doc/man1/openssl-x509.pod.in

   1 =pod
   2 {- OpenSSL::safe::output_do_not_edit_headers(); -}
   3
   4 =head1 NAME
   5
   6 openssl-x509 - Certificate display and signing command
   7
   8 =head1 SYNOPSIS
   9
  10 B<openssl> B<x509>
  11 [B<-help>]
  12 [B<-in> I<filename>|I<uri>]
  13 [B<-passin> I<arg>]
  14 [B<-new>]
  15 [B<-x509toreq>]
  16 [B<-req>]
  17 [B<-copy_extensions> I<arg>]
  18 [B<-inform> B<DER>|B<PEM>]
  19 [B<-vfyopt> I<nm>:I<v>]
  20 [B<-key> I<filename>|I<uri>]
  21 [B<-keyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>]
  22 [B<-signkey> I<filename>|I<uri>]
  23 [B<-out> I<filename>]
  24 [B<-outform> B<DER>|B<PEM>]
  25 [B<-nocert>]
  26 [B<-noout>]
  27 [B<-text>]
  28 [B<-certopt> I<option>]
  29 [B<-fingerprint>]
  30 [B<-alias>]
  31 [B<-serial>]
  32 [B<-startdate>]
  33 [B<-enddate>]
  34 [B<-dates>]
  35 [B<-subject>]
  36 [B<-issuer>]
  37 {- $OpenSSL::safe::opt_name_synopsis -}
  38 [B<-email>]
  39 [B<-hash>]
  40 [B<-subject_hash>]
  41 [B<-subject_hash_old>]
  42 [B<-issuer_hash>]
  43 [B<-issuer_hash_old>]
  44 [B<-ext> I<extensions>]
  45 [B<-ocspid>]
  46 [B<-ocsp_uri>]
  47 [B<-purpose>]
  48 [B<-pubkey>]
  49 [B<-modulus>]
  50 [B<-checkend> I<num>]
  51 [B<-checkhost> I<host>]
  52 [B<-checkemail> I<host>]
  53 [B<-checkip> I<ipaddr>]
  54 [B<-set_serial> I<n>]
  55 [B<-next_serial>]
  56 [B<-days> I<arg>]
  57 [B<-preserve_dates>]
  58 [B<-subj> I<arg>]
  59 [B<-force_pubkey> I<filename>]
  60 [B<-clrext>]
  61 [B<-extfile> I<filename>]
  62 [B<-extensions> I<section>]
  63 [B<-sigopt> I<nm>:I<v>]
  64 [B<-badsig>]
  65 [B<-I<digest>>]
  66 [B<-CA> I<filename>|I<uri>]
  67 [B<-CAform> B<DER>|B<PEM>|B<P12>]
  68 [B<-CAkey> I<filename>|I<uri>]
  69 [B<-CAkeyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>]
  70 [B<-CAserial> I<filename>]
  71 [B<-CAcreateserial>]
  72 [B<-trustout>]
  73 [B<-setalias> I<arg>]
  74 [B<-clrtrust>]
  75 [B<-addtrust> I<arg>]
  76 [B<-clrreject>]
  77 [B<-addreject> I<arg>]
  78 {- $OpenSSL::safe::opt_r_synopsis -}
  79 {- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_provider_synopsis -}
  80
  81 =head1 DESCRIPTION
  82
  83 This command is a multi-purposes certificate handling command.
  84 It can be used to print certificate information,
  85 convert certificates to various forms, edit certificate trust settings,
  86 generate certificates from scratch or from certificating requests
  87 and then self-signing them or signing them like a "micro CA".
  88
  89 Since there are a large number of options they will split up into
  90 various sections.
  91
  92 =head1 OPTIONS
  93
  94 =head2 Input, Output, and General Purpose Options
  95
  96 =over 4
  97
  98 =item B<-help>
  99
 100 Print out a usage message.
 101
 102 =item B<-in> I<filename>|I<uri>
 103
 104 If the B<-req> option is not used this specifies the input
 105 to read a certificate from or standard input if this option is not specified.
 106 With the B<-req> option this specifies a certificate request file.
 107
 108 =item B<-passin> I<arg>
 109
 110 The key and certificate file password source.
 111 For more information about the format of I<arg>
 112 see L<openssl-passphrase-options(1)>.
 113
 114 =item B<-new>
 115
 116 Generate a certificate from scratch, not using an input certificate
 117 or certificate request. So the B<-in> option must not be used in this case.
