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<-inform> B<DER>|B<PEM>]
  13 [B<-outform> B<DER>|B<PEM>]
  14 [B<-keyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>]
  15 [B<-CAform> B<DER>|B<PEM>|B<P12>]
  16 [B<-CAkeyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>]
  17 [B<-in> I<filename>]
  18 [B<-out> I<filename>]
  19 [B<-serial>]
  20 [B<-hash>]
  21 [B<-subject_hash>]
  22 [B<-subject_hash_old>]
  23 [B<-issuer_hash>]
  24 [B<-issuer_hash_old>]
  25 [B<-ocspid>]
  26 [B<-subject>]
  27 [B<-issuer>]
  28 [B<-email>]
  29 [B<-ocsp_uri>]
  30 [B<-startdate>]
  31 [B<-enddate>]
  32 [B<-purpose>]
  33 [B<-dates>]
  34 [B<-checkend> I<num>]
  35 [B<-modulus>]
  36 [B<-pubkey>]
  37 [B<-fingerprint>]
  38 [B<-alias>]
  39 [B<-noout>]
  40 [B<-trustout>]
  41 [B<-clrtrust>]
  42 [B<-clrreject>]
  43 [B<-addtrust> I<arg>]
  44 [B<-addreject> I<arg>]
  45 [B<-setalias> I<arg>]
  46 [B<-days> I<arg>]
  47 [B<-set_serial> I<n>]
  48 [B<-signkey> I<filename>|I<uri>]
  49 [B<-badsig>]
  50 [B<-passin> I<arg>]
  51 [B<-x509toreq>]
  52 [B<-req>]
  53 [B<-CA> I<filename>]
  54 [B<-CAkey> I<filename>|I<uri>]
  55 [B<-CAcreateserial>]
  56 [B<-CAserial> I<filename>]
  57 [B<-new>]
  58 [B<-next_serial>]
  59 [B<-nocert>]
  60 [B<-force_pubkey> I<filename>]
  61 [B<-subj> I<arg>]
  62 [B<-text>]
  63 [B<-ext> I<extensions>]
  64 [B<-certopt> I<option>]
  65 [B<-checkhost> I<host>]
  66 [B<-checkemail> I<host>]
  67 [B<-checkip> I<ipaddr>]
  68 [B<-I<digest>>]
  69 [B<-clrext>]
  70 [B<-extfile> I<filename>]
  71 [B<-extensions> I<section>]
  72 [B<-sigopt> I<nm>:I<v>]
  73 [B<-vfyopt> I<nm>:I<v>]
  74 [B<-preserve_dates>]
  75 {- $OpenSSL::safe::opt_name_synopsis -}
  76 {- $OpenSSL::safe::opt_r_synopsis -}
  77 {- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_provider_synopsis -}
  78
  79 =for openssl ifdef engine subject_hash_old issuer_hash_old
  80
  81 =head1 DESCRIPTION
  82
  83 This command is a multi-purposes certificate command. It can
  84 be used to display certificate information, convert certificates to
  85 various forms, sign certificate requests like a "mini CA" or edit
  86 certificate trust settings.
  87
  88 Since there are a large number of options they will split up into
  89 various sections.
  90
  91 =head1 OPTIONS
  92
  93 =head2 Input, Output, and General Purpose Options
  94
  95 =over 4
  96
  97 =item B<-help>
  98
  99 Print out a usage message.
 100
 101 =item B<-inform> B<DER>|B<PEM>
 102
 103 The CSR input format; the default is B<PEM>.
 104 See L<openssl-format-options(1)> for details.
 105
 106 The input is normally an X.509 certificate file of any format,
 107 but this can change if other options such as B<-req> are used.
 108
 109 B<-outform> B<DER>|B<PEM>
 110
 111 The output format; the default is B<PEM>.
 112 See L<openssl-format-options(1)> for details.
 113
 114 =item B<-in> I<filename>
 115
 116 This specifies the input filename to read a certificate from or standard input
 117 if this option is not specified.
 118
 119 =item B<-out> I<filename>
 120
 121 This specifies the output filename to write to or standard output by
 122 default.
 123
 124 =item B<-I<digest>>
 125
 126 The digest to use.
 127 This affects any signing or display option that uses a message
 128 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options.
