This is some preliminary documentation for OpenSSL.
-==============================================================================
- BUFFER Library
-==============================================================================
-
-The buffer library handles simple character arrays. Buffers are used for
-various purposes in the library, most notably memory BIOs.
-
-The library uses the BUF_MEM structure defined in buffer.h:
-
-typedef struct buf_mem_st
-{
- int length; /* current number of bytes */
- char *data;
- int max; /* size of buffer */
-} BUF_MEM;
-
-'length' is the current size of the buffer in bytes, 'max' is the amount of
-memory allocated to the buffer. There are three functions which handle these
-and one "miscellaneous" function.
-
-BUF_MEM *BUF_MEM_new()
-
-This allocates a new buffer of zero size. Returns the buffer or NULL on error.
-
-void BUF_MEM_free(BUF_MEM *a)
-
-This frees up an already existing buffer. The data is zeroed before freeing
-up in case the buffer contains sensitive data.
-
-int BUF_MEM_grow(BUF_MEM *str, int len)
-
-This changes the size of an already existing buffer. It returns zero on error
-or the new size (i.e. 'len'). Any data already in the buffer is preserved if
-it increases in size.
+Contents:
-char * BUF_strdup(char *str)
+ OpenSSL X509V3 extension configuration
+ X509V3 Extension code: programmers guide
+ PKCS#12 Library
-This is the previously mentioned strdup function: like the standard library
-strdup() it copies a null terminated string into a block of allocated memory
-and returns a pointer to the allocated block.
-
-Unlike the standard C library strdup() this function uses Malloc() and so
-should be used in preference to the standard library strdup() because it can
-be used for memory leak checking or replacing the malloc() function.
-
-The memory allocated from BUF_strdup() should be freed up using the Free()
-function.
==============================================================================
OpenSSL X509V3 extension configuration
For OpenSSL 0.9.2 the extension code has be considerably enhanced. It is now
possible to add and print out common X509 V3 certificate and CRL extensions.
-For more information about the meaning of extensions see:
+BEGINNERS NOTE
+
+For most simple applications you don't need to know too much about extensions:
+the default openssl.cnf values will usually do sensible things.
+
+If you want to know more you can initially quickly look through the sections
+describing how the standard OpenSSL utilities display and add extensions and
+then the list of supported extensions.
+
+For more technical information about the meaning of extensions see:
http://www.imc.org/ietf-pkix/
http://home.netscape.com/eng/security/certs.html
will give information in the extension printout, for example:
-
X509v3 extensions:
X509v3 Basic Constraints:
CA:TRUE
CRL entry extensions can be displayed.
NB. At this time Netscape Communicator rejects V2 CRLs: to get an old V1 CRL
-you should comment out the crl_extensions line in the configuration file.
+you should not include a crl_extensions line in the configuration file.
As with all configuration files you can use the inbuilt environment expansion
to allow the values to be passed in the environment. Therefore if you have
email.2=steve@there
This is because the configuration file code cannot handle the same name
-occurring twice in the same extension.
+occurring twice in the same section.
The syntax of raw extensions is governed by the extension code: it can
for example contain data in multiple sections. The correct syntax to
use is defined by the extension code itself: check out the certificate
policies extension for an example.
-In addition it is also possible to use the word DER to include arbitrary
-data in any extension.
+There are two ways to encode arbitrary extensions.
+
+The first way is to use the word ASN1 followed by the extension content
+using the same syntax as ASN1_generate_nconf(). For example:
+
+1.2.3.4=critical,ASN1:UTF8String:Some random data
+
+1.2.3.4=ASN1:SEQUENCE:seq_sect
+
+[seq_sect]
+
+field1 = UTF8:field1
+field2 = UTF8:field2
+
+It is also possible to use the word DER to include arbitrary data in any
+extension.
1.2.3.4=critical,DER:01:02:03:04
1.2.3.4=DER:01020304
CURRENTLY SUPPORTED EXTENSIONS.
+If you aren't sure about extensions then they can be largely ignored: its only
+when you want to do things like restrict certificate usage when you need to
+worry about them.
+
+The only extension that a beginner might want to look at is Basic Constraints.
+If in addition you want to try Netscape object signing the you should also
+look at Netscape Certificate Type.