 118 Instead, the B<-subj> option needs to be given.
 119 The public key to include can be given with the B<-force_pubkey> option
 120 and defaults to the key given with the B<-key> option,
 121 which implies self-signature.
 122
 123 =item B<-x509toreq>
 124
 125 Output a PKCS#10 certificate request (rather than a certificate).
 126 The B<-key> option must be used to provide the private key for self-signing;
 127 the corresponding public key is placed in the subjectPKInfo field.
 128
 129 X.509 extensions included in a certificate input are not copied by default.
 130 X.509 extensions to be added can be specified using the B<-extfile> option.
 131
 132 =item B<-req>
 133
 134 By default a certificate is expected on input.
 135 With this option a PKCS#10 certificate request is expected instead,
 136 which must be correctly self-signed.
 137
 138 X.509 extensions included in the request are not copied by default.
 139 X.509 extensions to be added can be specified using the B<-extfile> option.
 140
 141 =item B<-copy_extensions> I<arg>
 142
 143 Determines how to handle X.509 extensions
 144 when converting from a certificate to a request using the B<-x509toreq> option
 145 or converting from a request to a certificate using the B<-req> option.
 146 If I<arg> is B<none> or this option is not present then extensions are ignored.
 147 If I<arg> is B<copy> or B<copyall> then all extensions are copied,
 148 except that subject identifier and authority key identifier extensions
 149 are not taken over when producing a certificate request.
 150
 151 The B<-ext> option can be used to further restrict which extensions to copy.
 152
 153 =item B<-inform> B<DER>|B<PEM>
 154
 155 The input file format; unspecified by default.
 156 See L<openssl-format-options(1)> for details.
 157
 158 =item B<-vfyopt> I<nm>:I<v>
 159
 160 Pass options to the signature algorithm during verify operations.
 161 Names and values of these options are algorithm-specific.
 162
 163 =item B<-key> I<filename>|I<uri>
 164
 165 This option causes the new certificate or certificate request
 166 to be self-signed using the supplied private key.
 167 This cannot be used in conjunction with the B<-CA> option.
 168
 169 It sets the issuer name to the subject name (i.e., makes it self-issued)
 170 and changes the public key to the supplied value (unless overridden
 171 by B<-force_pubkey>).
 172 Unless the B<-preserve_dates> option is supplied,
 173 it sets the validity start date to the current time
 174 and the end date to a value determined by the B<-days> option.
 175
 176 =item B<-signkey> I<filename>|I<uri>
 177
 178 This option is an alias of B<-key>.
 179
 180 =item B<-keyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>
 181
 182 The key input format; unspecified by default.
 183 See L<openssl-format-options(1)> for details.
 184
 185 =item B<-out> I<filename>
 186
 187 This specifies the output filename to write to or standard output by default.
 188
 189 =item B<-outform> B<DER>|B<PEM>
 190
 191 The output format; the default is B<PEM>.
 192 See L<openssl-format-options(1)> for details.
 193
 194 =item B<-nocert>
 195
 196 Do not output a certificate (except for printing as requested by below options).
 197
 198 =item B<-noout>
 199
 200 This option prevents output except for printing as requested by below options.
 201
 202 =back
 203
 204 =head2 Certificate Printing Options
 205
 206 Note: the B<-alias> and B<-purpose> options are also printing options
 207 but are described in the L</Trust Settings> section.
 208
 209 =over 4
 210
 211 =item B<-text>
 212
 213 Prints out the certificate in text form. Full details are printed including the
 214 public key, signature algorithms, issuer and subject names, serial number
 215 any extensions present and any trust settings.
 216
 217 =item B<-certopt> I<option>
 218
 219 Customise the print format used with B<-text>. The I<option> argument
 220 can be a single option or multiple options separated by commas.
 221 The B<-certopt> switch may be also be used more than once to set multiple
 222 options. See the L</Text Printing Flags> section for more information.
 223
 224 =item B<-fingerprint>
 225
 226 Calculates and prints the digest of the DER encoded version of the entire
 227 certificate (see digest options).
 228 This is commonly called a "fingerprint". Because of the nature of message
 229 digests, the fingerprint of a certificate is unique to that certificate and
 230 two certificates with the same fingerprint can be considered to be the same.