 129 Any digest supported by the L<openssl-dgst(1)> command can be used.
 130 If not specified then SHA1 is used with B<-fingerprint> or
 131 the default digest for the signing algorithm is used, typically SHA256.
 132
 133 =item B<-preserve_dates>
 134
 135 When signing a certificate, preserve the "notBefore" and "notAfter" dates
 136 instead of adjusting them to current time and duration.
 137 Cannot be used with the B<-days> option.
 138
 139 {- $OpenSSL::safe::opt_r_synopsis -}
 140
 141 {- $OpenSSL::safe::opt_engine_item -}
 142
 143 {- $OpenSSL::safe::opt_provider_item -}
 144
 145 =back
 146
 147 =head2 Display Options
 148
 149 Note: the B<-alias> and B<-purpose> options are also display options
 150 but are described in the L</Trust Settings> section.
 151
 152 =over 4
 153
 154 =item B<-text>
 155
 156 Prints out the certificate in text form. Full details are output including the
 157 public key, signature algorithms, issuer and subject names, serial number
 158 any extensions present and any trust settings.
 159
 160 =item B<-ext> I<extensions>
 161
 162 Prints out the certificate extensions in text form. Extensions are specified
 163 with a comma separated string, e.g., "subjectAltName,subjectKeyIdentifier".
 164 See the L<x509v3_config(5)> manual page for the extension names.
 165
 166 =item B<-certopt> I<option>
 167
 168 Customise the output format used with B<-text>. The I<option> argument
 169 can be a single option or multiple options separated by commas. The
 170 B<-certopt> switch may be also be used more than once to set multiple
 171 options. See the L</Text Options> section for more information.
 172
 173 =item B<-checkhost> I<host>
 174
 175 Check that the certificate matches the specified host.
 176
 177 =item B<-checkemail> I<email>
 178
 179 Check that the certificate matches the specified email address.
 180
 181 =item B<-checkip> I<ipaddr>
 182
 183 Check that the certificate matches the specified IP address.
 184
 185 =item B<-noout>
 186
 187 This option prevents output of the encoded version of the certificate.
 188
 189 =item B<-pubkey>
 190
 191 Outputs the certificate's SubjectPublicKeyInfo block in PEM format.
 192
 193 =item B<-modulus>
 194
 195 This option prints out the value of the modulus of the public key
 196 contained in the certificate.
 197
 198 =item B<-serial>
 199
 200 Outputs the certificate serial number.
 201
 202 =item B<-subject_hash>
 203
 204 Outputs the "hash" of the certificate subject name. This is used in OpenSSL to
 205 form an index to allow certificates in a directory to be looked up by subject
 206 name.
 207
 208 =item B<-issuer_hash>
 209
 210 Outputs the "hash" of the certificate issuer name.
 211
 212 =item B<-ocspid>
 213
 214 Outputs the OCSP hash values for the subject name and public key.
 215
 216 =item B<-hash>
 217
 218 Synonym for "-subject_hash" for backward compatibility reasons.
 219
 220 =item B<-subject_hash_old>
 221
 222 Outputs the "hash" of the certificate subject name using the older algorithm
 223 as used by OpenSSL before version 1.0.0.
 224
 225 =item B<-issuer_hash_old>
 226
 227 Outputs the "hash" of the certificate issuer name using the older algorithm
 228 as used by OpenSSL before version 1.0.0.
 229
 230 =item B<-subject>
 231
 232 Outputs the subject name.
 233
 234 =item B<-issuer>
 235
 236 Outputs the issuer name.
 237
 238 {- $OpenSSL::safe::opt_name_item -}
 239
 240 =item B<-email>
 241
 242 Outputs the email address(es) if any.
 243
 244 =item B<-ocsp_uri>
 245
 246 Outputs the OCSP responder address(es) if any.
 247
 248 =item B<-startdate>
 249
 250 Prints out the start date of the certificate, that is the notBefore date.
 251
 252 =item B<-enddate>
 253
 254 Prints out the expiry date of the certificate, that is the notAfter date.
 255
 256 =item B<-dates>
 257
 258 Prints out the start and expiry dates of a certificate.
 259
 260 =item B<-checkend> I<arg>
 261
 262 Checks if the certificate expires within the next I<arg> seconds and exits
 263 nonzero if yes it will expire or zero if not.
