6 x509 - Certificate display and signing utility
11 [B<-inform DER|PEM|NET>]
12 [B<-outform DER|PEM|NET>]
15 [B<-CAkeyform DER|PEM>]
38 [B<-signkey filename>]
44 [B<-CAserial filename>]
47 [B<-md2|-md5|-sha1|-mdc2>]
49 [B<-extfile filename>]
50 [B<-extensions section>]
54 The B<x509> command is a multi purpose certificate utility. It can be
55 used to display certificate information, convert certificates to
56 various forms, sign certificate requests like a "mini CA" or edit
57 certificate trust settings.
59 Since there are a large number of options they will split up into
63 =head1 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS
67 =item B<-inform DER|PEM|NET>
69 This specifies the input format normally the command will expect an X509
70 certificate but this can change if other options such as B<-req> are
71 present. The DER format is the DER encoding of the certificate and PEM
72 is the base64 encoding of the DER encoding with header and footer lines
73 added. The NET option is an obscure Netscape server format that is now
76 =item B<-outform DER|PEM|NET>
78 This specifies the output format, the options have the same meaning as the
83 This specifies the input filename to read a certificate from or standard input
84 if this option is not specified.
86 =item B<-out filename>
88 This specifies the output filename to write to or standard output by
91 =item B<-md2|-md5|-sha1|-mdc2>
93 the digest to use. This affects any signing or display option that uses a message
94 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not
95 specified then MD5 is used. If the key being used to sign with is a DSA key then
96 this option has no effect: SHA1 is always used with DSA keys.
101 =head1 DISPLAY OPTIONS
103 Note: the B<-alias> and B<-purpose> options are also display options
104 but are described in the B<TRUST OPTIONS> section.
110 prints out the certificate in text form. Full details are output including the
111 public key, signature algorithms, issuer and subject names, serial number
112 any extensions present and any trust settings.
116 this option prevents output of the encoded version of the request.
120 this option prints out the value of the modulus of the public key
121 contained in the certificate.
125 outputs the certificate serial number.
129 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
130 form an index to allow certificates in a directory to be looked up by subject
135 outputs the subject name.
139 outputs the issuer name.
143 outputs the email address(es) if any.
147 prints out the start date of the certificate, that is the notBefore date.
151 prints out the expiry date of the certificate, that is the notAfter date.
155 prints out the start and expiry dates of a certificate.
157 =item B<-fingerprint>
159 prints out the digest of the DER encoded version of the whole certificate.
163 this outputs the certificate in the form of a C source file.
167 =head1 TRUST SETTINGS
169 Please note these options are currently experimental and may well change.
171 A B<trusted certificate> is an ordinary certificate which has several
172 additional pieces of information attached to it such as the permitted
173 and prohibited uses of the certificate and an "alias".
175 Normally when a certificate is being verified at least one certificate
176 must be "trusted". By default a trusted certificate must be stored
177 locally and must be a root CA: any certificate chain ending in this CA
178 is then usable for any purpose.
180 Trust settings currently are only used with a root CA. They allow a finer
181 control over the purposes the root CA can be used for. For example a CA
182 may be trusted for SSL client but not SSL server use.
184 See the description of the B<verify> utility for more information on the
185 meaning of trust settings.
187 Future versions of OpenSSL will recognize trust settings on any
188 certificate: not just root CAs.
195 this causes B<x509> to output a B<trusted> certificate. An ordinary
196 or trusted certificate can be input but by default an ordinary
197 certificate is output and any trust settings are discarded. With the
198 B<-trustout> option a trusted certificate is output. A trusted
199 certificate is automatically output if any trust settings are modified.
201 =item B<-setalias arg>
203 sets the alias of the certificate. This will allow the certificate
204 to be referred to using a nickname for example "Steve's Certificate".
208 outputs the certificate alias, if any.
212 clears all the permitted or trusted uses of the certificate.
216 clears all the prohibited or rejected uses of the certificate.
218 =item B<-addtrust arg>
220 adds a trusted certificate use. Any object name can be used here
221 but currently only B<clientAuth> (SSL client use), B<serverAuth>
222 (SSL server use) and B<emailProtection> (S/MIME email) are used.
223 Other OpenSSL applications may define additional uses.
225 =item B<-addreject arg>
227 adds a prohibited use. It accepts the same values as the B<-addtrust>
232 this option performs tests on the certificate extensions and outputs
233 the results. For a more complete description see the B<CERTIFICATE
238 =head1 SIGNING OPTIONS
240 The B<x509> utility can be used to sign certificates and requests: it
241 can thus behave like a "mini CA".
