openssl-req.pod.in 22 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687
  1. =pod
  2. {- OpenSSL::safe::output_do_not_edit_headers(); -}
  3. =head1 NAME
  4. openssl-req - PKCS#10 certificate request and certificate generating utility
  5. =head1 SYNOPSIS
  6. B<openssl> B<req>
  7. [B<-help>]
  8. [B<-inform> B<DER>|B<PEM>]
  9. [B<-outform> B<DER>|B<PEM>]
  10. [B<-in> I<filename>]
  11. [B<-passin> I<arg>]
  12. [B<-out> I<filename>]
  13. [B<-passout> I<arg>]
  14. [B<-text>]
  15. [B<-pubkey>]
  16. [B<-noout>]
  17. [B<-verify>]
  18. [B<-modulus>]
  19. [B<-new>]
  20. [B<-newkey> I<arg>]
  21. [B<-pkeyopt> I<opt>:I<value>]
  22. [B<-nodes>]
  23. [B<-key> I<filename>]
  24. [B<-keyform> B<DER>|B<PEM>]
  25. [B<-keyout> I<filename>]
  26. [B<-keygen_engine> I<id>]
  27. [B<-I<digest>>]
  28. [B<-config> I<filename>]
  29. [B<-multivalue-rdn>]
  30. [B<-x509>]
  31. [B<-days> I<n>]
  32. [B<-set_serial> I<n>]
  33. [B<-newhdr>]
  34. [B<-addext> I<ext>]
  35. [B<-extensions> I<section>]
  36. [B<-reqexts> I<section>]
  37. [B<-precert>]
  38. [B<-utf8>]
  39. [B<-reqopt>]
  40. [B<-subject>]
  41. [B<-subj> I<arg>]
  42. [B<-sigopt> I<nm>:I<v>]
  43. [B<-batch>]
  44. [B<-verbose>]
  45. [B<-sm2-id> I<string>]
  46. [B<-sm2-hex-id> I<hex-string>]
  47. {- $OpenSSL::safe::opt_name_synopsis -}
  48. {- $OpenSSL::safe::opt_r_synopsis -}
  49. {- $OpenSSL::safe::opt_engine_synopsis -}
  50. =for openssl ifdef engine keygen_engine sm2-id sm2-hex-id
  51. =head1 DESCRIPTION
  52. This command primarily creates and processes certificate requests
  53. in PKCS#10 format. It can additionally create self signed certificates
  54. for use as root CAs for example.
  55. =head1 OPTIONS
  56. =over 4
  57. =item B<-help>
  58. Print out a usage message.
  59. =item B<-inform> B<DER>|B<PEM>, B<-outform> B<DER>|B<PEM>
  60. The input and formats; the default is B<PEM>.
  61. See L<openssl(1)/Format Options> for details.
  62. The data is a PKCS#10 object.
  63. =item B<-in> I<filename>
  64. This specifies the input filename to read a request from or standard input
  65. if this option is not specified. A request is only read if the creation
  66. options (B<-new> and B<-newkey>) are not specified.
  67. =item B<-sigopt> I<nm>:I<v>
  68. Pass options to the signature algorithm during sign or verify operations.
  69. Names and values of these options are algorithm-specific.
  70. =item B<-passin> I<arg>, B<-passout> I<arg>
  71. The password source for the input and output file.
  72. For more information about the format of B<arg>
  73. see L<openssl(1)/Pass Phrase Options>.
  74. =item B<-out> I<filename>
  75. This specifies the output filename to write to or standard output by
  76. default.
  77. =item B<-text>
  78. Prints out the certificate request in text form.
  79. =item B<-subject>
  80. Prints out the request subject (or certificate subject if B<-x509> is
  81. specified)
  82. =item B<-pubkey>
  83. Outputs the public key.
  84. =item B<-noout>
  85. This option prevents output of the encoded version of the request.
  86. =item B<-modulus>
  87. This option prints out the value of the modulus of the public key
  88. contained in the request.