+
Literal String extensions.
In each case the 'value' of the extension is placed directly in the
nsCertType=server
-keyUsage=critical, digitalSignature, nonRepudiation
+keyUsage=digitalSignature, nonRepudiation
+
+Hints on Netscape Certificate Type.
+
+Other than Basic Constraints this is the only extension a beginner might
+want to use, if you want to try Netscape object signing, otherwise it can
+be ignored.
+
+If you want a certificate that can be used just for object signing then:
+
+nsCertType=objsign
+
+will do the job. If you want to use it as a normal end user and server
+certificate as well then
+
+nsCertType=objsign,email,server
+
+is more appropriate. You cannot use a self signed certificate for object
+signing (well Netscape signtool can but it cheats!) so you need to create
+a CA certificate and sign an end user certificate with it.
+
+Side note: If you want to conform to the Netscape specifications then you
+should really also set:
+
+nsCertType=objCA
+
+in the *CA* certificate for just an object signing CA and
+
+nsCertType=objCA,emailCA,sslCA
+for everything. Current Netscape software doesn't enforce this so it can
+be omitted.
Basic Constraints.
+This is generally the only extension you need to worry about for simple
+applications. If you want your certificate to be usable as a CA certificate
+(in addition to an end user certificate) then you set this to:
+
+basicConstraints=CA:TRUE
+
+if you want to be certain the certificate cannot be used as a CA then do:
+
+basicConstraints=CA:FALSE
+
+The rest of this section describes more advanced usage.
+
Basic constraints is a multi-valued extension that supports a CA and an
optional pathlen option. The CA option takes the values true and false and
pathlen takes an integer. Note if the CA option is false the pathlen option
-should be omitted.
+should be omitted.
+
+The pathlen parameter indicates the maximum number of CAs that can appear
+below this one in a chain. So if you have a CA with a pathlen of zero it can
+only be used to sign end user certificates and not further CAs. This all
+assumes that the software correctly interprets this extension of course.
Examples:
basicConstraints=CA:TRUE
-basicConstraints=critical,CA:TRUE, pathlen:10
+basicConstraints=critical,CA:TRUE, pathlen:0
NOTE: for a CA to be considered valid it must have the CA option set to
TRUE. An end user certificate MUST NOT have the CA value set to true.
According to PKIX recommendations it should exclude the extension entirely,
however some software may require CA set to FALSE for end entity certificates.
+Extended Key Usage.
+
+This extensions consists of a list of usages.
+
+These can either be object short names of the dotted numerical form of OIDs.
+While any OID can be used only certain values make sense. In particular the
+following PKIX, NS and MS values are meaningful:
+
+Value Meaning
+----- -------
+serverAuth SSL/TLS Web Server Authentication.
+clientAuth SSL/TLS Web Client Authentication.
+codeSigning Code signing.
+emailProtection E-mail Protection (S/MIME).
+timeStamping Trusted Timestamping
+msCodeInd Microsoft Individual Code Signing (authenticode)
+msCodeCom Microsoft Commercial Code Signing (authenticode)
+msCTLSign Microsoft Trust List Signing
+msSGC Microsoft Server Gated Crypto
+msEFS Microsoft Encrypted File System
+nsSGC Netscape Server Gated Crypto
+
+For example, under IE5 a CA can be used for any purpose: by including a list
+of the above usages the CA can be restricted to only authorised uses.
+
+Note: software packages may place additional interpretations on certificate
+use, in particular some usages may only work for selected CAs. Don't for example
+expect just including msSGC or nsSGC will automatically mean that a certificate
+can be used for SGC ("step up" encryption) otherwise anyone could use it.
+
+Examples:
+
+extendedKeyUsage=critical,codeSigning,1.2.3.4
+extendedKeyUsage=nsSGC,msSGC
+
Subject Key Identifier.
This is really a string extension and can take two possible values. Either
The subject alternative name extension allows various literal values to be
included in the configuration file. These include "email" (an email address)
"URI" a uniform resource indicator, "DNS" (a DNS domain name), RID (a
-registered ID: OBJECT IDENTIFIER) and IP (and IP address).
+registered ID: OBJECT IDENTIFIER), IP (and IP address) and otherName.
