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<-subject>] 23[B<-issuer>] 24[B<-nameopt option>] 25[B<-email>] 26[B<-startdate>] 27[B<-enddate>] 28[B<-purpose>] 29[B<-dates>] 30[B<-modulus>] 31[B<-fingerprint>] 32[B<-alias>] 33[B<-noout>] 34[B<-trustout>] 35[B<-clrtrust>] 36[B<-clrreject>] 37[B<-addtrust arg>] 38[B<-addreject arg>] 39[B<-setalias arg>] 40[B<-days arg>] 41[B<-set_serial n>] 42[B<-signkey filename>] 43[B<-x509toreq>] 44[B<-req>] 45[B<-CA filename>] 46[B<-CAkey filename>] 47[B<-CAcreateserial>] 48[B<-CAserial filename>] 49[B<-text>] 50[B<-C>] 51[B<-md2|-md5|-sha1|-mdc2>] 52[B<-clrext>] 53[B<-extfile filename>] 54[B<-extensions section>] 55[B<-engine id>] 56 57=head1 DESCRIPTION 58 59The B<x509> command is a multi purpose certificate utility. It can be 60used to display certificate information, convert certificates to 61various forms, sign certificate requests like a "mini CA" or edit 62certificate trust settings. 63 64Since there are a large number of options they will split up into 65various sections. 66 67=head1 OPTIONS 68 69=head2 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS 70 71=over 4 72 73=item B<-inform DER|PEM|NET> 74 75This specifies the input format normally the command will expect an X509 76certificate but this can change if other options such as B<-req> are 77present. The DER format is the DER encoding of the certificate and PEM 78is the base64 encoding of the DER encoding with header and footer lines 79added. The NET option is an obscure Netscape server format that is now 80obsolete. 81 82=item B<-outform DER|PEM|NET> 83 84This specifies the output format, the options have the same meaning as the 85B<-inform> option. 86 87=item B<-in filename> 88 89This specifies the input filename to read a certificate from or standard input 90if this option is not specified. 91 92=item B<-out filename> 93 94This specifies the output filename to write to or standard output by 95default. 96 97=item B<-md2|-md5|-sha1|-mdc2> 98 99the digest to use. This affects any signing or display option that uses a message 100digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not 101specified then SHA1 is used. If the key being used to sign with is a DSA key 102then this option has no effect: SHA1 is always used with DSA keys. 103 104=item B<-engine id> 105 106specifying an engine (by it's unique B<id> string) will cause B<req> 107to attempt to obtain a functional reference to the specified engine, 108thus initialising it if needed. The engine will then be set as the default 109for all available algorithms. 110 111=back 112 113=head2 DISPLAY OPTIONS 114 115Note: the B<-alias> and B<-purpose> options are also display options 116but are described in the B<TRUST SETTINGS> section. 117 118=over 4 119 120=item B<-text> 121 122prints out the certificate in text form. Full details are output including the 123public key, signature algorithms, issuer and subject names, serial number 124any extensions present and any trust settings. 125 126=item B<-certopt option> 127 128customise the output format used with B<-text>. The B<option> argument can be 129a single option or multiple options separated by commas. The B<-certopt> switch 130may be also be used more than once to set multiple options. See the B<TEXT OPTIONS> 131section for more information. 132 133=item B<-noout> 134 135this option prevents output of the encoded version of the request. 136 137=item B<-modulus> 138 139this option prints out the value of the modulus of the public key 140contained in the certificate. 141 142=item B<-serial> 143 144outputs the certificate serial number. 145 146=item B<-subject_hash> 147 148outputs the "hash" of the certificate subject name. This is used in OpenSSL to 149form an index to allow certificates in a directory to be looked up by subject 150name. 151 152=item B<-issuer_hash> 153 154outputs the "hash" of the certificate issuer name. 155 156=item B<-hash> 157 158synonym for "-subject_hash" for backward compatibility reasons. 159 160=item B<-subject> 161 162outputs the subject name. 163 164=item B<-issuer> 165 166outputs the issuer name. 167 168=item B<-nameopt option> 169 170option which determines how the subject or issuer names are displayed. The 171B<option> argument can be a single option or multiple options separated by 172commas. Alternatively the B<-nameopt> switch may be used more than once to 173set multiple options. See the B<NAME OPTIONS> section for more information. 