Import OpenSSL-1.0.1h.
[dragonfly.git] / crypto / openssl / doc / apps / verify.pod
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1=pod
2
3=head1 NAME
4
5verify - Utility to verify certificates.
6
7=head1 SYNOPSIS
8
9B<openssl> B<verify>
10[B<-CApath directory>]
11[B<-CAfile file>]
12[B<-purpose purpose>]
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13[B<-policy arg>]
14[B<-ignore_critical>]
15[B<-crl_check>]
16[B<-crl_check_all>]
17[B<-policy_check>]
18[B<-explicit_policy>]
19[B<-inhibit_any>]
20[B<-inhibit_map>]
21[B<-x509_strict>]
22[B<-extended_crl>]
23[B<-use_deltas>]
24[B<-policy_print>]
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25[B<-untrusted file>]
26[B<-help>]
27[B<-issuer_checks>]
4bb195ec 28[B<-attime timestamp>]
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29[B<-verbose>]
30[B<->]
31[certificates]
32
33
34=head1 DESCRIPTION
35
36The B<verify> command verifies certificate chains.
37
38=head1 COMMAND OPTIONS
39
40=over 4
41
42=item B<-CApath directory>
43
44A directory of trusted certificates. The certificates should have names
45of the form: hash.0 or have symbolic links to them of this
46form ("hash" is the hashed certificate subject name: see the B<-hash> option
47of the B<x509> utility). Under Unix the B<c_rehash> script will automatically
48create symbolic links to a directory of certificates.
49
50=item B<-CAfile file>
51
52A file of trusted certificates. The file should contain multiple certificates
53in PEM format concatenated together.
54
55=item B<-untrusted file>
56
57A file of untrusted certificates. The file should contain multiple certificates
9bb344e0 58in PEM format concatenated together.
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59
60=item B<-purpose purpose>
61
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62The intended use for the certificate. If this option is not specified,
63B<verify> will not consider certificate purpose during chain verification.
64Currently accepted uses are B<sslclient>, B<sslserver>, B<nssslserver>,
65B<smimesign>, B<smimeencrypt>. See the B<VERIFY OPERATION> section for more
66information.
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67
68=item B<-help>
69
9bb344e0 70Print out a usage message.
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71
72=item B<-verbose>
73
9bb344e0 74Print extra information about the operations being performed.
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75
76=item B<-issuer_checks>
77
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78Print out diagnostics relating to searches for the issuer certificate of the
79current certificate. This shows why each candidate issuer certificate was
80rejected. The presence of rejection messages does not itself imply that
81anything is wrong; during the normal verification process, several
82rejections may take place.
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84=item B<-attime timestamp>
85
86Perform validation checks using time specified by B<timestamp> and not
87current system time. B<timestamp> is the number of seconds since
8801.01.1970 (UNIX time).
89
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90=item B<-policy arg>
91
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92Enable policy processing and add B<arg> to the user-initial-policy-set (see
93RFC5280). The policy B<arg> can be an object name an OID in numeric form.
94This argument can appear more than once.
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95
96=item B<-policy_check>
97
98Enables certificate policy processing.
99
100=item B<-explicit_policy>
101
9bb344e0 102Set policy variable require-explicit-policy (see RFC5280).
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103
104=item B<-inhibit_any>
105
9bb344e0 106Set policy variable inhibit-any-policy (see RFC5280).
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107
108=item B<-inhibit_map>
109
9bb344e0 110Set policy variable inhibit-policy-mapping (see RFC5280).
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111
112=item B<-policy_print>
113
9bb344e0 114Print out diagnostics related to policy processing.
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115
116=item B<-crl_check>
117
9bb344e0 118Checks end entity certificate validity by attempting to look up a valid CRL.
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119If a valid CRL cannot be found an error occurs.
120
121=item B<-crl_check_all>
122
123Checks the validity of B<all> certificates in the chain by attempting
9bb344e0 124to look up valid CRLs.
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125
126=item B<-ignore_critical>
127
128Normally if an unhandled critical extension is present which is not
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129supported by OpenSSL the certificate is rejected (as required by RFC5280).
130If this option is set critical extensions are ignored.
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131
132=item B<-x509_strict>
133
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134For strict X.509 compliance, disable non-compliant workarounds for broken
135certificates.
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136
137=item B<-extended_crl>
138
139Enable extended CRL features such as indirect CRLs and alternate CRL
140signing keys.
141
142=item B<-use_deltas>
143
144Enable support for delta CRLs.
145
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146=item B<-check_ss_sig>
147
148Verify the signature on the self-signed root CA. This is disabled by default
149because it doesn't add any security.
150
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151=item B<->
152
9bb344e0 153Indicates the last option. All arguments following this are assumed to be
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154certificate files. This is useful if the first certificate filename begins
155with a B<->.
