x509.pod revision 279264
1 2=pod 3 4=head1 NAME 5 6x509 - Certificate display and signing utility 7 8=head1 SYNOPSIS 9 10B<openssl> B<x509> 11[B<-inform DER|PEM|NET>] 12[B<-outform DER|PEM|NET>] 13[B<-keyform DER|PEM>] 14[B<-CAform DER|PEM>] 15[B<-CAkeyform DER|PEM>] 16[B<-in filename>] 17[B<-out filename>] 18[B<-serial>] 19[B<-hash>] 20[B<-subject_hash>] 21[B<-issuer_hash>] 22[B<-ocspid>] 23[B<-subject>] 24[B<-issuer>] 25[B<-nameopt option>] 26[B<-email>] 27[B<-ocsp_uri>] 28[B<-startdate>] 29[B<-enddate>] 30[B<-purpose>] 31[B<-dates>] 32[B<-checkend num>] 33[B<-modulus>] 34[B<-pubkey>] 35[B<-fingerprint>] 36[B<-alias>] 37[B<-noout>] 38[B<-trustout>] 39[B<-clrtrust>] 40[B<-clrreject>] 41[B<-addtrust arg>] 42[B<-addreject arg>] 43[B<-setalias arg>] 44[B<-days arg>] 45[B<-set_serial n>] 46[B<-signkey filename>] 47[B<-passin arg>] 48[B<-x509toreq>] 49[B<-req>] 50[B<-CA filename>] 51[B<-CAkey filename>] 52[B<-CAcreateserial>] 53[B<-CAserial filename>] 54[B<-text>] 55[B<-certopt option>] 56[B<-C>] 57[B<-md2|-md5|-sha1|-mdc2>] 58[B<-clrext>] 59[B<-extfile filename>] 60[B<-extensions section>] 61[B<-engine id>] 62 63=head1 DESCRIPTION 64 65The B<x509> command is a multi purpose certificate utility. It can be 66used to display certificate information, convert certificates to 67various forms, sign certificate requests like a "mini CA" or edit 68certificate trust settings. 69 70Since there are a large number of options they will split up into 71various sections. 72 73=head1 OPTIONS 74 75=head2 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS 76 77=over 4 78 79=item B<-inform DER|PEM|NET> 80 81This specifies the input format normally the command will expect an X509 82certificate but this can change if other options such as B<-req> are 83present. The DER format is the DER encoding of the certificate and PEM 84is the base64 encoding of the DER encoding with header and footer lines 85added. The NET option is an obscure Netscape server format that is now 86obsolete. 87 88=item B<-outform DER|PEM|NET> 89 90This specifies the output format, the options have the same meaning as the 91B<-inform> option. 92 93=item B<-in filename> 94 95This specifies the input filename to read a certificate from or standard input 96if this option is not specified. 97 98=item B<-out filename> 99 100This specifies the output filename to write to or standard output by 101default. 102 103=item B<-md2|-md5|-sha1|-mdc2> 104 105the digest to use. This affects any signing or display option that uses a message 106digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not 107specified then SHA1 is used. If the key being used to sign with is a DSA key 108then this option has no effect: SHA1 is always used with DSA keys. 109 110=item B<-engine id> 111 112specifying an engine (by its unique B<id> string) will cause B<x509> 113to attempt to obtain a functional reference to the specified engine, 114thus initialising it if needed. The engine will then be set as the default 115for all available algorithms. 116 117=back 118 119=head2 DISPLAY OPTIONS 120 121Note: the B<-alias> and B<-purpose> options are also display options 122but are described in the B<TRUST SETTINGS> section. 123 124=over 4 125 126=item B<-text> 127 128prints out the certificate in text form. Full details are output including the 129public key, signature algorithms, issuer and subject names, serial number 130any extensions present and any trust settings. 131 132=item B<-certopt option> 133 134customise the output format used with B<-text>. The B<option> argument can be 135a single option or multiple options separated by commas. The B<-certopt> switch 136may be also be used more than once to set multiple options. See the B<TEXT OPTIONS> 137section for more information. 138 139=item B<-noout> 140 141this option prevents output of the encoded version of the request. 142 143=item B<-pubkey> 144 145outputs the certificate's SubjectPublicKeyInfo block in PEM format. 146 147=item B<-modulus> 148 149this option prints out the value of the modulus of the public key 150contained in the certificate. 151 152=item B<-serial> 153 154outputs the certificate serial number. 155 156=item B<-subject_hash> 157 158outputs the "hash" of the certificate subject name. This is used in OpenSSL to 159form an index to allow certificates in a directory to be looked up by subject 160name. 161 162=item B<-issuer_hash> 163 164outputs the "hash" of the certificate issuer name. 165 166=item B<-ocspid> 167 168outputs the OCSP hash values for the subject name and public key. 169 170=item B<-hash> 171 172synonym for "-subject_hash" for backward compatibility reasons. 173 174=item B<-subject_hash_old> 175 176outputs the "hash" of the certificate subject name using the older algorithm 177as used by OpenSSL versions before 1.0.0. 