 231
 232 =item B<-alias>
 233
 234 Prints the certificate "alias" (nickname), if any.
 235
 236 =item B<-serial>
 237
 238 Prints the certificate serial number.
 239
 240 =item B<-startdate>
 241
 242 Prints out the start date of the certificate, that is the notBefore date.
 243
 244 =item B<-enddate>
 245
 246 Prints out the expiry date of the certificate, that is the notAfter date.
 247
 248 =item B<-dates>
 249
 250 Prints out the start and expiry dates of a certificate.
 251
 252 =item B<-subject>
 253
 254 Prints the subject name.
 255
 256 =item B<-issuer>
 257
 258 Prints the issuer name.
 259
 260 {- $OpenSSL::safe::opt_name_item -}
 261
 262 =item B<-email>
 263
 264 Prints the email address(es) if any.
 265
 266 =item B<-hash>
 267
 268 Synonym for "-subject_hash" for backward compatibility reasons.
 269
 270 =item B<-subject_hash>
 271
 272 Prints the "hash" of the certificate subject name. This is used in OpenSSL to
 273 form an index to allow certificates in a directory to be looked up by subject
 274 name.
 275
 276 =item B<-subject_hash_old>
 277
 278 Prints the "hash" of the certificate subject name using the older algorithm
 279 as used by OpenSSL before version 1.0.0.
 280
 281 =item B<-issuer_hash>
 282
 283 Prints the "hash" of the certificate issuer name.
 284
 285 =item B<-issuer_hash_old>
 286
 287 Prints the "hash" of the certificate issuer name using the older algorithm
 288 as used by OpenSSL before version 1.0.0.
 289
 290 =item B<-ext> I<extensions>
 291
 292 Prints out the certificate extensions in text form.
 293 Can also be used to restrict which extensions to copy.
 294 Extensions are specified
 295 with a comma separated string, e.g., "subjectAltName,subjectKeyIdentifier".
 296 See the L<x509v3_config(5)> manual page for the extension names.
 297
 298 =item B<-ocspid>
 299
 300 Prints the OCSP hash values for the subject name and public key.
 301
 302 =item B<-ocsp_uri>
 303
 304 Prints the OCSP responder address(es) if any.
 305
 306 =item B<-purpose>
 307
 308 This option performs tests on the certificate extensions and outputs
 309 the results. For a more complete description see
 310 L<openssl-verification-options(1)/Certificate Extensions>.
 311
 312 =item B<-pubkey>
 313
 314 Prints the certificate's SubjectPublicKeyInfo block in PEM format.
 315
 316 =item B<-modulus>
 317
 318 This option prints out the value of the modulus of the public key
 319 contained in the certificate.
 320
 321 =back
 322
 323 =head2 Certificate Checking Options
 324
 325 =over 4
 326
 327 =item B<-checkend> I<arg>
 328
 329 Checks if the certificate expires within the next I<arg> seconds and exits
 330 nonzero if yes it will expire or zero if not.
 331
 332 =item B<-checkhost> I<host>
 333
 334 Check that the certificate matches the specified host.
 335
 336 =item B<-checkemail> I<email>
 337
 338 Check that the certificate matches the specified email address.
 339
 340 =item B<-checkip> I<ipaddr>
 341
 342 Check that the certificate matches the specified IP address.
 343
 344 =back
 345
 346 =head2 Certificate Output Options
 347
 348 =over 4
 349
 350 =item B<-set_serial> I<n>
 351
 352 Specifies the serial number to use. This option can be used with either
 353 the B<-key> or B<-CA> options. If used in conjunction with the B<-CA> option
 354 the serial number file (as specified by the B<-CAserial> option) is not used.
 355
 356 The serial number can be decimal or hex (if preceded by C<0x>).
 357
 358 =item B<-next_serial>
 359
 360 Set the serial to be one more than the number in the certificate.
 361
 362 =item B<-days> I<arg>
 363
 364 Specifies the number of days until a newly generated certificate expires.
 365 The default is 30.
 366 Cannot be used together with the B<-preserve_dates> option.
 367
 368 =item B<-preserve_dates>
 369
 370 When signing a certificate, preserve "notBefore" and "notAfter" dates of any
 371 input certificate instead of adjusting them to current time and duration.
 372 Cannot be used together with the B<-days> option.
 373
 374 =item B<-subj> I<arg>
 375
 376 When a certificate is created set its subject name to the given value.
 377 When the certificate is self-signed the issuer name is set to the same value.
 378
 379 The arg must be formatted as C</type0=value0/type1=value1/type2=...>.
 380 Special characters may be escaped by C<\> (backslash), whitespace is retained.
 381 Empty values are permitted, but the corresponding type will not be included
 382 in the certificate.
