2 This is some preliminary documentation for OpenSSL.
4 ==============================================================================
6 ==============================================================================
8 The buffer library handles simple character arrays. Buffers are used for
9 various purposes in the library, most notably memory BIOs.
11 The library uses the BUF_MEM structure defined in buffer.h:
13 typedef struct buf_mem_st
15 int length; /* current number of bytes */
17 int max; /* size of buffer */
20 'length' is the current size of the buffer in bytes, 'max' is the amount of
21 memory allocated to the buffer. There are three functions which handle these
22 and one "miscellaneous" function.
24 BUF_MEM *BUF_MEM_new()
26 This allocates a new buffer of zero size. Returns the buffer or NULL on error.
28 void BUF_MEM_free(BUF_MEM *a)
30 This frees up an already existing buffer. The data is zeroed before freeing
31 up in case the buffer contains sensitive data.
33 int BUF_MEM_grow(BUF_MEM *str, int len)
35 This changes the size of an already existing buffer. It returns zero on error
36 or the new size (i.e. 'len'). Any data already in the buffer is preserved if
39 char * BUF_strdup(char *str)
41 This is the previously mentioned strdup function: like the standard library
42 strdup() it copies a null terminated string into a block of allocated memory
43 and returns a pointer to the allocated block.
45 Unlike the standard C library strdup() this function uses Malloc() and so
46 should be used in preference to the standard library strdup() because it can
47 be used for memory leak checking or replacing the malloc() function.
49 The memory allocated from BUF_strdup() should be freed up using the Free()
52 ==============================================================================
53 OpenSSL X509V3 extension configuration
54 ==============================================================================
56 OpenSSL X509V3 extension configuration: preliminary documentation.
60 For OpenSSL 0.9.2 the extension code has be considerably enhanced. It is now
61 possible to add and print out common X509 V3 certificate and CRL extensions.
65 For most simple applications you don't need to know too much about extensions:
66 the default openssl.cnf values will usually do sensible things.
68 If you want to know more you can initially quickly look through the sections
69 describing how the standard OpenSSL utilities display and add extensions and
70 then the list of supported extensions.
72 For more technical information about the meaning of extensions see:
74 http://www.imc.org/ietf-pkix/
75 http://home.netscape.com/eng/security/certs.html
79 Extension values are automatically printed out for supported extensions.
81 openssl x509 -in cert.pem -text
82 openssl crl -in crl.pem -text
84 will give information in the extension printout, for example:
87 X509v3 Basic Constraints:
89 X509v3 Subject Key Identifier:
90 73:FE:F7:59:A7:E1:26:84:44:D6:44:36:EE:79:1A:95:7C:B1:4B:15
91 X509v3 Authority Key Identifier:
92 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
94 Certificate Sign, CRL Sign
95 X509v3 Subject Alternative Name:
96 email:email@1.address, email:email@2.address
100 The OpenSSL utilities 'ca' and 'req' can now have extension sections listing
101 which certificate extensions to include. In each case a line:
103 x509_extensions = extension_section
105 indicates which section contains the extensions. In the case of 'req' the
106 extension section is used when the -x509 option is present to create a
107 self signed root certificate.
109 The 'x509' utility also supports extensions when it signs a certificate.
110 The -extfile option is used to set the configuration file containing the
111 extensions. In this case a line with:
113 extensions = extension_section
115 in the nameless (default) section is used. If no such line is included then
116 it uses the default section.
118 You can also add extensions to CRLs: a line
120 crl_extensions = crl_extension_section
122 will include extensions when the -gencrl option is used with the 'ca' utility.
123 You can add any extension to a CRL but of the supported extensions only
124 issuerAltName and authorityKeyIdentifier make any real sense. Note: these are
125 CRL extensions NOT CRL *entry* extensions which cannot currently be generated.
126 CRL entry extensions can be displayed.
128 NB. At this time Netscape Communicator rejects V2 CRLs: to get an old V1 CRL
129 you should not include a crl_extensions line in the configuration file.
131 As with all configuration files you can use the inbuilt environment expansion
132 to allow the values to be passed in the environment. Therefore if you have
133 several extension sections used for different purposes you can have a line:
135 x509_extensions = $ENV::ENV_EXT
137 and set the ENV_EXT environment variable before calling the relevant utility.