178 179=item B<-issuer_hash_old> 180 181outputs the "hash" of the certificate issuer name using the older algorithm 182as used by OpenSSL versions before 1.0.0. 183 184=item B<-subject> 185 186outputs the subject name. 187 188=item B<-issuer> 189 190outputs the issuer name. 191 192=item B<-nameopt option> 193 194option which determines how the subject or issuer names are displayed. The 195B<option> argument can be a single option or multiple options separated by 196commas. Alternatively the B<-nameopt> switch may be used more than once to 197set multiple options. See the B<NAME OPTIONS> section for more information. 198 199=item B<-email> 200 201outputs the email address(es) if any. 202 203=item B<-ocsp_uri> 204 205outputs the OCSP responder address(es) if any. 206 207=item B<-startdate> 208 209prints out the start date of the certificate, that is the notBefore date. 210 211=item B<-enddate> 212 213prints out the expiry date of the certificate, that is the notAfter date. 214 215=item B<-dates> 216 217prints out the start and expiry dates of a certificate. 218 219=item B<-checkend arg> 220 221checks if the certificate expires within the next B<arg> seconds and exits 222non-zero if yes it will expire or zero if not. 223 224=item B<-fingerprint> 225 226prints out the digest of the DER encoded version of the whole certificate 227(see digest options). 228 229=item B<-C> 230 231this outputs the certificate in the form of a C source file. 232 233=back 234 235=head2 TRUST SETTINGS 236 237Please note these options are currently experimental and may well change. 238 239A B<trusted certificate> is an ordinary certificate which has several 240additional pieces of information attached to it such as the permitted 241and prohibited uses of the certificate and an "alias". 242 243Normally when a certificate is being verified at least one certificate 244must be "trusted". By default a trusted certificate must be stored 245locally and must be a root CA: any certificate chain ending in this CA 246is then usable for any purpose. 247 248Trust settings currently are only used with a root CA. They allow a finer 249control over the purposes the root CA can be used for. For example a CA 250may be trusted for SSL client but not SSL server use. 251 252See the description of the B<verify> utility for more information on the 253meaning of trust settings. 254 255Future versions of OpenSSL will recognize trust settings on any 256certificate: not just root CAs. 257 258 259=over 4 260 261=item B<-trustout> 262 263this causes B<x509> to output a B<trusted> certificate. An ordinary 264or trusted certificate can be input but by default an ordinary 265certificate is output and any trust settings are discarded. With the 266B<-trustout> option a trusted certificate is output. A trusted 267certificate is automatically output if any trust settings are modified. 268 269=item B<-setalias arg> 270 271sets the alias of the certificate. This will allow the certificate 272to be referred to using a nickname for example "Steve's Certificate". 273 274=item B<-alias> 275 276outputs the certificate alias, if any. 277 278=item B<-clrtrust> 279 280clears all the permitted or trusted uses of the certificate. 281 282=item B<-clrreject> 283 284clears all the prohibited or rejected uses of the certificate. 285 286=item B<-addtrust arg> 287 288adds a trusted certificate use. Any object name can be used here 289but currently only B<clientAuth> (SSL client use), B<serverAuth> 290(SSL server use) and B<emailProtection> (S/MIME email) are used. 291Other OpenSSL applications may define additional uses. 292 293=item B<-addreject arg> 294 295adds a prohibited use. It accepts the same values as the B<-addtrust> 296option. 297 298=item B<-purpose> 299 300this option performs tests on the certificate extensions and outputs 301the results. For a more complete description see the B<CERTIFICATE 302EXTENSIONS> section. 303 304=back 305 306=head2 SIGNING OPTIONS 307 308The B<x509> utility can be used to sign certificates and requests: it 309can thus behave like a "mini CA". 310 311=over 4 312 313=item B<-signkey filename> 314 315this option causes the input file to be self signed using the supplied 316private key. 317 318If the input file is a certificate it sets the issuer name to the 319subject name (i.e. makes it self signed) changes the public key to the 320supplied value and changes the start and end dates. The start date is 321set to the current time and the end date is set to a value determined 322by the B<-days> option. Any certificate extensions are retained unless 323the B<-clrext> option is supplied. 324 325If the input is a certificate request then a self signed certificate 326is created using the supplied private key using the subject name in 327the request. 