Also the email option include a special 'copy' value. This will automatically
include and email addresses contained in the certificate subject name in
the extension.
+otherName can include arbitrary data associated with an OID: the value
+should be the OID followed by a semicolon and the content in standard
+ASN1_generate_nconf() format.
+
Examples:
-subjectAltName=email:copy,email:my@other.address,URL:http://my.url.here/
+subjectAltName=email:copy,email:my@other.address,URI:http://my.url.here/
subjectAltName=email:my@other.address,RID:1.2.3.4
+subjectAltName=otherName:1.2.3.4;UTF8:some other identifier
Issuer Alternative Name.
that will copy all the subject alternative name values from the issuer
certificate (if possible).
+Example:
+
+issuserAltName = issuer:copy
+
+Authority Info Access.
+
+The authority information access extension gives details about how to access
+certain information relating to the CA. Its syntax is accessOID;location
+where 'location' has the same syntax as subject alternative name (except
+that email:copy is not supported). accessOID can be any valid OID but only
+certain values are meaningful for example OCSP and caIssuers. OCSP gives the
+location of an OCSP responder: this is used by Netscape PSM and other software.
+
+Example:
+
+authorityInfoAccess = OCSP;URI:http://ocsp.my.host/
+authorityInfoAccess = caIssuers;URI:http://my.ca/ca.html
+
CRL distribution points.
This is a multi-valued extension that supports all the literal options of
but cannot be set. These include private key usage period, CRL number, and
CRL reason.
+==============================================================================
+ X509V3 Extension code: programmers guide
+==============================================================================
+
+The purpose of the extension code is twofold. It allows an extension to be
+created from a string or structure describing its contents and it prints out an
+extension in a human or machine readable form.
+
+1. Initialisation and cleanup.
+
+No special initialisation is needed before calling the extension functions.
+You used to have to call X509V3_add_standard_extensions(); but this is no longer
+required and this function no longer does anything.
+
+void X509V3_EXT_cleanup(void);
+
+This function should be called to cleanup the extension code if any custom
+extensions have been added. If no custom extensions have been added then this
+call does nothing. After this call all custom extension code is freed up but
+you can still use the standard extensions.
+
+2. Printing and parsing extensions.
+
+The simplest way to print out extensions is via the standard X509 printing
+routines: if you use the standard X509_print() function, the supported
+extensions will be printed out automatically.
+
+The following functions allow finer control over extension display:
+
+int X509V3_EXT_print(BIO *out, X509_EXTENSION *ext, int flag, int indent);
+int X509V3_EXT_print_fp(FILE *out, X509_EXTENSION *ext, int flag, int indent);
+
+These two functions print out an individual extension to a BIO or FILE pointer.
+Currently the flag argument is unused and should be set to 0. The 'indent'
+argument is the number of spaces to indent each line.
+
+void *X509V3_EXT_d2i(X509_EXTENSION *ext);
+
+This function parses an extension and returns its internal structure. The
+precise structure you get back depends on the extension being parsed. If the
+extension if basicConstraints you will get back a pointer to a
+BASIC_CONSTRAINTS structure. Check out the source in crypto/x509v3 for more
+details about the structures returned. The returned structure should be freed
+after use using the relevant free function, BASIC_CONSTRAINTS_free() for
+example.
+
+void * X509_get_ext_d2i(X509 *x, int nid, int *crit, int *idx);
+void * X509_CRL_get_ext_d2i(X509_CRL *x, int nid, int *crit, int *idx);
+void * X509_REVOKED_get_ext_d2i(X509_REVOKED *x, int nid, int *crit, int *idx);
+void * X509V3_get_d2i(STACK_OF(X509_EXTENSION) *x, int nid, int *crit, int *idx);
+
+These functions combine the operations of searching for extensions and
+parsing them. They search a certificate, a CRL a CRL entry or a stack
+of extensions respectively for extension whose NID is 'nid' and return
+the parsed result of NULL if an error occurred. For example:
+
+BASIC_CONSTRAINTS *bs;
+bs = X509_get_ext_d2i(cert, NID_basic_constraints, NULL, NULL);
+
+This will search for the basicConstraints extension and either return
+it value or NULL. NULL can mean either the extension was not found, it
+occurred more than once or it could not be parsed.
