Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.218
1.218 ! djm 1: .\" $OpenBSD: ssh-keygen.1,v 1.217 2021/11/27 07:14:46 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: .\"
1.218 ! djm 38: .Dd $Mdocdate: November 27 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: .Fl I Ar signer_identity
156: .Fl f Ar allowed_signers_file
157: .Nm ssh-keygen
1.171 jmc 158: .Fl Y Cm check-novalidate
1.214 djm 159: .Op Fl O Ar option
1.171 jmc 160: .Fl n Ar namespace
161: .Fl s Ar signature_file
162: .Nm ssh-keygen
1.163 djm 163: .Fl Y Cm sign
164: .Fl f Ar key_file
165: .Fl n Ar namespace
166: .Ar
167: .Nm ssh-keygen
168: .Fl Y Cm verify
1.214 djm 169: .Op Fl O Ar option
1.171 jmc 170: .Fl f Ar allowed_signers_file
1.163 djm 171: .Fl I Ar signer_identity
172: .Fl n Ar namespace
173: .Fl s Ar signature_file
174: .Op Fl r Ar revocation_file
1.13 aaron 175: .Sh DESCRIPTION
1.2 deraadt 176: .Nm
1.37 markus 177: generates, manages and converts authentication keys for
1.2 deraadt 178: .Xr ssh 1 .
1.15 deraadt 179: .Nm
1.140 jmc 180: can create keys for use by SSH protocol version 2.
1.130 jmc 181: .Pp
1.58 jmc 182: The type of key to be generated is specified with the
1.25 markus 183: .Fl t
1.52 djm 184: option.
1.70 djm 185: If invoked without any arguments,
186: .Nm
1.141 naddy 187: will generate an RSA key.
1.15 deraadt 188: .Pp
1.60 djm 189: .Nm
190: is also used to generate groups for use in Diffie-Hellman group
191: exchange (DH-GEX).
192: See the
193: .Sx MODULI GENERATION
194: section for details.
195: .Pp
1.111 djm 196: Finally,
197: .Nm
198: can be used to generate and update Key Revocation Lists, and to test whether
1.112 jmc 199: given keys have been revoked by one.
200: See the
1.111 djm 201: .Sx KEY REVOCATION LISTS
202: section for details.
203: .Pp
1.2 deraadt 204: Normally each user wishing to use SSH
1.99 djm 205: with public key authentication runs this once to create the authentication
1.1 deraadt 206: key in
1.118 naddy 207: .Pa ~/.ssh/id_dsa ,
1.99 djm 208: .Pa ~/.ssh/id_ecdsa ,
1.173 naddy 209: .Pa ~/.ssh/id_ecdsa_sk ,
1.176 naddy 210: .Pa ~/.ssh/id_ed25519 ,
211: .Pa ~/.ssh/id_ed25519_sk
1.15 deraadt 212: or
1.68 djm 213: .Pa ~/.ssh/id_rsa .
1.15 deraadt 214: Additionally, the system administrator may use this to generate host keys,
215: as seen in
216: .Pa /etc/rc .
1.2 deraadt 217: .Pp
1.1 deraadt 218: Normally this program generates the key and asks for a file in which
1.12 aaron 219: to store the private key.
220: The public key is stored in a file with the same name but
1.2 deraadt 221: .Dq .pub
1.12 aaron 222: appended.
223: The program also asks for a passphrase.
224: The passphrase may be empty to indicate no passphrase
1.26 markus 225: (host keys must have an empty passphrase), or it may be a string of
1.12 aaron 226: arbitrary length.
1.51 stevesk 227: A passphrase is similar to a password, except it can be a phrase with a
228: series of words, punctuation, numbers, whitespace, or any string of
229: characters you want.
230: Good passphrases are 10-30 characters long, are
1.1 deraadt 231: not simple sentences or otherwise easily guessable (English
1.42 markus 232: prose has only 1-2 bits of entropy per character, and provides very bad
1.51 stevesk 233: passphrases), and contain a mix of upper and lowercase letters,
234: numbers, and non-alphanumeric characters.
1.12 aaron 235: The passphrase can be changed later by using the
1.2 deraadt 236: .Fl p
1.1 deraadt 237: option.
1.2 deraadt 238: .Pp
1.12 aaron 239: There is no way to recover a lost passphrase.
1.105 djm 240: If the passphrase is lost or forgotten, a new key must be generated
241: and the corresponding public key copied to other machines.
1.2 deraadt 242: .Pp
1.153 djm 243: .Nm
244: will by default write keys in an OpenSSH-specific format.
245: This format is preferred as it offers better protection for
246: keys at rest as well as allowing storage of key comments within
247: the private key file itself.
248: The key comment may be useful to help identify the key.
1.12 aaron 249: The comment is initialized to
1.2 deraadt 250: .Dq user@host
251: when the key is created, but can be changed using the
252: .Fl c
1.1 deraadt 253: option.
1.153 djm 254: .Pp
255: It is still possible for
256: .Nm
257: to write the previously-used PEM format private keys using the
258: .Fl m
259: flag.
260: This may be used when generating new keys, and existing new-format
261: keys may be converted using this option in conjunction with the
262: .Fl p
263: (change passphrase) flag.
1.2 deraadt 264: .Pp
1.205 solene 265: After a key is generated,
266: .Nm
267: will ask where the keys
1.15 deraadt 268: should be placed to be activated.
269: .Pp
1.2 deraadt 270: The options are as follows:
271: .Bl -tag -width Ds
1.102 stevesk 272: .It Fl A
1.175 djm 273: For each of the key types (rsa, dsa, ecdsa and ed25519)
1.118 naddy 274: for which host keys
1.102 stevesk 275: do not exist, generate the host keys with the default key file path,
276: an empty passphrase, default bits for the key type, and default comment.
1.144 jmc 277: If
1.143 djm 278: .Fl f
1.144 jmc 279: has also been specified, its argument is used as a prefix to the
1.143 djm 280: default path for the resulting host key files.