 383 Giving a single C</> will lead to an empty sequence of RDNs (a NULL-DN).
 384 Multi-valued RDNs can be formed by placing a C<+> character instead of a C</>
 385 between the AttributeValueAssertions (AVAs) that specify the members of the set.
 386 Example:
 387
 388 C</DC=org/DC=OpenSSL/DC=users/UID=123456+CN=John Doe>
 389
 390 This option can be used in conjunction with the B<-force_pubkey> option
 391 to create a certificate even without providing an input certificate
 392 or certificate request.
 393
 394 =item B<-force_pubkey> I<filename>
 395
 396 When a certificate is created set its public key to the key in I<filename>
 397 instead of the key contained in the input or given with the B<-key> option.
 398
 399 This option is useful for creating self-issued certificates that are not
 400 self-signed, for instance when the key cannot be used for signing, such as DH.
 401 It can also be used in conjunction with b<-new> and B<-subj> to directly
 402 generate a certificate containing any desired public key.
 403
 404 =item B<-clrext>
 405
 406 When transforming a certificate to a new certificate
 407 by default all certificate extensions are retained.
 408
 409 When transforming a certificate or certificate request,
 410 the B<-clrext> option prevents taking over any extensions from the source.
 411 In any case, when producing a certificate request,
 412 neither subject identifier nor authority key identifier extensions are included.
 413
 414 =item B<-extfile> I<filename>
 415
 416 Configuration file containing certificate and request X.509 extensions to add.
 417
 418 =item B<-extensions> I<section>
 419
 420 The section in the extfile to add X.509 extensions from.
 421 If this option is not
 422 specified then the extensions should either be contained in the unnamed
 423 (default) section or the default section should contain a variable called
 424 "extensions" which contains the section to use.
 425 See the L<x509v3_config(5)> manual page for details of the
 426 extension section format.
 427
 428 =item B<-sigopt> I<nm>:I<v>
 429
 430 Pass options to the signature algorithm during sign operations.
 431 This option may be given multiple times.
 432 Names and values provided using this option are algorithm-specific.
 433
 434 =item B<-badsig>
 435
 436 Corrupt the signature before writing it; this can be useful
 437 for testing.
 438
 439 =item B<-I<digest>>
 440
 441 The digest to use.
 442 This affects any signing or printing option that uses a message
 443 digest, such as the B<-fingerprint>, B<-key> and B<-CA> options.
 444 Any digest supported by the L<openssl-dgst(1)> command can be used.
 445 If not specified then SHA1 is used with B<-fingerprint> or
 446 the default digest for the signing algorithm is used, typically SHA256.
 447
 448 =back
 449
 450 =head2 Micro-CA Options
 451
 452 =over 4
 453
 454 =item B<-CA> I<filename>|I<uri>
 455
 456 Specifies the "CA" certificate to be used for signing.
 457 When present, this behaves like a "micro CA" as follows:
 458 The subject name of the "CA" certificate is placed as issuer name in the new
 459 certificate, which is then signed using the "CA" key given as detailed below.
 460
 461 This option cannot be used in conjunction with the B<-key> option.
 462 This option is normally combined with the B<-req> option referencing a CSR.
 463 Without the B<-req> option the input must be a self-signed certificate
 464 unless the B<-new> option is given, which generates a certificate from scratch.
 465
 466 =item B<-CAform> B<DER>|B<PEM>|B<P12>,
 467
 468 The format for the CA certificate; unspecifed by default.
 469 See L<openssl-format-options(1)> for details.
 470
 471 =item B<-CAkey> I<filename>|I<uri>
 472
 473 Sets the CA private key to sign a certificate with.
 474 The private key must match the public key of the certificate given with B<-CA>.
 475 If this option is not provided then the key must be present in the B<-CA> input.
 476
 477 =item B<-CAkeyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>
 478
 479 The format for the CA key; unspecified by default.
 480 See L<openssl-format-options(1)> for details.
 481
 482 =item B<-CAserial> I<filename>
 483
 484 Sets the CA serial number file to use.
 485
 486 When the B<-CA> option is used to sign a certificate it uses a serial
 487 number specified in a file. This file consists of one line containing
 488 an even number of hex digits with the serial number to use. After each
 489 use the serial number is incremented and written out to the file again.
 490
 491 The default filename consists of the CA certificate file base name with
 492 F<.srl> appended. For example if the CA certificate file is called
 493 F<mycacert.pem> it expects to find a serial number file called
 494 F<mycacert.srl>.
 495
 496 =item B<-CAcreateserial>
 497
 498 With this option the CA serial number file is created if it does not exist:
 499 it will contain the serial number "02" and the certificate being signed will
 500 have the 1 as its serial number. If the B<-CA> option is specified
 501 and the serial number file does not exist a random number is generated;
 502 this is the recommended practice.
