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1 | |||
2 | This is some preliminary documentation for OpenSSL. | ||
3 | |||
4 | Contents: | ||
5 | |||
6 | OpenSSL X509V3 extension configuration | ||
7 | X509V3 Extension code: programmers guide | ||
8 | PKCS#12 Library | ||
9 | |||
10 | |||
11 | ============================================================================== | ||
12 | OpenSSL X509V3 extension configuration | ||
13 | ============================================================================== | ||
14 | |||
15 | OpenSSL X509V3 extension configuration: preliminary documentation. | ||
16 | |||
17 | INTRODUCTION. | ||
18 | |||
19 | For OpenSSL 0.9.2 the extension code has be considerably enhanced. It is now | ||
20 | possible to add and print out common X509 V3 certificate and CRL extensions. | ||
21 | |||
22 | BEGINNERS NOTE | ||
23 | |||
24 | For most simple applications you don't need to know too much about extensions: | ||
25 | the default openssl.cnf values will usually do sensible things. | ||
26 | |||
27 | If you want to know more you can initially quickly look through the sections | ||
28 | describing how the standard OpenSSL utilities display and add extensions and | ||
29 | then the list of supported extensions. | ||
30 | |||
31 | For more technical information about the meaning of extensions see: | ||
32 | |||
33 | http://www.imc.org/ietf-pkix/ | ||
34 | http://home.netscape.com/eng/security/certs.html | ||
35 | |||
36 | PRINTING EXTENSIONS. | ||
37 | |||
38 | Extension values are automatically printed out for supported extensions. | ||
39 | |||
40 | openssl x509 -in cert.pem -text | ||
41 | openssl crl -in crl.pem -text | ||
42 | |||
43 | will give information in the extension printout, for example: | ||
44 | |||
45 | X509v3 extensions: | ||
46 | X509v3 Basic Constraints: | ||
47 | CA:TRUE | ||
48 | X509v3 Subject Key Identifier: | ||
49 | 73:FE:F7:59:A7:E1:26:84:44:D6:44:36:EE:79:1A:95:7C:B1:4B:15 | ||
50 | X509v3 Authority Key Identifier: | ||
51 | keyid:73:FE:F7:59:A7:E1:26:84:44:D6:44:36:EE:79:1A:95:7C:B1:4B:15, DirName:/C=AU/ST=Some-State/O=Internet Widgits Pty Ltd/Email=email@1.address/Email=email@2.address, serial:00 | ||
52 | X509v3 Key Usage: | ||
53 | Certificate Sign, CRL Sign | ||
54 | X509v3 Subject Alternative Name: | ||
55 | email:email@1.address, email:email@2.address | ||
56 | |||
57 | CONFIGURATION FILES. | ||
58 | |||
59 | The OpenSSL utilities 'ca' and 'req' can now have extension sections listing | ||
60 | which certificate extensions to include. In each case a line: | ||
61 | |||
62 | x509_extensions = extension_section | ||
63 | |||
64 | indicates which section contains the extensions. In the case of 'req' the | ||
65 | extension section is used when the -x509 option is present to create a | ||
66 | self signed root certificate. | ||
67 | |||
68 | The 'x509' utility also supports extensions when it signs a certificate. | ||
69 | The -extfile option is used to set the configuration file containing the | ||
70 | extensions. In this case a line with: | ||
71 | |||
72 | extensions = extension_section | ||
73 | |||
74 | in the nameless (default) section is used. If no such line is included then | ||
75 | it uses the default section. | ||
76 | |||
77 | You can also add extensions to CRLs: a line | ||
78 | |||
79 | crl_extensions = crl_extension_section | ||
80 | |||
81 | will include extensions when the -gencrl option is used with the 'ca' utility. | ||
82 | You can add any extension to a CRL but of the supported extensions only | ||
83 | issuerAltName and authorityKeyIdentifier make any real sense. Note: these are | ||
84 | CRL extensions NOT CRL *entry* extensions which cannot currently be generated. | ||
85 | CRL entry extensions can be displayed. | ||
86 | |||
87 | NB. At this time Netscape Communicator rejects V2 CRLs: to get an old V1 CRL | ||
88 | you should not include a crl_extensions line in the configuration file. | ||
89 | |||
90 | As with all configuration files you can use the inbuilt environment expansion | ||
91 | to allow the values to be passed in the environment. Therefore if you have | ||
92 | several extension sections used for different purposes you can have a line: | ||
93 | |||
94 | x509_extensions = $ENV::ENV_EXT | ||
95 | |||
96 | and set the ENV_EXT environment variable before calling the relevant utility. | ||
97 | |||
98 | EXTENSION SYNTAX. | ||
99 | |||
100 | Extensions have the basic form: | ||
101 | |||
102 | extension_name=[critical,] extension_options | ||
103 | |||
104 | the use of the critical option makes the extension critical. Extreme caution | ||
105 | should be made when using the critical flag. If an extension is marked | ||
106 | as critical then any client that does not understand the extension should | ||
107 | reject it as invalid. Some broken software will reject certificates which | ||
108 | have *any* critical extensions (these violates PKIX but we have to live | ||
109 | with it). | ||
110 | |||
111 | There are three main types of extension: string extensions, multi-valued | ||
112 | extensions, and raw extensions. | ||
113 | |||
114 | String extensions simply have a string which contains either the value itself | ||
115 | or how it is obtained. | ||
116 | |||
117 | For example: | ||
118 | |||
119 | nsComment="This is a Comment" | ||
120 | |||
121 | Multi-valued extensions have a short form and a long form. The short form | ||
122 | is a list of names and values: | ||
123 | |||
124 | basicConstraints=critical,CA:true,pathlen:1 | ||
125 | |||
126 | The long form allows the values to be placed in a separate section: | ||
127 | |||
128 | basicConstraints=critical,@bs_section | ||
129 | |||
130 | [bs_section] | ||
131 | |||
132 | CA=true | ||
133 | pathlen=1 | ||
134 | |||
135 | Both forms are equivalent. However it should be noted that in some cases the | ||
136 | same name can appear multiple times, for example, | ||
137 | |||
138 | subjectAltName=email:steve@here,email:steve@there | ||
139 | |||
140 | in this case an equivalent long form is: | ||
141 | |||
142 | subjectAltName=@alt_section | ||
143 | |||
144 | [alt_section] | ||
145 | |||
146 | email.1=steve@here | ||
147 | email.2=steve@there | ||
148 | |||
149 | This is because the configuration file code cannot handle the same name | ||
150 | occurring twice in the same section. | ||
151 | |||
152 | The syntax of raw extensions is governed by the extension code: it can | ||
153 | for example contain data in multiple sections. The correct syntax to | ||
154 | use is defined by the extension code itself: check out the certificate | ||
155 | policies extension for an example. | ||
156 | |||
157 | There are two ways to encode arbitrary extensions. | ||
158 | |||
159 | The first way is to use the word ASN1 followed by the extension content | ||
160 | using the same syntax as ASN1_generate_nconf(). For example: | ||
161 | |||
162 | 1.2.3.4=critical,ASN1:UTF8String:Some random data | ||
163 | |||
164 | 1.2.3.4=ASN1:SEQUENCE:seq_sect | ||
165 | |||
166 | [seq_sect] | ||
167 | |||
168 | field1 = UTF8:field1 | ||
169 | field2 = UTF8:field2 | ||
170 | |||
171 | It is also possible to use the word DER to include arbitrary data in any | ||
172 | extension. | ||
173 | |||
174 | 1.2.3.4=critical,DER:01:02:03:04 | ||
175 | 1.2.3.4=DER:01020304 | ||
176 | |||
177 | The value following DER is a hex dump of the DER encoding of the extension | ||