1.104 jmc 281: This is used by
1.102 stevesk 282: .Pa /etc/rc
283: to generate new host keys.
1.117 djm 284: .It Fl a Ar rounds
1.169 jmc 285: When saving a private key, this option specifies the number of KDF
1.211 dtucker 286: (key derivation function, currently
287: .Xr bcrypt_pbkdf 3 )
288: rounds used.
1.117 djm 289: Higher numbers result in slower passphrase verification and increased
290: resistance to brute-force password cracking (should the keys be stolen).
1.204 dtucker 291: The default is 16 rounds.
1.66 jmc 292: .It Fl B
293: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 294: .It Fl b Ar bits
1.12 aaron 295: Specifies the number of bits in the key to create.
1.158 dtucker 296: For RSA keys, the minimum size is 1024 bits and the default is 3072 bits.
297: Generally, 3072 bits is considered sufficient.
1.72 dtucker 298: DSA keys must be exactly 1024 bits as specified by FIPS 186-2.
1.106 djm 299: For ECDSA keys, the
300: .Fl b
1.107 deraadt 301: flag determines the key length by selecting from one of three elliptic
1.106 djm 302: curve sizes: 256, 384 or 521 bits.
303: Attempting to use bit lengths other than these three values for ECDSA keys
304: will fail.
1.176 naddy 305: ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the
1.118 naddy 306: .Fl b
307: flag will be ignored.
1.66 jmc 308: .It Fl C Ar comment
309: Provides a new comment.
1.2 deraadt 310: .It Fl c
1.1 deraadt 311: Requests changing the comment in the private and public key files.
312: The program will prompt for the file containing the private keys, for
1.41 stevesk 313: the passphrase if the key has one, and for the new comment.
1.81 markus 314: .It Fl D Ar pkcs11
1.157 naddy 315: Download the public keys provided by the PKCS#11 shared library
1.83 markus 316: .Ar pkcs11 .
1.98 djm 317: When used in combination with
318: .Fl s ,
319: this option indicates that a CA key resides in a PKCS#11 token (see the
320: .Sx CERTIFICATES
321: section for details).
1.124 djm 322: .It Fl E Ar fingerprint_hash
323: Specifies the hash algorithm used when displaying key fingerprints.
324: Valid options are:
325: .Dq md5
326: and
327: .Dq sha256 .
328: The default is
329: .Dq sha256 .
1.37 markus 330: .It Fl e
1.40 markus 331: This option will read a private or public OpenSSH key file and
1.154 djm 332: print to stdout a public key in one of the formats specified by the
1.95 djm 333: .Fl m
334: option.
335: The default export format is
336: .Dq RFC4716 .
1.96 jmc 337: This option allows exporting OpenSSH keys for use by other programs, including
1.95 djm 338: several commercial SSH implementations.
1.151 djm 339: .It Fl F Ar hostname | [hostname]:port
1.66 jmc 340: Search for the specified
341: .Ar hostname
1.151 djm 342: (with optional port number)
1.66 jmc 343: in a
344: .Pa known_hosts
345: file, listing any occurrences found.
346: This option is useful to find hashed host names or addresses and may also be
347: used in conjunction with the
348: .Fl H
349: option to print found keys in a hashed format.
350: .It Fl f Ar filename
351: Specifies the filename of the key file.
1.57 jakob 352: .It Fl g
1.62 jakob 353: Use generic DNS format when printing fingerprint resource records using the
1.63 jmc 354: .Fl r
1.62 jakob 355: command.
1.66 jmc 356: .It Fl H
357: Hash a
358: .Pa known_hosts
1.67 dtucker 359: file.
360: This replaces all hostnames and addresses with hashed representations
361: within the specified file; the original content is moved to a file with
362: a .old suffix.
1.66 jmc 363: These hashes may be used normally by
364: .Nm ssh
365: and
366: .Nm sshd ,
367: but they do not reveal identifying information should the file's contents
368: be disclosed.
369: This option will not modify existing hashed hostnames and is therefore safe
370: to use on files that mix hashed and non-hashed names.
1.84 djm 371: .It Fl h
372: When signing a key, create a host certificate instead of a user
373: certificate.
374: Please see the
375: .Sx CERTIFICATES
376: section for details.
1.85 jmc 377: .It Fl I Ar certificate_identity
1.84 djm 378: Specify the key identity when signing a public key.
379: Please see the
380: .Sx CERTIFICATES
381: section for details.
1.37 markus 382: .It Fl i
383: This option will read an unencrypted private (or public) key file
1.95 djm 384: in the format specified by the
385: .Fl m
386: option and print an OpenSSH compatible private
1.37 markus 387: (or public) key to stdout.
1.122 jmc 388: This option allows importing keys from other software, including several
389: commercial SSH implementations.
390: The default import format is
391: .Dq RFC4716 .
1.188 jmc 392: .It Fl K
1.187 djm 393: Download resident keys from a FIDO authenticator.
394: Public and private key files will be written to the current directory for
395: each downloaded key.
1.207 djm 396: If multiple FIDO authenticators are attached, keys will be downloaded from
397: the first touched authenticator.
1.111 djm 398: .It Fl k
399: Generate a KRL file.
400: In this mode,
401: .Nm
402: will generate a KRL file at the location specified via the
403: .Fl f
1.114 jmc 404: flag that revokes every key or certificate presented on the command line.
1.111 djm 405: Keys/certificates to be revoked may be specified by public key file or
406: using the format described in the
407: .Sx KEY REVOCATION LISTS
408: section.
1.86 djm 409: .It Fl L
1.129 djm 410: Prints the contents of one or more certificates.
1.9 markus 411: .It Fl l
1.77 grunk 412: Show fingerprint of specified public key file.
1.50 markus 413: For RSA and DSA keys
414: .Nm
1.78 jmc 415: tries to find the matching public key file and prints its fingerprint.
