6 x509 - Certificate display and signing utility
11 [B<-inform DER|PEM|NET>]
12 [B<-outform DER|PEM|NET>]
15 [B<-CAkeyform DER|PEM>]
37 [B<-signkey filename>]
43 [B<-CAserial filename>]
46 [B<-md2|-md5|-sha1|-mdc2>]
48 [B<-extfile filename>]
49 [B<-extensions section>]
53 The B<x509> command is a multi purpose certificate utility. It can be
54 used to display certificate information, convert certificates to
55 various forms, sign certificate requests like a "mini CA" or edit
56 certificate trust settings.
58 Since there are a large number of options they will split up into
62 =head1 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS
66 =item B<-inform DER|PEM|NET>
68 This specifies the input format normally the command will expect an X509
69 certificate but this can change if other options such as B<-req> are
70 present. The DER format is the DER encoding of the certificate and PEM
71 is the base64 encoding of the DER encoding with header and footer lines
72 added. The NET option is an obscure Netscape server format that is now
75 =item B<-outform DER|PEM|NET>
77 This specifies the output format, the options have the same meaning as the
82 This specifies the input filename to read a certificate from or standard input
83 if this option is not specified.
85 =item B<-out filename>
87 This specifies the output filename to write to or standard output by
90 =item B<-md2|-md5|-sha1|-mdc2>
92 the digest to use. This affects any signing or display option that uses a message
93 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not
94 specified then MD5 is used. If the key being used to sign with is a DSA key then
95 this option has no effect: SHA1 is always used with DSA keys.
100 =head1 DISPLAY OPTIONS
102 Note: the B<-alias> and B<-purpose> options are also display options
103 but are described in the B<TRUST OPTIONS> section.
109 prints out the certificate in text form. Full details are output including the
110 public key, signature algorithms, issuer and subject names, serial number
111 any extensions present and any trust settings.
115 this option prevents output of the encoded version of the request.
119 this option prints out the value of the modulus of the public key
120 contained in the certificate.
124 outputs the certificate serial number.
128 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
129 form an index to allow certificates in a directory to be looked up by subject
134 outputs the subject name.
138 outputs the issuer name.
142 prints out the start date of the certificate, that is the notBefore date.
146 prints out the expiry date of the certificate, that is the notAfter date.
150 prints out the start and expiry dates of a certificate.
152 =item B<-fingerprint>
154 prints out the digest of the DER encoded version of the whole certificate.
158 this outputs the certificate in the form of a C source file.
162 =head1 TRUST SETTINGS
164 Please note these options are currently experimental and may well change.
166 A B<trusted certificate> is an ordinary certificate which has several
167 additional pieces of information attached to it such as the permitted
168 and prohibited uses of the certificate and an "alias".
170 Normally when a certificate is being verified at least one certificate
171 must be "trusted". By default a trusted certificate must be stored
172 locally and must be a root CA: any certificate chain ending in this CA
173 is then usable for any purpose.
175 Trust settings currently are only used with a root CA. They allow a finer
176 control over the purposes the root CA can be used for. For example a CA
177 may be trusted for SSL client but not SSL server use.
179 See the description of the B<verify> utility for more information on the
180 meaning of trust settings.
182 Future versions of OpenSSL will recognise trust settings on any
183 certificate: not just root CAs.
190 this causes B<x509> to output a B<trusted> certificate. An ordinary
191 or trusted certificate can be input but by default an ordinary
192 certificate is output and any trust settings are discarded. With the
193 B<-trustout> option a trusted certificate is output. A trusted
194 certificate is automatically output if any trust settings are modified.
196 =item B<-setalias arg>
198 sets the alias of the certificate. This will allow the certificate
199 to be referred to using a nickname for example "Steve's Certificate".
203 outputs the certificate alias, if any.
207 clears all the permitted or trusted uses of the certificate.
211 clears all the prohibited or rejected uses of the certificate.
213 =item B<-addtrust arg>
215 adds a trusted certificate use. Currently acceptable values
216 are B<all> (any purpose), B<sslclient> (SSL client use), B<sslserver>
217 (SSL server use) B<email> (S/MIME email) and B<objsign> (Object signing).
219 =item B<-addreject arg>
221 adds a prohibited use. It accepts the same values as the B<-addtrust>
226 this option performs tests on the certificate extensions and outputs
227 the results. For a more complete description see the B<CERTIFICATE
232 =head1 SIGNING OPTIONS
234 The B<x509> utility can be used to sign certificates and requests: it
235 can thus behave like a "mini CA".
