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 recognize 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. Any object name can be used here
216 but currently only B<clientAuth> (SSL client use), B<serverAuth>
217 (SSL server use) and B<emailProtection> (S/MIME email) are used.
218 Other OpenSSL applications may define additional uses.
220 =item B<-addreject arg>
222 adds a prohibited use. It accepts the same values as the B<-addtrust>
227 this option performs tests on the certificate extensions and outputs
228 the results. For a more complete description see the B<CERTIFICATE
233 =head1 SIGNING OPTIONS
235 The B<x509> utility can be used to sign certificates and requests: it
236 can thus behave like a "mini CA".
240 =item B<-signkey filename>
242 this option causes the input file to be self signed using the supplied
245 If the input file is a certificate it sets the issuer name to the
246 subject name (i.e. makes it self signed) changes the public key to the
247 supplied value and changes the start and end dates. The start date is
248 set to the current time and the end date is set to a value determined
249 by the B<-days> option. Any certificate extensions are retained unless
250 the B<-clrext> option is supplied.
252 If the input is a certificate request then a self signed certificate
253 is created using the supplied private key using the subject name in
258 delete any extensions from a certificate. This option is used when a
259 certificate is being created from another certificate (for example with
260 the B<-signkey> or the B<-CA> options). Normally all extensions are
263 =item B<-keyform PEM|DER>
265 specifies the format (DER or PEM) of the private key file used in the
270 specifies the number of days to make a certificate valid for. The default
275 converts a certificate into a certificate request. The B<-signkey> option
276 is used to pass the required private key.
280 by default a certificate is expected on input. With this option a
281 certificate request is expected instead.
283 =item B<-CA filename>
285 specifies the CA certificate to be used for signing. When this option is
286 present B<x509> behaves like a "mini CA". The input file is signed by this
287 CA using this option: that is its issuer name is set to the subject name
288 of the CA and it is digitally signed using the CAs private key.
290 This option is normally combined with the B<-req> option. Without the
291 B<-req> option the input is a certificate which must be self signed.
293 =item B<-CAkey filename>
295 sets the CA private key to sign a certificate with. If this option is
296 not specified then it is assumed that the CA private key is present in
297 the CA certificate file.
299 =item B<-CAserial filename>
301 sets the CA serial number file to use.
303 When the B<-CA> option is used to sign a certificate it uses a serial
304 number specified in a file. This file consist of one line containing
305 an even number of hex digits with the serial number to use. After each
306 use the serial number is incremented and written out to the file again.
308 The default filename consists of the CA certificate file base name with
309 ".srl" appended. For example if the CA certificate file is called
310 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
312 =item B<-CAcreateserial filename>
314 with this option the CA serial number file is created if it does not exist:
315 it will contain the serial number "02" and the certificate being signed will
316 have the 1 as its serial number. Normally if the B<-CA> option is specified
317 and the serial number file does not exist it is an error.
319 =item B<-extfile filename>
321 file containing certificate extensions to use. If not specified then
322 no extensions are added to the certificate.
324 =item B<-extensions section>
326 the section to add certificate extensions from. If this option is not
327 specified then the extensions should either be contained in the unnamed
328 (default) section or the default section should contain a variable called
329 "extensions" which contains the section to use.
335 Note: in these examples the '\' means the example should be all on one
338 Display the contents of a certificate:
340 openssl x509 -in cert.pem -noout -text
342 Display the certificate serial number:
344 openssl x509 -in cert.pem -noout -serial
346 Display the certificate MD5 fingerprint:
348 openssl x509 -in cert.pem -noout -fingerprint
350 Display the certificate SHA1 fingerprint:
352 openssl x509 -sha1 -in cert.pem -noout -fingerprint
354 Convert a certificate from PEM to DER format:
356 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
358 Convert a certificate to a certificate request:
360 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
362 Convert a certificate request into a self signed certificate using
365 openssl x509 -req -in careq.pem -config openssl.cnf -extensions v3_ca \
366 -signkey key.pem -out cacert.pem
368 Sign a certificate request using the CA certificate above and add user
369 certificate extensions:
371 openssl x509 -req -in req.pem -config openssl.cnf -extensions v3_usr \
372 -CA cacert.pem -CAkey key.pem -CAcreateserial
375 Set a certificate to be trusted for SSL client use and change set its alias to
378 openssl x509 -in cert.pem -addtrust sslclient \
379 -alias "Steve's Class 1 CA" -out trust.pem
383 The PEM format uses the header and footer lines:
385 -----BEGIN CERTIFICATE----
386 -----END CERTIFICATE----
388 it will also handle files containing:
390 -----BEGIN X509 CERTIFICATE----
391 -----END X509 CERTIFICATE----
393 Trusted certificates have the lines
395 -----BEGIN TRUSTED CERTIFICATE----
396 -----END TRUSTED CERTIFICATE----
398 The B<-fingerprint> option takes the digest of the DER encoded certificate.
399 This is commonly called a "fingerprint". Because of the nature of message
400 digests the fingerprint of a certificate is unique to that certificate and
401 two certificates with the same fingerprint can be considered to be the same.