  89. =item B<-verify>
  90. Verifies the signature on the request.
  91. =item B<-new>
  92. This option generates a new certificate request. It will prompt
  93. the user for the relevant field values. The actual fields
  94. prompted for and their maximum and minimum sizes are specified
  95. in the configuration file and any requested extensions.
  96. If the B<-key> option is not used it will generate a new RSA private
  97. key using information specified in the configuration file.
  98. =item B<-newkey> I<arg>
  99. This option creates a new certificate request and a new private
  100. key. The argument takes one of several forms.
  101. B<rsa:>I<nbits>, where
  102. I<nbits> is the number of bits, generates an RSA key I<nbits>
  103. in size. If I<nbits> is omitted, i.e. B<-newkey> I<rsa> specified,
  104. the default key size, specified in the configuration file is used.
  105. All other algorithms support the B<-newkey> I<alg>:I<file> form, where file
  106. may be an algorithm parameter file, created with C<openssl genpkey -genparam>
  107. or an X.509 certificate for a key with appropriate algorithm.
  108. B<param:>I<file> generates a key using the parameter file or certificate
  109. I<file>, the algorithm is determined by the parameters. I<algname>:I<file>
  110. use algorithm I<algname> and parameter file I<file>: the two algorithms must
  111. match or an error occurs. I<algname> just uses algorithm I<algname>, and
  112. parameters, if necessary should be specified via B<-pkeyopt> parameter.
  113. B<dsa:>I<filename> generates a DSA key using the parameters
  114. in the file I<filename>. B<ec:>I<filename> generates EC key (usable both with
  115. ECDSA or ECDH algorithms), B<gost2001:>I<filename> generates GOST R
  116. 34.10-2001 key (requires B<gost> engine configured in the configuration
  117. file). If just B<gost2001> is specified a parameter set should be
  118. specified by B<-pkeyopt> I<paramset:X>
  119. =item B<-pkeyopt> I<opt>:I<value>
  120. Set the public key algorithm option I<opt> to I<value>. The precise set of
  121. options supported depends on the public key algorithm used and its
  122. implementation.
  123. See L<openssl-genpkey(1)/KEY GENERATION OPTIONS> for more details.
  124. =item B<-key> I<filename>
  125. This specifies the file to read the private key from. It also
  126. accepts PKCS#8 format private keys for PEM format files.
  127. =item B<-keyform> B<DER>|B<PEM>
  128. The format of the private key; the default is B<PEM>.
  129. See L<openssl(1)/Format Options> for details.
  130. =item B<-keyout> I<filename>
  131. This gives the filename to write the newly created private key to.
  132. If this option is not specified then the filename present in the
  133. configuration file is used.
  134. =item B<-nodes>
  135. If this option is specified then if a private key is created it
  136. will not be encrypted.
  137. =item B<-I<digest>>
  138. This specifies the message digest to sign the request.
  139. Any digest supported by the OpenSSL B<dgst> command can be used.
  140. This overrides the digest algorithm specified in
  141. the configuration file.
  142. Some public key algorithms may override this choice. For instance, DSA
  143. signatures always use SHA1, GOST R 34.10 signatures always use
  144. GOST R 34.11-94 (B<-md_gost94>), Ed25519 and Ed448 never use any digest.
  145. =item B<-config> I<filename>
  146. This allows an alternative configuration file to be specified.
  147. Optional; for a description of the default value,
  148. see L<openssl(1)/COMMAND SUMMARY>.
  149. =item B<-subj> I<arg>
  150. Sets subject name for new request or supersedes the subject name
  151. when processing a request.
  152. The arg must be formatted as C</type0=value0/type1=value1/type2=...>.
  153. Keyword characters may be escaped by \ (backslash), and whitespace is retained.
  154. Empty values are permitted, but the corresponding type will not be included
  155. in the request.