245 =item B<-signkey filename>
247 this option causes the input file to be self signed using the supplied
250 If the input file is a certificate it sets the issuer name to the
251 subject name (i.e. makes it self signed) changes the public key to the
252 supplied value and changes the start and end dates. The start date is
253 set to the current time and the end date is set to a value determined
254 by the B<-days> option. Any certificate extensions are retained unless
255 the B<-clrext> option is supplied.
257 If the input is a certificate request then a self signed certificate
258 is created using the supplied private key using the subject name in
263 delete any extensions from a certificate. This option is used when a
264 certificate is being created from another certificate (for example with
265 the B<-signkey> or the B<-CA> options). Normally all extensions are
268 =item B<-keyform PEM|DER>
270 specifies the format (DER or PEM) of the private key file used in the
275 specifies the number of days to make a certificate valid for. The default
280 converts a certificate into a certificate request. The B<-signkey> option
281 is used to pass the required private key.
285 by default a certificate is expected on input. With this option a
286 certificate request is expected instead.
288 =item B<-CA filename>
290 specifies the CA certificate to be used for signing. When this option is
291 present B<x509> behaves like a "mini CA". The input file is signed by this
292 CA using this option: that is its issuer name is set to the subject name
293 of the CA and it is digitally signed using the CAs private key.
295 This option is normally combined with the B<-req> option. Without the
296 B<-req> option the input is a certificate which must be self signed.
298 =item B<-CAkey filename>
300 sets the CA private key to sign a certificate with. If this option is
301 not specified then it is assumed that the CA private key is present in
302 the CA certificate file.
304 =item B<-CAserial filename>
306 sets the CA serial number file to use.
308 When the B<-CA> option is used to sign a certificate it uses a serial
309 number specified in a file. This file consist of one line containing
310 an even number of hex digits with the serial number to use. After each
311 use the serial number is incremented and written out to the file again.
313 The default filename consists of the CA certificate file base name with
314 ".srl" appended. For example if the CA certificate file is called
315 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
317 =item B<-CAcreateserial filename>
319 with this option the CA serial number file is created if it does not exist:
320 it will contain the serial number "02" and the certificate being signed will
321 have the 1 as its serial number. Normally if the B<-CA> option is specified
322 and the serial number file does not exist it is an error.
324 =item B<-extfile filename>
326 file containing certificate extensions to use. If not specified then
327 no extensions are added to the certificate.
329 =item B<-extensions section>
331 the section to add certificate extensions from. If this option is not
332 specified then the extensions should either be contained in the unnamed
333 (default) section or the default section should contain a variable called
334 "extensions" which contains the section to use.
340 Note: in these examples the '\' means the example should be all on one
343 Display the contents of a certificate:
345 openssl x509 -in cert.pem -noout -text
347 Display the certificate serial number:
349 openssl x509 -in cert.pem -noout -serial
351 Display the certificate MD5 fingerprint:
353 openssl x509 -in cert.pem -noout -fingerprint
355 Display the certificate SHA1 fingerprint:
357 openssl x509 -sha1 -in cert.pem -noout -fingerprint
359 Convert a certificate from PEM to DER format:
361 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
363 Convert a certificate to a certificate request:
365 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
367 Convert a certificate request into a self signed certificate using
370 openssl x509 -req -in careq.pem -config openssl.cnf -extensions v3_ca \
371 -signkey key.pem -out cacert.pem
373 Sign a certificate request using the CA certificate above and add user
374 certificate extensions:
376 openssl x509 -req -in req.pem -config openssl.cnf -extensions v3_usr \
377 -CA cacert.pem -CAkey key.pem -CAcreateserial
380 Set a certificate to be trusted for SSL client use and change set its alias to
383 openssl x509 -in cert.pem -addtrust sslclient \
384 -alias "Steve's Class 1 CA" -out trust.pem
388 The PEM format uses the header and footer lines:
390 -----BEGIN CERTIFICATE----
391 -----END CERTIFICATE----
393 it will also handle files containing:
395 -----BEGIN X509 CERTIFICATE----
396 -----END X509 CERTIFICATE----
398 Trusted certificates have the lines
400 -----BEGIN TRUSTED CERTIFICATE----
401 -----END TRUSTED CERTIFICATE----
403 The B<-fingerprint> option takes the digest of the DER encoded certificate.
404 This is commonly called a "fingerprint". Because of the nature of message
405 digests the fingerprint of a certificate is unique to that certificate and
406 two certificates with the same fingerprint can be considered to be the same.