174 175=item B<-email> 176 177outputs the email address(es) if any. 178 179=item B<-startdate> 180 181prints out the start date of the certificate, that is the notBefore date. 182 183=item B<-enddate> 184 185prints out the expiry date of the certificate, that is the notAfter date. 186 187=item B<-dates> 188 189prints out the start and expiry dates of a certificate. 190 191=item B<-fingerprint> 192 193prints out the digest of the DER encoded version of the whole certificate 194(see digest options). 195 196=item B<-C> 197 198this outputs the certificate in the form of a C source file. 199 200=back 201 202=head2 TRUST SETTINGS 203 204Please note these options are currently experimental and may well change. 205 206A B<trusted certificate> is an ordinary certificate which has several 207additional pieces of information attached to it such as the permitted 208and prohibited uses of the certificate and an "alias". 209 210Normally when a certificate is being verified at least one certificate 211must be "trusted". By default a trusted certificate must be stored 212locally and must be a root CA: any certificate chain ending in this CA 213is then usable for any purpose. 214 215Trust settings currently are only used with a root CA. They allow a finer 216control over the purposes the root CA can be used for. For example a CA 217may be trusted for SSL client but not SSL server use. 218 219See the description of the B<verify> utility for more information on the 220meaning of trust settings. 221 222Future versions of OpenSSL will recognize trust settings on any 223certificate: not just root CAs. 224 225 226=over 4 227 228=item B<-trustout> 229 230this causes B<x509> to output a B<trusted> certificate. An ordinary 231or trusted certificate can be input but by default an ordinary 232certificate is output and any trust settings are discarded. With the 233B<-trustout> option a trusted certificate is output. A trusted 234certificate is automatically output if any trust settings are modified. 235 236=item B<-setalias arg> 237 238sets the alias of the certificate. This will allow the certificate 239to be referred to using a nickname for example "Steve's Certificate". 240 241=item B<-alias> 242 243outputs the certificate alias, if any. 244 245=item B<-clrtrust> 246 247clears all the permitted or trusted uses of the certificate. 248 249=item B<-clrreject> 250 251clears all the prohibited or rejected uses of the certificate. 252 253=item B<-addtrust arg> 254 255adds a trusted certificate use. Any object name can be used here 256but currently only B<clientAuth> (SSL client use), B<serverAuth> 257(SSL server use) and B<emailProtection> (S/MIME email) are used. 258Other OpenSSL applications may define additional uses. 259 260=item B<-addreject arg> 261 262adds a prohibited use. It accepts the same values as the B<-addtrust> 263option. 264 265=item B<-purpose> 266 267this option performs tests on the certificate extensions and outputs 268the results. For a more complete description see the B<CERTIFICATE 269EXTENSIONS> section. 270 271=back 272 273=head2 SIGNING OPTIONS 274 275The B<x509> utility can be used to sign certificates and requests: it 276can thus behave like a "mini CA". 277 278=over 4 279 280=item B<-signkey filename> 281 282this option causes the input file to be self signed using the supplied 283private key. 284 285If the input file is a certificate it sets the issuer name to the 286subject name (i.e. makes it self signed) changes the public key to the 287supplied value and changes the start and end dates. The start date is 288set to the current time and the end date is set to a value determined 289by the B<-days> option. Any certificate extensions are retained unless 290the B<-clrext> option is supplied. 291 292If the input is a certificate request then a self signed certificate 293is created using the supplied private key using the subject name in 294the request. 295 296=item B<-clrext> 297 298delete any extensions from a certificate. This option is used when a 299certificate is being created from another certificate (for example with 300the B<-signkey> or the B<-CA> options). Normally all extensions are 301retained. 302 303=item B<-keyform PEM|DER> 304 305specifies the format (DER or PEM) of the private key file used in the 306B<-signkey> option. 307 308=item B<-days arg> 309 310specifies the number of days to make a certificate valid for. The default 311is 30 days. 312 313=item B<-x509toreq> 314 315converts a certificate into a certificate request. The B<-signkey> option 316is used to pass the required private key. 317 318=item B<-req> 319 320by default a certificate is expected on input. With this option a 321certificate request is expected instead. 