  156. =item B<-multivalue-rdn>
  157. This option causes the -subj argument to be interpreted with full
  158. support for multivalued RDNs. Example:
  159. C</DC=org/DC=OpenSSL/DC=users/UID=123456+CN=John Doe>
  160. If -multi-rdn is not used then the UID value is C<123456+CN=John Doe>.
  161. =item B<-x509>
  162. This option outputs a self signed certificate instead of a certificate
  163. request. This is typically used to generate a test certificate or
  164. a self signed root CA. The extensions added to the certificate
  165. (if any) are specified in the configuration file. Unless specified
  166. using the B<-set_serial> option, a large random number will be used for
  167. the serial number.
  168. If existing request is specified with the B<-in> option, it is converted
  169. to the self signed certificate otherwise new request is created.
  170. =item B<-days> I<n>
  171. When the B<-x509> option is being used this specifies the number of
  172. days to certify the certificate for, otherwise it is ignored. I<n> should
  173. be a positive integer. The default is 30 days.
  174. =item B<-set_serial> I<n>
  175. Serial number to use when outputting a self signed certificate. This
  176. may be specified as a decimal value or a hex value if preceded by C<0x>.
  177. =item B<-addext> I<ext>
  178. Add a specific extension to the certificate (if the B<-x509> option is
  179. present) or certificate request. The argument must have the form of
  180. a key=value pair as it would appear in a config file.
  181. This option can be given multiple times.
  182. =item B<-extensions> I<section>
  183. =item B<-reqexts> I<section>
  184. These options specify alternative sections to include certificate
  185. extensions (if the B<-x509> option is present) or certificate
  186. request extensions. This allows several different sections to
  187. be used in the same configuration file to specify requests for
  188. a variety of purposes.
  189. =item B<-precert>
  190. A poison extension will be added to the certificate, making it a
  191. "pre-certificate" (see RFC6962). This can be submitted to Certificate
  192. Transparency logs in order to obtain signed certificate timestamps (SCTs).
  193. These SCTs can then be embedded into the pre-certificate as an extension, before
  194. removing the poison and signing the certificate.
  195. This implies the B<-new> flag.
  196. =item B<-utf8>
  197. This option causes field values to be interpreted as UTF8 strings, by
  198. default they are interpreted as ASCII. This means that the field
  199. values, whether prompted from a terminal or obtained from a
  200. configuration file, must be valid UTF8 strings.
  201. =item B<-reqopt> I<option>
  202. Customise the output format used with B<-text>. The I<option> argument can be
  203. a single option or multiple options separated by commas.
  204. See discussion of the B<-certopt> parameter in the L<openssl-x509(1)>
  205. command.
  206. =item B<-newhdr>
  207. Adds the word B<NEW> to the PEM file header and footer lines on the outputted
  208. request. Some software (Netscape certificate server) and some CAs need this.
  209. =item B<-batch>
  210. Non-interactive mode.
  211. =item B<-verbose>
  212. Print extra details about the operations being performed.
  213. =item B<-keygen_engine> I<id>
  214. Specifies an engine (by its unique I<id> string) which would be used
  215. for key generation operations.
  216. =item B<-sm2-id>
  217. Specify the ID string to use when verifying an SM2 certificate request. The ID
  218. string is required by the SM2 signature algorithm for signing and verification.
  219. =item B<-sm2-hex-id>
  220. Specify a binary ID string to use when verifying an SM2 certificate request. The
  221. argument for this option is string of hexadecimal digits.
  222. {- $OpenSSL::safe::opt_name_item -}
  223. {- $OpenSSL::safe::opt_r_item -}
  224. {- $OpenSSL::safe::opt_engine_item -}
  225. =back
  226. =head1 CONFIGURATION FILE FORMAT
  227. The configuration options are specified in the B<req> section of
  228. the configuration file. As with all configuration files if no
  229. value is specified in the specific section (i.e. B<req>) then
  230. the initial unnamed or B<default> section is searched too.
  231. The options available are described in detail below.
  232. =over 4
  233. =item B<input_password output_password>
  234. The passwords for the input private key file (if present) and
  235. the output private key file (if one will be created). The
  236. command line options B<passin> and B<passout> override the
  237. configuration file values.