239 =item B<-signkey filename>
241 this option causes the input file to be self signed using the supplied
244 If the input file is a certificate it sets the issuer name to the
245 subject name (i.e. makes it self signed) changes the public key to the
246 supplied value and changes the start and end dates. The start date is
247 set to the current time and the end date is set to a value determined
248 by the B<-days> option. Any certificate extensions are retained unless
249 the B<-clrext> option is supplied.
251 If the input is a certificate request then a self signed certificate
252 is created using the supplied private key using the subject name in
257 delete any extensions from a certificate. This option is used when a
258 certificate is being created from another certificate (for example with
259 the B<-signkey> or the B<-CA> options). Normally all extensions are
262 =item B<-keyform PEM|DER>
264 specifies the format (DER or PEM) of the private key file used in the
269 specifies the number of days to make a certificate valid for. The default
274 converts a certificate into a certificate request. The B<-signkey> option
275 is used to pass the required private key.
279 by default a certificate is expected on input. With this option a
280 certificate request is expected instead.
282 =item B<-CA filename>
284 specifies the CA certificate to be used for signing. When this option is
285 present B<x509> behaves like a "mini CA". The input file is signed by this
286 CA using this option: that is its issuer name is set to the subject name
287 of the CA and it is digitally signed using the CAs private key.
289 This option is normally combined with the B<-req> option. Without the
290 B<-req> option the input is a certificate which must be self signed.
292 =item B<-CAkey filename>
294 sets the CA private key to sign a certificate with. If this option is
295 not specified then it is assumed that the CA private key is present in
296 the CA certificate file.
298 =item B<-CAserial filename>
300 sets the CA serial number file to use.
302 When the B<-CA> option is used to sign a certificate it uses a serial
303 number specified in a file. This file consist of one line containing
304 an even number of hex digits with the serial number to use. After each
305 use the serial number is incremented and written out to the file again.
307 The default filename consists of the CA certificate file base name with
308 ".srl" appended. For example if the CA certificate file is called
309 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
311 =item B<-CAcreateserial filename>
313 with this option the CA serial number file is created if it does not exist:
314 it will contain the serial number "02" and the certificate being signed will
315 have the 1 as its serial number. Normally if the B<-CA> option is specified
316 and the serial number file does not exist it is an error.
318 =item B<-extfile filename>
320 file containing certificate extensions to use. If not specified then
321 no extensions are added to the certificate.
323 =item B<-extensions section>
325 the section to add certificate extensions from. If this option is not
326 specified then the extensions should either be contained in the unnamed
327 (default) section or the default section should contain a variable called
328 "extensions" which contains the section to use.
334 Note: in these examples the '\' means the example should be all on one
337 Display the contents of a certificate:
339 openssl x509 -in cert.pem -noout -text
341 Display the certificate serial number:
343 openssl x509 -in cert.pem -noout -serial
345 Display the certificate MD5 fingerprint:
347 openssl x509 -in cert.pem -noout -fingerprint
349 Display the certificate SHA1 fingerprint:
351 openssl x509 -sha1 -in cert.pem -noout -fingerprint
353 Convert a certificate from PEM to DER format:
355 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
357 Convert a certificate to a certificate request:
359 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
361 Convert a certificate request into a self signed certificate using
364 openssl x509 -req -in careq.pem -config openssl.cnf -extensions v3_ca \
365 -signkey key.pem -out cacert.pem
367 Sign a certificate request using the CA certificate above and add user
368 certificate extensions:
370 openssl x509 -req -in req.pem -config openssl.cnf -extensions v3_usr \
371 -CA cacert.pem -CAkey key.pem -CAcreateserial
374 Set a certificate to be trusted for SSL client use and change set its alias to
377 openssl x509 -in cert.pem -addtrust sslclient \
378 -alias "Steve's Class 1 CA" -out trust.pem
382 The PEM format uses the header and footer lines:
384 -----BEGIN CERTIFICATE----
385 -----END CERTIFICATE----
387 it will also handle files containing:
389 -----BEGIN X509 CERTIFICATE----
390 -----END X509 CERTIFICATE----
392 Trusted certificates have the lines
394 -----BEGIN TRUSTED CERTIFICATE----
395 -----END TRUSTED CERTIFICATE----
397 The B<-fingerprint> option takes the digest of the DER encoded certificate.
398 This is commonly called a "fingerprint". Because of the nature of message
399 digests the fingerprint of a certificate is unique to that certificate and
400 two certificates with the same fingerprint can be considered to be the same.