416: If combined with
417: .Fl v ,
1.132 jmc 418: a visual ASCII art representation of the key is supplied with the
1.131 djm 419: fingerprint.
1.184 djm 420: .It Fl M Cm generate
421: Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for
422: eventual use by the
423: .Sq diffie-hellman-group-exchange-*
424: key exchange methods.
425: The numbers generated by this operation must be further screened before
426: use.
427: See the
428: .Sx MODULI GENERATION
429: section for more information.
430: .It Fl M Cm screen
431: Screen candidate parameters for Diffie-Hellman Group Exchange.
432: This will accept a list of candidate numbers and test that they are
433: safe (Sophie Germain) primes with acceptable group generators.
434: The results of this operation may be added to the
435: .Pa /etc/moduli
436: file.
437: See the
438: .Sx MODULI GENERATION
439: section for more information.
1.95 djm 440: .It Fl m Ar key_format
1.155 djm 441: Specify a key format for key generation, the
1.95 djm 442: .Fl i
1.155 djm 443: (import),
1.95 djm 444: .Fl e
1.155 djm 445: (export) conversion options, and the
446: .Fl p
447: change passphrase operation.
448: The latter may be used to convert between OpenSSH private key and PEM
449: private key formats.
1.95 djm 450: The supported key formats are:
451: .Dq RFC4716
1.96 jmc 452: (RFC 4716/SSH2 public or private key),
1.95 djm 453: .Dq PKCS8
1.161 djm 454: (PKCS8 public or private key)
1.95 djm 455: or
456: .Dq PEM
457: (PEM public key).
1.161 djm 458: By default OpenSSH will write newly-generated private keys in its own
459: format, but when converting public keys for export the default format is
1.95 djm 460: .Dq RFC4716 .
1.148 djm 461: Setting a format of
462: .Dq PEM
463: when generating or updating a supported private key type will cause the
464: key to be stored in the legacy PEM private key format.
1.66 jmc 465: .It Fl N Ar new_passphrase
466: Provides the new passphrase.
1.84 djm 467: .It Fl n Ar principals
468: Specify one or more principals (user or host names) to be included in
469: a certificate when signing a key.
470: Multiple principals may be specified, separated by commas.
471: Please see the
472: .Sx CERTIFICATES
473: section for details.
1.93 djm 474: .It Fl O Ar option
1.184 djm 475: Specify a key/value option.
476: These are specific to the operation that
477: .Nm
478: has been requested to perform.
479: .Pp
480: When signing certificates, one of the options listed in the
1.183 djm 481: .Sx CERTIFICATES
1.184 djm 482: section may be specified here.
483: .Pp
484: When performing moduli generation or screening, one of the options
485: listed in the
486: .Sx MODULI GENERATION
487: section may be specified.
488: .Pp
1.190 jmc 489: When generating a key that will be hosted on a FIDO authenticator,
490: this flag may be used to specify key-specific options.
491: Those supported at present are:
492: .Bl -tag -width Ds
493: .It Cm application
494: Override the default FIDO application/origin string of
1.189 djm 495: .Dq ssh: .
1.190 jmc 496: This may be useful when generating host or domain-specific resident keys.
1.200 djm 497: The specified application string must begin with
498: .Dq ssh: .
1.199 jmc 499: .It Cm challenge Ns = Ns Ar path
1.198 jmc 500: Specifies a path to a challenge string that will be passed to the
501: FIDO token during key generation.
1.199 jmc 502: The challenge string may be used as part of an out-of-band
503: protocol for key enrollment
504: (a random challenge is used by default).
1.190 jmc 505: .It Cm device
506: Explicitly specify a
1.189 djm 507: .Xr fido 4
508: device to use, rather than letting the token middleware select one.
1.190 jmc 509: .It Cm no-touch-required
510: Indicate that the generated private key should not require touch
1.185 djm 511: events (user presence) when making signatures.
512: Note that
513: .Xr sshd 8
514: will refuse such signatures by default, unless overridden via
515: an authorized_keys option.
1.190 jmc 516: .It Cm resident
517: Indicate that the key should be stored on the FIDO authenticator itself.
1.185 djm 518: Resident keys may be supported on FIDO2 tokens and typically require that
519: a PIN be set on the token prior to generation.
520: Resident keys may be loaded off the token using
521: .Xr ssh-add 1 .
1.190 jmc 522: .It Cm user
523: A username to be associated with a resident key,
1.189 djm 524: overriding the empty default username.
525: Specifying a username may be useful when generating multiple resident keys
526: for the same application name.
1.206 djm 527: .It Cm verify-required
528: Indicate that this private key should require user verification for
529: each signature.
1.208 jmc 530: Not all FIDO tokens support this option.
1.206 djm 531: Currently PIN authentication is the only supported verification method,
532: but other methods may be supported in the future.
1.199 jmc 533: .It Cm write-attestation Ns = Ns Ar path
1.209 djm 534: May be used at key generation time to record the attestation data
1.197 djm 535: returned from FIDO tokens during key generation.
1.209 djm 536: Please note that this information is potentially sensitive.
537: By default, this information is discarded.
1.190 jmc 538: .El
1.185 djm 539: .Pp
1.214 djm 540: When performing signature-related options using the
541: .Fl Y
542: flag, the following options are accepted:
543: .Bl -tag -width Ds
1.216 djm 544: .It Cm print-pubkey
545: Print the full public key to standard output after signature verification.
1.214 djm 546: .It Cm verify-time Ns = Ns Ar timestamp
547: Specifies a time to use when validating signatures instead of the current
548: time.
549: The time may be specified as a date in YYYYMMDD format or a time
550: in YYYYMMDDHHMM[SS] format.
551: .El
552: .Pp
1.185 djm 553: The
554: .Fl O
555: option may be specified multiple times.
1.66 jmc 556: .It Fl P Ar passphrase
557: Provides the (old) passphrase.