178 | Any extension can be placed in this form to override the default behaviour. | ||
179 | For example: | ||
180 | |||
181 | basicConstraints=critical,DER:00:01:02:03 | ||
182 | |||
183 | WARNING: DER should be used with caution. It is possible to create totally | ||
184 | invalid extensions unless care is taken. | ||
185 | |||
186 | CURRENTLY SUPPORTED EXTENSIONS. | ||
187 | |||
188 | If you aren't sure about extensions then they can be largely ignored: its only | ||
189 | when you want to do things like restrict certificate usage when you need to | ||
190 | worry about them. | ||
191 | |||
192 | The only extension that a beginner might want to look at is Basic Constraints. | ||
193 | If in addition you want to try Netscape object signing the you should also | ||
194 | look at Netscape Certificate Type. | ||
195 | |||
196 | Literal String extensions. | ||
197 | |||
198 | In each case the 'value' of the extension is placed directly in the | ||
199 | extension. Currently supported extensions in this category are: nsBaseUrl, | ||
200 | nsRevocationUrl, nsCaRevocationUrl, nsRenewalUrl, nsCaPolicyUrl, | ||
201 | nsSslServerName and nsComment. | ||
202 | |||
203 | For example: | ||
204 | |||
205 | nsComment="This is a test comment" | ||
206 | |||
207 | Bit Strings. | ||
208 | |||
209 | Bit string extensions just consist of a list of supported bits, currently | ||
210 | two extensions are in this category: PKIX keyUsage and the Netscape specific | ||
211 | nsCertType. | ||
212 | |||
213 | nsCertType (netscape certificate type) takes the flags: client, server, email, | ||
214 | objsign, reserved, sslCA, emailCA, objCA. | ||
215 | |||
216 | keyUsage (PKIX key usage) takes the flags: digitalSignature, nonRepudiation, | ||
217 | keyEncipherment, dataEncipherment, keyAgreement, keyCertSign, cRLSign, | ||
218 | encipherOnly, decipherOnly. | ||
219 | |||
220 | For example: | ||
221 | |||
222 | nsCertType=server | ||
223 | |||
224 | keyUsage=digitalSignature, nonRepudiation | ||
225 | |||
226 | Hints on Netscape Certificate Type. | ||
227 | |||
228 | Other than Basic Constraints this is the only extension a beginner might | ||
229 | want to use, if you want to try Netscape object signing, otherwise it can | ||
230 | be ignored. | ||
231 | |||
232 | If you want a certificate that can be used just for object signing then: | ||
233 | |||
234 | nsCertType=objsign | ||
235 | |||
236 | will do the job. If you want to use it as a normal end user and server | ||
237 | certificate as well then | ||
238 | |||
239 | nsCertType=objsign,email,server | ||
240 | |||
241 | is more appropriate. You cannot use a self signed certificate for object | ||
242 | signing (well Netscape signtool can but it cheats!) so you need to create | ||
243 | a CA certificate and sign an end user certificate with it. | ||
244 | |||
245 | Side note: If you want to conform to the Netscape specifications then you | ||
246 | should really also set: | ||
247 | |||
248 | nsCertType=objCA | ||
249 | |||
250 | in the *CA* certificate for just an object signing CA and | ||
251 | |||
252 | nsCertType=objCA,emailCA,sslCA | ||
253 | |||
254 | for everything. Current Netscape software doesn't enforce this so it can | ||
255 | be omitted. | ||
256 | |||
257 | Basic Constraints. | ||
258 | |||
259 | This is generally the only extension you need to worry about for simple | ||
260 | applications. If you want your certificate to be usable as a CA certificate | ||
261 | (in addition to an end user certificate) then you set this to: | ||
262 | |||
263 | basicConstraints=CA:TRUE | ||
264 | |||
265 | if you want to be certain the certificate cannot be used as a CA then do: | ||
266 | |||
267 | basicConstraints=CA:FALSE | ||
268 | |||
269 | The rest of this section describes more advanced usage. | ||
270 | |||
271 | Basic constraints is a multi-valued extension that supports a CA and an | ||
272 | optional pathlen option. The CA option takes the values true and false and | ||
273 | pathlen takes an integer. Note if the CA option is false the pathlen option | ||
274 | should be omitted. | ||
275 | |||
276 | The pathlen parameter indicates the maximum number of CAs that can appear | ||
277 | below this one in a chain. So if you have a CA with a pathlen of zero it can | ||
278 | only be used to sign end user certificates and not further CAs. This all | ||
279 | assumes that the software correctly interprets this extension of course. | ||
280 | |||
281 | Examples: | ||
282 | |||
283 | basicConstraints=CA:TRUE | ||
284 | basicConstraints=critical,CA:TRUE, pathlen:0 | ||
285 | |||
286 | NOTE: for a CA to be considered valid it must have the CA option set to | ||
287 | TRUE. An end user certificate MUST NOT have the CA value set to true. | ||
288 | According to PKIX recommendations it should exclude the extension entirely, | ||
289 | however some software may require CA set to FALSE for end entity certificates. | ||
290 | |||
291 | Extended Key Usage. | ||
292 | |||
293 | This extensions consists of a list of usages. | ||
294 | |||
295 | These can either be object short names of the dotted numerical form of OIDs. | ||
296 | While any OID can be used only certain values make sense. In particular the | ||
297 | following PKIX, NS and MS values are meaningful: | ||
298 | |||
299 | Value Meaning | ||
300 | ----- ------- | ||
301 | serverAuth SSL/TLS Web Server Authentication. | ||
302 | clientAuth SSL/TLS Web Client Authentication. | ||
303 | codeSigning Code signing. | ||
304 | emailProtection E-mail Protection (S/MIME). | ||
305 | timeStamping Trusted Timestamping | ||
306 | msCodeInd Microsoft Individual Code Signing (authenticode) | ||
307 | msCodeCom Microsoft Commercial Code Signing (authenticode) | ||
308 | msCTLSign Microsoft Trust List Signing | ||
309 | msSGC Microsoft Server Gated Crypto | ||
310 | msEFS Microsoft Encrypted File System | ||
311 | nsSGC Netscape Server Gated Crypto | ||
312 | |||
313 | For example, under IE5 a CA can be used for any purpose: by including a list | ||
314 | of the above usages the CA can be restricted to only authorised uses. | ||
315 | |||
316 | Note: software packages may place additional interpretations on certificate | ||
317 | use, in particular some usages may only work for selected CAs. Don't for example | ||
318 | expect just including msSGC or nsSGC will automatically mean that a certificate | ||
319 | can be used for SGC ("step up" encryption) otherwise anyone could use it. | ||
320 | |||
321 | Examples: | ||
322 | |||
323 | extendedKeyUsage=critical,codeSigning,1.2.3.4 | ||
324 | extendedKeyUsage=nsSGC,msSGC | ||
325 | |||
326 | Subject Key Identifier. | ||
327 | |||
328 | This is really a string extension and can take two possible values. Either | ||
329 | a hex string giving details of the extension value to include or the word | ||
330 | 'hash' which then automatically follow PKIX guidelines in selecting and | ||
331 | appropriate key identifier. The use of the hex string is strongly discouraged. | ||
332 | |||
333 | Example: subjectKeyIdentifier=hash | ||
334 | |||
335 | Authority Key Identifier. | ||
336 | |||
337 | The authority key identifier extension permits two options. keyid and issuer: | ||
338 | both can take the optional value "always". | ||
339 | |||
340 | If the keyid option is present an attempt is made to copy the subject key | ||
341 | identifier from the parent certificate. If the value "always" is present | ||