408 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
410 The B<-email> option searches the subject name and the subject alternative
411 name extension. Only unique email addresses will be printed out: it will
412 not print the same address more than once.
414 =head1 CERTIFICATE EXTENSIONS
416 The B<-purpose> option checks the certificate extensions and determines
417 what the certificate can be used for. The actual checks done are rather
418 complex and include various hacks and workarounds to handle broken
419 certificates and software.
421 The same code is used when verifying untrusted certificates in chains
422 so this section is useful if a chain is rejected by the verify code.
424 The basicConstraints extension CA flag is used to determine whether the
425 certificate can be used as a CA. If the CA flag is true then it is a CA,
426 if the CA flag is false then it is not a CA. B<All> CAs should have the
429 If the basicConstraints extension is absent then the certificate is
430 considered to be a "possible CA" other extensions are checked according
431 to the intended use of the certificate. A warning is given in this case
432 because the certificate should really not be regarded as a CA: however
433 it is allowed to be a CA to work around some broken software.
435 If the certificate is a V1 certificate (and thus has no extensions) and
436 it is self signed it is also assumed to be a CA but a warning is again
437 given: this is to work around the problem of Verisign roots which are V1
438 self signed certificates.
440 If the keyUsage extension is present then additional restraints are
441 made on the uses of the certificate. A CA certificate B<must> have the
442 keyCertSign bit set if the keyUsage extension is present.
444 The extended key usage extension places additional restrictions on the
445 certificate uses. If this extension is present (whether critical or not)
446 the key can only be used for the purposes specified.
448 A complete description of each test is given below. The comments about
449 basicConstraints and keyUsage and V1 certificates above apply to B<all>
457 The extended key usage extension must be absent or include the "web client
458 authentication" OID. keyUsage must be absent or it must have the
459 digitalSignature bit set. Netscape certificate type must be absent or it must
460 have the SSL client bit set.
462 =item B<SSL Client CA>
464 The extended key usage extension must be absent or include the "web client
465 authentication" OID. Netscape certificate type must be absent or it must have
466 the SSL CA bit set: this is used as a work around if the basicConstraints
471 The extended key usage extension must be absent or include the "web server
472 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
473 must have the digitalSignature, the keyEncipherment set or both bits set.
474 Netscape certificate type must be absent or have the SSL server bit set.
476 =item B<SSL Server CA>
478 The extended key usage extension must be absent or include the "web server
479 authentication" and/or one of the SGC OIDs. Netscape certificate type must
480 be absent or the SSL CA bit must be set: this is used as a work around if the
481 basicConstraints extension is absent.
483 =item B<Netscape SSL Server>
485 For Netscape SSL clients to connect to an SSL server it must have the
486 keyEncipherment bit set if the keyUsage extension is present. This isn't
487 always valid because some cipher suites use the key for digital signing.
488 Otherwise it is the same as a normal SSL server.
490 =item B<Common S/MIME Client Tests>
492 The extended key usage extension must be absent or include the "email
493 protection" OID. Netscape certificate type must be absent or should have the
494 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
495 then the SSL client bit is tolerated as an alternative but a warning is shown:
496 this is because some Verisign certificates don't set the S/MIME bit.
498 =item B<S/MIME Signing>
500 In addition to the common S/MIME client tests the digitalSignature bit must
501 be set if the keyUsage extension is present.
503 =item B<S/MIME Encryption>
505 In addition to the common S/MIME tests the keyEncipherment bit must be set
506 if the keyUsage extension is present.
510 The extended key usage extension must be absent or include the "email
511 protection" OID. Netscape certificate type must be absent or must have the
512 S/MIME CA bit set: this is used as a work around if the basicConstraints
517 The keyUsage extension must be absent or it must have the CRL signing bit
520 =item B<CRL Signing CA>
522 The normal CA tests apply. Except in this case the basicConstraints extension
529 The way DNs are printed is in a "historical SSLeay" format which doesn't
530 follow any published standard. It should follow some standard like RFC2253
531 or RFC1779 with options to make the stuff more readable.
533 Extensions in certificates are not transferred to certificate requests and
536 It is possible to produce invalid certificates or requests by specifying the
537 wrong private key or using inconsistent options in some cases: these should
540 There should be options to explicitly set such things as start and end
541 dates rather than an offset from the current time.
543 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
544 is currently being developed. It thus describes the intended behavior rather
545 than the current behaviour. It is hoped that it will represent reality in
546 OpenSSL 0.9.5 and later.
550 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
551 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>