 503
 504 =back
 505
 506 =head2 Trust Settings
 507
 508 A B<trusted certificate> is an ordinary certificate which has several
 509 additional pieces of information attached to it such as the permitted
 510 and prohibited uses of the certificate and possibly an "alias" (nickname).
 511
 512 Normally when a certificate is being verified at least one certificate
 513 must be "trusted". By default a trusted certificate must be stored
 514 locally and must be a root CA: any certificate chain ending in this CA
 515 is then usable for any purpose.
 516
 517 Trust settings currently are only used with a root CA.
 518 They allow a finer control over the purposes the root CA can be used for.
 519 For example, a CA may be trusted for SSL client but not SSL server use.
 520
 521 See L<openssl-verification-options(1)> for more information
 522 on the meaning of trust settings.
 523
 524 Future versions of OpenSSL will recognize trust settings on any
 525 certificate: not just root CAs.
 526
 527 =over 4
 528
 529 =item B<-trustout>
 530
 531 Mark any certificate PEM output as <trusted> certificate rather than ordinary.
 532 An ordinary or trusted certificate can be input but by default an ordinary
 533 certificate is output and any trust settings are discarded.
 534 With the B<-trustout> option a trusted certificate is output. A trusted
 535 certificate is automatically output if any trust settings are modified.
 536
 537 =item B<-setalias> I<arg>
 538
 539 Sets the "alias" of the certificate. This will allow the certificate
 540 to be referred to using a nickname for example "Steve's Certificate".
 541
 542 =item B<-clrtrust>
 543
 544 Clears all the permitted or trusted uses of the certificate.
 545
 546 =item B<-addtrust> I<arg>
 547
 548 Adds an allowed trust anchor purpose.
 549 Any object name can be used here but currently only those
 550 listed in L<openssl-verification-options(1)/Trust Anchors> are supported.
 551 Other OpenSSL applications may define additional purposes.
 552
 553 =item B<-clrreject>
 554
 555 Clears all the prohibited or rejected uses of the certificate.
 556
 557 =item B<-addreject> I<arg>
 558
 559 Adds a prohibited trust anchor purpose.
 560 It accepts the same values as the B<-addtrust> option.
 561
 562 =back
 563
 564 =head2 Generic options
 565
 566 =over 4
 567
 568 {- $OpenSSL::safe::opt_r_item -}
 569
 570 {- $OpenSSL::safe::opt_engine_item -}
 571
 572 {- $OpenSSL::safe::opt_provider_item -}
 573
 574 =back
 575
 576 =head2 Text Printing Flags
 577
 578 As well as customising the name printing format, it is also possible to
 579 customise the actual fields printed using the B<certopt> option when
 580 the B<text> option is present. The default behaviour is to print all fields.
 581
 582 =over 4
 583
 584 =item B<compatible>
 585
 586 Use the old format. This is equivalent to specifying no printing options at all.
 587
 588 =item B<no_header>
 589
 590 Don't print header information: that is the lines saying "Certificate"
 591 and "Data".
 592
 593 =item B<no_version>
 594
 595 Don't print out the version number.
 596
 597 =item B<no_serial>
 598
 599 Don't print out the serial number.
 600
 601 =item B<no_signame>
 602
 603 Don't print out the signature algorithm used.
 604
 605 =item B<no_validity>
 606
 607 Don't print the validity, that is the B<notBefore> and B<notAfter> fields.
 608
 609 =item B<no_subject>
 610
 611 Don't print out the subject name.
 612
 613 =item B<no_issuer>
 614
 615 Don't print out the issuer name.
 616
 617 =item B<no_pubkey>
 618
 619 Don't print out the public key.
 620
 621 =item B<no_sigdump>
 622
 623 Don't give a hexadecimal dump of the certificate signature.
 624
 625 =item B<no_aux>
 626
 627 Don't print out certificate trust information.
 628
 629 =item B<no_extensions>
 630
 631 Don't print out any X509V3 extensions.
 632
 633 =item B<ext_default>
 634
 635 Retain default extension behaviour: attempt to print out unsupported
 636 certificate extensions.