342 | then an error is returned if the option fails. | ||
343 | |||
344 | The issuer option copies the issuer and serial number from the issuer | ||
345 | certificate. Normally this will only be done if the keyid option fails or | ||
346 | is not included: the "always" flag will always include the value. | ||
347 | |||
348 | Subject Alternative Name. | ||
349 | |||
350 | The subject alternative name extension allows various literal values to be | ||
351 | included in the configuration file. These include "email" (an email address) | ||
352 | "URI" a uniform resource indicator, "DNS" (a DNS domain name), RID (a | ||
353 | registered ID: OBJECT IDENTIFIER), IP (and IP address) and otherName. | ||
354 | |||
355 | Also the email option include a special 'copy' value. This will automatically | ||
356 | include and email addresses contained in the certificate subject name in | ||
357 | the extension. | ||
358 | |||
359 | otherName can include arbitrary data associated with an OID: the value | ||
360 | should be the OID followed by a semicolon and the content in standard | ||
361 | ASN1_generate_nconf() format. | ||
362 | |||
363 | Examples: | ||
364 | |||
365 | subjectAltName=email:copy,email:my@other.address,URI:http://my.url.here/ | ||
366 | subjectAltName=email:my@other.address,RID:1.2.3.4 | ||
367 | subjectAltName=otherName:1.2.3.4;UTF8:some other identifier | ||
368 | |||
369 | Issuer Alternative Name. | ||
370 | |||
371 | The issuer alternative name option supports all the literal options of | ||
372 | subject alternative name. It does *not* support the email:copy option because | ||
373 | that would not make sense. It does support an additional issuer:copy option | ||
374 | that will copy all the subject alternative name values from the issuer | ||
375 | certificate (if possible). | ||
376 | |||
377 | Example: | ||
378 | |||
379 | issuserAltName = issuer:copy | ||
380 | |||
381 | Authority Info Access. | ||
382 | |||
383 | The authority information access extension gives details about how to access | ||
384 | certain information relating to the CA. Its syntax is accessOID;location | ||
385 | where 'location' has the same syntax as subject alternative name (except | ||
386 | that email:copy is not supported). accessOID can be any valid OID but only | ||
387 | certain values are meaningful for example OCSP and caIssuers. OCSP gives the | ||
388 | location of an OCSP responder: this is used by Netscape PSM and other software. | ||
389 | |||
390 | Example: | ||
391 | |||
392 | authorityInfoAccess = OCSP;URI:http://ocsp.my.host/ | ||
393 | authorityInfoAccess = caIssuers;URI:http://my.ca/ca.html | ||
394 | |||
395 | CRL distribution points. | ||
396 | |||
397 | This is a multi-valued extension that supports all the literal options of | ||
398 | subject alternative name. Of the few software packages that currently interpret | ||
399 | this extension most only interpret the URI option. | ||
400 | |||
401 | Currently each option will set a new DistributionPoint with the fullName | ||
402 | field set to the given value. | ||
403 | |||
404 | Other fields like cRLissuer and reasons cannot currently be set or displayed: | ||
405 | at this time no examples were available that used these fields. | ||
406 | |||
407 | If you see this extension with <UNSUPPORTED> when you attempt to print it out | ||
408 | or it doesn't appear to display correctly then let me know, including the | ||
409 | certificate (mail me at steve@openssl.org) . | ||
410 | |||
411 | Examples: | ||
412 | |||
413 | crlDistributionPoints=URI:http://www.myhost.com/myca.crl | ||
414 | crlDistributionPoints=URI:http://www.my.com/my.crl,URI:http://www.oth.com/my.crl | ||
415 | |||
416 | Certificate Policies. | ||
417 | |||
418 | This is a RAW extension. It attempts to display the contents of this extension: | ||
419 | unfortunately this extension is often improperly encoded. | ||
420 | |||
421 | The certificate policies extension will rarely be used in practice: few | ||
422 | software packages interpret it correctly or at all. IE5 does partially | ||
423 | support this extension: but it needs the 'ia5org' option because it will | ||
424 | only correctly support a broken encoding. Of the options below only the | ||
425 | policy OID, explicitText and CPS options are displayed with IE5. | ||
426 | |||
427 | All the fields of this extension can be set by using the appropriate syntax. | ||
428 | |||
429 | If you follow the PKIX recommendations of not including any qualifiers and just | ||
430 | using only one OID then you just include the value of that OID. Multiple OIDs | ||
431 | can be set separated by commas, for example: | ||
432 | |||
433 | certificatePolicies= 1.2.4.5, 1.1.3.4 | ||
434 | |||
435 | If you wish to include qualifiers then the policy OID and qualifiers need to | ||
436 | be specified in a separate section: this is done by using the @section syntax | ||
437 | instead of a literal OID value. | ||
438 | |||
439 | The section referred to must include the policy OID using the name | ||
440 | policyIdentifier, cPSuri qualifiers can be included using the syntax: | ||
441 | |||
442 | CPS.nnn=value | ||
443 | |||
444 | userNotice qualifiers can be set using the syntax: | ||
445 | |||
446 | userNotice.nnn=@notice | ||
447 | |||
448 | The value of the userNotice qualifier is specified in the relevant section. | ||
449 | This section can include explicitText, organization and noticeNumbers | ||
450 | options. explicitText and organization are text strings, noticeNumbers is a | ||
451 | comma separated list of numbers. The organization and noticeNumbers options | ||
452 | (if included) must BOTH be present. If you use the userNotice option with IE5 | ||
453 | then you need the 'ia5org' option at the top level to modify the encoding: | ||
454 | otherwise it will not be interpreted properly. | ||
455 | |||
456 | Example: | ||
457 | |||
458 | certificatePolicies=ia5org,1.2.3.4,1.5.6.7.8,@polsect | ||
459 | |||
460 | [polsect] | ||
461 | |||
462 | policyIdentifier = 1.3.5.8 | ||
463 | CPS.1="http://my.host.name/" | ||
464 | CPS.2="http://my.your.name/" | ||
465 | userNotice.1=@notice | ||
466 | |||
467 | [notice] | ||
468 | |||
469 | explicitText="Explicit Text Here" | ||
470 | organization="Organisation Name" | ||
471 | noticeNumbers=1,2,3,4 | ||
472 | |||
473 | TECHNICAL NOTE: the ia5org option changes the type of the 'organization' field, | ||
474 | according to PKIX it should be of type DisplayText but Verisign uses an | ||
475 | IA5STRING and IE5 needs this too. | ||
476 | |||
477 | Display only extensions. | ||
478 | |||
479 | Some extensions are only partially supported and currently are only displayed | ||
480 | but cannot be set. These include private key usage period, CRL number, and | ||
481 | CRL reason. | ||
482 | |||
483 | ============================================================================== | ||
484 | X509V3 Extension code: programmers guide | ||
485 | ============================================================================== | ||
486 | |||
487 | The purpose of the extension code is twofold. It allows an extension to be | ||
488 | created from a string or structure describing its contents and it prints out an | ||
489 | extension in a human or machine readable form. | ||
490 | |||
491 | 1. Initialisation and cleanup. | ||
492 | |||
493 | No special initialisation is needed before calling the extension functions. | ||