 264
 265 =item B<-fingerprint>
 266
 267 Calculates and outputs the digest of the DER encoded version of the entire
 268 certificate (see digest options).
 269 This is commonly called a "fingerprint". Because of the nature of message
 270 digests, the fingerprint of a certificate is unique to that certificate and
 271 two certificates with the same fingerprint can be considered to be the same.
 272
 273 =back
 274
 275 =head2 Trust Settings
 276
 277 A B<trusted certificate> is an ordinary certificate which has several
 278 additional pieces of information attached to it such as the permitted
 279 and prohibited uses of the certificate and an "alias".
 280
 281 Normally when a certificate is being verified at least one certificate
 282 must be "trusted". By default a trusted certificate must be stored
 283 locally and must be a root CA: any certificate chain ending in this CA
 284 is then usable for any purpose.
 285
 286 Trust settings currently are only used with a root CA. They allow a finer
 287 control over the purposes the root CA can be used for. For example a CA
 288 may be trusted for SSL client but not SSL server use.
 289
 290 See the description in L<openssl-verify(1)> for more information
 291 on the meaning of trust settings.
 292
 293 Future versions of OpenSSL will recognize trust settings on any
 294 certificate: not just root CAs.
 295
 296
 297 =over 4
 298
 299 =item B<-trustout>
 300
 301 Output a B<trusted> certificate rather than an ordinary. An ordinary
 302 or trusted certificate can be input but by default an ordinary
 303 certificate is output and any trust settings are discarded. With the
 304 B<-trustout> option a trusted certificate is output. A trusted
 305 certificate is automatically output if any trust settings are modified.
 306
 307 =item B<-setalias> I<arg>
 308
 309 Sets the alias of the certificate. This will allow the certificate
 310 to be referred to using a nickname for example "Steve's Certificate".
 311
 312 =item B<-alias>
 313
 314 Outputs the certificate alias, if any.
 315
 316 =item B<-clrtrust>
 317
 318 Clears all the permitted or trusted uses of the certificate.
 319
 320 =item B<-clrreject>
 321
 322 Clears all the prohibited or rejected uses of the certificate.
 323
 324 =item B<-addtrust> I<arg>
 325
 326 Adds a trusted certificate use.
 327 Any object name can be used here but currently only B<clientAuth> (SSL client
 328 use), B<serverAuth> (SSL server use), B<emailProtection> (S/MIME email) and
 329 B<anyExtendedKeyUsage> are used.
 330 As of OpenSSL 1.1.0, the last of these blocks all purposes when rejected or
 331 enables all purposes when trusted.
 332 Other OpenSSL applications may define additional uses.
 333
 334 =item B<-addreject> I<arg>
 335
 336 Adds a prohibited use. It accepts the same values as the B<-addtrust>
 337 option.
 338
 339 =item B<-purpose>
 340
 341 This option performs tests on the certificate extensions and outputs
 342 the results. For a more complete description see the
 343 L</CERTIFICATE EXTENSIONS> section.
 344
 345 =back
 346
 347 =head2 Signing Options
 348
 349 This command can be used to sign certificates and requests: it
 350 can thus behave like a "mini CA".
 351
 352 =over 4
 353
 354 =item B<-signkey> I<filename>|I<uri>
 355
 356 This option causes the input file to be self signed using the supplied
 357 private key.
 358
 359 It sets the issuer name to the subject name (i.e., makes it self-issued)
 360 and changes the public key to the supplied value (unless overridden by
 361 B<-force_pubkey>). It sets the validity start date to the current time
 362 and the end date to a value determined by the B<-days> option.
 363 It retains any certificate extensions unless the B<-clrext> option is supplied;
 364 this includes, for example, any existing key identifier extensions.
 365
 366 =item B<-badsig>
 367
 368 Corrupt the signature before writing it; this can be useful
 369 for testing.
 370
 371 =item B<-sigopt> I<nm>:I<v>
 372
 373 Pass options to the signature algorithm during sign operations.
 374 Names and values of these options are algorithm-specific.
 375
 376 =item B<-vfyopt> I<nm>:I<v>
 377
 378 Pass options to the signature algorithm during verify operations.
 379 Names and values of these options are algorithm-specific.
 380
 381 =item B<-passin> I<arg>
 382
 383 The key and certificate file password source.
 384 For more information about the format of I<arg>
 385 see L<openssl-passphrase-options(1)>.
