Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.214
1.214 ! djm 1: .\" $OpenBSD: ssh-keygen.1,v 1.213 2021/05/12 11:34:30 dtucker 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: .\"
1.214 ! djm 38: .Dd $Mdocdate: May 12 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
1.171 jmc 154: .Fl Y Cm check-novalidate
1.214 ! djm 155: .Op Fl O Ar option
1.171 jmc 156: .Fl n Ar namespace
157: .Fl s Ar signature_file
158: .Nm ssh-keygen
1.163 djm 159: .Fl Y Cm sign
160: .Fl f Ar key_file
161: .Fl n Ar namespace
162: .Ar
163: .Nm ssh-keygen
164: .Fl Y Cm verify
1.214 ! djm 165: .Op Fl O Ar option
1.171 jmc 166: .Fl f Ar allowed_signers_file
1.163 djm 167: .Fl I Ar signer_identity
168: .Fl n Ar namespace
169: .Fl s Ar signature_file
170: .Op Fl r Ar revocation_file
1.13 aaron 171: .Sh DESCRIPTION
1.2 deraadt 172: .Nm
1.37 markus 173: generates, manages and converts authentication keys for
1.2 deraadt 174: .Xr ssh 1 .
1.15 deraadt 175: .Nm
1.140 jmc 176: can create keys for use by SSH protocol version 2.
1.130 jmc 177: .Pp
1.58 jmc 178: The type of key to be generated is specified with the
1.25 markus 179: .Fl t
1.52 djm 180: option.
1.70 djm 181: If invoked without any arguments,
182: .Nm
1.141 naddy 183: will generate an RSA key.
1.15 deraadt 184: .Pp
1.60 djm 185: .Nm
186: is also used to generate groups for use in Diffie-Hellman group
187: exchange (DH-GEX).
188: See the
189: .Sx MODULI GENERATION
190: section for details.
191: .Pp
1.111 djm 192: Finally,
193: .Nm
194: can be used to generate and update Key Revocation Lists, and to test whether
1.112 jmc 195: given keys have been revoked by one.
196: See the
1.111 djm 197: .Sx KEY REVOCATION LISTS
198: section for details.
199: .Pp
1.2 deraadt 200: Normally each user wishing to use SSH
1.99 djm 201: with public key authentication runs this once to create the authentication
1.1 deraadt 202: key in
1.118 naddy 203: .Pa ~/.ssh/id_dsa ,
1.99 djm 204: .Pa ~/.ssh/id_ecdsa ,
1.173 naddy 205: .Pa ~/.ssh/id_ecdsa_sk ,
1.176 naddy 206: .Pa ~/.ssh/id_ed25519 ,
207: .Pa ~/.ssh/id_ed25519_sk
1.15 deraadt 208: or
1.68 djm 209: .Pa ~/.ssh/id_rsa .
1.15 deraadt 210: Additionally, the system administrator may use this to generate host keys,
211: as seen in
212: .Pa /etc/rc .
1.2 deraadt 213: .Pp
1.1 deraadt 214: Normally this program generates the key and asks for a file in which
1.12 aaron 215: to store the private key.
216: The public key is stored in a file with the same name but
1.2 deraadt 217: .Dq .pub
1.12 aaron 218: appended.
219: The program also asks for a passphrase.
220: The passphrase may be empty to indicate no passphrase
1.26 markus 221: (host keys must have an empty passphrase), or it may be a string of
1.12 aaron 222: arbitrary length.
1.51 stevesk 223: A passphrase is similar to a password, except it can be a phrase with a
224: series of words, punctuation, numbers, whitespace, or any string of
225: characters you want.
226: Good passphrases are 10-30 characters long, are
1.1 deraadt 227: not simple sentences or otherwise easily guessable (English
1.42 markus 228: prose has only 1-2 bits of entropy per character, and provides very bad
1.51 stevesk 229: passphrases), and contain a mix of upper and lowercase letters,
230: numbers, and non-alphanumeric characters.
1.12 aaron 231: The passphrase can be changed later by using the
1.2 deraadt 232: .Fl p
1.1 deraadt 233: option.
1.2 deraadt 234: .Pp
1.12 aaron 235: There is no way to recover a lost passphrase.
1.105 djm 236: If the passphrase is lost or forgotten, a new key must be generated
237: and the corresponding public key copied to other machines.
1.2 deraadt 238: .Pp
1.153 djm 239: .Nm
240: will by default write keys in an OpenSSH-specific format.
241: This format is preferred as it offers better protection for
242: keys at rest as well as allowing storage of key comments within
243: the private key file itself.
244: The key comment may be useful to help identify the key.
1.12 aaron 245: The comment is initialized to
1.2 deraadt 246: .Dq user@host
247: when the key is created, but can be changed using the
248: .Fl c
1.1 deraadt 249: option.
1.153 djm 250: .Pp
251: It is still possible for
252: .Nm
253: to write the previously-used PEM format private keys using the
254: .Fl m
255: flag.
256: This may be used when generating new keys, and existing new-format
257: keys may be converted using this option in conjunction with the
258: .Fl p
259: (change passphrase) flag.
1.2 deraadt 260: .Pp
1.205 solene 261: After a key is generated,
262: .Nm
263: will ask where the keys
1.15 deraadt 264: should be placed to be activated.
265: .Pp
1.2 deraadt 266: The options are as follows:
267: .Bl -tag -width Ds
1.102 stevesk 268: .It Fl A
1.175 djm 269: For each of the key types (rsa, dsa, ecdsa and ed25519)
1.118 naddy 270: for which host keys
1.102 stevesk 271: do not exist, generate the host keys with the default key file path,
272: an empty passphrase, default bits for the key type, and default comment.
1.144 jmc 273: If
1.143 djm 274: .Fl f
1.144 jmc 275: has also been specified, its argument is used as a prefix to the
1.143 djm 276: default path for the resulting host key files.