494 | You used to have to call X509V3_add_standard_extensions(); but this is no longer | ||
495 | required and this function no longer does anything. | ||
496 | |||
497 | void X509V3_EXT_cleanup(void); | ||
498 | |||
499 | This function should be called to cleanup the extension code if any custom | ||
500 | extensions have been added. If no custom extensions have been added then this | ||
501 | call does nothing. After this call all custom extension code is freed up but | ||
502 | you can still use the standard extensions. | ||
503 | |||
504 | 2. Printing and parsing extensions. | ||
505 | |||
506 | The simplest way to print out extensions is via the standard X509 printing | ||
507 | routines: if you use the standard X509_print() function, the supported | ||
508 | extensions will be printed out automatically. | ||
509 | |||
510 | The following functions allow finer control over extension display: | ||
511 | |||
512 | int X509V3_EXT_print(BIO *out, X509_EXTENSION *ext, int flag, int indent); | ||
513 | int X509V3_EXT_print_fp(FILE *out, X509_EXTENSION *ext, int flag, int indent); | ||
514 | |||
515 | These two functions print out an individual extension to a BIO or FILE pointer. | ||
516 | Currently the flag argument is unused and should be set to 0. The 'indent' | ||
517 | argument is the number of spaces to indent each line. | ||
518 | |||
519 | void *X509V3_EXT_d2i(X509_EXTENSION *ext); | ||
520 | |||
521 | This function parses an extension and returns its internal structure. The | ||
522 | precise structure you get back depends on the extension being parsed. If the | ||
523 | extension if basicConstraints you will get back a pointer to a | ||
524 | BASIC_CONSTRAINTS structure. Check out the source in crypto/x509v3 for more | ||
525 | details about the structures returned. The returned structure should be freed | ||
526 | after use using the relevant free function, BASIC_CONSTRAINTS_free() for | ||
527 | example. | ||
528 | |||
529 | void * X509_get_ext_d2i(X509 *x, int nid, int *crit, int *idx); | ||
530 | void * X509_CRL_get_ext_d2i(X509_CRL *x, int nid, int *crit, int *idx); | ||
531 | void * X509_REVOKED_get_ext_d2i(X509_REVOKED *x, int nid, int *crit, int *idx); | ||
532 | void * X509V3_get_d2i(STACK_OF(X509_EXTENSION) *x, int nid, int *crit, int *idx); | ||
533 | |||
534 | These functions combine the operations of searching for extensions and | ||
535 | parsing them. They search a certificate, a CRL a CRL entry or a stack | ||
536 | of extensions respectively for extension whose NID is 'nid' and return | ||
537 | the parsed result of NULL if an error occurred. For example: | ||
538 | |||
539 | BASIC_CONSTRAINTS *bs; | ||
540 | bs = X509_get_ext_d2i(cert, NID_basic_constraints, NULL, NULL); | ||
541 | |||
542 | This will search for the basicConstraints extension and either return | ||
543 | it value or NULL. NULL can mean either the extension was not found, it | ||
544 | occurred more than once or it could not be parsed. | ||
545 | |||
546 | If 'idx' is NULL then an extension is only parsed if it occurs precisely | ||
547 | once. This is standard behaviour because extensions normally cannot occur | ||
548 | more than once. If however more than one extension of the same type can | ||
549 | occur it can be used to parse successive extensions for example: | ||
550 | |||
551 | int i; | ||
552 | void *ext; | ||
553 | |||
554 | i = -1; | ||
555 | for(;;) { | ||
556 | ext = X509_get_ext_d2i(x, nid, crit, &idx); | ||
557 | if(ext == NULL) break; | ||
558 | /* Do something with ext */ | ||
559 | } | ||
560 | |||
561 | If 'crit' is not NULL and the extension was found then the int it points to | ||
562 | is set to 1 for critical extensions and 0 for non critical. Therefore if the | ||
563 | function returns NULL but 'crit' is set to 0 or 1 then the extension was | ||
564 | found but it could not be parsed. | ||
565 | |||
566 | The int pointed to by crit will be set to -1 if the extension was not found | ||
567 | and -2 if the extension occurred more than once (this will only happen if | ||
568 | idx is NULL). In both cases the function will return NULL. | ||
569 | |||
570 | 3. Generating extensions. | ||
571 | |||
572 | An extension will typically be generated from a configuration file, or some | ||
573 | other kind of configuration database. | ||
574 | |||
575 | int X509V3_EXT_add_conf(LHASH *conf, X509V3_CTX *ctx, char *section, | ||
576 | X509 *cert); | ||
577 | int X509V3_EXT_CRL_add_conf(LHASH *conf, X509V3_CTX *ctx, char *section, | ||
578 | X509_CRL *crl); | ||
579 | |||
580 | These functions add all the extensions in the given section to the given | ||
581 | certificate or CRL. They will normally be called just before the certificate | ||
582 | or CRL is due to be signed. Both return 0 on error on non zero for success. | ||
583 | |||
584 | In each case 'conf' is the LHASH pointer of the configuration file to use | ||
585 | and 'section' is the section containing the extension details. | ||
586 | |||
587 | See the 'context functions' section for a description of the ctx parameter. | ||
588 | |||
589 | |||
590 | X509_EXTENSION *X509V3_EXT_conf(LHASH *conf, X509V3_CTX *ctx, char *name, | ||
591 | char *value); | ||
592 | |||
593 | This function returns an extension based on a name and value pair, if the | ||
594 | pair will not need to access other sections in a config file (or there is no | ||
595 | config file) then the 'conf' parameter can be set to NULL. | ||
596 | |||
597 | X509_EXTENSION *X509V3_EXT_conf_nid(char *conf, X509V3_CTX *ctx, int nid, | ||
598 | char *value); | ||
599 | |||
600 | This function creates an extension in the same way as X509V3_EXT_conf() but | ||
601 | takes the NID of the extension rather than its name. | ||
602 | |||
603 | For example to produce basicConstraints with the CA flag and a path length of | ||
604 | 10: | ||
605 | |||
606 | x = X509V3_EXT_conf_nid(NULL, NULL, NID_basic_constraints,"CA:TRUE,pathlen:10"); | ||
607 | |||
608 | |||
609 | X509_EXTENSION *X509V3_EXT_i2d(int ext_nid, int crit, void *ext_struc); | ||
610 | |||
611 | This function sets up an extension from its internal structure. The ext_nid | ||
612 | parameter is the NID of the extension and 'crit' is the critical flag. | ||
613 | |||
614 | 4. Context functions. | ||
615 | |||
616 | The following functions set and manipulate an extension context structure. | ||
617 | The purpose of the extension context is to allow the extension code to | ||
618 | access various structures relating to the "environment" of the certificate: | ||
619 | for example the issuers certificate or the certificate request. | ||
620 | |||
621 | void X509V3_set_ctx(X509V3_CTX *ctx, X509 *issuer, X509 *subject, | ||
622 | X509_REQ *req, X509_CRL *crl, int flags); | ||
623 | |||
624 | This function sets up an X509V3_CTX structure with details of the certificate | ||
625 | environment: specifically the issuers certificate, the subject certificate, | ||
626 | the certificate request and the CRL: if these are not relevant or not | ||
627 | available then they can be set to NULL. The 'flags' parameter should be set | ||
628 | to zero. | ||
629 | |||
630 | X509V3_set_ctx_test(ctx) | ||
631 | |||
632 | This macro is used to set the 'ctx' structure to a 'test' value: this is to | ||
633 | allow the syntax of an extension (or configuration file) to be tested. | ||
634 | |||