 386
 387 =item B<-clrext>
 388
 389 Delete any extensions from a certificate. This option is used when a
 390 certificate is being created from another certificate (for example with
 391 the B<-signkey> or the B<-CA> options). Normally all extensions are
 392 retained.
 393
 394 =item B<-keyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>
 395
 396 The key format; the default is B<PEM>.
 397 The only value with effect is B<ENGINE>; all others have become obsolete.
 398 See L<openssl-format-options(1)> for details.
 399
 400 =item B<-CAform> B<DER>|B<PEM>|B<P12>,
 401
 402 The format for the CA certificate.
 403 This option has no effect and is retained for backward compatibility.
 404
 405 =item B<-CAkeyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>
 406
 407 The format for the CA key; the default is B<PEM>.
 408 The only value with effect is B<ENGINE>; all others have become obsolete.
 409 See L<openssl-format-options(1)> for details.
 410
 411 =item B<-days> I<arg>
 412
 413 Specifies the number of days to make a certificate valid for. The default
 414 is 30 days. Cannot be used with the B<-preserve_dates> option.
 415
 416 =item B<-x509toreq>
 417
 418 Converts a certificate into a certificate request. The B<-signkey> option
 419 is used to pass the required private key.
 420
 421 =item B<-req>
 422
 423 By default a certificate is expected on input. With this option a
 424 certificate request is expected instead.
 425
 426 =item B<-set_serial> I<n>
 427
 428 Specifies the serial number to use. This option can be used with either
 429 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
 430 option the serial number file (as specified by the B<-CAserial> or
 431 B<-CAcreateserial> options) is not used.
 432
 433 The serial number can be decimal or hex (if preceded by C<0x>).
 434
 435 =item B<-CA> I<filename>
 436
 437 Specifies the CA certificate to be used for signing. When this option is
 438 present, this command behaves like a "mini CA". The input file is signed by
 439 this CA using this option: that is its issuer name is set to the subject name
 440 of the CA and it is digitally signed using the CAs private key.
 441
 442 This option is normally combined with the B<-req> option. Without the
 443 B<-req> option the input is a certificate which must be self signed.
 444
 445 =item B<-CAkey> I<filename>|I<uri>
 446
 447 Sets the CA private key to sign a certificate with. If this option is
 448 not specified then it is assumed that the CA private key is present in
 449 the CA certificate file.
 450
 451 =item B<-CAserial> I<filename>
 452
 453 Sets the CA serial number file to use.
 454
 455 When the B<-CA> option is used to sign a certificate it uses a serial
 456 number specified in a file. This file consists of one line containing
 457 an even number of hex digits with the serial number to use. After each
 458 use the serial number is incremented and written out to the file again.
 459
 460 The default filename consists of the CA certificate file base name with
 461 F<.srl> appended. For example if the CA certificate file is called
 462 F<mycacert.pem> it expects to find a serial number file called
 463 F<mycacert.srl>.
 464
 465 =item B<-CAcreateserial>
 466
 467 With this option the CA serial number file is created if it does not exist:
 468 it will contain the serial number "02" and the certificate being signed will
 469 have the 1 as its serial number. If the B<-CA> option is specified
 470 and the serial number file does not exist a random number is generated;
 471 this is the recommended practice.
 472
 473 =item B<-extfile> I<filename>
 474
 475 File containing certificate extensions to use. If not specified then
 476 no extensions are added to the certificate.
 477
 478 =item B<-extensions> I<section>
 479
 480 The section to add certificate extensions from. If this option is not
 481 specified then the extensions should either be contained in the unnamed
 482 (default) section or the default section should contain a variable called
 483 "extensions" which contains the section to use. See the
 484 L<x509v3_config(5)> manual page for details of the
 485 extension section format.
 486
 487 =item B<-new>
 488
 489 Generate a certificate from scratch, not using an input certificate
 490 or certificate request. So the B<-in> option must not be used in this case.
 491 Instead, the B<-subj> option needs to be given.
 492 The public key to include defaults to the key given with the B<-signkey> option,
 493 which implies self-signature.