  238. =item B<default_bits>
  239. Specifies the default key size in bits.
  240. This option is used in conjunction with the B<-new> option to generate
  241. a new key. It can be overridden by specifying an explicit key size in
  242. the B<-newkey> option. The smallest accepted key size is 512 bits. If
  243. no key size is specified then 2048 bits is used.
  244. =item B<default_keyfile>
  245. This is the default filename to write a private key to. If not
  246. specified the key is written to standard output. This can be
  247. overridden by the B<-keyout> option.
  248. =item B<oid_file>
  249. This specifies a file containing additional B<OBJECT IDENTIFIERS>.
  250. Each line of the file should consist of the numerical form of the
  251. object identifier followed by white space then the short name followed
  252. by white space and finally the long name.
  253. =item B<oid_section>
  254. This specifies a section in the configuration file containing extra
  255. object identifiers. Each line should consist of the short name of the
  256. object identifier followed by B<=> and the numerical form. The short
  257. and long names are the same when this option is used.
  258. =item B<RANDFILE>
  259. At startup the specified file is loaded into the random number generator,
  260. and at exit 256 bytes will be written to it.
  261. It is used for private key generation.
  262. =item B<encrypt_key>
  263. If this is set to B<no> then if a private key is generated it is
  264. B<not> encrypted. This is equivalent to the B<-nodes> command line
  265. option. For compatibility B<encrypt_rsa_key> is an equivalent option.
  266. =item B<default_md>
  267. This option specifies the digest algorithm to use. Any digest supported by the
  268. OpenSSL B<dgst> command can be used. This option can be overridden on the
  269. command line. Certain signing algorithms (i.e. Ed25519 and Ed448) will ignore
  270. any digest that has been set.
  271. =item B<string_mask>
  272. This option masks out the use of certain string types in certain
  273. fields. Most users will not need to change this option.
  274. It can be set to several values B<default> which is also the default
  275. option uses PrintableStrings, T61Strings and BMPStrings if the
  276. B<pkix> value is used then only PrintableStrings and BMPStrings will
  277. be used. This follows the PKIX recommendation in RFC2459. If the
  278. B<utf8only> option is used then only UTF8Strings will be used: this
  279. is the PKIX recommendation in RFC2459 after 2003. Finally the B<nombstr>
  280. option just uses PrintableStrings and T61Strings: certain software has
  281. problems with BMPStrings and UTF8Strings: in particular Netscape.
  282. =item B<req_extensions>
  283. This specifies the configuration file section containing a list of
  284. extensions to add to the certificate request. It can be overridden
  285. by the B<-reqexts> command line switch. See the
  286. L<x509v3_config(5)> manual page for details of the
  287. extension section format.
  288. =item B<x509_extensions>
  289. This specifies the configuration file section containing a list of
  290. extensions to add to certificate generated when the B<-x509> switch
  291. is used. It can be overridden by the B<-extensions> command line switch.
  292. =item B<prompt>
  293. If set to the value B<no> this disables prompting of certificate fields
  294. and just takes values from the config file directly. It also changes the
  295. expected format of the B<distinguished_name> and B<attributes> sections.
  296. =item B<utf8>
  297. If set to the value B<yes> then field values to be interpreted as UTF8
  298. strings, by default they are interpreted as ASCII. This means that
  299. the field values, whether prompted from a terminal or obtained from a
  300. configuration file, must be valid UTF8 strings.
  301. =item B<attributes>
  302. This specifies the section containing any request attributes: its format
  303. is the same as B<distinguished_name>. Typically these may contain the
  304. challengePassword or unstructuredName types. They are currently ignored
  305. by OpenSSL's request signing utilities but some CAs might want them.
  306. =item B<distinguished_name>
  307. This specifies the section containing the distinguished name fields to
  308. prompt for when generating a certificate or certificate request. The format
  309. is described in the next section.