322 323=item B<-set_serial n> 324 325specifies the serial number to use. This option can be used with either 326the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA> 327option the serial number file (as specified by the B<-CAserial> or 328B<-CAcreateserial> options) is not used. 329 330The serial number can be decimal or hex (if preceded by B<0x>). Negative 331serial numbers can also be specified but their use is not recommended. 332 333=item B<-CA filename> 334 335specifies the CA certificate to be used for signing. When this option is 336present B<x509> behaves like a "mini CA". The input file is signed by this 337CA using this option: that is its issuer name is set to the subject name 338of the CA and it is digitally signed using the CAs private key. 339 340This option is normally combined with the B<-req> option. Without the 341B<-req> option the input is a certificate which must be self signed. 342 343=item B<-CAkey filename> 344 345sets the CA private key to sign a certificate with. If this option is 346not specified then it is assumed that the CA private key is present in 347the CA certificate file. 348 349=item B<-CAserial filename> 350 351sets the CA serial number file to use. 352 353When the B<-CA> option is used to sign a certificate it uses a serial 354number specified in a file. This file consist of one line containing 355an even number of hex digits with the serial number to use. After each 356use the serial number is incremented and written out to the file again. 357 358The default filename consists of the CA certificate file base name with 359".srl" appended. For example if the CA certificate file is called 360"mycacert.pem" it expects to find a serial number file called "mycacert.srl". 361 362=item B<-CAcreateserial> 363 364with this option the CA serial number file is created if it does not exist: 365it will contain the serial number "02" and the certificate being signed will 366have the 1 as its serial number. Normally if the B<-CA> option is specified 367and the serial number file does not exist it is an error. 368 369=item B<-extfile filename> 370 371file containing certificate extensions to use. If not specified then 372no extensions are added to the certificate. 373 374=item B<-extensions section> 375 376the section to add certificate extensions from. If this option is not 377specified then the extensions should either be contained in the unnamed 378(default) section or the default section should contain a variable called 379"extensions" which contains the section to use. 380 381=back 382 383=head2 NAME OPTIONS 384 385The B<nameopt> command line switch determines how the subject and issuer 386names are displayed. If no B<nameopt> switch is present the default "oneline" 387format is used which is compatible with previous versions of OpenSSL. 388Each option is described in detail below, all options can be preceded by 389a B<-> to turn the option off. Only the first four will normally be used. 390 391=over 4 392 393=item B<compat> 394 395use the old format. This is equivalent to specifying no name options at all. 396 397=item B<RFC2253> 398 399displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>, 400B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>, 401B<sep_comma_plus>, B<dn_rev> and B<sname>. 402 403=item B<oneline> 404 405a oneline format which is more readable than RFC2253. It is equivalent to 406specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>, 407B<dump_der>, B<use_quote>, B<sep_comma_plus_space>, B<space_eq> and B<sname> 408options. 409 410=item B<multiline> 411 412a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>, 413B<space_eq>, B<lname> and B<align>. 414 415=item B<esc_2253> 416 417escape the "special" characters required by RFC2253 in a field That is 418B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string 419and a space character at the beginning or end of a string. 420 421=item B<esc_ctrl> 422 423escape control characters. That is those with ASCII values less than 4240x20 (space) and the delete (0x7f) character. They are escaped using the 425RFC2253 \XX notation (where XX are two hex digits representing the 426character value). 427 428=item B<esc_msb> 429 430escape characters with the MSB set, that is with ASCII values larger than 431127. 432 433=item B<use_quote> 434 435escapes some characters by surrounding the whole string with B<"> characters, 436without the option all escaping is done with the B<\> character. 