 494 It may also be given explicity using the B<-force_pubkey> option.
 495
 496 =item B<-next_serial>
 497
 498 Set the serial to be one more than the number in the certificate.
 499
 500 =item B<-nocert>
 501
 502 Do not generate or output a certificate.
 503
 504 =item B<-force_pubkey> I<filename>
 505
 506 When a certificate is created set its public key to the key in I<filename>
 507 instead of the key contained in the input or given with the B<-signkey> option.
 508
 509 This option is useful for creating self-issued certificates that are not
 510 self-signed, for instance when the key cannot be used for signing, such as DH.
 511 It can also be used in conjunction with b<-new> and B<-subj> to directly
 512 generate a certificate containing any desired public key.
 513
 514 =item B<-subj> I<arg>
 515
 516 When a certificate is created set its subject name to the given value.
 517
 518 The arg must be formatted as C</type0=value0/type1=value1/type2=...>.
 519 Special characters may be escaped by C<\> (backslash), whitespace is retained.
 520 Empty values are permitted, but the corresponding type will not be included
 521 in the certificate.
 522 Giving a single C</> will lead to an empty sequence of RDNs (a NULL-DN).
 523 Multi-valued RDNs can be formed by placing a C<+> character instead of a C</>
 524 between the AttributeValueAssertions (AVAs) that specify the members of the set.
 525 Example:
 526
 527 C</DC=org/DC=OpenSSL/DC=users/UID=123456+CN=John Doe>
 528
 529 Unless the B<-CA> option is given the issuer is set to the same value.
 530
 531 This option can be used in conjunction with the B<-force_pubkey> option
 532 to create a certificate even without providing an input certificate
 533 or certificate request.
 534
 535 =back
 536
 537 =head2 Text Options
 538
 539 As well as customising the name output format, it is also possible to
 540 customise the actual fields printed using the B<certopt> options when
 541 the B<text> option is present. The default behaviour is to print all fields.
 542
 543 =over 4
 544
 545 =item B<compatible>
 546
 547 Use the old format. This is equivalent to specifying no output options at all.
 548
 549 =item B<no_header>
 550
 551 Don't print header information: that is the lines saying "Certificate"
 552 and "Data".
 553
 554 =item B<no_version>
 555
 556 Don't print out the version number.
 557
 558 =item B<no_serial>
 559
 560 Don't print out the serial number.
 561
 562 =item B<no_signame>
 563
 564 Don't print out the signature algorithm used.
 565
 566 =item B<no_validity>
 567
 568 Don't print the validity, that is the B<notBefore> and B<notAfter> fields.
 569
 570 =item B<no_subject>
 571
 572 Don't print out the subject name.
 573
 574 =item B<no_issuer>
 575
 576 Don't print out the issuer name.
 577
 578 =item B<no_pubkey>
 579
 580 Don't print out the public key.
 581
 582 =item B<no_sigdump>
 583
 584 Don't give a hexadecimal dump of the certificate signature.
 585
 586 =item B<no_aux>
 587
 588 Don't print out certificate trust information.
 589
 590 =item B<no_extensions>
 591
 592 Don't print out any X509V3 extensions.
 593
 594 =item B<ext_default>
 595
 596 Retain default extension behaviour: attempt to print out unsupported
 597 certificate extensions.
 598
 599 =item B<ext_error>
 600
 601 Print an error message for unsupported certificate extensions.
 602
 603 =item B<ext_parse>
 604
 605 ASN1 parse unsupported extensions.
 606
 607 =item B<ext_dump>
 608
 609 Hex dump unsupported extensions.
 610
 611 =item B<ca_default>
 612
 613 The value used by L<openssl-ca(1)>, equivalent to B<no_issuer>, B<no_pubkey>,
 614 B<no_header>, and B<no_version>.
 615
 616 =back
 617
 618 =head1 EXAMPLES
 619
 620 Note: in these examples the '\' means the example should be all on one
 621 line.