  310. =back
  311. =head1 DISTINGUISHED NAME AND ATTRIBUTE SECTION FORMAT
  312. There are two separate formats for the distinguished name and attribute
  313. sections. If the B<prompt> option is set to B<no> then these sections
  314. just consist of field names and values: for example,
  315. CN=My Name
  316. OU=My Organization
  317. emailAddress=someone@somewhere.org
  318. This allows external programs (e.g. GUI based) to generate a template file with
  319. all the field names and values and just pass it to this command. An example
  320. of this kind of configuration file is contained in the B<EXAMPLES> section.
  321. Alternatively if the B<prompt> option is absent or not set to B<no> then the
  322. file contains field prompting information. It consists of lines of the form:
  323. fieldName="prompt"
  324. fieldName_default="default field value"
  325. fieldName_min= 2
  326. fieldName_max= 4
  327. "fieldName" is the field name being used, for example commonName (or CN).
  328. The "prompt" string is used to ask the user to enter the relevant
  329. details. If the user enters nothing then the default value is used if no
  330. default value is present then the field is omitted. A field can
  331. still be omitted if a default value is present if the user just
  332. enters the '.' character.
  333. The number of characters entered must be between the fieldName_min and
  334. fieldName_max limits: there may be additional restrictions based
  335. on the field being used (for example countryName can only ever be
  336. two characters long and must fit in a PrintableString).
  337. Some fields (such as organizationName) can be used more than once
  338. in a DN. This presents a problem because configuration files will
  339. not recognize the same name occurring twice. To avoid this problem
  340. if the fieldName contains some characters followed by a full stop
  341. they will be ignored. So for example a second organizationName can
  342. be input by calling it "1.organizationName".
  343. The actual permitted field names are any object identifier short or
  344. long names. These are compiled into OpenSSL and include the usual
  345. values such as commonName, countryName, localityName, organizationName,
  346. organizationalUnitName, stateOrProvinceName. Additionally emailAddress
  347. is included as well as name, surname, givenName, initials, and dnQualifier.
  348. Additional object identifiers can be defined with the B<oid_file> or
  349. B<oid_section> options in the configuration file. Any additional fields
  350. will be treated as though they were a DirectoryString.
  351. =head1 EXAMPLES
  352. Examine and verify certificate request:
  353. openssl req -in req.pem -text -verify -noout
  354. Create a private key and then generate a certificate request from it:
  355. openssl genrsa -out key.pem 2048
  356. openssl req -new -key key.pem -out req.pem
  357. The same but just using req:
  358. openssl req -newkey rsa:2048 -keyout key.pem -out req.pem
  359. Generate a self signed root certificate:
  360. openssl req -x509 -newkey rsa:2048 -keyout key.pem -out req.pem
  361. Create an SM2 private key and then generate a certificate request from it:
  362. openssl ecparam -genkey -name SM2 -out sm2.key
  363. openssl req -new -key sm2.key -out sm2.csr -sm3 -sigopt "sm2_id:1234567812345678"
  364. Examine and verify an SM2 certificate request:
  365. openssl req -verify -in sm2.csr -sm3 -sm2-id 1234567812345678
  366. Example of a file pointed to by the B<oid_file> option:
  367. 1.2.3.4 shortName A longer Name
  368. 1.2.3.6 otherName Other longer Name
  369. Example of a section pointed to by B<oid_section> making use of variable
  370. expansion:
  371. testoid1=1.2.3.5
  372. testoid2=${testoid1}.6
  373. Sample configuration file prompting for field values:
  374. [ req ]
  375. default_bits = 2048
  376. default_keyfile = privkey.pem
  377. distinguished_name = req_distinguished_name
  378. attributes = req_attributes
  379. req_extensions = v3_ca
  380. dirstring_type = nobmp
  381. [ req_distinguished_name ]
  382. countryName = Country Name (2 letter code)
  383. countryName_default = AU
  384. countryName_min = 2
  385. countryName_max = 2
  386. localityName = Locality Name (eg, city)
  387. organizationalUnitName = Organizational Unit Name (eg, section)