328 329=item B<-passin arg> 330 331the key password source. For more information about the format of B<arg> 332see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 333 334=item B<-clrext> 335 336delete any extensions from a certificate. This option is used when a 337certificate is being created from another certificate (for example with 338the B<-signkey> or the B<-CA> options). Normally all extensions are 339retained. 340 341=item B<-keyform PEM|DER> 342 343specifies the format (DER or PEM) of the private key file used in the 344B<-signkey> option. 345 346=item B<-days arg> 347 348specifies the number of days to make a certificate valid for. The default 349is 30 days. 350 351=item B<-x509toreq> 352 353converts a certificate into a certificate request. The B<-signkey> option 354is used to pass the required private key. 355 356=item B<-req> 357 358by default a certificate is expected on input. With this option a 359certificate request is expected instead. 360 361=item B<-set_serial n> 362 363specifies the serial number to use. This option can be used with either 364the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA> 365option the serial number file (as specified by the B<-CAserial> or 366B<-CAcreateserial> options) is not used. 367 368The serial number can be decimal or hex (if preceded by B<0x>). Negative 369serial numbers can also be specified but their use is not recommended. 370 371=item B<-CA filename> 372 373specifies the CA certificate to be used for signing. When this option is 374present B<x509> behaves like a "mini CA". The input file is signed by this 375CA using this option: that is its issuer name is set to the subject name 376of the CA and it is digitally signed using the CAs private key. 377 378This option is normally combined with the B<-req> option. Without the 379B<-req> option the input is a certificate which must be self signed. 380 381=item B<-CAkey filename> 382 383sets the CA private key to sign a certificate with. If this option is 384not specified then it is assumed that the CA private key is present in 385the CA certificate file. 386 387=item B<-CAserial filename> 388 389sets the CA serial number file to use. 390 391When the B<-CA> option is used to sign a certificate it uses a serial 392number specified in a file. This file consist of one line containing 393an even number of hex digits with the serial number to use. After each 394use the serial number is incremented and written out to the file again. 395 396The default filename consists of the CA certificate file base name with 397".srl" appended. For example if the CA certificate file is called 398"mycacert.pem" it expects to find a serial number file called "mycacert.srl". 399 400=item B<-CAcreateserial> 401 402with this option the CA serial number file is created if it does not exist: 403it will contain the serial number "02" and the certificate being signed will 404have the 1 as its serial number. Normally if the B<-CA> option is specified 405and the serial number file does not exist it is an error. 406 407=item B<-extfile filename> 408 409file containing certificate extensions to use. If not specified then 410no extensions are added to the certificate. 411 412=item B<-extensions section> 413 414the section to add certificate extensions from. If this option is not 415specified then the extensions should either be contained in the unnamed 416(default) section or the default section should contain a variable called 417"extensions" which contains the section to use. See the 418L<x509v3_config(5)|x509v3_config(5)> manual page for details of the 419extension section format. 420 421=back 422 423=head2 NAME OPTIONS 424 425The B<nameopt> command line switch determines how the subject and issuer 426names are displayed. If no B<nameopt> switch is present the default "oneline" 427format is used which is compatible with previous versions of OpenSSL. 428Each option is described in detail below, all options can be preceded by 429a B<-> to turn the option off. Only the first four will normally be used. 430 431=over 4 432 433=item B<compat> 434 435use the old format. This is equivalent to specifying no name options at all. 436 437=item B<RFC2253> 438 439displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>, 440B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>, 441B<sep_comma_plus>, B<dn_rev> and B<sname>. 442 443=item B<oneline> 444 445a oneline format which is more readable than RFC2253. It is equivalent to 446specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>, 447B<dump_der>, B<use_quote>, B<sep_comma_plus_space>, B<space_eq> and B<sname> 448options. 449 450=item B<multiline> 451 452a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>, 453B<space_eq>, B<lname> and B<align>. 454 455=item B<esc_2253> 456 457escape the "special" characters required by RFC2253 in a field That is 458B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string 459and a space character at the beginning or end of a string. 