plain public key.
1.111 djm 1101: .It Cm sha1 : Ar public_key
1.149 djm 1102: Revokes the specified key by including its SHA1 hash in the KRL.
1103: .It Cm sha256 : Ar public_key
1104: Revokes the specified key by including its SHA256 hash in the KRL.
1105: KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions
1106: prior to 7.9.
1107: .It Cm hash : Ar fingerprint
1.150 djm 1108: Revokes a key using a fingerprint hash, as obtained from a
1.149 djm 1109: .Xr sshd 8
1110: authentication log message or the
1111: .Nm
1112: .Fl l
1113: flag.
1114: Only SHA256 fingerprints are supported here and resultant KRLs are
1115: not supported by OpenSSH versions prior to 7.9.
1.111 djm 1116: .El
1117: .Pp
1118: KRLs may be updated using the
1119: .Fl u
1120: flag in addition to
1121: .Fl k .
1.114 jmc 1122: When this option is specified, keys listed via the command line are merged into
1.111 djm 1123: the KRL, adding to those already there.
1124: .Pp
1125: It is also possible, given a KRL, to test whether it revokes a particular key
1126: (or keys).
1127: The
1128: .Fl Q
1.128 jmc 1129: flag will query an existing KRL, testing each key specified on the command line.
1.114 jmc 1130: If any key listed on the command line has been revoked (or an error encountered)
1.111 djm 1131: then
1132: .Nm
1133: will exit with a non-zero exit status.
1134: A zero exit status will only be returned if no key was revoked.
1.163 djm 1135: .Sh ALLOWED SIGNERS
1136: When verifying signatures,
1137: .Nm
1138: uses a simple list of identities and keys to determine whether a signature
1139: comes from an authorized source.
1140: This "allowed signers" file uses a format patterned after the
1141: AUTHORIZED_KEYS FILE FORMAT described in
1.165 jmc 1142: .Xr sshd 8 .
1.163 djm 1143: Each line of the file contains the following space-separated fields:
1144: principals, options, keytype, base64-encoded key.
1145: Empty lines and lines starting with a
1146: .Ql #
1147: are ignored as comments.
1148: .Pp
1.210 dtucker 1149: The principals field is a pattern-list (see PATTERNS in
1.163 djm 1150: .Xr ssh_config 5 )
1151: consisting of one or more comma-separated USER@DOMAIN identity patterns
1152: that are accepted for signing.
1153: When verifying, the identity presented via the
1.172 jmc 1154: .Fl I
1155: option must match a principals pattern in order for the corresponding key to be
1.163 djm 1156: considered acceptable for verification.
1157: .Pp
1158: The options (if present) consist of comma-separated option specifications.
1159: No spaces are permitted, except within double quotes.
1160: The following option specifications are supported (note that option keywords
1161: are case-insensitive):
1162: .Bl -tag -width Ds
1163: .It Cm cert-authority
1164: Indicates that this key is accepted as a certificate authority (CA) and
1165: that certificates signed by this CA may be accepted for verification.
1.214 djm 1166: .It Cm namespaces Ns = Ns "namespace-list"
1.163 djm 1167: Specifies a pattern-list of namespaces that are accepted for this key.
1.164 djm 1168: If this option is present, the signature namespace embedded in the
1.163 djm 1169: signature object and presented on the verification command-line must
1170: match the specified list before the key will be considered acceptable.
1.214 djm 1171: .It Cm valid-after Ns = Ns "timestamp"
1172: Indicates that the key is valid for use at or after the specified timestamp,
1.215 jmc 1173: which may be a date in YYYYMMDD format or a time in YYYYMMDDHHMM[SS] format.
1.214 djm 1174: .It Cm valid-before Ns = Ns "timestamp"
1175: Indicates that the key is valid for use at or before the specified timestamp.
1.163 djm 1176: .El
1177: .Pp
1178: When verifying signatures made by certificates, the expected principal
1179: name must match both the principals pattern in the allowed signers file and
1180: the principals embedded in the certificate itself.
1181: .Pp
1182: An example allowed signers file:
1183: .Bd -literal -offset 3n
1184: # Comments allowed at start of line
1185: user1@example.com,user2@example.com ssh-rsa AAAAX1...