1.2 deraadt 558: .It Fl p
1.1 deraadt 559: Requests changing the passphrase of a private key file instead of
1.12 aaron 560: creating a new private key.
561: The program will prompt for the file
1.1 deraadt 562: containing the private key, for the old passphrase, and twice for the
563: new passphrase.
1.113 jmc 564: .It Fl Q
565: Test whether keys have been revoked in a KRL.
1.203 djm 566: If the
567: .Fl l
568: option is also specified then the contents of the KRL will be printed.
1.5 aaron 569: .It Fl q
570: Silence
571: .Nm ssh-keygen .
1.152 djm 572: .It Fl R Ar hostname | [hostname]:port
1.151 djm 573: Removes all keys belonging to the specified
1.64 djm 574: .Ar hostname
1.151 djm 575: (with optional port number)
1.65 jmc 576: from a
1.64 djm 577: .Pa known_hosts
578: file.
1.65 jmc 579: This option is useful to delete hashed hosts (see the
1.64 djm 580: .Fl H
581: option above).
1.66 jmc 582: .It Fl r Ar hostname
583: Print the SSHFP fingerprint resource record named
584: .Ar hostname
585: for the specified public key file.
1.84 djm 586: .It Fl s Ar ca_key
587: Certify (sign) a public key using the specified CA key.
588: Please see the
589: .Sx CERTIFICATES
590: section for details.
1.111 djm 591: .Pp
592: When generating a KRL,
593: .Fl s
1.112 jmc 594: specifies a path to a CA public key file used to revoke certificates directly
1.111 djm 595: by key ID or serial number.
596: See the
597: .Sx KEY REVOCATION LISTS
598: section for details.
1.175 djm 599: .It Fl t Cm dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa
1.66 jmc 600: Specifies the type of key to create.
601: The possible values are
1.100 naddy 602: .Dq dsa ,
1.118 naddy 603: .Dq ecdsa ,
1.173 naddy 604: .Dq ecdsa-sk ,
1.118 naddy 605: .Dq ed25519 ,
1.175 djm 606: .Dq ed25519-sk ,
1.100 naddy 607: or
1.139 jmc 608: .Dq rsa .
1.159 djm 609: .Pp
610: This flag may also be used to specify the desired signature type when
1.160 jmc 611: signing certificates using an RSA CA key.
1.159 djm 612: The available RSA signature variants are
613: .Dq ssh-rsa
614: (SHA1 signatures, not recommended),
1.160 jmc 615: .Dq rsa-sha2-256 ,
616: and
1.159 djm 617: .Dq rsa-sha2-512
618: (the default).
1.142 djm 619: .It Fl U
620: When used in combination with
621: .Fl s ,
622: this option indicates that a CA key resides in a
623: .Xr ssh-agent 1 .
624: See the
625: .Sx CERTIFICATES
626: section for more information.
1.112 jmc 627: .It Fl u
628: Update a KRL.
629: When specified with
630: .Fl k ,
1.114 jmc 631: keys listed via the command line are added to the existing KRL rather than
1.112 jmc 632: a new KRL being created.
1.84 djm 633: .It Fl V Ar validity_interval
634: Specify a validity interval when signing a certificate.
635: A validity interval may consist of a single time, indicating that the
636: certificate is valid beginning now and expiring at that time, or may consist
637: of two times separated by a colon to indicate an explicit time interval.
1.145 djm 638: .Pp
639: The start time may be specified as the string
640: .Dq always
641: to indicate the certificate has no specified start time,
1.147 djm 642: a date in YYYYMMDD format, a time in YYYYMMDDHHMM[SS] format,
1.145 djm 643: a relative time (to the current time) consisting of a minus sign followed by
644: an interval in the format described in the
1.116 jmc 645: TIME FORMATS section of
1.90 jmc 646: .Xr sshd_config 5 .
1.145 djm 647: .Pp
1.147 djm 648: The end time may be specified as a YYYYMMDD date, a YYYYMMDDHHMM[SS] time,
1.145 djm 649: a relative time starting with a plus character or the string
650: .Dq forever
1.202 dtucker 651: to indicate that the certificate has no expiry date.
1.84 djm 652: .Pp
653: For example:
654: .Dq +52w1d
655: (valid from now to 52 weeks and one day from now),
656: .Dq -4w:+4w
657: (valid from four weeks ago to four weeks from now),
658: .Dq 20100101123000:20110101123000
659: (valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011),
660: .Dq -1d:20110101
1.210 dtucker 661: (valid from yesterday to midnight, January 1st, 2011),
1.145 djm 662: .Dq -1m:forever
663: (valid from one minute ago and never expiring).
1.61 djm 664: .It Fl v
665: Verbose mode.
666: Causes
667: .Nm
668: to print debugging messages about its progress.
669: This is helpful for debugging moduli generation.
670: Multiple
671: .Fl v
672: options increase the verbosity.
673: The maximum is 3.
1.173 naddy 674: .It Fl w Ar provider
1.180 naddy 675: Specifies a path to a library that will be used when creating
676: FIDO authenticator-hosted keys, overriding the default of using
677: the internal USB HID support.
1.196 djm 678: .It Fl Y Cm find-principals
679: Find the principal(s) associated with the public key of a signature,
1.194 djm 680: provided using the
681: .Fl s
682: flag in an authorized signers file provided using the
683: .Fl f
684: flag.
685: The format of the allowed signers file is documented in the
686: .Sx ALLOWED SIGNERS
1.195 jmc 687: section below.
1.217 djm 688: If one or more matching principals are found, they are returned on
689: standard output.
690: .It Fl Y Cm match-principals
691: Find principal matching the principal name provided using the
692: .Fl I
693: flag in the authorized signers file specified using the
694: .Fl f
695: flag.
1.196 djm 696: If one or more matching principals are found, they are returned on
697: standard output.
1.182 jmc 698: .It Fl Y Cm check-novalidate
699: Checks that a signature generated using
700: .Nm
701: .Fl Y Cm sign
702: has a valid structure.