141 Extensions have the basic form:
143 extension_name=[critical,] extension_options
145 the use of the critical option makes the extension critical. Extreme caution
146 should be made when using the critical flag. If an extension is marked
147 as critical then any client that does not understand the extension should
148 reject it as invalid. Some broken software will reject certificates which
149 have *any* critical extensions (these violates PKIX but we have to live
152 There are three main types of extension: string extensions, multi-valued
153 extensions, and raw extensions.
155 String extensions simply have a string which contains either the value itself
156 or how it is obtained.
160 nsComment="This is a Comment"
162 Multi-valued extensions have a short form and a long form. The short form
163 is a list of names and values:
165 basicConstraints=critical,CA:true,pathlen:1
167 The long form allows the values to be placed in a separate section:
169 basicConstraints=critical,@bs_section
176 Both forms are equivalent. However it should be noted that in some cases the
177 same name can appear multiple times, for example,
179 subjectAltName=email:steve@here,email:steve@there
181 in this case an equivalent long form is:
183 subjectAltName=@alt_section
190 This is because the configuration file code cannot handle the same name
191 occurring twice in the same extension.
193 The syntax of raw extensions is governed by the extension code: it can
194 for example contain data in multiple sections. The correct syntax to
195 use is defined by the extension code itself: check out the certificate
196 policies extension for an example.
198 In addition it is also possible to use the word DER to include arbitrary
199 data in any extension.
201 1.2.3.4=critical,DER:01:02:03:04
204 The value following DER is a hex dump of the DER encoding of the extension
205 Any extension can be placed in this form to override the default behaviour.
208 basicConstraints=critical,DER:00:01:02:03
210 WARNING: DER should be used with caution. It is possible to create totally
211 invalid extensions unless care is taken.
213 CURRENTLY SUPPORTED EXTENSIONS.
215 If you aren't sure about extensions then they can be largely ignored: its only
216 when you want to do things like restrict certificate usage when you need to
219 The only extension that a beginner might want to look at is Basic Constraints.
220 If in addition you want to try Netscape object signing the you should also
221 look at Netscape Certificate Type.
223 Literal String extensions.
225 In each case the 'value' of the extension is placed directly in the
226 extension. Currently supported extensions in this category are: nsBaseUrl,
227 nsRevocationUrl, nsCaRevocationUrl, nsRenewalUrl, nsCaPolicyUrl,
228 nsSslServerName and nsComment.
232 nsComment="This is a test comment"
236 Bit string extensions just consist of a list of supported bits, currently
237 two extensions are in this category: PKIX keyUsage and the Netscape specific
240 nsCertType (netscape certificate type) takes the flags: client, server, email,
241 objsign, reserved, sslCA, emailCA, objCA.
243 keyUsage (PKIX key usage) takes the flags: digitalSignature, nonRepudiation,
244 keyEncipherment, dataEncipherment, keyAgreement, keyCertSign, cRLSign,
245 encipherOnly, decipherOnly.
251 keyUsage=digitalSignature, nonRepudiation
253 Hints on Netscape Certificate Type.
255 Other than Basic Constraints this is the only extension a beginner might
256 want to use, if you want to try Netscape object signing, otherwise it can
259 If you want a certificate that can be used just for object signing then:
263 will do the job. If you want to use it as a normal end user and server
264 certificate as well then
266 nsCertType=objsign,email,server
268 is more appropriate. You cannot use a self signed certificate for object
269 signing (well Netscape signtool can but it cheats!) so you need to create
270 a CA certificate and sign an end user certificate with it.
272 Side note: If you want to conform to the Netscape specifications then you
273 should really also set:
277 in the *CA* certificate for just an object signing CA and
279 nsCertType=objCA,emailCA,sslCA
281 for everything. Current Netscape software doesn't enforce this so it can
286 This is generally the only extension you need to worry about for simple
287 applications. If you want your certificate to be usable as a CA certificate
288 (in addition to an end user certificate) then you set this to:
290 basicConstraints=CA:TRUE
292 if you want to be certain the certificate cannot be used as a CA then do:
294 basicConstraints=CA:FALSE
296 The rest of this section describes more advanced usage.
298 Basic constraints is a multi-valued extension that supports a CA and an
299 optional pathlen option. The CA option takes the values true and false and
300 pathlen takes an integer. Note if the CA option is false the pathlen option
303 The pathlen parameter indicates the maximum number of CAs that can appear
304 below this one in a chain. So if you have a CA with a pathlen of zero it can
305 only be used to sign end user certificates and not further CAs. This all
306 assumes that the software correctly interprets this extension of course.