437 438=item B<utf8> 439 440convert all strings to UTF8 format first. This is required by RFC2253. If 441you are lucky enough to have a UTF8 compatible terminal then the use 442of this option (and B<not> setting B<esc_msb>) may result in the correct 443display of multibyte (international) characters. Is this option is not 444present then multibyte characters larger than 0xff will be represented 445using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits. 446Also if this option is off any UTF8Strings will be converted to their 447character form first. 448 449=item B<no_type> 450 451this option does not attempt to interpret multibyte characters in any 452way. That is their content octets are merely dumped as though one octet 453represents each character. This is useful for diagnostic purposes but 454will result in rather odd looking output. 455 456=item B<show_type> 457 458show the type of the ASN1 character string. The type precedes the 459field contents. For example "BMPSTRING: Hello World". 460 461=item B<dump_der> 462 463when this option is set any fields that need to be hexdumped will 464be dumped using the DER encoding of the field. Otherwise just the 465content octets will be displayed. Both options use the RFC2253 466B<#XXXX...> format. 467 468=item B<dump_nostr> 469 470dump non character string types (for example OCTET STRING) if this 471option is not set then non character string types will be displayed 472as though each content octet represents a single character. 473 474=item B<dump_all> 475 476dump all fields. This option when used with B<dump_der> allows the 477DER encoding of the structure to be unambiguously determined. 478 479=item B<dump_unknown> 480 481dump any field whose OID is not recognised by OpenSSL. 482 483=item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>, 484B<sep_multiline> 485 486these options determine the field separators. The first character is 487between RDNs and the second between multiple AVAs (multiple AVAs are 488very rare and their use is discouraged). The options ending in 489"space" additionally place a space after the separator to make it 490more readable. The B<sep_multiline> uses a linefeed character for 491the RDN separator and a spaced B<+> for the AVA separator. It also 492indents the fields by four characters. 493 494=item B<dn_rev> 495 496reverse the fields of the DN. This is required by RFC2253. As a side 497effect this also reverses the order of multiple AVAs but this is 498permissible. 499 500=item B<nofname>, B<sname>, B<lname>, B<oid> 501 502these options alter how the field name is displayed. B<nofname> does 503not display the field at all. B<sname> uses the "short name" form 504(CN for commonName for example). B<lname> uses the long form. 505B<oid> represents the OID in numerical form and is useful for 506diagnostic purpose. 507 508=item B<align> 509 510align field values for a more readable output. Only usable with 511B<sep_multiline>. 512 513=item B<space_eq> 514 515places spaces round the B<=> character which follows the field 516name. 517 518=back 519 520=head2 TEXT OPTIONS 521 522As well as customising the name output format, it is also possible to 523customise the actual fields printed using the B<certopt> options when 524the B<text> option is present. The default behaviour is to print all fields. 525 526=over 4 527 528=item B<compatible> 529 530use the old format. This is equivalent to specifying no output options at all. 531 532=item B<no_header> 533 534don't print header information: that is the lines saying "Certificate" and "Data". 535 536=item B<no_version> 537 538don't print out the version number. 539 540=item B<no_serial> 541 542don't print out the serial number. 543 544=item B<no_signame> 545 546don't print out the signature algorithm used. 547 548=item B<no_validity> 549 550don't print the validity, that is the B<notBefore> and B<notAfter> fields. 551 552=item B<no_subject> 553 554don't print out the subject name. 555 556=item B<no_issuer> 557 558don't print out the issuer name. 559 560=item B<no_pubkey> 561 562don't print out the public key. 563 564=item B<no_sigdump> 565 566don't give a hexadecimal dump of the certificate signature. 567 568=item B<no_aux> 569 570don't print out certificate trust information. 571 572=item B<no_extensions> 573 574don't print out any X509V3 extensions. 575 576=item B<ext_default> 577 578retain default extension behaviour: attempt to print out unsupported certificate extensions. 579 580=item B<ext_error> 581 582print an error message for unsupported certificate extensions. 