1.104 jmc 277: This is used by
1.102 stevesk 278: .Pa /etc/rc
279: to generate new host keys.
1.117 djm 280: .It Fl a Ar rounds
1.169 jmc 281: When saving a private key, this option specifies the number of KDF
1.211 dtucker 282: (key derivation function, currently
283: .Xr bcrypt_pbkdf 3 )
284: rounds used.
1.117 djm 285: Higher numbers result in slower passphrase verification and increased
286: resistance to brute-force password cracking (should the keys be stolen).
1.204 dtucker 287: The default is 16 rounds.
1.66 jmc 288: .It Fl B
289: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 290: .It Fl b Ar bits
1.12 aaron 291: Specifies the number of bits in the key to create.
1.158 dtucker 292: For RSA keys, the minimum size is 1024 bits and the default is 3072 bits.
293: Generally, 3072 bits is considered sufficient.
1.72 dtucker 294: DSA keys must be exactly 1024 bits as specified by FIPS 186-2.
1.106 djm 295: For ECDSA keys, the
296: .Fl b
1.107 deraadt 297: flag determines the key length by selecting from one of three elliptic
1.106 djm 298: curve sizes: 256, 384 or 521 bits.
299: Attempting to use bit lengths other than these three values for ECDSA keys
300: will fail.
1.176 naddy 301: ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the
1.118 naddy 302: .Fl b
303: flag will be ignored.
1.66 jmc 304: .It Fl C Ar comment
305: Provides a new comment.
1.2 deraadt 306: .It Fl c
1.1 deraadt 307: Requests changing the comment in the private and public key files.
308: The program will prompt for the file containing the private keys, for
1.41 stevesk 309: the passphrase if the key has one, and for the new comment.
1.81 markus 310: .It Fl D Ar pkcs11
1.157 naddy 311: Download the public keys provided by the PKCS#11 shared library
1.83 markus 312: .Ar pkcs11 .
1.98 djm 313: When used in combination with
314: .Fl s ,
315: this option indicates that a CA key resides in a PKCS#11 token (see the
316: .Sx CERTIFICATES
317: section for details).
1.124 djm 318: .It Fl E Ar fingerprint_hash
319: Specifies the hash algorithm used when displaying key fingerprints.
320: Valid options are:
321: .Dq md5
322: and
323: .Dq sha256 .
324: The default is
325: .Dq sha256 .
1.37 markus 326: .It Fl e
1.40 markus 327: This option will read a private or public OpenSSH key file and
1.154 djm 328: print to stdout a public key in one of the formats specified by the
1.95 djm 329: .Fl m
330: option.
331: The default export format is
332: .Dq RFC4716 .
1.96 jmc 333: This option allows exporting OpenSSH keys for use by other programs, including
1.95 djm 334: several commercial SSH implementations.
1.151 djm 335: .It Fl F Ar hostname | [hostname]:port
1.66 jmc 336: Search for the specified
337: .Ar hostname
1.151 djm 338: (with optional port number)
1.66 jmc 339: in a
340: .Pa known_hosts
341: file, listing any occurrences found.
342: This option is useful to find hashed host names or addresses and may also be
343: used in conjunction with the
344: .Fl H
345: option to print found keys in a hashed format.
346: .It Fl f Ar filename
347: Specifies the filename of the key file.
1.57 jakob 348: .It Fl g
1.62 jakob 349: Use generic DNS format when printing fingerprint resource records using the
1.63 jmc 350: .Fl r
1.62 jakob 351: command.
1.66 jmc 352: .It Fl H
353: Hash a
354: .Pa known_hosts
1.67 dtucker 355: file.
356: This replaces all hostnames and addresses with hashed representations
357: within the specified file; the original content is moved to a file with
358: a .old suffix.
1.66 jmc 359: These hashes may be used normally by
360: .Nm ssh
361: and
362: .Nm sshd ,
363: but they do not reveal identifying information should the file's contents
364: be disclosed.
365: This option will not modify existing hashed hostnames and is therefore safe
366: to use on files that mix hashed and non-hashed names.
1.84 djm 367: .It Fl h
368: When signing a key, create a host certificate instead of a user
369: certificate.
370: Please see the
371: .Sx CERTIFICATES
372: section for details.
1.85 jmc 373: .It Fl I Ar certificate_identity
1.84 djm 374: Specify the key identity when signing a public key.
375: Please see the
376: .Sx CERTIFICATES
377: section for details.
1.37 markus 378: .It Fl i
379: This option will read an unencrypted private (or public) key file
1.95 djm 380: in the format specified by the
381: .Fl m
382: option and print an OpenSSH compatible private
1.37 markus 383: (or public) key to stdout.
1.122 jmc 384: This option allows importing keys from other software, including several
385: commercial SSH implementations.
386: The default import format is
387: .Dq RFC4716 .
1.188 jmc 388: .It Fl K
1.187 djm 389: Download resident keys from a FIDO authenticator.
390: Public and private key files will be written to the current directory for
391: each downloaded key.
1.207 djm 392: If multiple FIDO authenticators are attached, keys will be downloaded from
393: the first touched authenticator.
1.111 djm 394: .It Fl k
395: Generate a KRL file.
396: In this mode,
397: .Nm
398: will generate a KRL file at the location specified via the
399: .Fl f
1.114 jmc 400: flag that revokes every key or certificate presented on the command line.
1.111 djm 401: Keys/certificates to be revoked may be specified by public key file or
402: using the format described in the
403: .Sx KEY REVOCATION LISTS
404: section.
1.86 djm 405: .It Fl L
1.129 djm 406: Prints the contents of one or more certificates.
1.9 markus 407: .It Fl l
1.77 grunk 408: Show fingerprint of specified public key file.
1.50 markus 409: For RSA and DSA keys
410: .Nm
1.78 jmc 411: tries to find the matching public key file and prints its fingerprint.
412: If combined with
413: .Fl v ,
1.132 jmc 414: a visual ASCII art representation of the key is supplied with the
1.131 djm 415: fingerprint.
1.184 djm 416: .It Fl M Cm generate
417: Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for
418: eventual use by the
419: .Sq diffie-hellman-group-exchange-*
420: key exchange methods.
421: The numbers generated by this operation must be further screened before
422: use.
423: See the
424: .Sx MODULI GENERATION
425: section for more information.
426: .It Fl M Cm screen
427: Screen candidate parameters for Diffie-Hellman Group Exchange.
428: This will accept a list of candidate numbers and test that they are
429: safe (Sophie Germain) primes with acceptable group generators.
430: The results of this operation may be added to the
431: .Pa /etc/moduli
432: file.
433: See the
434: .Sx MODULI GENERATION
435: section for more information.
1.95 djm 436: .It Fl m Ar key_format
1.155 djm 437: Specify a key format for key generation, the
1.95 djm 438: .Fl i
1.155 djm 439: (import),
1.95 djm 440: .Fl e
1.155 djm 441: (export) conversion options, and the
442: .Fl p
443: change passphrase operation.
444: The latter may be used to convert between OpenSSH private key and PEM
445: private key formats.
1.95 djm 446: The supported key formats are:
447: .Dq RFC4716
1.96 jmc 448: (RFC 4716/SSH2 public or private key),
1.95 djm 449: .Dq PKCS8
1.161 djm 450: (PKCS8 public or private key)
1.95 djm 451: or
452: .Dq PEM
453: (PEM public key).
1.161 djm 454: By default OpenSSH will write newly-generated private keys in its own
455: format, but when converting public keys for export the default format is
1.95 djm 456: .Dq RFC4716 .
1.148 djm 457: Setting a format of
458: .Dq PEM
459: when generating or updating a supported private key type will cause the
460: key to be stored in the legacy PEM private key format.
1.66 jmc 461: .It Fl N Ar new_passphrase
462: Provides the new passphrase.
1.84 djm 463: .It Fl n Ar principals
464: Specify one or more principals (user or host names) to be included in
465: a certificate when signing a key.
466: Multiple principals may be specified, separated by commas.
467: Please see the
468: .Sx CERTIFICATES
469: section for details.
1.93 djm 470: .It Fl O Ar option
1.184 djm 471: Specify a key/value option.
472: These are specific to the operation that
473: .Nm
474: has been requested to perform.
475: .Pp
476: When signing certificates, one of the options listed in the
1.183 djm 477: .Sx CERTIFICATES
1.184 djm 478: section may be specified here.
479: .Pp
480: When performing moduli generation or screening, one of the options
481: listed in the
482: .Sx MODULI GENERATION
483: section may be specified.
484: .Pp
1.190 jmc 485: When generating a key that will be hosted on a FIDO authenticator,
486: this flag may be used to specify key-specific options.
487: Those supported at present are:
488: .Bl -tag -width Ds
489: .It Cm application
490: Override the default FIDO application/origin string of
1.189 djm 491: .Dq ssh: .
1.190 jmc 492: This may be useful when generating host or domain-specific resident keys.
1.200 djm 493: The specified application string must begin with
494: .Dq ssh: .
1.199 jmc 495: .It Cm challenge Ns = Ns Ar path
1.198 jmc 496: Specifies a path to a challenge string that will be passed to the
497: FIDO token during key generation.
1.199 jmc 498: The challenge string may be used as part of an out-of-band
499: protocol for key enrollment
500: (a random challenge is used by default).
1.190 jmc 501: .It Cm device
502: Explicitly specify a
1.189 djm 503: .Xr fido 4
504: device to use, rather than letting the token middleware select one.
1.190 jmc 505: .It Cm no-touch-required
506: Indicate that the generated private key should not require touch
1.185 djm 507: events (user presence) when making signatures.
508: Note that
509: .Xr sshd 8
510: will refuse such signatures by default, unless overridden via
511: an authorized_keys option.
1.190 jmc 512: .It Cm resident
513: Indicate that the key should be stored on the FIDO authenticator itself.
1.185 djm 514: Resident keys may be supported on FIDO2 tokens and typically require that
515: a PIN be set on the token prior to generation.
516: Resident keys may be loaded off the token using
517: .Xr ssh-add 1 .
1.190 jmc 518: .It Cm user
519: A username to be associated with a resident key,
1.189 djm 520: overriding the empty default username.
521: Specifying a username may be useful when generating multiple resident keys
522: for the same application name.
1.206 djm 523: .It Cm verify-required
524: Indicate that this private key should require user verification for
525: each signature.
1.208 jmc 526: Not all FIDO tokens support this option.
1.206 djm 527: Currently PIN authentication is the only supported verification method,
528: but other methods may be supported in the future.
1.199 jmc 529: .It Cm write-attestation Ns = Ns Ar path
1.209 djm 530: May be used at key generation time to record the attestation data
1.197 djm 531: returned from FIDO tokens during key generation.
1.209 djm 532: Please note that this information is potentially sensitive.
533: By default, this information is discarded.
1.190 jmc 534: .El
1.185 djm 535: .Pp
1.214 ! djm 536: When performing signature-related options using the
! 537: .Fl Y
! 538: flag, the following options are accepted:
! 539: .Bl -tag -width Ds
! 540: .It Cm verify-time Ns = Ns Ar timestamp
! 541: Specifies a time to use when validating signatures instead of the current
! 542: time.
! 543: The time may be specified as a date in YYYYMMDD format or a time
! 544: in YYYYMMDDHHMM[SS] format.
! 545: .El
! 546: .Pp
1.185 djm 547: The
548: .Fl O
549: option may be specified multiple times.
1.66 jmc 550: .It Fl P Ar passphrase
551: Provides the (old) passphrase.
1.2 deraadt 552: .It Fl p
1.1 deraadt 553: Requests changing the passphrase of a private key file instead of
1.12 aaron 554: creating a new private key.
555: The program will prompt for the file
1.1 deraadt 556: containing the private key, for the old passphrase, and twice for the
557: new passphrase.
1.113 jmc 558: .It Fl Q
559: Test whether keys have been revoked in a KRL.
1.203 djm 560: If the
561: .Fl l
562: option is also specified then the contents of the KRL will be printed.
1.5 aaron 563: .It Fl q
564: Silence
565: .Nm ssh-keygen .
1.152 djm 566: .It Fl R Ar hostname | [hostname]:port
1.151 djm 567: Removes all keys belonging to the specified
1.64 djm 568: .Ar hostname
1.151 djm 569: (with optional port number)
1.65 jmc 570: from a
1.64 djm 571: .Pa known_hosts
572: file.
1.65 jmc 573: This option is useful to delete hashed hosts (see the
1.64 djm 574: .Fl H
575: option above).
1.66 jmc 576: .It Fl r Ar hostname
577: Print the SSHFP fingerprint resource record named
578: .Ar hostname
579: for the specified public key file.
1.84 djm 580: .It Fl s Ar ca_key
581: Certify (sign) a public key using the specified CA key.
582: Please see the
583: .Sx CERTIFICATES
584: section for details.
1.111 djm 585: .Pp
586: When generating a KRL,
587: .Fl s
1.112 jmc 588: specifies a path to a CA public key file used to revoke certificates directly
1.111 djm 589: by key ID or serial number.
590: See the
591: .Sx KEY REVOCATION LISTS
592: section for details.
1.175 djm 593: .It Fl t Cm dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa
1.66 jmc 594: Specifies the type of key to create.
595: The possible values are
1.100 naddy 596: .Dq dsa ,
1.118 naddy 597: .Dq ecdsa ,
1.173 naddy 598: .Dq ecdsa-sk ,
1.118 naddy 599: .Dq ed25519 ,
1.175 djm 600: .Dq ed25519-sk ,
1.100 naddy 601: or
1.139 jmc 602: .Dq rsa .
1.159 djm 603: .Pp
604: This flag may also be used to specify the desired signature type when
1.160 jmc 605: signing certificates using an RSA CA key.
1.159 djm 606: The available RSA signature variants are
607: .Dq ssh-rsa
608: (SHA1 signatures, not recommended),
1.160 jmc 609: .Dq rsa-sha2-256 ,
610: and
1.159 djm 611: .Dq rsa-sha2-512
612: (the default).
1.142 djm 613: .It Fl U
614: When used in combination with
615: .Fl s ,
616: this option indicates that a CA key resides in a
617: .Xr ssh-agent 1 .
618: See the
619: .Sx CERTIFICATES
620: section for more information.
1.112 jmc 621: .It Fl u
622: Update a KRL.
623: When specified with
624: .Fl k ,
1.114 jmc 625: keys listed via the command line are added to the existing KRL rather than
1.112 jmc 626: a new KRL being created.
1.84 djm 627: .It Fl V Ar validity_interval
628: Specify a validity interval when signing a certificate.
629: A validity interval may consist of a single time, indicating that the
630: certificate is valid beginning now and expiring at that time, or may consist
631: of two times separated by a colon to indicate an explicit time interval.
1.145 djm 632: .Pp
633: The start time may be specified as the string
634: .Dq always
635: to indicate the certificate has no specified start time,
1.147 djm 636: a date in YYYYMMDD format, a time in YYYYMMDDHHMM[SS] format,
1.145 djm 637: a relative time (to the current time) consisting of a minus sign followed by
638: an interval in the format described in the
1.116 jmc 639: TIME FORMATS section of
1.90 jmc 640: .Xr sshd_config 5 .
1.145 djm 641: .Pp
1.147 djm 642: The end time may be specified as a YYYYMMDD date, a YYYYMMDDHHMM[SS] time,
1.145 djm 643: a relative time starting with a plus character or the string
644: .Dq forever
1.202 dtucker 645: to indicate that the certificate has no expiry date.
1.84 djm 646: .Pp
647: For example:
648: .Dq +52w1d
649: (valid from now to 52 weeks and one day from now),
650: .Dq -4w:+4w
651: (valid from four weeks ago to four weeks from now),
652: .Dq 20100101123000:20110101123000
653: (valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011),
654: .Dq -1d:20110101
1.210 dtucker 655: (valid from yesterday to midnight, January 1st, 2011),
1.145 djm 656: .Dq -1m:forever
657: (valid from one minute ago and never expiring).
1.61 djm 658: .It Fl v
659: Verbose mode.
660: Causes
661: .Nm
662: to print debugging messages about its progress.
663: This is helpful for debugging moduli generation.
664: Multiple
665: .Fl v
666: options increase the verbosity.
667: The maximum is 3.
1.173 naddy 668: .It Fl w Ar provider
1.180 naddy 669: Specifies a path to a library that will be used when creating
670: FIDO authenticator-hosted keys, overriding the default of using
671: the internal USB HID support.
1.196 djm 672: .It Fl Y Cm find-principals
673: Find the principal(s) associated with the public key of a signature,
1.194 djm 674: provided using the
675: .Fl s
676: flag in an authorized signers file provided using the
677: .Fl f
678: flag.
679: The format of the allowed signers file is documented in the
680: .Sx ALLOWED SIGNERS
1.195 jmc 681: section below.
1.196 djm 682: If one or more matching principals are found, they are returned on
683: standard output.
1.182 jmc 684: .It Fl Y Cm check-novalidate
685: Checks that a signature generated using
686: .Nm
687: .Fl Y Cm sign
688: has a valid structure.
689: This does not validate if a signature comes from an authorized signer.
690: When testing a signature,
691: .Nm
692: accepts a message on standard input and a signature namespace using
693: .Fl n .
694: A file containing the corresponding signature must also be supplied using the
695: .Fl s
696: flag.
697: Successful testing of the signature is signalled by
698: .Nm
699: returning a zero exit status.
1.166 jmc 700: .It Fl Y Cm sign
1.163 djm 701: Cryptographically sign a file or some data using a SSH key.
702: When signing,
703: .Nm
704: accepts zero or more files to sign on the command-line - if no files
705: are specified then
706: .Nm
707: will sign data presented on standard input.
708: Signatures are written to the path of the input file with
709: .Dq .sig
710: appended, or to standard output if the message to be signed was read from
711: standard input.
712: .Pp
713: The key used for signing is specified using the
714: .Fl f
715: option and may refer to either a private key, or a public key with the private
716: half available via
717: .Xr ssh-agent 1 .
718: An additional signature namespace, used to prevent signature confusion across
719: different domains of use (e.g. file signing vs email signing) must be provided
720: via the
721: .Fl n
722: flag.
723: Namespaces are arbitrary strings, and may include:
724: .Dq file
725: for file signing,
726: .Dq email
727: for email signing.
728: For custom uses, it is recommended to use names following a
729: NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces.
1.166 jmc 730: .It Fl Y Cm verify
1.163 djm 731: Request to verify a signature generated using
732: .Nm
1.166 jmc 733: .Fl Y Cm sign
1.163 djm 734: as described above.
735: When verifying a signature,
736: .Nm
737: accepts a message on standard input and a signature namespace using
738: .Fl n .
739: A file containing the corresponding signature must also be supplied using the
740: .Fl s
741: flag, along with the identity of the signer using
742: .Fl I
743: and a list of allowed signers via the
744: .Fl f
745: flag.
746: The format of the allowed signers file is documented in the
747: .Sx ALLOWED SIGNERS
748: section below.
749: A file containing revoked keys can be passed using the
750: .Fl r
1.165 jmc 751: flag.
752: The revocation file may be a KRL or a one-per-line list of public keys.
1.163 djm 753: Successful verification by an authorized signer is signalled by
754: .Nm
755: returning a zero exit status.
1.181 jmc 756: .It Fl y
757: This option will read a private
758: OpenSSH format file and print an OpenSSH public key to stdout.
1.212 dtucker 759: .It Fl Z Ar cipher
760: Specifies the cipher to use for encryption when writing an OpenSSH-format
761: private key file.
762: The list of available ciphers may be obtained using
763: .Qq ssh -Q cipher .
764: The default is
765: .Dq aes256-ctr .
1.93 djm 766: .It Fl z Ar serial_number
767: Specifies a serial number to be embedded in the certificate to distinguish
768: this certificate from others from the same CA.
1.156 djm 769: If the
770: .Ar serial_number
771: is prefixed with a
772: .Sq +
773: character, then the serial number will be incremented for each certificate
774: signed on a single command-line.
1.93 djm 775: The default serial number is zero.
1.111 djm 776: .Pp
777: When generating a KRL, the
778: .Fl z
779: flag is used to specify a KRL version number.
1.2 deraadt 780: .El
1.60 djm 781: .Sh MODULI GENERATION
782: .Nm
783: may be used to generate groups for the Diffie-Hellman Group Exchange
784: (DH-GEX) protocol.
785: Generating these groups is a two-step process: first, candidate
786: primes are generated using a fast, but memory intensive process.
787: These candidate primes are then tested for suitability (a CPU-intensive
788: process).
789: .Pp
790: Generation of primes is performed using the
1.184 djm 791: .Fl M Cm generate
1.60 djm 792: option.
793: The desired length of the primes may be specified by the
1.184 djm 794: .Fl O Cm bits
1.60 djm 795: option.
796: For example:
797: .Pp
1.184 djm 798: .Dl # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates
1.60 djm 799: .Pp
800: By default, the search for primes begins at a random point in the
801: desired length range.
802: This may be overridden using the
1.184 djm 803: .Fl O Cm start
1.60 djm 804: option, which specifies a different start point (in hex).
805: .Pp
1.109 dtucker 806: Once a set of candidates have been generated, they must be screened for
1.60 djm 807: suitability.
808: This may be performed using the
1.184 djm 809: .Fl M Cm screen
1.60 djm 810: option.
811: In this mode
812: .Nm
813: will read candidates from standard input (or a file specified using the
814: .Fl f
815: option).
816: For example:
817: .Pp
1.184 djm 818: .Dl # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048
1.60 djm 819: .Pp
820: By default, each candidate will be subjected to 100 primality tests.
821: This may be overridden using the
1.184 djm 822: .Fl O Cm prime-tests
1.60 djm 823: option.
824: The DH generator value will be chosen automatically for the
825: prime under consideration.
826: If a specific generator is desired, it may be requested using the
1.184 djm 827: .Fl O Cm generator
1.60 djm 828: option.
1.66 jmc 829: Valid generator values are 2, 3, and 5.
1.60 djm 830: .Pp
831: Screened DH groups may be installed in
832: .Pa /etc/moduli .
1.213 dtucker 833: It is important that this file contains moduli of a range of bit lengths.
1.184 djm 834: .Pp
835: A number of options are available for moduli generation and screening via the
836: .Fl O
837: flag:
1.186 jmc 838: .Bl -tag -width Ds
1.184 djm 839: .It Ic lines Ns = Ns Ar number
840: Exit after screening the specified number of lines while performing DH
841: candidate screening.
842: .It Ic start-line Ns = Ns Ar line-number
843: Start screening at the specified line number while performing DH candidate
844: screening.
845: .It Ic checkpoint Ns = Ns Ar filename
846: Write the last line processed to the specified file while performing DH
847: candidate screening.
848: This will be used to skip lines in the input file that have already been
849: processed if the job is restarted.
850: .It Ic memory Ns = Ns Ar mbytes
851: Specify the amount of memory to use (in megabytes) when generating
852: candidate moduli for DH-GEX.
853: .It Ic start Ns = Ns Ar hex-value
854: Specify start point (in hex) when generating candidate moduli for DH-GEX.
855: .It Ic generator Ns = Ns Ar value
856: Specify desired generator (in decimal) when testing candidate moduli for DH-GEX.
857: .El
1.84 djm 858: .Sh CERTIFICATES
859: .Nm
860: supports signing of keys to produce certificates that may be used for
861: user or host authentication.
862: Certificates consist of a public key, some identity information, zero or
1.94 jmc 863: more principal (user or host) names and a set of options that
1.84 djm 864: are signed by a Certification Authority (CA) key.
865: Clients or servers may then trust only the CA key and verify its signature
866: on a certificate rather than trusting many user/host keys.
867: Note that OpenSSH certificates are a different, and much simpler, format to
868: the X.509 certificates used in
869: .Xr ssl 8 .
870: .Pp
871: .Nm
872: supports two types of certificates: user and host.
873: User certificates authenticate users to servers, whereas host certificates
1.85 jmc 874: authenticate server hosts to users.
875: To generate a user certificate:
1.84 djm 876: .Pp
877: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub
878: .Pp
879: The resultant certificate will be placed in
1.91 djm 880: .Pa /path/to/user_key-cert.pub .
1.84 djm 881: A host certificate requires the
882: .Fl h
883: option:
884: .Pp
885: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub
886: .Pp
887: The host certificate will be output to
1.91 djm 888: .Pa /path/to/host_key-cert.pub .
1.98 djm 889: .Pp
890: It is possible to sign using a CA key stored in a PKCS#11 token by
891: providing the token library using
892: .Fl D
893: and identifying the CA key by providing its public half as an argument
894: to
895: .Fl s :
896: .Pp
1.127 naddy 897: .Dl $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub
1.142 djm 898: .Pp
899: Similarly, it is possible for the CA key to be hosted in a
900: .Xr ssh-agent 1 .
901: This is indicated by the
902: .Fl U
903: flag and, again, the CA key must be identified by its public half.
904: .Pp
905: .Dl $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub
1.98 djm 906: .Pp
907: In all cases,
1.84 djm 908: .Ar key_id
909: is a "key identifier" that is logged by the server when the certificate
910: is used for authentication.
911: .Pp
912: Certificates may be limited to be valid for a set of principal (user/host)
913: names.
914: By default, generated certificates are valid for all users or hosts.
915: To generate a certificate for a specified set of principals:
916: .Pp
917: .Dl $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub
1.127 naddy 918: .Dl "$ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub"
1.84 djm 919: .Pp
920: Additional limitations on the validity and use of user certificates may
1.94 jmc 921: be specified through certificate options.
1.93 djm 922: A certificate option may disable features of the SSH session, may be
1.84 djm 923: valid only when presented from particular source addresses or may
924: force the use of a specific command.
1.183 djm 925: .Pp
926: The options that are valid for user certificates are:
927: .Pp
928: .Bl -tag -width Ds -compact
929: .It Ic clear
930: Clear all enabled permissions.
931: This is useful for clearing the default set of permissions so permissions may
932: be added individually.
933: .Pp
934: .It Ic critical : Ns Ar name Ns Op Ns = Ns Ar contents
935: .It Ic extension : Ns Ar name Ns Op Ns = Ns Ar contents
936: Includes an arbitrary certificate critical option or extension.
937: The specified
938: .Ar name
939: should include a domain suffix, e.g.\&
940: .Dq name@example.com .
941: If
942: .Ar contents
943: is specified then it is included as the contents of the extension/option
944: encoded as a string, otherwise the extension/option is created with no
945: contents (usually indicating a flag).
946: Extensions may be ignored by a client or server that does not recognise them,
947: whereas unknown critical options will cause the certificate to be refused.
948: .Pp
949: .It Ic force-command Ns = Ns Ar command
950: Forces the execution of
951: .Ar command
952: instead of any shell or command specified by the user when
953: the certificate is used for authentication.
954: .Pp
955: .It Ic no-agent-forwarding
956: Disable
957: .Xr ssh-agent 1
958: forwarding (permitted by default).
959: .Pp
960: .It Ic no-port-forwarding
961: Disable port forwarding (permitted by default).
962: .Pp
963: .It Ic no-pty
964: Disable PTY allocation (permitted by default).
965: .Pp
966: .It Ic no-user-rc
967: Disable execution of
968: .Pa ~/.ssh/rc
969: by
970: .Xr sshd 8
971: (permitted by default).
972: .Pp
973: .It Ic no-x11-forwarding
974: Disable X11 forwarding (permitted by default).
975: .Pp
976: .It Ic permit-agent-forwarding
977: Allows
978: .Xr ssh-agent 1
979: forwarding.
980: .Pp
981: .It Ic permit-port-forwarding
982: Allows port forwarding.
983: .Pp
984: .It Ic permit-pty
985: Allows PTY allocation.
986: .Pp
987: .It Ic permit-user-rc
988: Allows execution of
989: .Pa ~/.ssh/rc
990: by
991: .Xr sshd 8 .
992: .Pp
993: .It Ic permit-X11-forwarding
994: Allows X11 forwarding.
995: .Pp
996: .It Ic no-touch-required
1.206 djm 997: Do not require signatures made using this key include demonstration
1.193 naddy 998: of user presence (e.g. by having the user touch the authenticator).
1.192 naddy 999: This option only makes sense for the FIDO authenticator algorithms
1.183 djm 1000: .Cm ecdsa-sk
1001: and
1002: .Cm ed25519-sk .
1003: .Pp
1004: .It Ic source-address Ns = Ns Ar address_list
1005: Restrict the source addresses from which the certificate is considered valid.
1006: The
1007: .Ar address_list
1008: is a comma-separated list of one or more address/netmask pairs in CIDR
1009: format.
1.206 djm 1010: .Pp
1011: .It Ic verify-required
1012: Require signatures made using this key indicate that the user was first
1013: verified.
1014: This option only makes sense for the FIDO authenticator algorithms
1015: .Cm ecdsa-sk
1016: and
1017: .Cm ed25519-sk .
1018: Currently PIN authentication is the only supported verification method,
1019: but other methods may be supported in the future.
1.183 djm 1020: .El
1021: .Pp
1022: At present, no standard options are valid for host keys.
1.84 djm 1023: .Pp
1024: Finally, certificates may be defined with a validity lifetime.
1025: The
1026: .Fl V
1027: option allows specification of certificate start and end times.
1028: A certificate that is presented at a time outside this range will not be
1029: considered valid.
1.210 dtucker 1030: By default, certificates are valid from the
1.110 jmc 1031: .Ux
1032: Epoch to the distant future.
1.84 djm 1033: .Pp
1034: For certificates to be used for user or host authentication, the CA
1035: public key must be trusted by
1036: .Xr sshd 8
1037: or
1038: .Xr ssh 1 .
1039: Please refer to those manual pages for details.
1.111 djm 1040: .Sh KEY REVOCATION LISTS
1041: .Nm
1042: is able to manage OpenSSH format Key Revocation Lists (KRLs).
1043: These binary files specify keys or certificates to be revoked using a
1.119 tedu 1044: compact format, taking as little as one bit per certificate if they are being
1.111 djm 1045: revoked by serial number.
1046: .Pp
1047: KRLs may be generated using the
1048: .Fl k
1049: flag.
1.114 jmc 1050: This option reads one or more files from the command line and generates a new
1.111 djm 1051: KRL.
1052: The files may either contain a KRL specification (see below) or public keys,
1053: listed one per line.
1054: Plain public keys are revoked by listing their hash or contents in the KRL and
1055: certificates revoked by serial number or key ID (if the serial is zero or
1056: not available).
1057: .Pp
1058: Revoking keys using a KRL specification offers explicit control over the
1059: types of record used to revoke keys and may be used to directly revoke
1060: certificates by serial number or key ID without having the complete original
1061: certificate on hand.
1062: A KRL specification consists of lines containing one of the following directives
1063: followed by a colon and some directive-specific information.
1064: .Bl -tag -width Ds
1.115 jmc 1065: .It Cm serial : Ar serial_number Ns Op - Ns Ar serial_number
1.111 djm 1066: Revokes a certificate with the specified serial number.
1.112 jmc 1067: Serial numbers are 64-bit values, not including zero and may be expressed
1.111 djm 1068: in decimal, hex or octal.
1069: If two serial numbers are specified separated by a hyphen, then the range
1070: of serial numbers including and between each is revoked.
1071: The CA key must have been specified on the
1072: .Nm
1.114 jmc 1073: command line using the
1.111 djm 1074: .Fl s
1075: option.
1076: .It Cm id : Ar key_id
1077: Revokes a certificate with the specified key ID string.
1078: The CA key must have been specified on the
1079: .Nm
1.114 jmc 1080: command line using the
1.111 djm 1081: .Fl s
1082: option.
1083: .It Cm key : Ar public_key
1084: Revokes the specified key.
1.112 jmc 1085: If a certificate is listed, then it is revoked as a plain public key.
1.111 djm 1086: .It Cm sha1 : Ar public_key
1.149 djm 1087: Revokes the specified key by including its SHA1 hash in the KRL.
1088: .It Cm sha256 : Ar public_key
1089: Revokes the specified key by including its SHA256 hash in the KRL.
1090: KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions
1091: prior to 7.9.
1092: .It Cm hash : Ar fingerprint
1.150 djm 1093: Revokes a key using a fingerprint hash, as obtained from a
1.149 djm 1094: .Xr sshd 8
1095: authentication log message or the
1096: .Nm
1097: .Fl l
1098: flag.
1099: Only SHA256 fingerprints are supported here and resultant KRLs are
1100: not supported by OpenSSH versions prior to 7.9.
1.111 djm 1101: .El
1102: .Pp
1103: KRLs may be updated using the
1104: .Fl u
1105: flag in addition to
1106: .Fl k .
1.114 jmc 1107: When this option is specified, keys listed via the command line are merged into
1.111 djm 1108: the KRL, adding to those already there.
1109: .Pp
1110: It is also possible, given a KRL, to test whether it revokes a particular key
1111: (or keys).
1112: The
1113: .Fl Q
1.128 jmc 1114: flag will query an existing KRL, testing each key specified on the command line.
1.114 jmc 1115: If any key listed on the command line has been revoked (or an error encountered)
1.111 djm 1116: then
1117: .Nm
1118: will exit with a non-zero exit status.
1119: A zero exit status will only be returned if no key was revoked.
1.163 djm 1120: .Sh ALLOWED SIGNERS
1121: When verifying signatures,
1122: .Nm
1123: uses a simple list of identities and keys to determine whether a signature
1124: comes from an authorized source.
1125: This "allowed signers" file uses a format patterned after the
1126: AUTHORIZED_KEYS FILE FORMAT described in
1.165 jmc 1127: .Xr sshd 8 .
1.163 djm 1128: Each line of the file contains the following space-separated fields:
1129: principals, options, keytype, base64-encoded key.
1130: Empty lines and lines starting with a
1131: .Ql #
1132: are ignored as comments.
1133: .Pp
1.210 dtucker 1134: The principals field is a pattern-list (see PATTERNS in
1.163 djm 1135: .Xr ssh_config 5 )
1136: consisting of one or more comma-separated USER@DOMAIN identity patterns
1137: that are accepted for signing.
1138: When verifying, the identity presented via the
1.172 jmc 1139: .Fl I
1140: option must match a principals pattern in order for the corresponding key to be
1.163 djm 1141: considered acceptable for verification.
1142: .Pp
1143: The options (if present) consist of comma-separated option specifications.
1144: No spaces are permitted, except within double quotes.
1145: The following option specifications are supported (note that option keywords
1146: are case-insensitive):
1147: .Bl -tag -width Ds
1148: .It Cm cert-authority
1149: Indicates that this key is accepted as a certificate authority (CA) and
1150: that certificates signed by this CA may be accepted for verification.
1.214 ! djm 1151: .It Cm namespaces Ns = Ns "namespace-list"
1.163 djm 1152: Specifies a pattern-list of namespaces that are accepted for this key.
1.164 djm 1153: If this option is present, the signature namespace embedded in the
1.163 djm 1154: signature object and presented on the verification command-line must
1155: match the specified list before the key will be considered acceptable.
1.214 ! djm 1156: .It Cm valid-after Ns = Ns "timestamp"
! 1157: Indicates that the key is valid for use at or after the specified timestamp,
! 1158: which may be a date in YYYYMMDD format or a time in YYYYMMDDHHMM[SS] format,
! 1159: .It Cm valid-before Ns = Ns "timestamp"
! 1160: Indicates that the key is valid for use at or before the specified timestamp.
1.163 djm 1161: .El
1162: .Pp
1163: When verifying signatures made by certificates, the expected principal
1164: name must match both the principals pattern in the allowed signers file and
1165: the principals embedded in the certificate itself.
1166: .Pp
1167: An example allowed signers file:
1168: .Bd -literal -offset 3n
1169: # Comments allowed at start of line
1170: user1@example.com,user2@example.com ssh-rsa AAAAX1...
1171: # A certificate authority, trusted for all principals in a domain.
1172: *@example.com cert-authority ssh-ed25519 AAAB4...
1173: # A key that is accepted only for file signing.
1174: user2@example.com namespaces="file" ssh-ed25519 AAA41...
1175: .Ed
1.173 naddy 1176: .Sh ENVIRONMENT
1177: .Bl -tag -width Ds
1178: .It Ev SSH_SK_PROVIDER
1.201 djm 1179: Specifies a path to a library that will be used when loading any
1180: FIDO authenticator-hosted keys, overriding the default of using
1181: the built-in USB HID support.
1.173 naddy 1182: .El
1.2 deraadt 1183: .Sh FILES
1.100 naddy 1184: .Bl -tag -width Ds -compact
1.68 djm 1185: .It Pa ~/.ssh/id_dsa
1.100 naddy 1186: .It Pa ~/.ssh/id_ecdsa
1.173 naddy 1187: .It Pa ~/.ssh/id_ecdsa_sk
1.118 naddy 1188: .It Pa ~/.ssh/id_ed25519
1.176 naddy 1189: .It Pa ~/.ssh/id_ed25519_sk
1.100 naddy 1190: .It Pa ~/.ssh/id_rsa
1.180 naddy 1191: Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
1192: authenticator-hosted Ed25519 or RSA authentication identity of the user.
1.15 deraadt 1193: This file should not be readable by anyone but the user.
1194: It is possible to
1195: specify a passphrase when generating the key; that passphrase will be
1.80 dtucker 1196: used to encrypt the private part of this file using 128-bit AES.
1.15 deraadt 1197: This file is not automatically accessed by
1198: .Nm
1199: but it is offered as the default file for the private key.
1.46 markus 1200: .Xr ssh 1
1.15 deraadt 1201: will read this file when a login attempt is made.
1.100 naddy 1202: .Pp
1.68 djm 1203: .It Pa ~/.ssh/id_dsa.pub
1.100 naddy 1204: .It Pa ~/.ssh/id_ecdsa.pub
1.173 naddy 1205: .It Pa ~/.ssh/id_ecdsa_sk.pub
1.118 naddy 1206: .It Pa ~/.ssh/id_ed25519.pub
1.176 naddy 1207: .It Pa ~/.ssh/id_ed25519_sk.pub
1.68 djm 1208: .It Pa ~/.ssh/id_rsa.pub
1.180 naddy 1209: Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
1210: authenticator-hosted Ed25519 or RSA public key for authentication.
1.15 deraadt 1211: The contents of this file should be added to
1.68 djm 1212: .Pa ~/.ssh/authorized_keys
1.15 deraadt 1213: on all machines
1.49 deraadt 1214: where the user wishes to log in using public key authentication.
1.12 aaron 1215: There is no need to keep the contents of this file secret.
1.100 naddy 1216: .Pp
1.60 djm 1217: .It Pa /etc/moduli
1218: Contains Diffie-Hellman groups used for DH-GEX.
1219: The file format is described in
1220: .Xr moduli 5 .
1.19 aaron 1221: .El
1.2 deraadt 1222: .Sh SEE ALSO
1223: .Xr ssh 1 ,
1224: .Xr ssh-add 1 ,
1.8 ericj 1225: .Xr ssh-agent 1 ,
1.60 djm 1226: .Xr moduli 5 ,
1.30 itojun 1227: .Xr sshd 8
1.37 markus 1228: .Rs
1.73 markus 1229: .%R RFC 4716
1230: .%T "The Secure Shell (SSH) Public Key File Format"
1231: .%D 2006
1.37 markus 1232: .Re
1.59 jmc 1233: .Sh AUTHORS
1234: OpenSSH is a derivative of the original and free
1235: ssh 1.2.12 release by Tatu Ylonen.
1236: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
1237: Theo de Raadt and Dug Song
1238: removed many bugs, re-added newer features and
1239: created OpenSSH.
1240: Markus Friedl contributed the support for SSH
1241: protocol versions 1.5 and 2.0.
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