460 461=item B<esc_ctrl> 462 463escape control characters. That is those with ASCII values less than 4640x20 (space) and the delete (0x7f) character. They are escaped using the 465RFC2253 \XX notation (where XX are two hex digits representing the 466character value). 467 468=item B<esc_msb> 469 470escape characters with the MSB set, that is with ASCII values larger than 471127. 472 473=item B<use_quote> 474 475escapes some characters by surrounding the whole string with B<"> characters, 476without the option all escaping is done with the B<\> character. 477 478=item B<utf8> 479 480convert all strings to UTF8 format first. This is required by RFC2253. If 481you are lucky enough to have a UTF8 compatible terminal then the use 482of this option (and B<not> setting B<esc_msb>) may result in the correct 483display of multibyte (international) characters. Is this option is not 484present then multibyte characters larger than 0xff will be represented 485using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits. 486Also if this option is off any UTF8Strings will be converted to their 487character form first. 488 489=item B<ignore_type> 490 491this option does not attempt to interpret multibyte characters in any 492way. That is their content octets are merely dumped as though one octet 493represents each character. This is useful for diagnostic purposes but 494will result in rather odd looking output. 495 496=item B<show_type> 497 498show the type of the ASN1 character string. The type precedes the 499field contents. For example "BMPSTRING: Hello World". 500 501=item B<dump_der> 502 503when this option is set any fields that need to be hexdumped will 504be dumped using the DER encoding of the field. Otherwise just the 505content octets will be displayed. Both options use the RFC2253 506B<#XXXX...> format. 507 508=item B<dump_nostr> 509 510dump non character string types (for example OCTET STRING) if this 511option is not set then non character string types will be displayed 512as though each content octet represents a single character. 513 514=item B<dump_all> 515 516dump all fields. This option when used with B<dump_der> allows the 517DER encoding of the structure to be unambiguously determined. 518 519=item B<dump_unknown> 520 521dump any field whose OID is not recognised by OpenSSL. 522 523=item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>, 524B<sep_multiline> 525 526these options determine the field separators. The first character is 527between RDNs and the second between multiple AVAs (multiple AVAs are 528very rare and their use is discouraged). The options ending in 529"space" additionally place a space after the separator to make it 530more readable. The B<sep_multiline> uses a linefeed character for 531the RDN separator and a spaced B<+> for the AVA separator. It also 532indents the fields by four characters. 533 534=item B<dn_rev> 535 536reverse the fields of the DN. This is required by RFC2253. As a side 537effect this also reverses the order of multiple AVAs but this is 538permissible. 539 540=item B<nofname>, B<sname>, B<lname>, B<oid> 541 542these options alter how the field name is displayed. B<nofname> does 543not display the field at all. B<sname> uses the "short name" form 544(CN for commonName for example). B<lname> uses the long form. 545B<oid> represents the OID in numerical form and is useful for 546diagnostic purpose. 547 548=item B<align> 549 550align field values for a more readable output. Only usable with 551B<sep_multiline>. 552 553=item B<space_eq> 554 555places spaces round the B<=> character which follows the field 556name. 557 558=back 559 560=head2 TEXT OPTIONS 561 562As well as customising the name output format, it is also possible to 563customise the actual fields printed using the B<certopt> options when 564the B<text> option is present. The default behaviour is to print all fields. 565 566=over 4 567 568=item B<compatible> 569 570use the old format. This is equivalent to specifying no output options at all. 571 572=item B<no_header> 573 574don't print header information: that is the lines saying "Certificate" and "Data". 575 576=item B<no_version> 577 578don't print out the version number. 579 580=item B<no_serial> 581 582don't print out the serial number. 583 584=item B<no_signame> 585 586don't print out the signature algorithm used. 587 588=item B<no_validity> 589 590don't print the validity, that is the B<notBefore> and B<notAfter> fields. 591 592=item B<no_subject> 593 594don't print out the subject name. 595 596=item B<no_issuer> 597 598don't print out the issuer name. 599 600=item B<no_pubkey> 601 602don't print out the public key. 603 604=item B<no_sigdump> 605 606don't give a hexadecimal dump of the certificate signature. 607 608=item B<no_aux> 609 610don't print out certificate trust information. 611 612=item B<no_extensions> 613 614don't print out any X509V3 extensions. 