635 | X509V3_set_ctx_nodb(ctx) | ||
636 | |||
637 | This macro is used when no configuration database is present. | ||
638 | |||
639 | void X509V3_set_conf_lhash(X509V3_CTX *ctx, LHASH *lhash); | ||
640 | |||
641 | This function is used to set the configuration database when it is an LHASH | ||
642 | structure: typically a configuration file. | ||
643 | |||
644 | The following functions are used to access a configuration database: they | ||
645 | should only be used in RAW extensions. | ||
646 | |||
647 | char * X509V3_get_string(X509V3_CTX *ctx, char *name, char *section); | ||
648 | |||
649 | This function returns the value of the parameter "name" in "section", or NULL | ||
650 | if there has been an error. | ||
651 | |||
652 | void X509V3_string_free(X509V3_CTX *ctx, char *str); | ||
653 | |||
654 | This function frees up the string returned by the above function. | ||
655 | |||
656 | STACK_OF(CONF_VALUE) * X509V3_get_section(X509V3_CTX *ctx, char *section); | ||
657 | |||
658 | This function returns a whole section as a STACK_OF(CONF_VALUE) . | ||
659 | |||
660 | void X509V3_section_free( X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *section); | ||
661 | |||
662 | This function frees up the STACK returned by the above function. | ||
663 | |||
664 | Note: it is possible to use the extension code with a custom configuration | ||
665 | database. To do this the "db_meth" element of the X509V3_CTX structure should | ||
666 | be set to an X509V3_CTX_METHOD structure. This structure contains the following | ||
667 | function pointers: | ||
668 | |||
669 | char * (*get_string)(void *db, char *section, char *value); | ||
670 | STACK_OF(CONF_VALUE) * (*get_section)(void *db, char *section); | ||
671 | void (*free_string)(void *db, char * string); | ||
672 | void (*free_section)(void *db, STACK_OF(CONF_VALUE) *section); | ||
673 | |||
674 | these will be called and passed the 'db' element in the X509V3_CTX structure | ||
675 | to access the database. If a given function is not implemented or not required | ||
676 | it can be set to NULL. | ||
677 | |||
678 | 5. String helper functions. | ||
679 | |||
680 | There are several "i2s" and "s2i" functions that convert structures to and | ||
681 | from ASCII strings. In all the "i2s" cases the returned string should be | ||
682 | freed using Free() after use. Since some of these are part of other extension | ||
683 | code they may take a 'method' parameter. Unless otherwise stated it can be | ||
684 | safely set to NULL. | ||
685 | |||
686 | char *i2s_ASN1_OCTET_STRING(X509V3_EXT_METHOD *method, ASN1_OCTET_STRING *oct); | ||
687 | |||
688 | This returns a hex string from an ASN1_OCTET_STRING. | ||
689 | |||
690 | char * i2s_ASN1_INTEGER(X509V3_EXT_METHOD *meth, ASN1_INTEGER *aint); | ||
691 | char * i2s_ASN1_ENUMERATED(X509V3_EXT_METHOD *meth, ASN1_ENUMERATED *aint); | ||
692 | |||
693 | These return a string decimal representations of an ASN1_INTEGER and an | ||
694 | ASN1_ENUMERATED type, respectively. | ||
695 | |||
696 | ASN1_OCTET_STRING *s2i_ASN1_OCTET_STRING(X509V3_EXT_METHOD *method, | ||
697 | X509V3_CTX *ctx, char *str); | ||
698 | |||
699 | This converts an ASCII hex string to an ASN1_OCTET_STRING. | ||
700 | |||
701 | ASN1_INTEGER * s2i_ASN1_INTEGER(X509V3_EXT_METHOD *meth, char *value); | ||
702 | |||
703 | This converts a decimal ASCII string into an ASN1_INTEGER. | ||
704 | |||
705 | 6. Multi valued extension helper functions. | ||
706 | |||
707 | The following functions can be used to manipulate STACKs of CONF_VALUE | ||
708 | structures, as used by multi valued extensions. | ||
709 | |||
710 | int X509V3_get_value_bool(CONF_VALUE *value, int *asn1_bool); | ||
711 | |||
712 | This function expects a boolean value in 'value' and sets 'asn1_bool' to | ||
713 | it. That is it sets it to 0 for FALSE or 0xff for TRUE. The following | ||
714 | strings are acceptable: "TRUE", "true", "Y", "y", "YES", "yes", "FALSE" | ||
715 | "false", "N", "n", "NO" or "no". | ||
716 | |||
717 | int X509V3_get_value_int(CONF_VALUE *value, ASN1_INTEGER **aint); | ||
718 | |||
719 | This accepts a decimal integer of arbitrary length and sets an ASN1_INTEGER. | ||
720 | |||
721 | int X509V3_add_value(const char *name, const char *value, | ||
722 | STACK_OF(CONF_VALUE) **extlist); | ||
723 | |||
724 | This simply adds a string name and value pair. | ||
725 | |||
726 | int X509V3_add_value_uchar(const char *name, const unsigned char *value, | ||
727 | STACK_OF(CONF_VALUE) **extlist); | ||
728 | |||
729 | The same as above but for an unsigned character value. | ||
730 | |||
731 | int X509V3_add_value_bool(const char *name, int asn1_bool, | ||
732 | STACK_OF(CONF_VALUE) **extlist); | ||
733 | |||
734 | This adds either "TRUE" or "FALSE" depending on the value of 'asn1_bool' | ||
735 | |||
736 | int X509V3_add_value_bool_nf(char *name, int asn1_bool, | ||
737 | STACK_OF(CONF_VALUE) **extlist); | ||
738 | |||
739 | This is the same as above except it adds nothing if asn1_bool is FALSE. | ||
740 | |||
741 | int X509V3_add_value_int(const char *name, ASN1_INTEGER *aint, | ||
742 | STACK_OF(CONF_VALUE) **extlist); | ||
743 | |||
744 | This function adds the value of the ASN1_INTEGER in decimal form. | ||
745 | |||
746 | 7. Other helper functions. | ||
747 | |||
748 | <to be added> | ||
749 | |||
750 | ADDING CUSTOM EXTENSIONS. | ||
751 | |||
752 | Currently there are three types of supported extensions. | ||
753 | |||
754 | String extensions are simple strings where the value is placed directly in the | ||
755 | extensions, and the string returned is printed out. | ||
756 | |||
757 | Multi value extensions are passed a STACK_OF(CONF_VALUE) name and value pairs | ||
758 | or return a STACK_OF(CONF_VALUE). | ||
759 | |||
760 | Raw extensions are just passed a BIO or a value and it is the extensions | ||
761 | responsibility to handle all the necessary printing. | ||
762 | |||
763 | There are two ways to add an extension. One is simply as an alias to an already | ||
764 | existing extension. An alias is an extension that is identical in ASN1 structure | ||
765 | to an existing extension but has a different OBJECT IDENTIFIER. This can be | ||
766 | done by calling: | ||
767 | |||
768 | int X509V3_EXT_add_alias(int nid_to, int nid_from); | ||
769 | |||
770 | 'nid_to' is the new extension NID and 'nid_from' is the already existing | ||
771 | extension NID. | ||
772 | |||
773 | Alternatively an extension can be written from scratch. This involves writing | ||
774 | the ASN1 code to encode and decode the extension and functions to print out and | ||
775 | generate the extension from strings. The relevant functions are then placed in | ||
776 | a X509V3_EXT_METHOD structure and int X509V3_EXT_add(X509V3_EXT_METHOD *ext); | ||
777 | called. | ||
778 | |||
779 | The X509V3_EXT_METHOD structure is described below. | ||
780 | |||
781 | struct { | ||
782 | int ext_nid; | ||
783 | int ext_flags; | ||
784 | X509V3_EXT_NEW ext_new; | ||
785 | X509V3_EXT_FREE ext_free; | ||
786 | X509V3_EXT_D2I d2i; | ||
787 | X509V3_EXT_I2D i2d; | ||
788 | X509V3_EXT_I2S i2s; | ||
789 | X509V3_EXT_S2I s2i; | ||
790 | X509V3_EXT_I2V i2v; | ||
791 | X509V3_EXT_V2I v2i; | ||
792 | X509V3_EXT_R2I r2i; | ||
793 | X509V3_EXT_I2R i2r; | ||
794 | |||
795 | void *usr_data; | ||
796 | }; | ||
797 | |||
798 | The elements have the following meanings. | ||
799 | |||