  388. commonName = Common Name (eg, YOUR name)
  389. commonName_max = 64
  390. emailAddress = Email Address
  391. emailAddress_max = 40
  392. [ req_attributes ]
  393. challengePassword = A challenge password
  394. challengePassword_min = 4
  395. challengePassword_max = 20
  396. [ v3_ca ]
  397. subjectKeyIdentifier=hash
  398. authorityKeyIdentifier=keyid:always,issuer:always
  399. basicConstraints = critical, CA:true
  400. Sample configuration containing all field values:
  401. [ req ]
  402. default_bits = 2048
  403. default_keyfile = keyfile.pem
  404. distinguished_name = req_distinguished_name
  405. attributes = req_attributes
  406. prompt = no
  407. output_password = mypass
  408. [ req_distinguished_name ]
  409. C = GB
  410. ST = Test State or Province
  411. L = Test Locality
  412. O = Organization Name
  413. OU = Organizational Unit Name
  414. CN = Common Name
  415. emailAddress = test@email.address
  416. [ req_attributes ]
  417. challengePassword = A challenge password
  418. Example of giving the most common attributes (subject and extensions)
  419. on the command line:
  420. openssl req -new -subj "/C=GB/CN=foo" \
  421. -addext "subjectAltName = DNS:foo.co.uk" \
  422. -addext "certificatePolicies = 1.2.3.4" \
  423. -newkey rsa:2048 -keyout key.pem -out req.pem
  424. =head1 NOTES
  425. The certificate requests generated by B<Xenroll> with MSIE have extensions
  426. added. It includes the B<keyUsage> extension which determines the type of
  427. key (signature only or general purpose) and any additional OIDs entered
  428. by the script in an B<extendedKeyUsage> extension.
  429. =head1 DIAGNOSTICS
  430. The following messages are frequently asked about:
  431. Using configuration from /some/path/openssl.cnf
  432. Unable to load config info
  433. This is followed some time later by:
  434. unable to find 'distinguished_name' in config
  435. problems making Certificate Request
  436. The first error message is the clue: it can't find the configuration
  437. file! Certain operations (like examining a certificate request) don't
  438. need a configuration file so its use isn't enforced. Generation of
  439. certificates or requests however does need a configuration file. This
  440. could be regarded as a bug.
  441. Another puzzling message is this:
  442. Attributes:
  443. a0:00
  444. this is displayed when no attributes are present and the request includes
  445. the correct empty B<SET OF> structure (the DER encoding of which is 0xa0
  446. 0x00). If you just see:
  447. Attributes:
  448. then the B<SET OF> is missing and the encoding is technically invalid (but
  449. it is tolerated). See the description of the command line option B<-asn1-kludge>
  450. for more information.
  451. =head1 BUGS
  452. OpenSSL's handling of T61Strings (aka TeletexStrings) is broken: it effectively
  453. treats them as ISO-8859-1 (Latin 1), Netscape and MSIE have similar behaviour.
  454. This can cause problems if you need characters that aren't available in
  455. PrintableStrings and you don't want to or can't use BMPStrings.
  456. As a consequence of the T61String handling the only correct way to represent
  457. accented characters in OpenSSL is to use a BMPString: unfortunately Netscape
  458. currently chokes on these. If you have to use accented characters with Netscape
  459. and MSIE then you currently need to use the invalid T61String form.
  460. The current prompting is not very friendly. It doesn't allow you to confirm what
  461. you've just entered. Other things like extensions in certificate requests are
  462. statically defined in the configuration file. Some of these: like an email
  463. address in subjectAltName should be input by the user.
  464. =head1 SEE ALSO
  465. L<openssl(1)>,
  466. L<openssl-x509(1)>,
  467. L<openssl-ca(1)>,
  468. L<openssl-genrsa(1)>,
  469. L<openssl-gendsa(1)>,
  470. L<config(5)>,
  471. L<x509v3_config(5)>
  472. =head1 COPYRIGHT
  473. Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
  474. Licensed under the Apache License 2.0 (the "License"). You may not use
  475. this file except in compliance with the License. You can obtain a copy
  476. in the file LICENSE in the source distribution or at
  477. L<https://www.openssl.org/source/license.html>.
  478. =cut