310 basicConstraints=CA:TRUE
311 basicConstraints=critical,CA:TRUE, pathlen:0
313 NOTE: for a CA to be considered valid it must have the CA option set to
314 TRUE. An end user certificate MUST NOT have the CA value set to true.
315 According to PKIX recommendations it should exclude the extension entirely,
316 however some software may require CA set to FALSE for end entity certificates.
318 Subject Key Identifier.
320 This is really a string extension and can take two possible values. Either
321 a hex string giving details of the extension value to include or the word
322 'hash' which then automatically follow PKIX guidelines in selecting and
323 appropriate key identifier. The use of the hex string is strongly discouraged.
325 Example: subjectKeyIdentifier=hash
327 Authority Key Identifier.
329 The authority key identifier extension permits two options. keyid and issuer:
330 both can take the optional value "always".
332 If the keyid option is present an attempt is made to copy the subject key
333 identifier from the parent certificate. If the value "always" is present
334 then an error is returned if the option fails.
336 The issuer option copies the issuer and serial number from the issuer
337 certificate. Normally this will only be done if the keyid option fails or
338 is not included: the "always" flag will always include the value.
340 Subject Alternative Name.
342 The subject alternative name extension allows various literal values to be
343 included in the configuration file. These include "email" (an email address)
344 "URI" a uniform resource indicator, "DNS" (a DNS domain name), RID (a
345 registered ID: OBJECT IDENTIFIER) and IP (and IP address).
347 Also the email option include a special 'copy' value. This will automatically
348 include and email addresses contained in the certificate subject name in
353 subjectAltName=email:copy,email:my@other.address,URL:http://my.url.here/
354 subjectAltName=email:my@other.address,RID:1.2.3.4
356 Issuer Alternative Name.
358 The issuer alternative name option supports all the literal options of
359 subject alternative name. It does *not* support the email:copy option because
360 that would not make sense. It does support an additional issuer:copy option
361 that will copy all the subject alternative name values from the issuer
362 certificate (if possible).
364 CRL distribution points.
366 This is a multi-valued extension that supports all the literal options of
367 subject alternative name. Of the few software packages that currently interpret
368 this extension most only interpret the URI option.
370 Currently each option will set a new DistributionPoint with the fullName
371 field set to the given value.
373 Other fields like cRLissuer and reasons cannot currently be set or displayed:
374 at this time no examples were available that used these fields.
376 If you see this extension with <UNSUPPORTED> when you attempt to print it out
377 or it doesn't appear to display correctly then let me know, including the
378 certificate (mail me at steve@openssl.org) .
382 crlDistributionPoints=URI:http://www.myhost.com/myca.crl
383 crlDistributionPoints=URI:http://www.my.com/my.crl,URI:http://www.oth.com/my.crl
385 Certificate Policies.
387 This is a RAW extension. It attempts to display the contents of this extension:
388 unfortunately this extension is often improperly encoded.
390 The certificate policies extension will rarely be used in practice: few
391 software packages interpret it correctly or at all. IE5 does partially
392 support this extension: but it needs the 'ia5org' option because it will
393 only correctly support a broken encoding. Of the options below only the
394 policy OID, explicitText and CPS options are displayed with IE5.
396 All the fields of this extension can be set by using the appropriate syntax.
398 If you follow the PKIX recommendations of not including any qualifiers and just
399 using only one OID then you just include the value of that OID. Multiple OIDs
400 can be set separated by commas, for example:
402 certificatePolicies= 1.2.4.5, 1.1.3.4
404 If you wish to include qualifiers then the policy OID and qualifiers need to
405 be specified in a separate section: this is done by using the @section syntax
406 instead of a literal OID value.
408 The section referred to must include the policy OID using the name
409 policyIdentifier, cPSuri qualifiers can be included using the syntax:
413 userNotice qualifiers can be set using the syntax:
415 userNotice.nnn=@notice
417 The value of the userNotice qualifier is specified in the relevant section.
418 This section can include explicitText, organization and noticeNumbers
419 options. explicitText and organization are text strings, noticeNumbers is a
420 comma separated list of numbers. The organization and noticeNumbers options
421 (if included) must BOTH be present. If you use the userNotice option with IE5
422 then you need the 'ia5org' option at the top level to modify the encoding:
423 otherwise it will not be interpreted properly.