 637
 638 =item B<ext_error>
 639
 640 Print an error message for unsupported certificate extensions.
 641
 642 =item B<ext_parse>
 643
 644 ASN1 parse unsupported extensions.
 645
 646 =item B<ext_dump>
 647
 648 Hex dump unsupported extensions.
 649
 650 =item B<ca_default>
 651
 652 The value used by L<openssl-ca(1)>, equivalent to B<no_issuer>, B<no_pubkey>,
 653 B<no_header>, and B<no_version>.
 654
 655 =back
 656
 657 =head1 EXAMPLES
 658
 659 Note: in these examples the '\' means the example should be all on one
 660 line.
 661
 662 Print the contents of a certificate:
 663
 664  openssl x509 -in cert.pem -noout -text
 665
 666 Print the "Subject Alternative Name" extension of a certificate:
 667
 668  openssl x509 -in cert.pem -noout -ext subjectAltName
 669
 670 Print more extensions of a certificate:
 671
 672  openssl x509 -in cert.pem -noout -ext subjectAltName,nsCertType
 673
 674 Print the certificate serial number:
 675
 676  openssl x509 -in cert.pem -noout -serial
 677
 678 Print the certificate subject name:
 679
 680  openssl x509 -in cert.pem -noout -subject
 681
 682 Print the certificate subject name in RFC2253 form:
 683
 684  openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
 685
 686 Print the certificate subject name in oneline form on a terminal
 687 supporting UTF8:
 688
 689  openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb
 690
 691 Print the certificate SHA1 fingerprint:
 692
 693  openssl x509 -sha1 -in cert.pem -noout -fingerprint
 694
 695 Convert a certificate from PEM to DER format:
 696
 697  openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
 698
 699 Convert a certificate to a certificate request:
 700
 701  openssl x509 -x509toreq -in cert.pem -out req.pem -key key.pem
 702
 703 Convert a certificate request into a self-signed certificate using
 704 extensions for a CA:
 705
 706  openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
 707         -key key.pem -out cacert.pem
 708
 709 Sign a certificate request using the CA certificate above and add user
 710 certificate extensions:
 711
 712  openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
 713         -CA cacert.pem -CAkey key.pem -CAcreateserial
 714
 715 Set a certificate to be trusted for SSL client use and change set its alias to
 716 "Steve's Class 1 CA"
 717
 718  openssl x509 -in cert.pem -addtrust clientAuth \
 719         -setalias "Steve's Class 1 CA" -out trust.pem
 720
 721 =head1 NOTES
 722
 723 The conversion to UTF8 format used with the name options assumes that
 724 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
 725 and MSIE do this as do many certificates. So although this is incorrect
 726 it is more likely to print the majority of certificates correctly.
 727
 728 The B<-email> option searches the subject name and the subject alternative
 729 name extension. Only unique email addresses will be printed out: it will
 730 not print the same address more than once.
 731
 732 =head1 BUGS
 733
 734 It is possible to produce invalid certificates or requests by specifying the
 735 wrong private key, using unsuitable X.509 extensions,
 736 or using inconsistent options in some cases: these should be checked.
 737
 738 There should be options to explicitly set such things as start and end
 739 dates rather than an offset from the current time.
 740
 741 =head1 SEE ALSO
 742
 743 L<openssl(1)>,
 744 L<openssl-req(1)>,
 745 L<openssl-ca(1)>,
 746 L<openssl-genrsa(1)>,
 747 L<openssl-gendsa(1)>,
 748 L<openssl-verify(1)>,
 749 L<x509v3_config(5)>
 750
 751 =head1 HISTORY
 752
 753 The hash algorithm used in the B<-subject_hash> and B<-issuer_hash> options
 754 before OpenSSL 1.0.0 was based on the deprecated MD5 algorithm and the encoding
 755 of the distinguished name. In OpenSSL 1.0.0 and later it is based on a canonical
 756 version of the DN using SHA1. This means that any directories using the old
 757 form must have their links rebuilt using L<openssl-rehash(1)> or similar.
 758
 759 The B<-signkey> option has been renamed to B<-key> in OpenSSL 3.0,
 760 keeping the old name as an alias.
 761
 762 The B<-engine> option was deprecated in OpenSSL 3.0.
 763
 764 The B<-C> option was removed in OpenSSL 3.0.
 765
 766 =head1 COPYRIGHT
 767
 768 Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
 769
 770 Licensed under the Apache License 2.0 (the "License").  You may not use
 771 this file except in compliance with the License.  You can obtain a copy
 772 in the file LICENSE in the source distribution or at
 773 L<https://www.openssl.org/source/license.html>.
 774
 775 =cut