703: This does not validate if a signature comes from an authorized signer.
704: When testing a signature,
705: .Nm
706: accepts a message on standard input and a signature namespace using
707: .Fl n .
708: A file containing the corresponding signature must also be supplied using the
709: .Fl s
710: flag.
711: Successful testing of the signature is signalled by
712: .Nm
713: returning a zero exit status.
1.166 jmc 714: .It Fl Y Cm sign
1.163 djm 715: Cryptographically sign a file or some data using a SSH key.
716: When signing,
717: .Nm
718: accepts zero or more files to sign on the command-line - if no files
719: are specified then
720: .Nm
721: will sign data presented on standard input.
722: Signatures are written to the path of the input file with
723: .Dq .sig
724: appended, or to standard output if the message to be signed was read from
725: standard input.
726: .Pp
727: The key used for signing is specified using the
728: .Fl f
729: option and may refer to either a private key, or a public key with the private
730: half available via
731: .Xr ssh-agent 1 .
732: An additional signature namespace, used to prevent signature confusion across
733: different domains of use (e.g. file signing vs email signing) must be provided
734: via the
735: .Fl n
736: flag.
737: Namespaces are arbitrary strings, and may include:
738: .Dq file
739: for file signing,
740: .Dq email
741: for email signing.
742: For custom uses, it is recommended to use names following a
743: NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces.
1.166 jmc 744: .It Fl Y Cm verify
1.163 djm 745: Request to verify a signature generated using
746: .Nm
1.166 jmc 747: .Fl Y Cm sign
1.163 djm 748: as described above.
749: When verifying a signature,
750: .Nm
751: accepts a message on standard input and a signature namespace using
752: .Fl n .
753: A file containing the corresponding signature must also be supplied using the
754: .Fl s
755: flag, along with the identity of the signer using
756: .Fl I
757: and a list of allowed signers via the
758: .Fl f
759: flag.
760: The format of the allowed signers file is documented in the
761: .Sx ALLOWED SIGNERS
762: section below.
763: A file containing revoked keys can be passed using the
764: .Fl r
1.165 jmc 765: flag.
766: The revocation file may be a KRL or a one-per-line list of public keys.
1.163 djm 767: Successful verification by an authorized signer is signalled by
768: .Nm
769: returning a zero exit status.
1.181 jmc 770: .It Fl y
771: This option will read a private
772: OpenSSH format file and print an OpenSSH public key to stdout.
1.212 dtucker 773: .It Fl Z Ar cipher
774: Specifies the cipher to use for encryption when writing an OpenSSH-format
775: private key file.
776: The list of available ciphers may be obtained using
777: .Qq ssh -Q cipher .
778: The default is
779: .Dq aes256-ctr .
1.93 djm 780: .It Fl z Ar serial_number
781: Specifies a serial number to be embedded in the certificate to distinguish
782: this certificate from others from the same CA.
1.156 djm 783: If the
784: .Ar serial_number
785: is prefixed with a
786: .Sq +
787: character, then the serial number will be incremented for each certificate
788: signed on a single command-line.
1.93 djm 789: The default serial number is zero.
1.111 djm 790: .Pp
791: When generating a KRL, the
792: .Fl z
793: flag is used to specify a KRL version number.
1.2 deraadt 794: .El
1.60 djm 795: .Sh MODULI GENERATION
796: .Nm
797: may be used to generate groups for the Diffie-Hellman Group Exchange
798: (DH-GEX) protocol.
799: Generating these groups is a two-step process: first, candidate
800: primes are generated using a fast, but memory intensive process.
801: These candidate primes are then tested for suitability (a CPU-intensive
802: process).
803: .Pp
804: Generation of primes is performed using the
1.184 djm 805: .Fl M Cm generate
1.60 djm 806: option.
807: The desired length of the primes may be specified by the
1.184 djm 808: .Fl O Cm bits
1.60 djm 809: option.
810: For example:
811: .Pp
1.184 djm 812: .Dl # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates
1.60 djm 813: .Pp
814: By default, the search for primes begins at a random point in the
815: desired length range.
816: This may be overridden using the
1.184 djm 817: .Fl O Cm start
1.60 djm 818: option, which specifies a different start point (in hex).
819: .Pp
1.109 dtucker 820: Once a set of candidates have been generated, they must be screened for
1.60 djm 821: suitability.
822: This may be performed using the
1.184 djm 823: .Fl M Cm screen
1.60 djm 824: option.
825: In this mode
826: .Nm
827: will read candidates from standard input (or a file specified using the
828: .Fl f
829: option).
830: For example:
831: .Pp
1.184 djm 832: .Dl # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048
1.60 djm 833: .Pp
834: By default, each candidate will be subjected to 100 primality tests.
835: This may be overridden using the
1.184 djm 836: .Fl O Cm prime-tests
1.60 djm 837: option.
838: The DH generator value will be chosen automatically for the
839: prime under consideration.
840: If a specific generator is desired, it may be requested using the
1.184 djm 841: .Fl O Cm generator
1.60 djm 842: option.
1.66 jmc 843: Valid generator values are 2, 3, and 5.
1.60 djm 844: .Pp
845: Screened DH groups may be installed in
846: .Pa /etc/moduli .
1.213 dtucker 847: It is important that this file contains moduli of a range of bit lengths.
1.184 djm 848: .Pp
849: A number of options are available for moduli generation and screening via the
850: .Fl O
851: flag:
1.186 jmc 852: .Bl -tag -width Ds
1.184 djm 853: .It Ic lines Ns = Ns Ar number
854: Exit after screening the specified number of lines while performing DH
855: candidate screening.
856: .It Ic start-line Ns = Ns Ar line-number
857: Start screening at the specified line number while performing DH candidate
858: screening.
859: .It Ic checkpoint Ns = Ns Ar filename
860: Write the last line processed to the specified file while performing DH
861: candidate screening.