583 584=item B<ext_parse> 585 586ASN1 parse unsupported extensions. 587 588=item B<ext_dump> 589 590hex dump unsupported extensions. 591 592=item B<ca_default> 593 594the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>, 595B<no_version>, B<no_sigdump> and B<no_signame>. 596 597=back 598 599=head1 EXAMPLES 600 601Note: in these examples the '\' means the example should be all on one 602line. 603 604Display the contents of a certificate: 605 606 openssl x509 -in cert.pem -noout -text 607 608Display the certificate serial number: 609 610 openssl x509 -in cert.pem -noout -serial 611 612Display the certificate subject name: 613 614 openssl x509 -in cert.pem -noout -subject 615 616Display the certificate subject name in RFC2253 form: 617 618 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253 619 620Display the certificate subject name in oneline form on a terminal 621supporting UTF8: 622 623 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb 624 625Display the certificate MD5 fingerprint: 626 627 openssl x509 -in cert.pem -noout -fingerprint 628 629Display the certificate SHA1 fingerprint: 630 631 openssl x509 -sha1 -in cert.pem -noout -fingerprint 632 633Convert a certificate from PEM to DER format: 634 635 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER 636 637Convert a certificate to a certificate request: 638 639 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem 640 641Convert a certificate request into a self signed certificate using 642extensions for a CA: 643 644 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \ 645 -signkey key.pem -out cacert.pem 646 647Sign a certificate request using the CA certificate above and add user 648certificate extensions: 649 650 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \ 651 -CA cacert.pem -CAkey key.pem -CAcreateserial 652 653 654Set a certificate to be trusted for SSL client use and change set its alias to 655"Steve's Class 1 CA" 656 657 openssl x509 -in cert.pem -addtrust clientAuth \ 658 -setalias "Steve's Class 1 CA" -out trust.pem 659 660=head1 NOTES 661 662The PEM format uses the header and footer lines: 663 664 -----BEGIN CERTIFICATE----- 665 -----END CERTIFICATE----- 666 667it will also handle files containing: 668 669 -----BEGIN X509 CERTIFICATE----- 670 -----END X509 CERTIFICATE----- 671 672Trusted certificates have the lines 673 674 -----BEGIN TRUSTED CERTIFICATE----- 675 -----END TRUSTED CERTIFICATE----- 676 677The conversion to UTF8 format used with the name options assumes that 678T61Strings use the ISO8859-1 character set. This is wrong but Netscape 679and MSIE do this as do many certificates. So although this is incorrect 680it is more likely to display the majority of certificates correctly. 681 682The B<-fingerprint> option takes the digest of the DER encoded certificate. 683This is commonly called a "fingerprint". Because of the nature of message 684digests the fingerprint of a certificate is unique to that certificate and 685two certificates with the same fingerprint can be considered to be the same. 686 687The Netscape fingerprint uses MD5 whereas MSIE uses SHA1. 688 689The B<-email> option searches the subject name and the subject alternative 690name extension. Only unique email addresses will be printed out: it will 691not print the same address more than once. 692 693=head1 CERTIFICATE EXTENSIONS 694 695The B<-purpose> option checks the certificate extensions and determines 696what the certificate can be used for. The actual checks done are rather 697complex and include various hacks and workarounds to handle broken 698certificates and software. 699 700The same code is used when verifying untrusted certificates in chains 701so this section is useful if a chain is rejected by the verify code. 702 703The basicConstraints extension CA flag is used to determine whether the 704certificate can be used as a CA. If the CA flag is true then it is a CA, 705if the CA flag is false then it is not a CA. B<All> CAs should have the 706CA flag set to true. 707 708If the basicConstraints extension is absent then the certificate is 709considered to be a "possible CA" other extensions are checked according 710to the intended use of the certificate. A warning is given in this case 711because the certificate should really not be regarded as a CA: however 712it is allowed to be a CA to work around some broken software. 