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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 | |||