862: This will be used to skip lines in the input file that have already been
863: processed if the job is restarted.
864: .It Ic memory Ns = Ns Ar mbytes
865: Specify the amount of memory to use (in megabytes) when generating
866: candidate moduli for DH-GEX.
867: .It Ic start Ns = Ns Ar hex-value
868: Specify start point (in hex) when generating candidate moduli for DH-GEX.
869: .It Ic generator Ns = Ns Ar value
870: Specify desired generator (in decimal) when testing candidate moduli for DH-GEX.
871: .El
1.84 djm 872: .Sh CERTIFICATES
873: .Nm
874: supports signing of keys to produce certificates that may be used for
875: user or host authentication.
876: Certificates consist of a public key, some identity information, zero or
1.94 jmc 877: more principal (user or host) names and a set of options that
1.84 djm 878: are signed by a Certification Authority (CA) key.
879: Clients or servers may then trust only the CA key and verify its signature
880: on a certificate rather than trusting many user/host keys.
881: Note that OpenSSH certificates are a different, and much simpler, format to
882: the X.509 certificates used in
883: .Xr ssl 8 .
884: .Pp
885: .Nm
886: supports two types of certificates: user and host.
887: User certificates authenticate users to servers, whereas host certificates
1.85 jmc 888: authenticate server hosts to users.
889: To generate a user certificate:
1.84 djm 890: .Pp
891: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub
892: .Pp
893: The resultant certificate will be placed in
1.91 djm 894: .Pa /path/to/user_key-cert.pub .
1.84 djm 895: A host certificate requires the
896: .Fl h
897: option:
898: .Pp
899: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub
900: .Pp
901: The host certificate will be output to
1.91 djm 902: .Pa /path/to/host_key-cert.pub .
1.98 djm 903: .Pp
904: It is possible to sign using a CA key stored in a PKCS#11 token by
905: providing the token library using
906: .Fl D
907: and identifying the CA key by providing its public half as an argument
908: to
909: .Fl s :
910: .Pp
1.127 naddy 911: .Dl $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub
1.142 djm 912: .Pp
913: Similarly, it is possible for the CA key to be hosted in a
914: .Xr ssh-agent 1 .
915: This is indicated by the
916: .Fl U
917: flag and, again, the CA key must be identified by its public half.
918: .Pp
919: .Dl $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub
1.98 djm 920: .Pp
921: In all cases,
1.84 djm 922: .Ar key_id
923: is a "key identifier" that is logged by the server when the certificate
924: is used for authentication.
925: .Pp
926: Certificates may be limited to be valid for a set of principal (user/host)
927: names.
928: By default, generated certificates are valid for all users or hosts.
929: To generate a certificate for a specified set of principals:
930: .Pp
931: .Dl $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub
1.127 naddy 932: .Dl "$ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub"
1.84 djm 933: .Pp
934: Additional limitations on the validity and use of user certificates may
1.94 jmc 935: be specified through certificate options.
1.93 djm 936: A certificate option may disable features of the SSH session, may be
1.84 djm 937: valid only when presented from particular source addresses or may
938: force the use of a specific command.
1.183 djm 939: .Pp
940: The options that are valid for user certificates are:
941: .Pp
942: .Bl -tag -width Ds -compact
943: .It Ic clear
944: Clear all enabled permissions.
945: This is useful for clearing the default set of permissions so permissions may
946: be added individually.
947: .Pp
948: .It Ic critical : Ns Ar name Ns Op Ns = Ns Ar contents
949: .It Ic extension : Ns Ar name Ns Op Ns = Ns Ar contents
950: Includes an arbitrary certificate critical option or extension.
951: The specified
952: .Ar name
953: should include a domain suffix, e.g.\&
954: .Dq name@example.com .
955: If
956: .Ar contents
957: is specified then it is included as the contents of the extension/option
958: encoded as a string, otherwise the extension/option is created with no
959: contents (usually indicating a flag).
960: Extensions may be ignored by a client or server that does not recognise them,
961: whereas unknown critical options will cause the certificate to be refused.
962: .Pp
963: .It Ic force-command Ns = Ns Ar command
964: Forces the execution of
965: .Ar command
966: instead of any shell or command specified by the user when
967: the certificate is used for authentication.
968: .Pp
969: .It Ic no-agent-forwarding
970: Disable
971: .Xr ssh-agent 1
972: forwarding (permitted by default).
973: .Pp
974: .It Ic no-port-forwarding
975: Disable port forwarding (permitted by default).
976: .Pp
977: .It Ic no-pty
978: Disable PTY allocation (permitted by default).
979: .Pp
980: .It Ic no-user-rc
981: Disable execution of
982: .Pa ~/.ssh/rc
983: by
984: .Xr sshd 8
985: (permitted by default).
986: .Pp
987: .It Ic no-x11-forwarding
988: Disable X11 forwarding (permitted by default).
989: .Pp
990: .It Ic permit-agent-forwarding
991: Allows
992: .Xr ssh-agent 1
993: forwarding.
994: .Pp
995: .It Ic permit-port-forwarding
996: Allows port forwarding.
997: .Pp
998: .It Ic permit-pty
999: Allows PTY allocation.
1000: .Pp
1001: .It Ic permit-user-rc
1002: Allows execution of
1003: .Pa ~/.ssh/rc
1004: by
1005: .Xr sshd 8 .
1006: .Pp
1007: .It Ic permit-X11-forwarding
1008: Allows X11 forwarding.
1009: .Pp
1010: .It Ic no-touch-required
1.206 djm 1011: Do not require signatures made using this key include demonstration
1.193 naddy 1012: of user presence (e.g. by having the user touch the authenticator).
1.192 naddy 1013: This option only makes sense for the FIDO authenticator algorithms
1.183 djm 1014: .Cm ecdsa-sk
1015: and
1016: .Cm ed25519-sk .