800 | ext_nid is the NID of the object identifier of the extension. | ||
801 | |||
802 | ext_flags is set of flags. Currently the only external flag is | ||
803 | X509V3_EXT_MULTILINE which means a multi valued extensions | ||
804 | should be printed on separate lines. | ||
805 | |||
806 | usr_data is an extension specific pointer to any relevant data. This | ||
807 | allows extensions to share identical code but have different | ||
808 | uses. An example of this is the bit string extension which uses | ||
809 | usr_data to contain a list of the bit names. | ||
810 | |||
811 | All the remaining elements are function pointers. | ||
812 | |||
813 | ext_new is a pointer to a function that allocates memory for the | ||
814 | extension ASN1 structure: for example ASN1_OBJECT_new(). | ||
815 | |||
816 | ext_free is a pointer to a function that free up memory of the extension | ||
817 | ASN1 structure: for example ASN1_OBJECT_free(). | ||
818 | |||
819 | d2i is the standard ASN1 function that converts a DER buffer into | ||
820 | the internal ASN1 structure: for example d2i_ASN1_IA5STRING(). | ||
821 | |||
822 | i2d is the standard ASN1 function that converts the internal | ||
823 | structure into the DER representation: for example | ||
824 | i2d_ASN1_IA5STRING(). | ||
825 | |||
826 | The remaining functions are depend on the type of extension. One i2X and | ||
827 | one X2i should be set and the rest set to NULL. The types set do not need | ||
828 | to match up, for example the extension could be set using the multi valued | ||
829 | v2i function and printed out using the raw i2r. | ||
830 | |||
831 | All functions have the X509V3_EXT_METHOD passed to them in the 'method' | ||
832 | parameter and an X509V3_CTX structure. Extension code can then access the | ||
833 | parent structure via the 'method' parameter to for example make use of the value | ||
834 | of usr_data. If the code needs to use detail relating to the request it can | ||
835 | use the 'ctx' parameter. | ||
836 | |||
837 | A note should be given here about the 'flags' member of the 'ctx' parameter. | ||
838 | If it has the value CTX_TEST then the configuration syntax is being checked | ||
839 | and no actual certificate or CRL exists. Therefore any attempt in the config | ||
840 | file to access such information should silently succeed. If the syntax is OK | ||
841 | then it should simply return a (possibly bogus) extension, otherwise it | ||
842 | should return NULL. | ||
843 | |||
844 | char *i2s(struct v3_ext_method *method, void *ext); | ||
845 | |||
846 | This function takes the internal structure in the ext parameter and returns | ||
847 | a Malloc'ed string representing its value. | ||
848 | |||
849 | void * s2i(struct v3_ext_method *method, struct v3_ext_ctx *ctx, char *str); | ||
850 | |||
851 | This function takes the string representation in the ext parameter and returns | ||
852 | an allocated internal structure: ext_free() will be used on this internal | ||
853 | structure after use. | ||
854 | |||
855 | i2v and v2i handle a STACK_OF(CONF_VALUE): | ||
856 | |||
857 | typedef struct | ||
858 | { | ||
859 | char *section; | ||
860 | char *name; | ||
861 | char *value; | ||
862 | } CONF_VALUE; | ||
863 | |||
864 | Only the name and value members are currently used. | ||
865 | |||
866 | STACK_OF(CONF_VALUE) * i2v(struct v3_ext_method *method, void *ext); | ||
867 | |||
868 | This function is passed the internal structure in the ext parameter and | ||
869 | returns a STACK of CONF_VALUE structures. The values of name, value, | ||
870 | section and the structure itself will be freed up with Free after use. | ||
871 | Several helper functions are available to add values to this STACK. | ||
872 | |||
873 | void * v2i(struct v3_ext_method *method, struct v3_ext_ctx *ctx, | ||
874 | STACK_OF(CONF_VALUE) *values); | ||
875 | |||
876 | This function takes a STACK_OF(CONF_VALUE) structures and should set the | ||
877 | values of the external structure. This typically uses the name element to | ||
878 | determine which structure element to set and the value element to determine | ||
879 | what to set it to. Several helper functions are available for this | ||
880 | purpose (see above). | ||
881 | |||
882 | int i2r(struct v3_ext_method *method, void *ext, BIO *out, int indent); | ||
883 | |||
884 | This function is passed the internal extension structure in the ext parameter | ||
885 | and sends out a human readable version of the extension to out. The 'indent' | ||
886 | parameter should be noted to determine the necessary amount of indentation | ||
887 | needed on the output. | ||
888 | |||
889 | void * r2i(struct v3_ext_method *method, struct v3_ext_ctx *ctx, char *str); | ||
890 | |||
891 | This is just passed the string representation of the extension. It is intended | ||
892 | to be used for more elaborate extensions where the standard single and multi | ||
893 | valued options are insufficient. They can use the 'ctx' parameter to parse the | ||
894 | configuration database themselves. See the context functions section for details | ||
895 | of how to do this. | ||
896 | |||
897 | Note: although this type takes the same parameters as the "r2s" function there | ||
898 | is a subtle difference. Whereas an "r2i" function can access a configuration | ||
899 | database an "s2i" function MUST NOT. This is so the internal code can safely | ||
900 | assume that an "s2i" function will work without a configuration database. | ||
901 | |||
902 | ============================================================================== | ||
903 | PKCS#12 Library | ||
904 | ============================================================================== | ||
905 | |||
906 | This section describes the internal PKCS#12 support. There are very few | ||
907 | differences between the old external library and the new internal code at | ||
908 | present. This may well change because the external library will not be updated | ||
909 | much in future. | ||
910 | |||
911 | This version now includes a couple of high level PKCS#12 functions which | ||
912 | generally "do the right thing" and should make it much easier to handle PKCS#12 | ||
913 | structures. | ||
914 | |||
915 | HIGH LEVEL FUNCTIONS. | ||
916 | |||
917 | For most applications you only need concern yourself with the high level | ||
918 | functions. They can parse and generate simple PKCS#12 files as produced by | ||
919 | Netscape and MSIE or indeed any compliant PKCS#12 file containing a single | ||
920 | private key and certificate pair. | ||
921 | |||
922 | 1. Initialisation and cleanup. | ||
923 | |||
924 | No special initialisation is needed for the internal PKCS#12 library: the | ||
925 | standard SSLeay_add_all_algorithms() is sufficient. If you do not wish to | ||
926 | add all algorithms (you should at least add SHA1 though) then you can manually | ||
927 | initialise the PKCS#12 library with: | ||
928 | |||
929 | PKCS12_PBE_add(); | ||
930 | |||
931 | The memory allocated by the PKCS#12 library is freed up when EVP_cleanup() is | ||
932 | called or it can be directly freed with: | ||
933 | |||
934 | EVP_PBE_cleanup(); | ||
935 | |||
936 | after this call (or EVP_cleanup() ) no more PKCS#12 library functions should | ||
937 | be called. | ||
938 | |||
939 | 2. I/O functions. | ||
940 | |||
941 | i2d_PKCS12_bio(bp, p12) | ||
942 | |||
943 | This writes out a PKCS12 structure to a BIO. | ||
944 | |||