1186: # A certificate authority, trusted for all principals in a domain.
1187: *@example.com cert-authority ssh-ed25519 AAAB4...
1188: # A key that is accepted only for file signing.
1189: user2@example.com namespaces="file" ssh-ed25519 AAA41...
1190: .Ed
1.173 naddy 1191: .Sh ENVIRONMENT
1192: .Bl -tag -width Ds
1193: .It Ev SSH_SK_PROVIDER
1.201 djm 1194: Specifies a path to a library that will be used when loading any
1195: FIDO authenticator-hosted keys, overriding the default of using
1196: the built-in USB HID support.
1.173 naddy 1197: .El
1.2 deraadt 1198: .Sh FILES
1.100 naddy 1199: .Bl -tag -width Ds -compact
1.68 djm 1200: .It Pa ~/.ssh/id_dsa
1.100 naddy 1201: .It Pa ~/.ssh/id_ecdsa
1.173 naddy 1202: .It Pa ~/.ssh/id_ecdsa_sk
1.118 naddy 1203: .It Pa ~/.ssh/id_ed25519
1.176 naddy 1204: .It Pa ~/.ssh/id_ed25519_sk
1.100 naddy 1205: .It Pa ~/.ssh/id_rsa
1.180 naddy 1206: Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
1207: authenticator-hosted Ed25519 or RSA authentication identity of the user.
1.15 deraadt 1208: This file should not be readable by anyone but the user.
1209: It is possible to
1210: specify a passphrase when generating the key; that passphrase will be
1.80 dtucker 1211: used to encrypt the private part of this file using 128-bit AES.
1.15 deraadt 1212: This file is not automatically accessed by
1213: .Nm
1214: but it is offered as the default file for the private key.
1.46 markus 1215: .Xr ssh 1
1.15 deraadt 1216: will read this file when a login attempt is made.
1.100 naddy 1217: .Pp
1.68 djm 1218: .It Pa ~/.ssh/id_dsa.pub
1.100 naddy 1219: .It Pa ~/.ssh/id_ecdsa.pub
1.173 naddy 1220: .It Pa ~/.ssh/id_ecdsa_sk.pub
1.118 naddy 1221: .It Pa ~/.ssh/id_ed25519.pub
1.176 naddy 1222: .It Pa ~/.ssh/id_ed25519_sk.pub
1.68 djm 1223: .It Pa ~/.ssh/id_rsa.pub
1.180 naddy 1224: Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
1225: authenticator-hosted Ed25519 or RSA public key for authentication.
1.15 deraadt 1226: The contents of this file should be added to
1.68 djm 1227: .Pa ~/.ssh/authorized_keys
1.15 deraadt 1228: on all machines
1.49 deraadt 1229: where the user wishes to log in using public key authentication.
1.12 aaron 1230: There is no need to keep the contents of this file secret.
1.100 naddy 1231: .Pp
1.60 djm 1232: .It Pa /etc/moduli
1233: Contains Diffie-Hellman groups used for DH-GEX.
1234: The file format is described in
1235: .Xr moduli 5 .
1.19 aaron 1236: .El
1.2 deraadt 1237: .Sh SEE ALSO
1238: .Xr ssh 1 ,
1239: .Xr ssh-add 1 ,
1.8 ericj 1240: .Xr ssh-agent 1 ,
1.60 djm 1241: .Xr moduli 5 ,
1.30 itojun 1242: .Xr sshd 8
1.37 markus 1243: .Rs
1.73 markus 1244: .%R RFC 4716
1245: .%T "The Secure Shell (SSH) Public Key File Format"
1246: .%D 2006
1.37 markus 1247: .Re
1.59 jmc 1248: .Sh AUTHORS
1249: OpenSSH is a derivative of the original and free
1250: ssh 1.2.12 release by Tatu Ylonen.
1251: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
1252: Theo de Raadt and Dug Song
1253: removed many bugs, re-added newer features and
1254: created OpenSSH.
1255: Markus Friedl contributed the support for SSH
1256: protocol versions 1.5 and 2.0.
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