1017: .Pp
1018: .It Ic source-address Ns = Ns Ar address_list
1019: Restrict the source addresses from which the certificate is considered valid.
1020: The
1021: .Ar address_list
1022: is a comma-separated list of one or more address/netmask pairs in CIDR
1023: format.
1.206 djm 1024: .Pp
1025: .It Ic verify-required
1026: Require signatures made using this key indicate that the user was first
1027: verified.
1028: This option only makes sense for the FIDO authenticator algorithms
1029: .Cm ecdsa-sk
1030: and
1031: .Cm ed25519-sk .
1032: Currently PIN authentication is the only supported verification method,
1033: but other methods may be supported in the future.
1.183 djm 1034: .El
1035: .Pp
1036: At present, no standard options are valid for host keys.
1.84 djm 1037: .Pp
1038: Finally, certificates may be defined with a validity lifetime.
1039: The
1040: .Fl V
1041: option allows specification of certificate start and end times.
1042: A certificate that is presented at a time outside this range will not be
1043: considered valid.
1.210 dtucker 1044: By default, certificates are valid from the
1.110 jmc 1045: .Ux
1046: Epoch to the distant future.
1.84 djm 1047: .Pp
1048: For certificates to be used for user or host authentication, the CA
1049: public key must be trusted by
1050: .Xr sshd 8
1051: or
1052: .Xr ssh 1 .
1053: Please refer to those manual pages for details.
1.111 djm 1054: .Sh KEY REVOCATION LISTS
1055: .Nm
1056: is able to manage OpenSSH format Key Revocation Lists (KRLs).
1057: These binary files specify keys or certificates to be revoked using a
1.119 tedu 1058: compact format, taking as little as one bit per certificate if they are being
1.111 djm 1059: revoked by serial number.
1060: .Pp
1061: KRLs may be generated using the
1062: .Fl k
1063: flag.
1.114 jmc 1064: This option reads one or more files from the command line and generates a new
1.111 djm 1065: KRL.
1066: The files may either contain a KRL specification (see below) or public keys,
1067: listed one per line.
1068: Plain public keys are revoked by listing their hash or contents in the KRL and
1069: certificates revoked by serial number or key ID (if the serial is zero or
1070: not available).
1071: .Pp
1072: Revoking keys using a KRL specification offers explicit control over the
1073: types of record used to revoke keys and may be used to directly revoke
1074: certificates by serial number or key ID without having the complete original
1075: certificate on hand.
1076: A KRL specification consists of lines containing one of the following directives
1077: followed by a colon and some directive-specific information.
1078: .Bl -tag -width Ds
1.115 jmc 1079: .It Cm serial : Ar serial_number Ns Op - Ns Ar serial_number
1.111 djm 1080: Revokes a certificate with the specified serial number.
1.112 jmc 1081: Serial numbers are 64-bit values, not including zero and may be expressed
1.111 djm 1082: in decimal, hex or octal.
1083: If two serial numbers are specified separated by a hyphen, then the range
1084: of serial numbers including and between each is revoked.
1085: The CA key must have been specified on the
1086: .Nm
1.114 jmc 1087: command line using the
1.111 djm 1088: .Fl s
1089: option.
1090: .It Cm id : Ar key_id
1091: Revokes a certificate with the specified key ID string.
1092: The CA key must have been specified on the
1093: .Nm
1.114 jmc 1094: command line using the
1.111 djm 1095: .Fl s
1096: option.
1097: .It Cm key : Ar public_key
1098: Revokes the specified key.
1.112 jmc 1099: If a certificate is listed, then it is revoked as a plain public key.
1.111 djm 1100: .It Cm sha1 : Ar public_key
1.149 djm 1101: Revokes the specified key by including its SHA1 hash in the KRL.
1102: .It Cm sha256 : Ar public_key
1103: Revokes the specified key by including its SHA256 hash in the KRL.
1104: KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions
1105: prior to 7.9.
1106: .It Cm hash : Ar fingerprint
1.150 djm 1107: Revokes a key using a fingerprint hash, as obtained from a
1.149 djm 1108: .Xr sshd 8
1109: authentication log message or the
1110: .Nm
1111: .Fl l
1112: flag.
1113: Only SHA256 fingerprints are supported here and resultant KRLs are
1114: not supported by OpenSSH versions prior to 7.9.
1.111 djm 1115: .El
1116: .Pp
1117: KRLs may be updated using the
1118: .Fl u
1119: flag in addition to
1120: .Fl k .
1.114 jmc 1121: When this option is specified, keys listed via the command line are merged into
1.111 djm 1122: the KRL, adding to those already there.
1123: .Pp
1124: It is also possible, given a KRL, to test whether it revokes a particular key
1125: (or keys).
1126: The
1127: .Fl Q
1.128 jmc 1128: flag will query an existing KRL, testing each key specified on the command line.
1.114 jmc 1129: If any key listed on the command line has been revoked (or an error encountered)
1.111 djm 1130: then
1131: .Nm
1132: will exit with a non-zero exit status.
1133: A zero exit status will only be returned if no key was revoked.
1.163 djm 1134: .Sh ALLOWED SIGNERS
1135: When verifying signatures,
1136: .Nm
1137: uses a simple list of identities and keys to determine whether a signature
1138: comes from an authorized source.
1139: This "allowed signers" file uses a format patterned after the
1140: AUTHORIZED_KEYS FILE FORMAT described in
1.165 jmc 1141: .Xr sshd 8 .
1.163 djm 1142: Each line of the file contains the following space-separated fields:
1143: principals, options, keytype, base64-encoded key.
1144: Empty lines and lines starting with a
1145: .Ql #
1146: are ignored as comments.
1147: .Pp
1.210 dtucker 1148: The principals field is a pattern-list (see PATTERNS in
1.163 djm 1149: .Xr ssh_config 5 )
1150: consisting of one or more comma-separated USER@DOMAIN identity patterns
1151: that are accepted for signing.