403 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
405 =head1 CERTIFICATE EXTENSIONS
407 The B<-purpose> option checks the certificate extensions and determines
408 what the certificate can be used for. The actual checks done are rather
409 complex and include various hacks and workarounds to handle broken
410 certificates and software.
412 The same code is used when verifying untrusted certificates in chains
413 so this section is useful if a chain is rejected by the verify code.
415 The basicConstraints extension CA flag is used to determine whether the
416 certificate can be used as a CA. If the CA flag is true then it is a CA,
417 if the CA flag is false then it is not a CA. B<All> CAs should have the
420 If the basicConstraints extension is absent then the certificate is
421 considered to be a "possible CA" other extensions are checked according
422 to the intended use of the certificate. A warning is given in this case
423 because the certificate should really not be regarded as a CA: however
424 it is allowed to be a CA to work around some broken software.
426 If the certificate is a V1 certificate (and thus has no extensions) and
427 it is self signed it is also assumed to be a CA but a warning is again
428 given: this is to work around the problem of Verisign roots which are V1
429 self signed certificates.
431 If the keyUsage extension is present then additional restraints are
432 made on the uses of the certificate. A CA certificate B<must> have the
433 keyCertSign bit set if the keyUsage extension is present.
435 The extended key usage extension places additional restrictions on the
436 certificate uses. If this extension is present (whether critical or not)
437 the key can only be used for the purposes specified.
439 A complete description of each test is given below. The comments about
440 basicConstraints and keyUsage and V1 certificates above apply to B<all>
448 The extended key usage extension must be absent or include the "web client
449 authentication" OID. keyUsage must be absent or it must have the
450 digitalSignature bit set. Netscape certificate type must be absent or it must
451 have the SSL client bit set.
453 =item B<SSL Client CA>
455 The extended key usage extension must be absent or include the "web client
456 authentication" OID. Netscape certificate type must be absent or it must have
457 the SSL CA bit set: this is used as a work around if the basicConstraints
462 The extended key usage extension must be absent or include the "web server
463 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
464 must have the digitalSignature, the keyEncipherment set or both bits set.
465 Netscape certificate type must be absent or have the SSL server bit set.
467 =item B<SSL Server CA>
469 The extended key usage extension must be absent or include the "web server
470 authentication" and/or one of the SGC OIDs. Netscape certificate type must
471 be absent or the SSL CA bit must be set: this is used as a work around if the
472 basicConstraints extension is absent.
474 =item B<Netscape SSL Server>
476 For Netscape SSL clients to connect to an SSL server it must have the
477 keyEncipherment bit set if the keyUsage extension is present. This isn't
478 always valid because some cipher suites use the key for digital signing.
479 Otherwise it is the same as a normal SSL server.
481 =item B<Common S/MIME Client Tests>
483 The extended key usage extension must be absent or include the "email
484 protection" OID. Netscape certificate type must be absent or should have the
485 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
486 then the SSL client bit is tolerated as an alternative but a warning is shown:
487 this is because some Verisign certificates don't set the S/MIME bit.
489 =item B<S/MIME Signing>
491 In addition to the common S/MIME client tests the digitalSignature bit must
492 be set if the keyUsage extension is present.
494 =item B<S/MIME Encryption>
496 In addition to the common S/MIME tests the keyEncipherment bit must be set
497 if the keyUsage extension is present.
501 The extended key usage extension must be absent or include the "email
502 protection" OID. Netscape certificate type must be absent or must have the
503 S/MIME CA bit set: this is used as a work around if the basicConstraints
508 The keyUsage extension must be absent or it must have the CRL signing bit
511 =item B<CRL Signing CA>
513 The normal CA tests apply. Except in this case the basicConstraints extension
520 The way DNs are printed is in a "historical SSLeay" format which doesn't
521 follow any published standard. It should follow some standard like RFC2253
522 or RFC1779 with options to make the stuff more readable.
524 Extensions in certificates are not transferred to certificate requests and
527 It is possible to produce invalid certificates or requests by specifying the
528 wrong private key or using inconsistent options in some cases: these should
531 There should be options to explicitly set such things as start and end
532 dates rather than an offset from the current time.
534 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
535 is currently being developed. It thus describes the intended behavior rather
536 than the current behaviour. It is hoped that it will represent reality in
537 OpenSSL 0.9.5 and later.
541 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
542 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>