 622
 623 Display the contents of a certificate:
 624
 625  openssl x509 -in cert.pem -noout -text
 626
 627 Display the "Subject Alternative Name" extension of a certificate:
 628
 629  openssl x509 -in cert.pem -noout -ext subjectAltName
 630
 631 Display more extensions of a certificate:
 632
 633  openssl x509 -in cert.pem -noout -ext subjectAltName,nsCertType
 634
 635 Display the certificate serial number:
 636
 637  openssl x509 -in cert.pem -noout -serial
 638
 639 Display the certificate subject name:
 640
 641  openssl x509 -in cert.pem -noout -subject
 642
 643 Display the certificate subject name in RFC2253 form:
 644
 645  openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
 646
 647 Display the certificate subject name in oneline form on a terminal
 648 supporting UTF8:
 649
 650  openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb
 651
 652 Display the certificate SHA1 fingerprint:
 653
 654  openssl x509 -sha1 -in cert.pem -noout -fingerprint
 655
 656 Convert a certificate from PEM to DER format:
 657
 658  openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
 659
 660 Convert a certificate to a certificate request:
 661
 662  openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
 663
 664 Convert a certificate request into a self signed certificate using
 665 extensions for a CA:
 666
 667  openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
 668         -signkey key.pem -out cacert.pem
 669
 670 Sign a certificate request using the CA certificate above and add user
 671 certificate extensions:
 672
 673  openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
 674         -CA cacert.pem -CAkey key.pem -CAcreateserial
 675
 676
 677 Set a certificate to be trusted for SSL client use and change set its alias to
 678 "Steve's Class 1 CA"
 679
 680  openssl x509 -in cert.pem -addtrust clientAuth \
 681         -setalias "Steve's Class 1 CA" -out trust.pem
 682
 683 =head1 NOTES
 684
 685 The conversion to UTF8 format used with the name options assumes that
 686 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
 687 and MSIE do this as do many certificates. So although this is incorrect
 688 it is more likely to display the majority of certificates correctly.
 689
 690 The B<-email> option searches the subject name and the subject alternative
 691 name extension. Only unique email addresses will be printed out: it will
 692 not print the same address more than once.
 693
 694 =head1 CERTIFICATE EXTENSIONS
 695
 696 The B<-purpose> option checks the certificate extensions and determines
 697 what the certificate can be used for. The actual checks done are rather
 698 complex and include various hacks and workarounds to handle broken
 699 certificates and software.
 700
 701 The same code is used when verifying untrusted certificates in chains
 702 so this section is useful if a chain is rejected by the verify code.
 703
 704 The basicConstraints extension CA flag is used to determine whether the
 705 certificate can be used as a CA. If the CA flag is true then it is a CA,
 706 if the CA flag is false then it is not a CA. B<All> CAs should have the
 707 CA flag set to true.
 708
 709 If the basicConstraints extension is absent then the certificate is
 710 considered to be a "possible CA" other extensions are checked according
 711 to the intended use of the certificate. A warning is given in this case
 712 because the certificate should really not be regarded as a CA: however
 713 it is allowed to be a CA to work around some broken software.
 714
 715 If the certificate is a V1 certificate (and thus has no extensions) and
 716 it is self signed it is also assumed to be a CA but a warning is again
 717 given: this is to work around the problem of Verisign roots which are V1
 718 self signed certificates.
 719
 720 If the keyUsage extension is present then additional restraints are
 721 made on the uses of the certificate. A CA certificate B<must> have the
 722 keyCertSign bit set if the keyUsage extension is present.
 723
 724 The extended key usage extension places additional restrictions on the
 725 certificate uses. If this extension is present (whether critical or not)
 726 the key can only be used for the purposes specified.
 727
 728 A complete description of each test is given below. The comments about
 729 basicConstraints and keyUsage and V1 certificates above apply to B<all>
 730 CA certificates.
 731
 732
 733 =over 4
 734
 735 =item B<SSL Client>
 736
 737 The extended key usage extension must be absent or include the "web client
 738 authentication" OID.  keyUsage must be absent or it must have the
 739 digitalSignature bit set. Netscape certificate type must be absent or it must
 740 have the SSL client bit set.
 741
 742 =item B<SSL Client CA>
 743
 744 The extended key usage extension must be absent or include the "web client
 745 authentication" OID. Netscape certificate type must be absent or it must have
 746 the SSL CA bit set: this is used as a work around if the basicConstraints
 747 extension is absent.