156
157=item B<certificates>
158
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159One or more certificates to verify. If no certificates are given, B<verify>
160will attempt to read a certificate from standard input. Certificates must be
161in PEM format.
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162
163=back
164
165=head1 VERIFY OPERATION
166
167The B<verify> program uses the same functions as the internal SSL and S/MIME
168verification, therefore this description applies to these verify operations
169too.
170
171There is one crucial difference between the verify operations performed
172by the B<verify> program: wherever possible an attempt is made to continue
173after an error whereas normally the verify operation would halt on the
174first error. This allows all the problems with a certificate chain to be
175determined.
176
177The verify operation consists of a number of separate steps.
178
179Firstly a certificate chain is built up starting from the supplied certificate
180and ending in the root CA. It is an error if the whole chain cannot be built
181up. The chain is built up by looking up the issuers certificate of the current
182certificate. If a certificate is found which is its own issuer it is assumed
183to be the root CA.
184
185The process of 'looking up the issuers certificate' itself involves a number
186of steps. In versions of OpenSSL before 0.9.5a the first certificate whose
187subject name matched the issuer of the current certificate was assumed to be
188the issuers certificate. In OpenSSL 0.9.6 and later all certificates
189whose subject name matches the issuer name of the current certificate are
190subject to further tests. The relevant authority key identifier components
191of the current certificate (if present) must match the subject key identifier
192(if present) and issuer and serial number of the candidate issuer, in addition
193the keyUsage extension of the candidate issuer (if present) must permit
194certificate signing.
195
196The lookup first looks in the list of untrusted certificates and if no match
197is found the remaining lookups are from the trusted certificates. The root CA
198is always looked up in the trusted certificate list: if the certificate to
199verify is a root certificate then an exact match must be found in the trusted
200list.
201
202The second operation is to check every untrusted certificate's extensions for
203consistency with the supplied purpose. If the B<-purpose> option is not included
204then no checks are done. The supplied or "leaf" certificate must have extensions
205compatible with the supplied purpose and all other certificates must also be valid
206CA certificates. The precise extensions required are described in more detail in
207the B<CERTIFICATE EXTENSIONS> section of the B<x509> utility.
208
209The third operation is to check the trust settings on the root CA. The root
210CA should be trusted for the supplied purpose. For compatibility with previous
211versions of SSLeay and OpenSSL a certificate with no trust settings is considered
212to be valid for all purposes.
213
214The final operation is to check the validity of the certificate chain. The validity
215period is checked against the current system time and the notBefore and notAfter
216dates in the certificate. The certificate signatures are also checked at this
217point.
218
219If all operations complete successfully then certificate is considered valid. If
220any operation fails then the certificate is not valid.
221
222=head1 DIAGNOSTICS
223
224When a verify operation fails the output messages can be somewhat cryptic. The
225general form of the error message is:
226
227 server.pem: /C=AU/ST=Queensland/O=CryptSoft Pty Ltd/CN=Test CA (1024 bit)
228 error 24 at 1 depth lookup:invalid CA certificate
229
230The first line contains the name of the certificate being verified followed by
231the subject name of the certificate. The second line contains the error number
232and the depth. The depth is number of the certificate being verified when a
233problem was detected starting with zero for the certificate being verified itself
234then 1 for the CA that signed the certificate and so on. Finally a text version
235of the error number is presented.
236
237An exhaustive list of the error codes and messages is shown below, this also
238includes the name of the error code as defined in the header file x509_vfy.h
239Some of the error codes are defined but never returned: these are described
240as "unused".
241
242=over 4
243
244=item B<0 X509_V_OK: ok>
245
246the operation was successful.
247
248=item B<2 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer certificate>
249
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250the issuer certificate of a looked up certificate could not be found. This
251normally means the list of trusted certificates is not complete.
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252
253=item B<3 X509_V_ERR_UNABLE_TO_GET_CRL: unable to get certificate CRL>
254
919b01cc 255the CRL of a certificate could not be found.
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256
257=item B<4 X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE: unable to decrypt certificate's signature>
258
259the certificate signature could not be decrypted. This means that the actual signature value
260could not be determined rather than it not matching the expected value, this is only
261meaningful for RSA keys.
262
263=item B<5 X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: unable to decrypt CRL's signature>
264
265the CRL signature could not be decrypted: this means that the actual signature value
266could not be determined rather than it not matching the expected value. Unused.
267
268=item B<6 X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: unable to decode issuer public key>
269
270the public key in the certificate SubjectPublicKeyInfo could not be read.
271
272=item B<7 X509_V_ERR_CERT_SIGNATURE_FAILURE: certificate signature failure>
273
274the signature of the certificate is invalid.
275
276=item B<8 X509_V_ERR_CRL_SIGNATURE_FAILURE: CRL signature failure>
277
919b01cc 278the signature of the certificate is invalid.