945 | i2d_PKCS12_fp(fp, p12) | ||
946 | |||
947 | This is the same but for a FILE pointer. | ||
948 | |||
949 | d2i_PKCS12_bio(bp, p12) | ||
950 | |||
951 | This reads in a PKCS12 structure from a BIO. | ||
952 | |||
953 | d2i_PKCS12_fp(fp, p12) | ||
954 | |||
955 | This is the same but for a FILE pointer. | ||
956 | |||
957 | 3. High level functions. | ||
958 | |||
959 | 3.1 Parsing with PKCS12_parse(). | ||
960 | |||
961 | int PKCS12_parse(PKCS12 *p12, char *pass, EVP_PKEY **pkey, X509 **cert, | ||
962 | STACK **ca); | ||
963 | |||
964 | This function takes a PKCS12 structure and a password (ASCII, null terminated) | ||
965 | and returns the private key, the corresponding certificate and any CA | ||
966 | certificates. If any of these is not required it can be passed as a NULL. | ||
967 | The 'ca' parameter should be either NULL, a pointer to NULL or a valid STACK | ||
968 | structure. Typically to read in a PKCS#12 file you might do: | ||
969 | |||
970 | p12 = d2i_PKCS12_fp(fp, NULL); | ||
971 | PKCS12_parse(p12, password, &pkey, &cert, NULL); /* CAs not wanted */ | ||
972 | PKCS12_free(p12); | ||
973 | |||
974 | 3.2 PKCS#12 creation with PKCS12_create(). | ||
975 | |||
976 | PKCS12 *PKCS12_create(char *pass, char *name, EVP_PKEY *pkey, X509 *cert, | ||
977 | STACK *ca, int nid_key, int nid_cert, int iter, | ||
978 | int mac_iter, int keytype); | ||
979 | |||
980 | This function will create a PKCS12 structure from a given password, name, | ||
981 | private key, certificate and optional STACK of CA certificates. The remaining | ||
982 | 5 parameters can be set to 0 and sensible defaults will be used. | ||
983 | |||
984 | The parameters nid_key and nid_cert are the key and certificate encryption | ||
985 | algorithms, iter is the encryption iteration count, mac_iter is the MAC | ||
986 | iteration count and keytype is the type of private key. If you really want | ||
987 | to know what these last 5 parameters do then read the low level section. | ||
988 | |||
989 | Typically to create a PKCS#12 file the following could be used: | ||
990 | |||
991 | p12 = PKCS12_create(pass, "My Certificate", pkey, cert, NULL, 0,0,0,0,0); | ||
992 | i2d_PKCS12_fp(fp, p12); | ||
993 | PKCS12_free(p12); | ||
994 | |||
995 | 3.3 Changing a PKCS#12 structure password. | ||
996 | |||
997 | int PKCS12_newpass(PKCS12 *p12, char *oldpass, char *newpass); | ||
998 | |||
999 | This changes the password of an already existing PKCS#12 structure. oldpass | ||
1000 | is the old password and newpass is the new one. An error occurs if the old | ||
1001 | password is incorrect. | ||
1002 | |||
1003 | LOW LEVEL FUNCTIONS. | ||
1004 | |||
1005 | In some cases the high level functions do not provide the necessary | ||
1006 | functionality. For example if you want to generate or parse more complex | ||
1007 | PKCS#12 files. The sample pkcs12 application uses the low level functions | ||
1008 | to display details about the internal structure of a PKCS#12 file. | ||
1009 | |||
1010 | Introduction. | ||
1011 | |||
1012 | This is a brief description of how a PKCS#12 file is represented internally: | ||
1013 | some knowledge of PKCS#12 is assumed. | ||
1014 | |||
1015 | A PKCS#12 object contains several levels. | ||
1016 | |||
1017 | At the lowest level is a PKCS12_SAFEBAG. This can contain a certificate, a | ||
1018 | CRL, a private key, encrypted or unencrypted, a set of safebags (so the | ||
1019 | structure can be nested) or other secrets (not documented at present). | ||
1020 | A safebag can optionally have attributes, currently these are: a unicode | ||
1021 | friendlyName (a Unicode string) or a localKeyID (a string of bytes). | ||
1022 | |||
1023 | At the next level is an authSafe which is a set of safebags collected into | ||
1024 | a PKCS#7 ContentInfo. This can be just plain data, or encrypted itself. | ||
1025 | |||
1026 | At the top level is the PKCS12 structure itself which contains a set of | ||
1027 | authSafes in an embedded PKCS#7 Contentinfo of type data. In addition it | ||
1028 | contains a MAC which is a kind of password protected digest to preserve | ||
1029 | integrity (so any unencrypted stuff below can't be tampered with). | ||
1030 | |||
1031 | The reason for these levels is so various objects can be encrypted in various | ||
1032 | ways. For example you might want to encrypt a set of private keys with | ||
1033 | triple-DES and then include the related certificates either unencrypted or | ||
1034 | with lower encryption. Yes it's the dreaded crypto laws at work again which | ||
1035 | allow strong encryption on private keys and only weak encryption on other | ||
1036 | stuff. | ||
1037 | |||
1038 | To build one of these things you turn all certificates and keys into safebags | ||
1039 | (with optional attributes). You collect the safebags into (one or more) STACKS | ||
1040 | and convert these into authsafes (encrypted or unencrypted). The authsafes | ||
1041 | are collected into a STACK and added to a PKCS12 structure. Finally a MAC | ||
1042 | inserted. | ||
1043 | |||
1044 | Pulling one apart is basically the reverse process. The MAC is verified against | ||
1045 | the given password. The authsafes are extracted and each authsafe split into | ||
1046 | a set of safebags (possibly involving decryption). Finally the safebags are | ||
1047 | decomposed into the original keys and certificates and the attributes used to | ||
1048 | match up private key and certificate pairs. | ||
1049 | |||
1050 | Anyway here are the functions that do the dirty work. | ||
1051 | |||
1052 | 1. Construction functions. | ||
1053 | |||
1054 | 1.1 Safebag functions. | ||
1055 | |||
1056 | M_PKCS12_x5092certbag(x509) | ||
1057 | |||
1058 | This macro takes an X509 structure and returns a certificate bag. The | ||
1059 | X509 structure can be freed up after calling this function. | ||
1060 | |||
1061 | M_PKCS12_x509crl2certbag(crl) | ||
1062 | |||
1063 | As above but for a CRL. | ||
1064 | |||
1065 | PKCS8_PRIV_KEY_INFO *PKEY2PKCS8(EVP_PKEY *pkey) | ||
1066 | |||
1067 | Take a private key and convert it into a PKCS#8 PrivateKeyInfo structure. | ||
1068 | Works for both RSA and DSA private keys. NB since the PKCS#8 PrivateKeyInfo | ||
1069 | structure contains a private key data in plain text form it should be free'd | ||
1070 | up as soon as it has been encrypted for security reasons (freeing up the | ||
1071 | structure zeros out the sensitive data). This can be done with | ||
1072 | PKCS8_PRIV_KEY_INFO_free(). | ||
1073 | |||
1074 | PKCS8_add_keyusage(PKCS8_PRIV_KEY_INFO *p8, int usage) | ||
1075 | |||
1076 | This sets the key type when a key is imported into MSIE or Outlook 98. Two | ||
1077 | values are currently supported: KEY_EX and KEY_SIG. KEY_EX is an exchange type | ||
1078 | key that can also be used for signing but its size is limited in the export | ||
1079 | versions of MS software to 512 bits, it is also the default. KEY_SIG is a | ||
1080 | signing only key but the keysize is unlimited (well 16K is supposed to work). | ||
1081 | If you are using the domestic version of MSIE then you can ignore this because | ||
1082 | KEY_EX is not limited and can be used for both. | ||
1083 | |||
1084 | PKCS12_SAFEBAG *PKCS12_MAKE_KEYBAG(PKCS8_PRIV_KEY_INFO *p8) | ||
1085 | |||
1086 | Convert a PKCS8 private key structure into a keybag. This routine embeds the | ||
1087 | p8 structure in the keybag so p8 should not be freed up or used after it is | ||