 748
 749 =item B<SSL Server>
 750
 751 The extended key usage extension must be absent or include the "web server
 752 authentication" and/or one of the SGC OIDs.  keyUsage must be absent or it
 753 must have the digitalSignature, the keyEncipherment set or both bits set.
 754 Netscape certificate type must be absent or have the SSL server bit set.
 755
 756 =item B<SSL Server CA>
 757
 758 The extended key usage extension must be absent or include the "web server
 759 authentication" and/or one of the SGC OIDs.  Netscape certificate type must
 760 be absent or the SSL CA bit must be set: this is used as a work around if the
 761 basicConstraints extension is absent.
 762
 763 =item B<Netscape SSL Server>
 764
 765 For Netscape SSL clients to connect to an SSL server it must have the
 766 keyEncipherment bit set if the keyUsage extension is present. This isn't
 767 always valid because some cipher suites use the key for digital signing.
 768 Otherwise it is the same as a normal SSL server.
 769
 770 =item B<Common S/MIME Client Tests>
 771
 772 The extended key usage extension must be absent or include the "email
 773 protection" OID. Netscape certificate type must be absent or should have the
 774 S/MIME bit set. If the S/MIME bit is not set in Netscape certificate type
 775 then the SSL client bit is tolerated as an alternative but a warning is shown:
 776 this is because some Verisign certificates don't set the S/MIME bit.
 777
 778 =item B<S/MIME Signing>
 779
 780 In addition to the common S/MIME client tests the digitalSignature bit or
 781 the nonRepudiation bit must be set if the keyUsage extension is present.
 782
 783 =item B<S/MIME Encryption>
 784
 785 In addition to the common S/MIME tests the keyEncipherment bit must be set
 786 if the keyUsage extension is present.
 787
 788 =item B<S/MIME CA>
 789
 790 The extended key usage extension must be absent or include the "email
 791 protection" OID. Netscape certificate type must be absent or must have the
 792 S/MIME CA bit set: this is used as a work around if the basicConstraints
 793 extension is absent.
 794
 795 =item B<CRL Signing>
 796
 797 The keyUsage extension must be absent or it must have the CRL signing bit
 798 set.
 799
 800 =item B<CRL Signing CA>
 801
 802 The normal CA tests apply. Except in this case the basicConstraints extension
 803 must be present.
 804
 805 =back
 806
 807 =head1 BUGS
 808
 809 Extensions in certificates are not transferred to certificate requests and
 810 vice versa.
 811
 812 It is possible to produce invalid certificates or requests by specifying the
 813 wrong private key or using inconsistent options in some cases: these should
 814 be checked.
 815
 816 There should be options to explicitly set such things as start and end
 817 dates rather than an offset from the current time.
 818
 819 =head1 SEE ALSO
 820
 821 L<openssl(1)>,
 822 L<openssl-req(1)>,
 823 L<openssl-ca(1)>,
 824 L<openssl-genrsa(1)>,
 825 L<openssl-gendsa(1)>,
 826 L<openssl-verify(1)>,
 827 L<x509v3_config(5)>
 828
 829 =head1 HISTORY
 830
 831 The hash algorithm used in the B<-subject_hash> and B<-issuer_hash> options
 832 before OpenSSL 1.0.0 was based on the deprecated MD5 algorithm and the encoding
 833 of the distinguished name. In OpenSSL 1.0.0 and later it is based on a canonical
 834 version of the DN using SHA1. This means that any directories using the old
 835 form must have their links rebuilt using L<openssl-rehash(1)> or similar.
 836
 837 All B<-keyform> and B<-CAkeyform> values except B<ENGINE>
 838 have become obsolete in OpenSSL 3.0.0 and have no effect.
 839
 840 The B<-CAform> option has become obsolete in OpenSSL 3.0.0 and has no effect.
 841
 842 The B<-engine> option was deprecated in OpenSSL 3.0.
 843
 844 The B<-C> option was removed in OpenSSL 3.0.
 845
 846 =head1 COPYRIGHT
 847
 848 Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
 849
 850 Licensed under the Apache License 2.0 (the "License").  You may not use
 851 this file except in compliance with the License.  You can obtain a copy
 852 in the file LICENSE in the source distribution or at
 853 L<https://www.openssl.org/source/license.html>.
 854
 855 =cut