427 certificatePolicies=ia5org,1.2.3.4,1.5.6.7.8,@polsect
431 policyIdentifier = 1.3.5.8
432 CPS.1="http://my.host.name/"
433 CPS.2="http://my.your.name/"
438 explicitText="Explicit Text Here"
439 organization="Organisation Name"
440 noticeNumbers=1,2,3,4
442 TECHNICAL NOTE: the ia5org option changes the type of the 'organization' field,
443 according to PKIX it should be of type DisplayText but Verisign uses an
444 IA5STRING and IE5 needs this too.
446 Display only extensions.
448 Some extensions are only partially supported and currently are only displayed
449 but cannot be set. These include private key usage period, CRL number, and
452 ==============================================================================
454 ==============================================================================
456 This section describes the internal PKCS#12 support. There are very few
457 differences between the old external library and the new internal code at
458 present. This may well change because the external library will not be updated
461 This version now includes a couple of high level PKCS#12 functions which
462 generally "do the right thing" and should make it much easier to handle PKCS#12
465 HIGH LEVEL FUNCTIONS.
467 For most applications you only need concern yourself with the high level
468 functions. They can parse and generate simple PKCS#12 files as produced by
469 Netscape and MSIE or indeed any compliant PKCS#12 file containing a single
470 private key and certificate pair.
472 1. Initialisation and cleanup.
474 No special initialisation is needed for the internal PKCS#12 library: the
475 standard SSLeay_add_all_algorithms() is sufficient. If you do not wish to
476 add all algorithms (you should at least add SHA1 though) then you can manually
477 initialise the PKCS#12 library with:
481 The memory allocated by the PKCS#12 library is freed up when EVP_cleanup() is
482 called or it can be directly freed with:
486 after this call (or EVP_cleanup() ) no more PKCS#12 library functions should
491 i2d_PKCS12_bio(bp, p12)
493 This writes out a PKCS12 structure to a BIO.
495 i2d_PKCS12_fp(fp, p12)
497 This is the same but for a FILE pointer.
499 d2i_PKCS12_bio(bp, p12)
501 This reads in a PKCS12 structure from a BIO.
503 d2i_PKCS12_fp(fp, p12)
505 This is the same but for a FILE pointer.
507 3. Parsing and creation functions.
509 3.1 Parsing with PKCS12_parse().
511 int PKCS12_parse(PKCS12 *p12, char *pass, EVP_PKEY **pkey, X509 **cert,
514 This function takes a PKCS12 structure and a password (ASCII, null terminated)
515 and returns the private key, the corresponding certificate and any CA
516 certificates. If any of these is not required it can be passed as a NULL.
517 The 'ca' parameter should be either NULL, a pointer to NULL or a valid STACK
518 structure. Typically to read in a PKCS#12 file you might do:
520 p12 = d2i_PKCS12_fp(fp, NULL);
521 PKCS12_parse(p12, password, &pkey, &cert, NULL); /* CAs not wanted */
524 3.2 PKCS#12 creation with PKCS12_create().
526 PKCS12 *PKCS12_create(char *pass, char *name, EVP_PKEY *pkey, X509 *cert,
527 STACK *ca, int nid_key, int nid_cert, int iter,
528 int mac_iter, int keytype);
530 This function will create a PKCS12 structure from a given password, name,
531 private key, certificate and optional STACK of CA certificates. The remaining
532 5 parameters can be set to 0 and sensible defaults will be used.
534 The parameters nid_key and nid_cert are the key and certificate encryption
535 algorithms, iter is the encryption iteration count, mac_iter is the MAC
536 iteration count and keytype is the type of private key. If you really want
537 to know what these last 5 parameters do then read the low level section.
539 Typically to create a PKCS#12 file the following could be used:
541 p12 = PKCS12_create(pass, "My Certificate", pkey, cert, NULL, 0,0,0,0,0);
542 i2d_PKCS12_fp(fp, p12);
547 In some cases the high level functions do not provide the necessary
548 functionality. For example if you want to generate or parse more complex
549 PKCS#12 files. The sample pkcs12 application uses the low level functions
550 to display details about the internal structure of a PKCS#12 file.
554 This is a brief description of how a PKCS#12 file is represented internally:
555 some knowledge of PKCS#12 is assumed.
557 A PKCS#12 object contains several levels.
559 At the lowest level is a PKCS12_SAFEBAG. This can contain a certificate, a
560 CRL, a private key, encrypted or unencrypted, a set of safebags (so the
561 structure can be nested) or other secrets (not documented at present).
562 A safebag can optionally have attributes, currently these are: a unicode
563 friendlyName (a Unicode string) or a localKeyID (a string of bytes).
565 At the next level is an authSafe which is a set of safebags collected into
566 a PKCS#7 ContentInfo. This can be just plain data, or encrypted itself.