1088 | called. The p8 structure will be freed up when the safebag is freed. | ||
1089 | |||
1090 | PKCS12_SAFEBAG *PKCS12_MAKE_SHKEYBAG(int pbe_nid, unsigned char *pass, int passlen, unsigned char *salt, int saltlen, int iter, PKCS8_PRIV_KEY_INFO *p8) | ||
1091 | |||
1092 | Convert a PKCS#8 structure into a shrouded key bag (encrypted). p8 is not | ||
1093 | embedded and can be freed up after use. | ||
1094 | |||
1095 | int PKCS12_add_localkeyid(PKCS12_SAFEBAG *bag, unsigned char *name, int namelen) | ||
1096 | int PKCS12_add_friendlyname(PKCS12_SAFEBAG *bag, unsigned char *name, int namelen) | ||
1097 | |||
1098 | Add a local key id or a friendlyname to a safebag. | ||
1099 | |||
1100 | 1.2 Authsafe functions. | ||
1101 | |||
1102 | PKCS7 *PKCS12_pack_p7data(STACK *sk) | ||
1103 | Take a stack of safebags and convert them into an unencrypted authsafe. The | ||
1104 | stack of safebags can be freed up after calling this function. | ||
1105 | |||
1106 | PKCS7 *PKCS12_pack_p7encdata(int pbe_nid, unsigned char *pass, int passlen, unsigned char *salt, int saltlen, int iter, STACK *bags); | ||
1107 | |||
1108 | As above but encrypted. | ||
1109 | |||
1110 | 1.3 PKCS12 functions. | ||
1111 | |||
1112 | PKCS12 *PKCS12_init(int mode) | ||
1113 | |||
1114 | Initialise a PKCS12 structure (currently mode should be NID_pkcs7_data). | ||
1115 | |||
1116 | M_PKCS12_pack_authsafes(p12, safes) | ||
1117 | |||
1118 | This macro takes a STACK of authsafes and adds them to a PKCS#12 structure. | ||
1119 | |||
1120 | int PKCS12_set_mac(PKCS12 *p12, unsigned char *pass, int passlen, unsigned char *salt, int saltlen, int iter, EVP_MD *md_type); | ||
1121 | |||
1122 | Add a MAC to a PKCS12 structure. If EVP_MD is NULL use SHA-1, the spec suggests | ||
1123 | that SHA-1 should be used. | ||
1124 | |||
1125 | 2. Extraction Functions. | ||
1126 | |||
1127 | 2.1 Safebags. | ||
1128 | |||
1129 | M_PKCS12_bag_type(bag) | ||
1130 | |||
1131 | Return the type of "bag". Returns one of the following | ||
1132 | |||
1133 | NID_keyBag | ||
1134 | NID_pkcs8ShroudedKeyBag 7 | ||
1135 | NID_certBag 8 | ||
1136 | NID_crlBag 9 | ||
1137 | NID_secretBag 10 | ||
1138 | NID_safeContentsBag 11 | ||
1139 | |||
1140 | M_PKCS12_cert_bag_type(bag) | ||
1141 | |||
1142 | Returns type of certificate bag, following are understood. | ||
1143 | |||
1144 | NID_x509Certificate 14 | ||
1145 | NID_sdsiCertificate 15 | ||
1146 | |||
1147 | M_PKCS12_crl_bag_type(bag) | ||
1148 | |||
1149 | Returns crl bag type, currently only NID_crlBag is recognised. | ||
1150 | |||
1151 | M_PKCS12_certbag2x509(bag) | ||
1152 | |||
1153 | This macro extracts an X509 certificate from a certificate bag. | ||
1154 | |||
1155 | M_PKCS12_certbag2x509crl(bag) | ||
1156 | |||
1157 | As above but for a CRL. | ||
1158 | |||
1159 | EVP_PKEY * PKCS82PKEY(PKCS8_PRIV_KEY_INFO *p8) | ||
1160 | |||
1161 | Extract a private key from a PKCS8 private key info structure. | ||
1162 | |||
1163 | M_PKCS12_decrypt_skey(bag, pass, passlen) | ||
1164 | |||
1165 | Decrypt a shrouded key bag and return a PKCS8 private key info structure. | ||
1166 | Works with both RSA and DSA keys | ||
1167 | |||
1168 | char *PKCS12_get_friendlyname(bag) | ||
1169 | |||
1170 | Returns the friendlyName of a bag if present or NULL if none. The returned | ||
1171 | string is a null terminated ASCII string allocated with Malloc(). It should | ||
1172 | thus be freed up with Free() after use. | ||
1173 | |||
1174 | 2.2 AuthSafe functions. | ||
1175 | |||
1176 | M_PKCS12_unpack_p7data(p7) | ||
1177 | |||
1178 | Extract a STACK of safe bags from a PKCS#7 data ContentInfo. | ||
1179 | |||
1180 | #define M_PKCS12_unpack_p7encdata(p7, pass, passlen) | ||
1181 | |||
1182 | As above but for an encrypted content info. | ||
1183 | |||
1184 | 2.3 PKCS12 functions. | ||
1185 | |||
1186 | M_PKCS12_unpack_authsafes(p12) | ||
1187 | |||
1188 | Extract a STACK of authsafes from a PKCS12 structure. | ||
1189 | |||
1190 | M_PKCS12_mac_present(p12) | ||
1191 | |||
1192 | Check to see if a MAC is present. | ||
1193 | |||
1194 | int PKCS12_verify_mac(PKCS12 *p12, unsigned char *pass, int passlen) | ||
1195 | |||
1196 | Verify a MAC on a PKCS12 structure. Returns an error if MAC not present. | ||
1197 | |||
1198 | |||
1199 | Notes. | ||
1200 | |||
1201 | 1. All the function return 0 or NULL on error. | ||
1202 | 2. Encryption based functions take a common set of parameters. These are | ||
1203 | described below. | ||
1204 | |||
1205 | pass, passlen | ||
1206 | ASCII password and length. The password on the MAC is called the "integrity | ||
1207 | password" the encryption password is called the "privacy password" in the | ||
1208 | PKCS#12 documentation. The passwords do not have to be the same. If -1 is | ||
1209 | passed for the length it is worked out by the function itself (currently | ||
1210 | this is sometimes done whatever is passed as the length but that may change). | ||
1211 | |||
1212 | salt, saltlen | ||
1213 | A 'salt' if salt is NULL a random salt is used. If saltlen is also zero a | ||
1214 | default length is used. | ||
1215 | |||
1216 | iter | ||
1217 | Iteration count. This is a measure of how many times an internal function is | ||
1218 | called to encrypt the data. The larger this value is the longer it takes, it | ||
1219 | makes dictionary attacks on passwords harder. NOTE: Some implementations do | ||
1220 | not support an iteration count on the MAC. If the password for the MAC and | ||
1221 | encryption is the same then there is no point in having a high iteration | ||
1222 | count for encryption if the MAC has no count. The MAC could be attacked | ||
1223 | and the password used for the main decryption. | ||
1224 | |||
1225 | pbe_nid | ||
1226 | This is the NID of the password based encryption method used. The following are | ||
1227 | supported. | ||
1228 | NID_pbe_WithSHA1And128BitRC4 | ||
1229 | NID_pbe_WithSHA1And40BitRC4 | ||
1230 | NID_pbe_WithSHA1And3_Key_TripleDES_CBC | ||
1231 | NID_pbe_WithSHA1And2_Key_TripleDES_CBC | ||
1232 | NID_pbe_WithSHA1And128BitRC2_CBC | ||
1233 | NID_pbe_WithSHA1And40BitRC2_CBC | ||
1234 | |||
1235 | Which you use depends on the implementation you are exporting to. "Export | ||
1236 | grade" (i.e. cryptographically challenged) products cannot support all | ||
1237 | algorithms. Typically you may be able to use any encryption on shrouded key | ||
1238 | bags but they must then be placed in an unencrypted authsafe. Other authsafes | ||
1239 | may only support 40bit encryption. Of course if you are using SSLeay | ||
1240 | throughout you can strongly encrypt everything and have high iteration counts | ||
1241 | on everything. | ||
1242 | |||
1243 | 3. For decryption routines only the password and length are needed. | ||
1244 | |||
1245 | 4. Unlike the external version the nid's of objects are the values of the | ||
1246 | constants: that is NID_certBag is the real nid, therefore there is no | ||
1247 | PKCS12_obj_offset() function. Note the object constants are not the same as | ||
1248 | those of the external version. If you use these constants then you will need | ||
1249 | to recompile your code. | ||
1250 | |||
1251 | 5. With the exception of PKCS12_MAKE_KEYBAG(), after calling any function or | ||
1252 | macro of the form PKCS12_MAKE_SOMETHING(other) the "other" structure can be | ||
1253 | reused or freed up safely. | ||
1254 | |||