615 616=item B<ext_default> 617 618retain default extension behaviour: attempt to print out unsupported certificate extensions. 619 620=item B<ext_error> 621 622print an error message for unsupported certificate extensions. 623 624=item B<ext_parse> 625 626ASN1 parse unsupported extensions. 627 628=item B<ext_dump> 629 630hex dump unsupported extensions. 631 632=item B<ca_default> 633 634the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>, 635B<no_version>, B<no_sigdump> and B<no_signame>. 636 637=back 638 639=head1 EXAMPLES 640 641Note: in these examples the '\' means the example should be all on one 642line. 643 644Display the contents of a certificate: 645 646 openssl x509 -in cert.pem -noout -text 647 648Display the certificate serial number: 649 650 openssl x509 -in cert.pem -noout -serial 651 652Display the certificate subject name: 653 654 openssl x509 -in cert.pem -noout -subject 655 656Display the certificate subject name in RFC2253 form: 657 658 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253 659 660Display the certificate subject name in oneline form on a terminal 661supporting UTF8: 662 663 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb 664 665Display the certificate MD5 fingerprint: 666 667 openssl x509 -in cert.pem -noout -fingerprint 668 669Display the certificate SHA1 fingerprint: 670 671 openssl x509 -sha1 -in cert.pem -noout -fingerprint 672 673Convert a certificate from PEM to DER format: 674 675 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER 676 677Convert a certificate to a certificate request: 678 679 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem 680 681Convert a certificate request into a self signed certificate using 682extensions for a CA: 683 684 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \ 685 -signkey key.pem -out cacert.pem 686 687Sign a certificate request using the CA certificate above and add user 688certificate extensions: 689 690 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \ 691 -CA cacert.pem -CAkey key.pem -CAcreateserial 692 693 694Set a certificate to be trusted for SSL client use and change set its alias to 695"Steve's Class 1 CA" 696 697 openssl x509 -in cert.pem -addtrust clientAuth \ 698 -setalias "Steve's Class 1 CA" -out trust.pem 699 700=head1 NOTES 701 702The PEM format uses the header and footer lines: 703 704 -----BEGIN CERTIFICATE----- 705 -----END CERTIFICATE----- 706 707it will also handle files containing: 708 709 -----BEGIN X509 CERTIFICATE----- 710 -----END X509 CERTIFICATE----- 711 712Trusted certificates have the lines 713 714 -----BEGIN TRUSTED CERTIFICATE----- 715 -----END TRUSTED CERTIFICATE----- 716 717The conversion to UTF8 format used with the name options assumes that 718T61Strings use the ISO8859-1 character set. This is wrong but Netscape 719and MSIE do this as do many certificates. So although this is incorrect 720it is more likely to display the majority of certificates correctly. 721 722The B<-fingerprint> option takes the digest of the DER encoded certificate. 723This is commonly called a "fingerprint". Because of the nature of message 724digests the fingerprint of a certificate is unique to that certificate and 725two certificates with the same fingerprint can be considered to be the same. 726 727The Netscape fingerprint uses MD5 whereas MSIE uses SHA1. 728 729The B<-email> option searches the subject name and the subject alternative 730name extension. Only unique email addresses will be printed out: it will 731not print the same address more than once. 732 733=head1 CERTIFICATE EXTENSIONS 734 735The B<-purpose> option checks the certificate extensions and determines 736what the certificate can be used for. The actual checks done are rather 737complex and include various hacks and workarounds to handle broken 738certificates and software. 739 740The same code is used when verifying untrusted certificates in chains 741so this section is useful if a chain is rejected by the verify code. 742 743The basicConstraints extension CA flag is used to determine whether the 744certificate can be used as a CA. If the CA flag is true then it is a CA, 745if the CA flag is false then it is not a CA. B<All> CAs should have the 746CA flag set to true. 747 748If the basicConstraints extension is absent then the certificate is 749considered to be a "possible CA" other extensions are checked according 750to the intended use of the certificate. A warning is given in this case 751because the certificate should really not be regarded as a CA: however 752it is allowed to be a CA to work around some broken software. 753 754If the certificate is a V1 certificate (and thus has no extensions) and 755it is self signed it is also assumed to be a CA but a warning is again 756given: this is to work around the problem of Verisign roots which are V1 757self signed certificates. 