568 At the top level is the PKCS12 structure itself which contains a set of
569 authSafes in an embedded PKCS#7 Contentinfo of type data. In addition it
570 contains a MAC which is a kind of password protected digest to preserve
571 integrity (so any unencrypted stuff below can't be tampered with).
573 The reason for these levels is so various objects can be encrypted in various
574 ways. For example you might want to encrypt a set of private keys with
575 triple-DES and then include the related certificates either unencrypted or
576 with lower encryption. Yes it's the dreaded crypto laws at work again which
577 allow strong encryption on private keys and only weak encryption on other
580 To build one of these things you turn all certificates and keys into safebags
581 (with optional attributes). You collect the safebags into (one or more) STACKS
582 and convert these into authsafes (encrypted or unencrypted). The authsafes
583 are collected into a STACK and added to a PKCS12 structure. Finally a MAC
586 Pulling one apart is basically the reverse process. The MAC is verified against
587 the given password. The authsafes are extracted and each authsafe split into
588 a set of safebags (possibly involving decryption). Finally the safebags are
589 decomposed into the original keys and certificates and the attributes used to
590 match up private key and certificate pairs.
592 Anyway here are the functions that do the dirty work.
594 1. Construction functions.
596 1.1 Safebag functions.
598 M_PKCS12_x5092certbag(x509)
600 This macro takes an X509 structure and returns a certificate bag. The
601 X509 structure can be freed up after calling this function.
603 M_PKCS12_x509crl2certbag(crl)
605 As above but for a CRL.
607 PKCS8_PRIV_KEY_INFO *PKEY2PKCS8(EVP_PKEY *pkey)
609 Take a private key and convert it into a PKCS#8 PrivateKeyInfo structure.
610 Works for both RSA and DSA private keys. NB since the PKCS#8 PrivateKeyInfo
611 structure contains a private key data in plain text form it should be free'd
612 up as soon as it has been encrypted for security reasons (freeing up the
613 structure zeros out the sensitive data). This can be done with
614 PKCS8_PRIV_KEY_INFO_free().
616 PKCS8_add_keyusage(PKCS8_PRIV_KEY_INFO *p8, int usage)
618 This sets the key type when a key is imported into MSIE or Outlook 98. Two
619 values are currently supported: KEY_EX and KEY_SIG. KEY_EX is an exchange type
620 key that can also be used for signing but its size is limited in the export
621 versions of MS software to 512 bits, it is also the default. KEY_SIG is a
622 signing only key but the keysize is unlimited (well 16K is supposed to work).
623 If you are using the domestic version of MSIE then you can ignore this because
624 KEY_EX is not limited and can be used for both.
626 PKCS12_SAFEBAG *PKCS12_MAKE_KEYBAG(PKCS8_PRIV_KEY_INFO *p8)
628 Convert a PKCS8 private key structure into a keybag. This routine embeds the
629 p8 structure in the keybag so p8 should not be freed up or used after it is
630 called. The p8 structure will be freed up when the safebag is freed.
632 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)
634 Convert a PKCS#8 structure into a shrouded key bag (encrypted). p8 is not
635 embedded and can be freed up after use.
637 int PKCS12_add_localkeyid(PKCS12_SAFEBAG *bag, unsigned char *name, int namelen)
638 int PKCS12_add_friendlyname(PKCS12_SAFEBAG *bag, unsigned char *name, int namelen)
640 Add a local key id or a friendlyname to a safebag.
642 1.2 Authsafe functions.
644 PKCS7 *PKCS12_pack_p7data(STACK *sk)
645 Take a stack of safebags and convert them into an unencrypted authsafe. The
646 stack of safebags can be freed up after calling this function.
648 PKCS7 *PKCS12_pack_p7encdata(int pbe_nid, unsigned char *pass, int passlen, unsigned char *salt, int saltlen, int iter, STACK *bags);
650 As above but encrypted.
652 1.3 PKCS12 functions.
654 PKCS12 *PKCS12_init(int mode)
656 Initialise a PKCS12 structure (currently mode should be NID_pkcs7_data).
658 M_PKCS12_pack_authsafes(p12, safes)
660 This macro takes a STACK of authsafes and adds them to a PKCS#12 structure.
662 int PKCS12_set_mac(PKCS12 *p12, unsigned char *pass, int passlen, unsigned char *salt, int saltlen, int iter, EVP_MD *md_type);
664 Add a MAC to a PKCS12 structure. If EVP_MD is NULL use SHA-1, the spec suggests
665 that SHA-1 should be used.