+
+If 'idx' is NULL then an extension is only parsed if it occurs precisely
+once. This is standard behaviour because extensions normally cannot occur
+more than once. If however more than one extension of the same type can
+occur it can be used to parse successive extensions for example:
+
+int i;
+void *ext;
+
+i = -1;
+for(;;) {
+ ext = X509_get_ext_d2i(x, nid, crit, &idx);
+ if(ext == NULL) break;
+ /* Do something with ext */
+}
+
+If 'crit' is not NULL and the extension was found then the int it points to
+is set to 1 for critical extensions and 0 for non critical. Therefore if the
+function returns NULL but 'crit' is set to 0 or 1 then the extension was
+found but it could not be parsed.
+
+The int pointed to by crit will be set to -1 if the extension was not found
+and -2 if the extension occurred more than once (this will only happen if
+idx is NULL). In both cases the function will return NULL.
+
+3. Generating extensions.
+
+An extension will typically be generated from a configuration file, or some
+other kind of configuration database.
+
+int X509V3_EXT_add_conf(LHASH *conf, X509V3_CTX *ctx, char *section,
+ X509 *cert);
+int X509V3_EXT_CRL_add_conf(LHASH *conf, X509V3_CTX *ctx, char *section,
+ X509_CRL *crl);
+
+These functions add all the extensions in the given section to the given
+certificate or CRL. They will normally be called just before the certificate
+or CRL is due to be signed. Both return 0 on error on non zero for success.
+
+In each case 'conf' is the LHASH pointer of the configuration file to use
+and 'section' is the section containing the extension details.
+
+See the 'context functions' section for a description of the ctx parameter.
+
+
+X509_EXTENSION *X509V3_EXT_conf(LHASH *conf, X509V3_CTX *ctx, char *name,
+ char *value);
+
+This function returns an extension based on a name and value pair, if the
+pair will not need to access other sections in a config file (or there is no
+config file) then the 'conf' parameter can be set to NULL.
+
+X509_EXTENSION *X509V3_EXT_conf_nid(char *conf, X509V3_CTX *ctx, int nid,
+ char *value);
+
+This function creates an extension in the same way as X509V3_EXT_conf() but
+takes the NID of the extension rather than its name.
+
+For example to produce basicConstraints with the CA flag and a path length of
+10:
+
+x = X509V3_EXT_conf_nid(NULL, NULL, NID_basic_constraints,"CA:TRUE,pathlen:10");
+
+
+X509_EXTENSION *X509V3_EXT_i2d(int ext_nid, int crit, void *ext_struc);
+
+This function sets up an extension from its internal structure. The ext_nid
+parameter is the NID of the extension and 'crit' is the critical flag.
+
+4. Context functions.
+
+The following functions set and manipulate an extension context structure.
+The purpose of the extension context is to allow the extension code to
+access various structures relating to the "environment" of the certificate:
+for example the issuers certificate or the certificate request.
+
+void X509V3_set_ctx(X509V3_CTX *ctx, X509 *issuer, X509 *subject,
+ X509_REQ *req, X509_CRL *crl, int flags);
+
+This function sets up an X509V3_CTX structure with details of the certificate
+environment: specifically the issuers certificate, the subject certificate,
+the certificate request and the CRL: if these are not relevant or not
+available then they can be set to NULL. The 'flags' parameter should be set
+to zero.
+
+X509V3_set_ctx_test(ctx)
+
+This macro is used to set the 'ctx' structure to a 'test' value: this is to
+allow the syntax of an extension (or configuration file) to be tested.
+
+X509V3_set_ctx_nodb(ctx)
+
+This macro is used when no configuration database is present.
+
+void X509V3_set_conf_lhash(X509V3_CTX *ctx, LHASH *lhash);
+
+This function is used to set the configuration database when it is an LHASH
+structure: typically a configuration file.
+
+The following functions are used to access a configuration database: they
+should only be used in RAW extensions.
+
+char * X509V3_get_string(X509V3_CTX *ctx, char *name, char *section);
+
+This function returns the value of the parameter "name" in "section", or NULL
+if there has been an error.
+
+void X509V3_string_free(X509V3_CTX *ctx, char *str);
+
+This function frees up the string returned by the above function.