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279
280=item B<9 X509_V_ERR_CERT_NOT_YET_VALID: certificate is not yet valid>
281
282the certificate is not yet valid: the notBefore date is after the current time.
283
284=item B<10 X509_V_ERR_CERT_HAS_EXPIRED: certificate has expired>
285
286the certificate has expired: that is the notAfter date is before the current time.
287
288=item B<11 X509_V_ERR_CRL_NOT_YET_VALID: CRL is not yet valid>
289
919b01cc 290the CRL is not yet valid.
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291
292=item B<12 X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired>
293
919b01cc 294the CRL has expired.
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295
296=item B<13 X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: format error in certificate's notBefore field>
297
298the certificate notBefore field contains an invalid time.
299
300=item B<14 X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in certificate's notAfter field>
301
302the certificate notAfter field contains an invalid time.
303
304=item B<15 X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: format error in CRL's lastUpdate field>
305
919b01cc 306the CRL lastUpdate field contains an invalid time.
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307
308=item B<16 X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: format error in CRL's nextUpdate field>
309
919b01cc 310the CRL nextUpdate field contains an invalid time.
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311
312=item B<17 X509_V_ERR_OUT_OF_MEM: out of memory>
313
314an error occurred trying to allocate memory. This should never happen.
315
316=item B<18 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: self signed certificate>
317
318the passed certificate is self signed and the same certificate cannot be found in the list of
319trusted certificates.
320
321=item B<19 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed certificate in certificate chain>
322
323the certificate chain could be built up using the untrusted certificates but the root could not
324be found locally.
325
326=item B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to get local issuer certificate>
327
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328the issuer certificate could not be found: this occurs if the issuer
329certificate of an untrusted certificate cannot be found.
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330
331=item B<21 X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to verify the first certificate>
332
333no signatures could be verified because the chain contains only one certificate and it is not
334self signed.
335
336=item B<22 X509_V_ERR_CERT_CHAIN_TOO_LONG: certificate chain too long>
337
338the certificate chain length is greater than the supplied maximum depth. Unused.
339
340=item B<23 X509_V_ERR_CERT_REVOKED: certificate revoked>
341
919b01cc 342the certificate has been revoked.
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343
344=item B<24 X509_V_ERR_INVALID_CA: invalid CA certificate>
345
346a CA certificate is invalid. Either it is not a CA or its extensions are not consistent
347with the supplied purpose.
348
349=item B<25 X509_V_ERR_PATH_LENGTH_EXCEEDED: path length constraint exceeded>
350
351the basicConstraints pathlength parameter has been exceeded.
352
353=item B<26 X509_V_ERR_INVALID_PURPOSE: unsupported certificate purpose>
354
355the supplied certificate cannot be used for the specified purpose.
356
357=item B<27 X509_V_ERR_CERT_UNTRUSTED: certificate not trusted>
358
359the root CA is not marked as trusted for the specified purpose.
360
361=item B<28 X509_V_ERR_CERT_REJECTED: certificate rejected>
362
363the root CA is marked to reject the specified purpose.
364
365=item B<29 X509_V_ERR_SUBJECT_ISSUER_MISMATCH: subject issuer mismatch>
366
367the current candidate issuer certificate was rejected because its subject name
368did not match the issuer name of the current certificate. Only displayed when
369the B<-issuer_checks> option is set.
370
371=item B<30 X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key identifier mismatch>
372
373the current candidate issuer certificate was rejected because its subject key
374identifier was present and did not match the authority key identifier current
375certificate. Only displayed when the B<-issuer_checks> option is set.
376
377=item B<31 X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and issuer serial number mismatch>
378
379the current candidate issuer certificate was rejected because its issuer name
380and serial number was present and did not match the authority key identifier
381of the current certificate. Only displayed when the B<-issuer_checks> option is set.
382
383=item B<32 X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not include certificate signing>
384
385the current candidate issuer certificate was rejected because its keyUsage extension
386does not permit certificate signing.
387
388=item B<50 X509_V_ERR_APPLICATION_VERIFICATION: application verification failure>
389
390an application specific error. Unused.
391
392=back
393
394=head1 BUGS
395
4bb195ec 396Although the issuer checks are a considerable improvement over the old technique they still
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397suffer from limitations in the underlying X509_LOOKUP API. One consequence of this is that
398trusted certificates with matching subject name must either appear in a file (as specified by the
399B<-CAfile> option) or a directory (as specified by B<-CApath>. If they occur in both then only
400the certificates in the file will be recognised.
401
402Previous versions of OpenSSL assume certificates with matching subject name are identical and
403mishandled them.
404
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405Previous versions of this documentation swapped the meaning of the
406B<X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT> and
407B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY> error codes.
408
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409=head1 SEE ALSO
410
411L<x509(1)|x509(1)>
412
413=cut