667 2. Extraction Functions.
671 M_PKCS12_bag_type(bag)
673 Return the type of "bag". Returns one of the following
676 NID_pkcs8ShroudedKeyBag 7
680 NID_safeContentsBag 11
682 M_PKCS12_cert_bag_type(bag)
684 Returns type of certificate bag, following are understood.
686 NID_x509Certificate 14
687 NID_sdsiCertificate 15
689 M_PKCS12_crl_bag_type(bag)
691 Returns crl bag type, currently only NID_crlBag is recognised.
693 M_PKCS12_certbag2x509(bag)
695 This macro extracts an X509 certificate from a certificate bag.
697 M_PKCS12_certbag2x509crl(bag)
699 As above but for a CRL.
701 EVP_PKEY * PKCS82PKEY(PKCS8_PRIV_KEY_INFO *p8)
703 Extract a private key from a PKCS8 private key info structure.
705 M_PKCS12_decrypt_skey(bag, pass, passlen)
707 Decrypt a shrouded key bag and return a PKCS8 private key info structure.
708 Works with both RSA and DSA keys
710 char *PKCS12_get_friendlyname(bag)
712 Returns the friendlyName of a bag if present or NULL if none. The returned
713 string is a null terminated ASCII string allocated with Malloc(). It should
714 thus be freed up with Free() after use.
716 2.2 AuthSafe functions.
718 M_PKCS12_unpack_p7data(p7)
720 Extract a STACK of safe bags from a PKCS#7 data ContentInfo.
722 #define M_PKCS12_unpack_p7encdata(p7, pass, passlen)
724 As above but for an encrypted content info.
726 2.3 PKCS12 functions.
728 M_PKCS12_unpack_authsafes(p12)
730 Extract a STACK of authsafes from a PKCS12 structure.
732 M_PKCS12_mac_present(p12)
734 Check to see if a MAC is present.
736 int PKCS12_verify_mac(PKCS12 *p12, unsigned char *pass, int passlen)
738 Verify a MAC on a PKCS12 structure. Returns an error if MAC not present.
743 1. All the function return 0 or NULL on error.
744 2. Encryption based functions take a common set of parameters. These are
748 ASCII password and length. The password on the MAC is called the "integrity
749 password" the encryption password is called the "privacy password" in the
750 PKCS#12 documentation. The passwords do not have to be the same. If -1 is
751 passed for the length it is worked out by the function itself (currently
752 this is sometimes done whatever is passed as the length but that may change).
755 A 'salt' if salt is NULL a random salt is used. If saltlen is also zero a
756 default length is used.
759 Iteration count. This is a measure of how many times an internal function is
760 called to encrypt the data. The larger this value is the longer it takes, it
761 makes dictionary attacks on passwords harder. NOTE: Some implementations do
762 not support an iteration count on the MAC. If the password for the MAC and
763 encryption is the same then there is no point in having a high iteration
764 count for encryption if the MAC has no count. The MAC could be attacked
765 and the password used for the main decryption.
768 This is the NID of the password based encryption method used. The following are
770 NID_pbe_WithSHA1And128BitRC4
771 NID_pbe_WithSHA1And40BitRC4
772 NID_pbe_WithSHA1And3_Key_TripleDES_CBC
773 NID_pbe_WithSHA1And2_Key_TripleDES_CBC
774 NID_pbe_WithSHA1And128BitRC2_CBC
775 NID_pbe_WithSHA1And40BitRC2_CBC
777 Which you use depends on the implementation you are exporting to. "Export
778 grade" (i.e. cryptographically challenged) products cannot support all
779 algorithms. Typically you may be able to use any encryption on shrouded key
780 bags but they must then be placed in an unencrypted authsafe. Other authsafes
781 may only support 40bit encryption. Of course if you are using SSLeay
782 throughout you can strongly encrypt everything and have high iteration counts
785 3. For decryption routines only the password and length are needed.
787 4. Unlike the external version the nid's of objects are the values of the
788 constants: that is NID_certBag is the real nid, therefore there is no
789 PKCS12_obj_offset() function. Note the object constants are not the same as
790 those of the external version. If you use these constants then you will need
791 to recompile your code.
793 5. With the exception of PKCS12_MAKE_KEYBAG(), after calling any function or
794 macro of the form PKCS12_MAKE_SOMETHING(other) the "other" structure can be
795 reused or freed up safely.