758 759If the keyUsage extension is present then additional restraints are 760made on the uses of the certificate. A CA certificate B<must> have the 761keyCertSign bit set if the keyUsage extension is present. 762 763The extended key usage extension places additional restrictions on the 764certificate uses. If this extension is present (whether critical or not) 765the key can only be used for the purposes specified. 766 767A complete description of each test is given below. The comments about 768basicConstraints and keyUsage and V1 certificates above apply to B<all> 769CA certificates. 770 771 772=over 4 773 774=item B<SSL Client> 775 776The extended key usage extension must be absent or include the "web client 777authentication" OID. keyUsage must be absent or it must have the 778digitalSignature bit set. Netscape certificate type must be absent or it must 779have the SSL client bit set. 780 781=item B<SSL Client CA> 782 783The extended key usage extension must be absent or include the "web client 784authentication" OID. Netscape certificate type must be absent or it must have 785the SSL CA bit set: this is used as a work around if the basicConstraints 786extension is absent. 787 788=item B<SSL Server> 789 790The extended key usage extension must be absent or include the "web server 791authentication" and/or one of the SGC OIDs. keyUsage must be absent or it 792must have the digitalSignature, the keyEncipherment set or both bits set. 793Netscape certificate type must be absent or have the SSL server bit set. 794 795=item B<SSL Server CA> 796 797The extended key usage extension must be absent or include the "web server 798authentication" and/or one of the SGC OIDs. Netscape certificate type must 799be absent or the SSL CA bit must be set: this is used as a work around if the 800basicConstraints extension is absent. 801 802=item B<Netscape SSL Server> 803 804For Netscape SSL clients to connect to an SSL server it must have the 805keyEncipherment bit set if the keyUsage extension is present. This isn't 806always valid because some cipher suites use the key for digital signing. 807Otherwise it is the same as a normal SSL server. 808 809=item B<Common S/MIME Client Tests> 810 811The extended key usage extension must be absent or include the "email 812protection" OID. Netscape certificate type must be absent or should have the 813S/MIME bit set. If the S/MIME bit is not set in netscape certificate type 814then the SSL client bit is tolerated as an alternative but a warning is shown: 815this is because some Verisign certificates don't set the S/MIME bit. 816 817=item B<S/MIME Signing> 818 819In addition to the common S/MIME client tests the digitalSignature bit must 820be set if the keyUsage extension is present. 821 822=item B<S/MIME Encryption> 823 824In addition to the common S/MIME tests the keyEncipherment bit must be set 825if the keyUsage extension is present. 826 827=item B<S/MIME CA> 828 829The extended key usage extension must be absent or include the "email 830protection" OID. Netscape certificate type must be absent or must have the 831S/MIME CA bit set: this is used as a work around if the basicConstraints 832extension is absent. 833 834=item B<CRL Signing> 835 836The keyUsage extension must be absent or it must have the CRL signing bit 837set. 838 839=item B<CRL Signing CA> 840 841The normal CA tests apply. Except in this case the basicConstraints extension 842must be present. 843 844=back 845 846=head1 BUGS 847 848Extensions in certificates are not transferred to certificate requests and 849vice versa. 850 851It is possible to produce invalid certificates or requests by specifying the 852wrong private key or using inconsistent options in some cases: these should 853be checked. 854 855There should be options to explicitly set such things as start and end 856dates rather than an offset from the current time. 857 858The code to implement the verify behaviour described in the B<TRUST SETTINGS> 859is currently being developed. It thus describes the intended behaviour rather 860than the current behaviour. It is hoped that it will represent reality in 861OpenSSL 0.9.5 and later. 862 863=head1 SEE ALSO 864 865L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>, 866L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>, 867L<x509v3_config(5)|x509v3_config(5)> 868 869=head1 HISTORY 870 871Before OpenSSL 0.9.8, the default digest for RSA keys was MD5. 872 873The hash algorithm used in the B<-subject_hash> and B<-issuer_hash> options 874before OpenSSL 1.0.0 was based on the deprecated MD5 algorithm and the encoding 875of the distinguished name. In OpenSSL 1.0.0 and later it is based on a 876canonical version of the DN using SHA1. This means that any directories using 877the old form must have their links rebuilt using B<c_rehash> or similar. 878 879=cut 880