713 714If the certificate is a V1 certificate (and thus has no extensions) and 715it is self signed it is also assumed to be a CA but a warning is again 716given: this is to work around the problem of Verisign roots which are V1 717self signed certificates. 718 719If the keyUsage extension is present then additional restraints are 720made on the uses of the certificate. A CA certificate B<must> have the 721keyCertSign bit set if the keyUsage extension is present. 722 723The extended key usage extension places additional restrictions on the 724certificate uses. If this extension is present (whether critical or not) 725the key can only be used for the purposes specified. 726 727A complete description of each test is given below. The comments about 728basicConstraints and keyUsage and V1 certificates above apply to B<all> 729CA certificates. 730 731 732=over 4 733 734=item B<SSL Client> 735 736The extended key usage extension must be absent or include the "web client 737authentication" OID. keyUsage must be absent or it must have the 738digitalSignature bit set. Netscape certificate type must be absent or it must 739have the SSL client bit set. 740 741=item B<SSL Client CA> 742 743The extended key usage extension must be absent or include the "web client 744authentication" OID. Netscape certificate type must be absent or it must have 745the SSL CA bit set: this is used as a work around if the basicConstraints 746extension is absent. 747 748=item B<SSL Server> 749 750The extended key usage extension must be absent or include the "web server 751authentication" and/or one of the SGC OIDs. keyUsage must be absent or it 752must have the digitalSignature, the keyEncipherment set or both bits set. 753Netscape certificate type must be absent or have the SSL server bit set. 754 755=item B<SSL Server CA> 756 757The extended key usage extension must be absent or include the "web server 758authentication" and/or one of the SGC OIDs. Netscape certificate type must 759be absent or the SSL CA bit must be set: this is used as a work around if the 760basicConstraints extension is absent. 761 762=item B<Netscape SSL Server> 763 764For Netscape SSL clients to connect to an SSL server it must have the 765keyEncipherment bit set if the keyUsage extension is present. This isn't 766always valid because some cipher suites use the key for digital signing. 767Otherwise it is the same as a normal SSL server. 768 769=item B<Common S/MIME Client Tests> 770 771The extended key usage extension must be absent or include the "email 772protection" OID. Netscape certificate type must be absent or should have the 773S/MIME bit set. If the S/MIME bit is not set in netscape certificate type 774then the SSL client bit is tolerated as an alternative but a warning is shown: 775this is because some Verisign certificates don't set the S/MIME bit. 776 777=item B<S/MIME Signing> 778 779In addition to the common S/MIME client tests the digitalSignature bit must 780be set if the keyUsage extension is present. 781 782=item B<S/MIME Encryption> 783 784In addition to the common S/MIME tests the keyEncipherment bit must be set 785if the keyUsage extension is present. 786 787=item B<S/MIME CA> 788 789The extended key usage extension must be absent or include the "email 790protection" OID. Netscape certificate type must be absent or must have the 791S/MIME CA bit set: this is used as a work around if the basicConstraints 792extension is absent. 793 794=item B<CRL Signing> 795 796The keyUsage extension must be absent or it must have the CRL signing bit 797set. 798 799=item B<CRL Signing CA> 800 801The normal CA tests apply. Except in this case the basicConstraints extension 802must be present. 803 804=back 805 806=head1 BUGS 807 808Extensions in certificates are not transferred to certificate requests and 809vice versa. 810 811It is possible to produce invalid certificates or requests by specifying the 812wrong private key or using inconsistent options in some cases: these should 813be checked. 814 815There should be options to explicitly set such things as start and end 816dates rather than an offset from the current time. 817 818The code to implement the verify behaviour described in the B<TRUST SETTINGS> 819is currently being developed. It thus describes the intended behaviour rather 820than the current behaviour. It is hoped that it will represent reality in 821OpenSSL 0.9.5 and later. 822 823=head1 SEE ALSO 824 825L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>, 826L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)> 827 828=head1 HISTORY 829 830Before OpenSSL 0.9.8, the default digest for RSA keys was MD5. 831 832=cut 833