1152: When verifying, the identity presented via the
1.172 jmc 1153: .Fl I
1154: option must match a principals pattern in order for the corresponding key to be
1.163 djm 1155: considered acceptable for verification.
1156: .Pp
1157: The options (if present) consist of comma-separated option specifications.
1158: No spaces are permitted, except within double quotes.
1159: The following option specifications are supported (note that option keywords
1160: are case-insensitive):
1161: .Bl -tag -width Ds
1162: .It Cm cert-authority
1163: Indicates that this key is accepted as a certificate authority (CA) and
1164: that certificates signed by this CA may be accepted for verification.
1.214 djm 1165: .It Cm namespaces Ns = Ns "namespace-list"
1.163 djm 1166: Specifies a pattern-list of namespaces that are accepted for this key.
1.164 djm 1167: If this option is present, the signature namespace embedded in the
1.163 djm 1168: signature object and presented on the verification command-line must
1169: match the specified list before the key will be considered acceptable.
1.214 djm 1170: .It Cm valid-after Ns = Ns "timestamp"
1171: Indicates that the key is valid for use at or after the specified timestamp,
1.215 jmc 1172: which may be a date in YYYYMMDD format or a time in YYYYMMDDHHMM[SS] format.
1.214 djm 1173: .It Cm valid-before Ns = Ns "timestamp"
1174: Indicates that the key is valid for use at or before the specified timestamp.
1.163 djm 1175: .El
1176: .Pp
1177: When verifying signatures made by certificates, the expected principal
1178: name must match both the principals pattern in the allowed signers file and
1179: the principals embedded in the certificate itself.
1180: .Pp
1181: An example allowed signers file:
1182: .Bd -literal -offset 3n
1183: # Comments allowed at start of line
1184: user1@example.com,user2@example.com ssh-rsa AAAAX1...
1185: # A certificate authority, trusted for all principals in a domain.
1186: *@example.com cert-authority ssh-ed25519 AAAB4...
1187: # A key that is accepted only for file signing.
1188: user2@example.com namespaces="file" ssh-ed25519 AAA41...
1189: .Ed
1.173 naddy 1190: .Sh ENVIRONMENT
1191: .Bl -tag -width Ds
1192: .It Ev SSH_SK_PROVIDER
1.201 djm 1193: Specifies a path to a library that will be used when loading any
1194: FIDO authenticator-hosted keys, overriding the default of using
1195: the built-in USB HID support.
1.173 naddy 1196: .El
1.2 deraadt 1197: .Sh FILES
1.100 naddy 1198: .Bl -tag -width Ds -compact
1.68 djm 1199: .It Pa ~/.ssh/id_dsa
1.100 naddy 1200: .It Pa ~/.ssh/id_ecdsa
1.173 naddy 1201: .It Pa ~/.ssh/id_ecdsa_sk
1.118 naddy 1202: .It Pa ~/.ssh/id_ed25519
1.176 naddy 1203: .It Pa ~/.ssh/id_ed25519_sk
1.100 naddy 1204: .It Pa ~/.ssh/id_rsa
1.180 naddy 1205: Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
1206: authenticator-hosted Ed25519 or RSA authentication identity of the user.
1.15 deraadt 1207: This file should not be readable by anyone but the user.
1208: It is possible to
1209: specify a passphrase when generating the key; that passphrase will be
1.80 dtucker 1210: used to encrypt the private part of this file using 128-bit AES.
1.15 deraadt 1211: This file is not automatically accessed by
1212: .Nm
1213: but it is offered as the default file for the private key.
1.46 markus 1214: .Xr ssh 1
1.15 deraadt 1215: will read this file when a login attempt is made.
1.100 naddy 1216: .Pp
1.68 djm 1217: .It Pa ~/.ssh/id_dsa.pub
1.100 naddy 1218: .It Pa ~/.ssh/id_ecdsa.pub
1.173 naddy 1219: .It Pa ~/.ssh/id_ecdsa_sk.pub
1.118 naddy 1220: .It Pa ~/.ssh/id_ed25519.pub
1.176 naddy 1221: .It Pa ~/.ssh/id_ed25519_sk.pub
1.68 djm 1222: .It Pa ~/.ssh/id_rsa.pub
1.180 naddy 1223: Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
1224: authenticator-hosted Ed25519 or RSA public key for authentication.
1.15 deraadt 1225: The contents of this file should be added to
1.68 djm 1226: .Pa ~/.ssh/authorized_keys
1.15 deraadt 1227: on all machines
1.49 deraadt 1228: where the user wishes to log in using public key authentication.
1.12 aaron 1229: There is no need to keep the contents of this file secret.
1.100 naddy 1230: .Pp
1.60 djm 1231: .It Pa /etc/moduli
1232: Contains Diffie-Hellman groups used for DH-GEX.
1233: The file format is described in
1234: .Xr moduli 5 .
1.19 aaron 1235: .El
1.2 deraadt 1236: .Sh SEE ALSO
1237: .Xr ssh 1 ,
1238: .Xr ssh-add 1 ,
1.8 ericj 1239: .Xr ssh-agent 1 ,
1.60 djm 1240: .Xr moduli 5 ,
1.30 itojun 1241: .Xr sshd 8
1.37 markus 1242: .Rs
1.73 markus 1243: .%R RFC 4716
1244: .%T "The Secure Shell (SSH) Public Key File Format"
1245: .%D 2006
1.37 markus 1246: .Re
1.59 jmc 1247: .Sh AUTHORS
1248: OpenSSH is a derivative of the original and free
1249: ssh 1.2.12 release by Tatu Ylonen.
1250: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
1251: Theo de Raadt and Dug Song
1252: removed many bugs, re-added newer features and
1253: created OpenSSH.
1254: Markus Friedl contributed the support for SSH
1255: protocol versions 1.5 and 2.0.
![[BACK]](/icons/back.gif){kind=icon}
Return to ssh-keygen.1 CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh