1.\" $OpenBSD: ssh-keygen.1,v 1.122 2014/03/31 13:39:34 jmc Exp $ 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.\" 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.\" 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. 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. 26.\" 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. 37.\" 38.Dd $Mdocdate: March 31 2014 $ 39.Dt SSH-KEYGEN 1 40.Os 41.Sh NAME 42.Nm ssh-keygen 43.Nd authentication key generation, management and conversion 44.Sh SYNOPSIS 45.Bk -words 46.Nm ssh-keygen 47.Op Fl q 48.Op Fl b Ar bits 49.Op Fl t Cm dsa | ecdsa | ed25519 | rsa | rsa1 50.Op Fl N Ar new_passphrase 51.Op Fl C Ar comment 52.Op Fl f Ar output_keyfile 53.Nm ssh-keygen 54.Fl p 55.Op Fl P Ar old_passphrase 56.Op Fl N Ar new_passphrase 57.Op Fl f Ar keyfile 58.Nm ssh-keygen 59.Fl i 60.Op Fl m Ar key_format 61.Op Fl f Ar input_keyfile 62.Nm ssh-keygen 63.Fl e 64.Op Fl m Ar key_format 65.Op Fl f Ar input_keyfile 66.Nm ssh-keygen 67.Fl y 68.Op Fl f Ar input_keyfile 69.Nm ssh-keygen 70.Fl c 71.Op Fl P Ar passphrase 72.Op Fl C Ar comment 73.Op Fl f Ar keyfile 74.Nm ssh-keygen 75.Fl l 76.Op Fl f Ar input_keyfile 77.Nm ssh-keygen 78.Fl B 79.Op Fl f Ar input_keyfile 80.Nm ssh-keygen 81.Fl D Ar pkcs11 82.Nm ssh-keygen 83.Fl F Ar hostname 84.Op Fl f Ar known_hosts_file 85.Op Fl l 86.Nm ssh-keygen 87.Fl H 88.Op Fl f Ar known_hosts_file 89.Nm ssh-keygen 90.Fl R Ar hostname 91.Op Fl f Ar known_hosts_file 92.Nm ssh-keygen 93.Fl r Ar hostname 94.Op Fl f Ar input_keyfile 95.Op Fl g 96.Nm ssh-keygen 97.Fl G Ar output_file 98.Op Fl v 99.Op Fl b Ar bits 100.Op Fl M Ar memory 101.Op Fl S Ar start_point 102.Nm ssh-keygen 103.Fl T Ar output_file 104.Fl f Ar input_file 105.Op Fl v 106.Op Fl a Ar rounds 107.Op Fl J Ar num_lines 108.Op Fl j Ar start_line 109.Op Fl K Ar checkpt 110.Op Fl W Ar generator 111.Nm ssh-keygen 112.Fl s Ar ca_key 113.Fl I Ar certificate_identity 114.Op Fl h 115.Op Fl n Ar principals 116.Op Fl O Ar option 117.Op Fl V Ar validity_interval 118.Op Fl z Ar serial_number 119.Ar 120.Nm ssh-keygen 121.Fl L 122.Op Fl f Ar input_keyfile 123.Nm ssh-keygen 124.Fl A 125.Nm ssh-keygen 126.Fl k 127.Fl f Ar krl_file 128.Op Fl u 129.Op Fl s Ar ca_public 130.Op Fl z Ar version_number 131.Ar 132.Nm ssh-keygen 133.Fl Q 134.Fl f Ar krl_file 135.Ar 136.Ek 137.Sh DESCRIPTION 138.Nm 139generates, manages and converts authentication keys for 140.Xr ssh 1 . 141.Nm 142can create RSA keys for use by SSH protocol version 1 and 143DSA, ECDSA, ED25519 or RSA keys for use by SSH protocol version 2. 144The type of key to be generated is specified with the 145.Fl t 146option. 147If invoked without any arguments, 148.Nm 149will generate an RSA key for use in SSH protocol 2 connections. 150.Pp 151.Nm 152is also used to generate groups for use in Diffie-Hellman group 153exchange (DH-GEX). 154See the 155.Sx MODULI GENERATION 156section for details. 157.Pp 158Finally, 159.Nm 160can be used to generate and update Key Revocation Lists, and to test whether 161given keys have been revoked by one. 162See the 163.Sx KEY REVOCATION LISTS 164section for details. 165.Pp 166Normally each user wishing to use SSH 167with public key authentication runs this once to create the authentication 168key in 169.Pa ~/.ssh/identity , 170.Pa ~/.ssh/id_dsa , 171.Pa ~/.ssh/id_ecdsa , 172.Pa ~/.ssh/id_ed25519 173or 174.Pa ~/.ssh/id_rsa . 175Additionally, the system administrator may use this to generate host keys, 176as seen in 177.Pa /etc/rc . 178.Pp 179Normally this program generates the key and asks for a file in which 180to store the private key. 181The public key is stored in a file with the same name but 182.Dq .pub 183appended. 184The program also asks for a passphrase. 185The passphrase may be empty to indicate no passphrase 186(host keys must have an empty passphrase), or it may be a string of 187arbitrary length. 188A passphrase is similar to a password, except it can be a phrase with a 189series of words, punctuation, numbers, whitespace, or any string of 190characters you want. 191Good passphrases are 10-30 characters long, are 192not simple sentences or otherwise easily guessable (English 193prose has only 1-2 bits of entropy per character, and provides very bad 194passphrases), and contain a mix of upper and lowercase letters, 195numbers, and non-alphanumeric characters. 196The passphrase can be changed later by using the 197.Fl p 198option. 199.Pp 200There is no way to recover a lost passphrase. 201If the passphrase is lost or forgotten, a new key must be generated 202and the corresponding public key copied to other machines. 203.Pp 204For RSA1 keys, 205there is also a comment field in the key file that is only for 206convenience to the user to help identify the key. 207The comment can tell what the key is for, or whatever is useful. 208The comment is initialized to 209.Dq user@host 210when the key is created, but can be changed using the 211.Fl c 212option. 213.Pp 214After a key is generated, instructions below detail where the keys 215should be placed to be activated. 216.Pp 217The options are as follows: 218.Bl -tag -width Ds 219.It Fl A 220For each of the key types (rsa1, rsa, dsa, ecdsa and ed25519) 221for which host keys 222do not exist, generate the host keys with the default key file path, 223an empty passphrase, default bits for the key type, and default comment. 224This is used by 225.Pa /etc/rc 226to generate new host keys. 227.It Fl a Ar rounds 228When saving a new-format private key (i.e. an ed25519 key or any SSH protocol 2292 key when the 230.Fl o 231flag is set), this option specifies the number of KDF (key derivation function) 232rounds used. 233Higher numbers result in slower passphrase verification and increased 234resistance to brute-force password cracking (should the keys be stolen). 235.Pp 236When screening DH-GEX candidates ( 237using the 238.Fl T 239command). 240This option specifies the number of primality tests to perform. 241.It Fl B 242Show the bubblebabble digest of specified private or public key file. 243.It Fl b Ar bits 244Specifies the number of bits in the key to create. 245For RSA keys, the minimum size is 768 bits and the default is 2048 bits. 246Generally, 2048 bits is considered sufficient. 247DSA keys must be exactly 1024 bits as specified by FIPS 186-2. 248For ECDSA keys, the 249.Fl b 250flag determines the key length by selecting from one of three elliptic 251curve sizes: 256, 384 or 521 bits. 252Attempting to use bit lengths other than these three values for ECDSA keys 253will fail. 254ED25519 keys have a fixed length and the 255.Fl b 256flag will be ignored. 257.It Fl C Ar comment 258Provides a new comment. 259.It Fl c 260Requests changing the comment in the private and public key files. 261This operation is only supported for RSA1 keys. 262The program will prompt for the file containing the private keys, for 263the passphrase if the key has one, and for the new comment. 264.It Fl D Ar pkcs11 265Download the RSA public keys provided by the PKCS#11 shared library 266.Ar pkcs11 . 267When used in combination with 268.Fl s , 269this option indicates that a CA key resides in a PKCS#11 token (see the 270.Sx CERTIFICATES 271section for details). 272.It Fl e 273This option will read a private or public OpenSSH key file and 274print to stdout the key in one of the formats specified by the 275.Fl m 276option. 277The default export format is 278.Dq RFC4716 . 279This option allows exporting OpenSSH keys for use by other programs, including 280several commercial SSH implementations. 281.It Fl F Ar hostname 282Search for the specified 283.Ar hostname 284in a 285.Pa known_hosts 286file, listing any occurrences found. 287This option is useful to find hashed host names or addresses and may also be 288used in conjunction with the 289.Fl H 290option to print found keys in a hashed format. 291.It Fl f Ar filename 292Specifies the filename of the key file. 293.It Fl G Ar output_file 294Generate candidate primes for DH-GEX. 295These primes must be screened for 296safety (using the 297.Fl T 298option) before use. 299.It Fl g 300Use generic DNS format when printing fingerprint resource records using the 301.Fl r 302command. 303.It Fl H 304Hash a 305.Pa known_hosts 306file. 307This replaces all hostnames and addresses with hashed representations 308within the specified file; the original content is moved to a file with 309a .old suffix. 310These hashes may be used normally by 311.Nm ssh 312and 313.Nm sshd , 314but they do not reveal identifying information should the file's contents 315be disclosed. 316This option will not modify existing hashed hostnames and is therefore safe 317to use on files that mix hashed and non-hashed names. 318.It Fl h 319When signing a key, create a host certificate instead of a user 320certificate. 321Please see the 322.Sx CERTIFICATES 323section for details. 324.It Fl I Ar certificate_identity 325Specify the key identity when signing a public key. 326Please see the 327.Sx CERTIFICATES 328section for details. 329.It Fl i 330This option will read an unencrypted private (or public) key file 331in the format specified by the 332.Fl m 333option and print an OpenSSH compatible private 334(or public) key to stdout. 335This option allows importing keys from other software, including several 336commercial SSH implementations. 337The default import format is 338.Dq RFC4716 . 339.It Fl J Ar num_lines 340Exit after screening the specified number of lines 341while performing DH candidate screening using the 342.Fl T 343option. 344.It Fl j Ar start_line 345Start screening at the specified line number 346while performing DH candidate screening using the 347.Fl T 348option. 349.It Fl K Ar checkpt 350Write the last line processed to the file 351.Ar checkpt 352while performing DH candidate screening using the 353.Fl T 354option. 355This will be used to skip lines in the input file that have already been 356processed if the job is restarted. 357.It Fl k 358Generate a KRL file. 359In this mode, 360.Nm 361will generate a KRL file at the location specified via the 362.Fl f 363flag that revokes every key or certificate presented on the command line. 364Keys/certificates to be revoked may be specified by public key file or 365using the format described in the 366.Sx KEY REVOCATION LISTS 367section. 368.It Fl L 369Prints the contents of a certificate. 370.It Fl l 371Show fingerprint of specified public key file. 372Private RSA1 keys are also supported. 373For RSA and DSA keys 374.Nm 375tries to find the matching public key file and prints its fingerprint. 376If combined with 377.Fl v , 378an ASCII art representation of the key is supplied with the fingerprint. 379.It Fl M Ar memory 380Specify the amount of memory to use (in megabytes) when generating 381candidate moduli for DH-GEX. 382.It Fl m Ar key_format 383Specify a key format for the 384.Fl i 385(import) or 386.Fl e 387(export) conversion options. 388The supported key formats are: 389.Dq RFC4716 390(RFC 4716/SSH2 public or private key), 391.Dq PKCS8 392(PEM PKCS8 public key) 393or 394.Dq PEM 395(PEM public key). 396The default conversion format is 397.Dq RFC4716 . 398.It Fl N Ar new_passphrase 399Provides the new passphrase. 400.It Fl n Ar principals 401Specify one or more principals (user or host names) to be included in 402a certificate when signing a key. 403Multiple principals may be specified, separated by commas. 404Please see the 405.Sx CERTIFICATES 406section for details. 407.It Fl O Ar option 408Specify a certificate option when signing a key. 409This option may be specified multiple times. 410Please see the 411.Sx CERTIFICATES 412section for details. 413The options that are valid for user certificates are: 414.Bl -tag -width Ds 415.It Ic clear 416Clear all enabled permissions. 417This is useful for clearing the default set of permissions so permissions may 418be added individually. 419.It Ic force-command Ns = Ns Ar command 420Forces the execution of 421.Ar command 422instead of any shell or command specified by the user when 423the certificate is used for authentication. 424.It Ic no-agent-forwarding 425Disable 426.Xr ssh-agent 1 427forwarding (permitted by default). 428.It Ic no-port-forwarding 429Disable port forwarding (permitted by default). 430.It Ic no-pty 431Disable PTY allocation (permitted by default). 432.It Ic no-user-rc 433Disable execution of 434.Pa ~/.ssh/rc 435by 436.Xr sshd 8 437(permitted by default). 438.It Ic no-x11-forwarding 439Disable X11 forwarding (permitted by default). 440.It Ic permit-agent-forwarding 441Allows 442.Xr ssh-agent 1 443forwarding. 444.It Ic permit-port-forwarding 445Allows port forwarding. 446.It Ic permit-pty 447Allows PTY allocation. 448.It Ic permit-user-rc 449Allows execution of 450.Pa ~/.ssh/rc 451by 452.Xr sshd 8 . 453.It Ic permit-x11-forwarding 454Allows X11 forwarding. 455.It Ic source-address Ns = Ns Ar address_list 456Restrict the source addresses from which the certificate is considered valid. 457The 458.Ar address_list 459is a comma-separated list of one or more address/netmask pairs in CIDR 460format. 461.El 462.Pp 463At present, no options are valid for host keys. 464.It Fl o 465Causes 466.Nm 467to save SSH protocol 2 private keys using the new OpenSSH format rather than 468the more compatible PEM format. 469The new format has increased resistance to brute-force password cracking 470but is not supported by versions of OpenSSH prior to 6.5. 471Ed25519 keys always use the new private key format. 472.It Fl P Ar passphrase 473Provides the (old) passphrase. 474.It Fl p 475Requests changing the passphrase of a private key file instead of 476creating a new private key. 477The program will prompt for the file 478containing the private key, for the old passphrase, and twice for the 479new passphrase. 480.It Fl Q 481Test whether keys have been revoked in a KRL. 482.It Fl q 483Silence 484.Nm ssh-keygen . 485.It Fl R Ar hostname 486Removes all keys belonging to 487.Ar hostname 488from a 489.Pa known_hosts 490file. 491This option is useful to delete hashed hosts (see the 492.Fl H 493option above). 494.It Fl r Ar hostname 495Print the SSHFP fingerprint resource record named 496.Ar hostname 497for the specified public key file. 498.It Fl S Ar start 499Specify start point (in hex) when generating candidate moduli for DH-GEX. 500.It Fl s Ar ca_key 501Certify (sign) a public key using the specified CA key. 502Please see the 503.Sx CERTIFICATES 504section for details. 505.Pp 506When generating a KRL, 507.Fl s 508specifies a path to a CA public key file used to revoke certificates directly 509by key ID or serial number. 510See the 511.Sx KEY REVOCATION LISTS 512section for details. 513.It Fl T Ar output_file 514Test DH group exchange candidate primes (generated using the 515.Fl G 516option) for safety. 517.It Fl t Cm dsa | ecdsa | ed25519 | rsa | rsa1 518Specifies the type of key to create. 519The possible values are 520.Dq rsa1 521for protocol version 1 and 522.Dq dsa , 523.Dq ecdsa , 524.Dq ed25519 , 525or 526.Dq rsa 527for protocol version 2. 528.It Fl u 529Update a KRL. 530When specified with 531.Fl k , 532keys listed via the command line are added to the existing KRL rather than 533a new KRL being created. 534.It Fl V Ar validity_interval 535Specify a validity interval when signing a certificate. 536A validity interval may consist of a single time, indicating that the 537certificate is valid beginning now and expiring at that time, or may consist 538of two times separated by a colon to indicate an explicit time interval. 539The start time may be specified as a date in YYYYMMDD format, a time 540in YYYYMMDDHHMMSS format or a relative time (to the current time) consisting 541of a minus sign followed by a relative time in the format described in the 542TIME FORMATS section of 543.Xr sshd_config 5 . 544The end time may be specified as a YYYYMMDD date, a YYYYMMDDHHMMSS time or 545a relative time starting with a plus character. 546.Pp 547For example: 548.Dq +52w1d 549(valid from now to 52 weeks and one day from now), 550.Dq -4w:+4w 551(valid from four weeks ago to four weeks from now), 552.Dq 20100101123000:20110101123000 553(valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011), 554.Dq -1d:20110101 555(valid from yesterday to midnight, January 1st, 2011). 556.It Fl v 557Verbose mode. 558Causes 559.Nm 560to print debugging messages about its progress. 561This is helpful for debugging moduli generation. 562Multiple 563.Fl v 564options increase the verbosity. 565The maximum is 3. 566.It Fl W Ar generator 567Specify desired generator when testing candidate moduli for DH-GEX. 568.It Fl y 569This option will read a private 570OpenSSH format file and print an OpenSSH public key to stdout. 571.It Fl z Ar serial_number 572Specifies a serial number to be embedded in the certificate to distinguish 573this certificate from others from the same CA. 574The default serial number is zero. 575.Pp 576When generating a KRL, the 577.Fl z 578flag is used to specify a KRL version number. 579.El 580.Sh MODULI GENERATION 581.Nm 582may be used to generate groups for the Diffie-Hellman Group Exchange 583(DH-GEX) protocol. 584Generating these groups is a two-step process: first, candidate 585primes are generated using a fast, but memory intensive process. 586These candidate primes are then tested for suitability (a CPU-intensive 587process). 588.Pp 589Generation of primes is performed using the 590.Fl G 591option. 592The desired length of the primes may be specified by the 593.Fl b 594option. 595For example: 596.Pp 597.Dl # ssh-keygen -G moduli-2048.candidates -b 2048 598.Pp 599By default, the search for primes begins at a random point in the 600desired length range. 601This may be overridden using the 602.Fl S 603option, which specifies a different start point (in hex). 604.Pp 605Once a set of candidates have been generated, they must be screened for 606suitability. 607This may be performed using the 608.Fl T 609option. 610In this mode 611.Nm 612will read candidates from standard input (or a file specified using the 613.Fl f 614option). 615For example: 616.Pp 617.Dl # ssh-keygen -T moduli-2048 -f moduli-2048.candidates 618.Pp 619By default, each candidate will be subjected to 100 primality tests. 620This may be overridden using the 621.Fl a 622option. 623The DH generator value will be chosen automatically for the 624prime under consideration. 625If a specific generator is desired, it may be requested using the 626.Fl W 627option. 628Valid generator values are 2, 3, and 5. 629.Pp 630Screened DH groups may be installed in 631.Pa /etc/moduli . 632It is important that this file contains moduli of a range of bit lengths and 633that both ends of a connection share common moduli. 634.Sh CERTIFICATES 635.Nm 636supports signing of keys to produce certificates that may be used for 637user or host authentication. 638Certificates consist of a public key, some identity information, zero or 639more principal (user or host) names and a set of options that 640are signed by a Certification Authority (CA) key. 641Clients or servers may then trust only the CA key and verify its signature 642on a certificate rather than trusting many user/host keys. 643Note that OpenSSH certificates are a different, and much simpler, format to 644the X.509 certificates used in 645.Xr ssl 8 . 646.Pp 647.Nm 648supports two types of certificates: user and host. 649User certificates authenticate users to servers, whereas host certificates 650authenticate server hosts to users. 651To generate a user certificate: 652.Pp 653.Dl $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub 654.Pp 655The resultant certificate will be placed in 656.Pa /path/to/user_key-cert.pub . 657A host certificate requires the 658.Fl h 659option: 660.Pp 661.Dl $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub 662.Pp 663The host certificate will be output to 664.Pa /path/to/host_key-cert.pub . 665.Pp 666It is possible to sign using a CA key stored in a PKCS#11 token by 667providing the token library using 668.Fl D 669and identifying the CA key by providing its public half as an argument 670to 671.Fl s : 672.Pp 673.Dl $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id host_key.pub 674.Pp 675In all cases, 676.Ar key_id 677is a "key identifier" that is logged by the server when the certificate 678is used for authentication. 679.Pp 680Certificates may be limited to be valid for a set of principal (user/host) 681names. 682By default, generated certificates are valid for all users or hosts. 683To generate a certificate for a specified set of principals: 684.Pp 685.Dl $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub 686.Dl "$ ssh-keygen -s ca_key -I key_id -h -n host.domain user_key.pub" 687.Pp 688Additional limitations on the validity and use of user certificates may 689be specified through certificate options. 690A certificate option may disable features of the SSH session, may be 691valid only when presented from particular source addresses or may 692force the use of a specific command. 693For a list of valid certificate options, see the documentation for the 694.Fl O 695option above. 696.Pp 697Finally, certificates may be defined with a validity lifetime. 698The 699.Fl V 700option allows specification of certificate start and end times. 701A certificate that is presented at a time outside this range will not be 702considered valid. 703By default, certificates are valid from 704.Ux 705Epoch to the distant future. 706.Pp 707For certificates to be used for user or host authentication, the CA 708public key must be trusted by 709.Xr sshd 8 710or 711.Xr ssh 1 . 712Please refer to those manual pages for details. 713.Sh KEY REVOCATION LISTS 714.Nm 715is able to manage OpenSSH format Key Revocation Lists (KRLs). 716These binary files specify keys or certificates to be revoked using a 717compact format, taking as little as one bit per certificate if they are being 718revoked by serial number. 719.Pp 720KRLs may be generated using the 721.Fl k 722flag. 723This option reads one or more files from the command line and generates a new 724KRL. 725The files may either contain a KRL specification (see below) or public keys, 726listed one per line. 727Plain public keys are revoked by listing their hash or contents in the KRL and 728certificates revoked by serial number or key ID (if the serial is zero or 729not available). 730.Pp 731Revoking keys using a KRL specification offers explicit control over the 732types of record used to revoke keys and may be used to directly revoke 733certificates by serial number or key ID without having the complete original 734certificate on hand. 735A KRL specification consists of lines containing one of the following directives 736followed by a colon and some directive-specific information. 737.Bl -tag -width Ds 738.It Cm serial : Ar serial_number Ns Op - Ns Ar serial_number 739Revokes a certificate with the specified serial number. 740Serial numbers are 64-bit values, not including zero and may be expressed 741in decimal, hex or octal. 742If two serial numbers are specified separated by a hyphen, then the range 743of serial numbers including and between each is revoked. 744The CA key must have been specified on the 745.Nm 746command line using the 747.Fl s 748option. 749.It Cm id : Ar key_id 750Revokes a certificate with the specified key ID string. 751The CA key must have been specified on the 752.Nm 753command line using the 754.Fl s 755option. 756.It Cm key : Ar public_key 757Revokes the specified key. 758If a certificate is listed, then it is revoked as a plain public key. 759.It Cm sha1 : Ar public_key 760Revokes the specified key by its SHA1 hash. 761.El 762.Pp 763KRLs may be updated using the 764.Fl u 765flag in addition to 766.Fl k . 767When this option is specified, keys listed via the command line are merged into 768the KRL, adding to those already there. 769.Pp 770It is also possible, given a KRL, to test whether it revokes a particular key 771(or keys). 772The 773.Fl Q 774flag will query an existing KRL, testing each key specified on the commandline. 775If any key listed on the command line has been revoked (or an error encountered) 776then 777.Nm 778will exit with a non-zero exit status. 779A zero exit status will only be returned if no key was revoked. 780.Sh FILES 781.Bl -tag -width Ds -compact 782.It Pa ~/.ssh/identity 783Contains the protocol version 1 RSA authentication identity of the user. 784This file should not be readable by anyone but the user. 785It is possible to 786specify a passphrase when generating the key; that passphrase will be 787used to encrypt the private part of this file using 3DES. 788This file is not automatically accessed by 789.Nm 790but it is offered as the default file for the private key. 791.Xr ssh 1 792will read this file when a login attempt is made. 793.Pp 794.It Pa ~/.ssh/identity.pub 795Contains the protocol version 1 RSA public key for authentication. 796The contents of this file should be added to 797.Pa ~/.ssh/authorized_keys 798on all machines 799where the user wishes to log in using RSA authentication. 800There is no need to keep the contents of this file secret. 801.Pp 802.It Pa ~/.ssh/id_dsa 803.It Pa ~/.ssh/id_ecdsa 804.It Pa ~/.ssh/id_ed25519 805.It Pa ~/.ssh/id_rsa 806Contains the protocol version 2 DSA, ECDSA, ED25519 or RSA 807authentication identity of the user. 808This file should not be readable by anyone but the user. 809It is possible to 810specify a passphrase when generating the key; that passphrase will be 811used to encrypt the private part of this file using 128-bit AES. 812This file is not automatically accessed by 813.Nm 814but it is offered as the default file for the private key. 815.Xr ssh 1 816will read this file when a login attempt is made. 817.Pp 818.It Pa ~/.ssh/id_dsa.pub 819.It Pa ~/.ssh/id_ecdsa.pub 820.It Pa ~/.ssh/id_ed25519.pub 821.It Pa ~/.ssh/id_rsa.pub 822Contains the protocol version 2 DSA, ECDSA, ED25519 or RSA 823public key for authentication. 824The contents of this file should be added to 825.Pa ~/.ssh/authorized_keys 826on all machines 827where the user wishes to log in using public key authentication. 828There is no need to keep the contents of this file secret. 829.Pp 830.It Pa /etc/moduli 831Contains Diffie-Hellman groups used for DH-GEX. 832The file format is described in 833.Xr moduli 5 . 834.El 835.Sh SEE ALSO 836.Xr ssh 1 , 837.Xr ssh-add 1 , 838.Xr ssh-agent 1 , 839.Xr moduli 5 , 840.Xr sshd 8 841.Rs 842.%R RFC 4716 843.%T "The Secure Shell (SSH) Public Key File Format" 844.%D 2006 845.Re 846.Sh AUTHORS 847OpenSSH is a derivative of the original and free 848ssh 1.2.12 release by Tatu Ylonen. 849Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, 850Theo de Raadt and Dug Song 851removed many bugs, re-added newer features and 852created OpenSSH. 853Markus Friedl contributed the support for SSH 854protocol versions 1.5 and 2.0. 855