402 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
404 =head1 CERTIFICATE EXTENSIONS
406 The B<-purpose> option checks the certificate extensions and determines
407 what the certificate can be used for. The actual checks done are rather
408 complex and include various hacks and workarounds to handle broken
409 certificates and software.
411 The same code is used when verifying untrusted certificates in chains
412 so this section is useful if a chain is rejected by the verify code.
414 The basicConstraints extension CA flag is used to determine whether the
415 certificate can be used as a CA. If the CA flag is true then it is a CA,
416 if the CA flag is false then it is not a CA. B<All> CAs should have the
419 If the basicConstraints extension is absent then the certificate is
420 considered to be a "possible CA" other extensions are checked according
421 to the intended use of the certificate. A warning is given in this case
422 because the certificate should really not be regarded as a CA: however
423 it is allowed to be a CA to work around some broken software.
425 If the certificate is a V1 certificate (and thus has no extensions) and
426 it is self signed it is also assumed to be a CA but a warning is again
427 given: this is to work around the problem of Verisign roots which are V1
428 self signed certificates.
430 If the keyUsage extension is present then additional restraints are
431 made on the uses of the certificate. A CA certificate B<must> have the
432 keyCertSign bit set if the keyUsage extension is present.
434 The extended key usage extension places additional restrictions on the
435 certificate uses. If this extension is present (whether critical or not)
436 the key can only be used for the purposes specified.
438 A complete description of each test is given below. The comments about
439 basicConstraints and keyUsage and V1 certificates above apply to B<all>
447 The extended key usage extension must be absent or include the "web client
448 authentication" OID. keyUsage must be absent or it must have the
449 digitalSignature bit set. Netscape certificate type must be absent or it must
450 have the SSL client bit set.
452 =item B<SSL Client CA>
454 The extended key usage extension must be absent or include the "web client
455 authentication" OID. Netscape certificate type must be absent or it must have
456 the SSL CA bit set: this is used as a work around if the basicConstraints
461 The extended key usage extension must be absent or include the "web server
462 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
463 must have the digitalSignature, the keyEncipherment set or both bits set.
464 Netscape certificate type must be absent or have the SSL server bit set.
466 =item B<SSL Server CA>
468 The extended key usage extension must be absent or include the "web server
469 authentication" and/or one of the SGC OIDs. Netscape certificate type must
470 be absent or the SSL CA bit must be set: this is used as a work around if the
471 basicConstraints extension is absent.
473 =item B<Netscape SSL Server>
475 For Netscape SSL clients to connect to an SSL server it must have the
476 keyEncipherment bit set if the keyUsage extension is present. This isn't
477 always valid because some cipher suites use the key for digital signing.
478 Otherwise it is the same as a normal SSL server.
480 =item B<Common S/MIME Client Tests>
482 The extended key usage extension must be absent or include the "email
483 protection" OID. Netscape certificate type must be absent or should have the
484 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
485 then the SSL client bit is tolerated as an alternative but a warning is shown:
486 this is because some Verisign certificates don't set the S/MIME bit.
488 =item B<S/MIME Signing>
490 In addition to the common S/MIME client tests the digitalSignature bit must
491 be set if the keyUsage extension is present.
493 =item B<S/MIME Encryption>
495 In addition to the common S/MIME tests the keyEncipherment bit must be set
496 if the keyUsage extension is present.
500 The extended key usage extension must be absent or include the "email
501 protection" OID. Netscape certificate type must be absent or must have the
502 S/MIME CA bit set: this is used as a work around if the basicConstraints
507 The keyUsage extension must be absent or it must have the CRL signing bit
510 =item B<CRL Signing CA>
512 The normal CA tests apply. Except in this case the basicConstraints extension
519 The way DNs are printed is in a "historical SSLeay" format which doesn't
520 follow any published standard. It should follow some standard like RFC2253
521 or RFC1779 with options to make the stuff more readable.
523 Extensions in certificates are not transferred to certificate requests and
526 It is possible to produce invalid certificates or requests by specifying the
527 wrong private key or using inconsistent options in some cases: these should
530 There should be options to explicitly set such things as start and end
531 dates rather than an offset from the current time.
533 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
534 is currently being developed. It thus describes the intended behavior rather
535 than the current behaviour. It is hoped that it will represent reality in
536 OpenSSL 0.9.5 and later.
540 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
541 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>