+
+STACK_OF(CONF_VALUE) * X509V3_get_section(X509V3_CTX *ctx, char *section);
+
+This function returns a whole section as a STACK_OF(CONF_VALUE) .
+
+void X509V3_section_free( X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *section);
+
+This function frees up the STACK returned by the above function.
+
+Note: it is possible to use the extension code with a custom configuration
+database. To do this the "db_meth" element of the X509V3_CTX structure should
+be set to an X509V3_CTX_METHOD structure. This structure contains the following
+function pointers:
+
+char * (*get_string)(void *db, char *section, char *value);
+STACK_OF(CONF_VALUE) * (*get_section)(void *db, char *section);
+void (*free_string)(void *db, char * string);
+void (*free_section)(void *db, STACK_OF(CONF_VALUE) *section);
+
+these will be called and passed the 'db' element in the X509V3_CTX structure
+to access the database. If a given function is not implemented or not required
+it can be set to NULL.
+
+5. String helper functions.
+
+There are several "i2s" and "s2i" functions that convert structures to and
+from ASCII strings. In all the "i2s" cases the returned string should be
+freed using Free() after use. Since some of these are part of other extension
+code they may take a 'method' parameter. Unless otherwise stated it can be
+safely set to NULL.
+
+char *i2s_ASN1_OCTET_STRING(X509V3_EXT_METHOD *method, ASN1_OCTET_STRING *oct);
+
+This returns a hex string from an ASN1_OCTET_STRING.
+
+char * i2s_ASN1_INTEGER(X509V3_EXT_METHOD *meth, ASN1_INTEGER *aint);
+char * i2s_ASN1_ENUMERATED(X509V3_EXT_METHOD *meth, ASN1_ENUMERATED *aint);
+
+These return a string decimal representations of an ASN1_INTEGER and an
+ASN1_ENUMERATED type, respectively.
+
+ASN1_OCTET_STRING *s2i_ASN1_OCTET_STRING(X509V3_EXT_METHOD *method,
+ X509V3_CTX *ctx, char *str);
+
+This converts an ASCII hex string to an ASN1_OCTET_STRING.
+
+ASN1_INTEGER * s2i_ASN1_INTEGER(X509V3_EXT_METHOD *meth, char *value);
+
+This converts a decimal ASCII string into an ASN1_INTEGER.
+
+6. Multi valued extension helper functions.
+
+The following functions can be used to manipulate STACKs of CONF_VALUE
+structures, as used by multi valued extensions.
+
+int X509V3_get_value_bool(CONF_VALUE *value, int *asn1_bool);
+
+This function expects a boolean value in 'value' and sets 'asn1_bool' to
+it. That is it sets it to 0 for FALSE or 0xff for TRUE. The following
+strings are acceptable: "TRUE", "true", "Y", "y", "YES", "yes", "FALSE"
+"false", "N", "n", "NO" or "no".
+
+int X509V3_get_value_int(CONF_VALUE *value, ASN1_INTEGER **aint);
+
+This accepts a decimal integer of arbitrary length and sets an ASN1_INTEGER.
+
+int X509V3_add_value(const char *name, const char *value,
+ STACK_OF(CONF_VALUE) **extlist);
+
+This simply adds a string name and value pair.
+
+int X509V3_add_value_uchar(const char *name, const unsigned char *value,
+ STACK_OF(CONF_VALUE) **extlist);
+
+The same as above but for an unsigned character value.
+
+int X509V3_add_value_bool(const char *name, int asn1_bool,
+ STACK_OF(CONF_VALUE) **extlist);
+
+This adds either "TRUE" or "FALSE" depending on the value of 'asn1_bool'
+
+int X509V3_add_value_bool_nf(char *name, int asn1_bool,
+ STACK_OF(CONF_VALUE) **extlist);
+
+This is the same as above except it adds nothing if asn1_bool is FALSE.
+
+int X509V3_add_value_int(const char *name, ASN1_INTEGER *aint,
+ STACK_OF(CONF_VALUE) **extlist);
+
+This function adds the value of the ASN1_INTEGER in decimal form.
+
+7. Other helper functions.
+
+<to be added>
+
+ADDING CUSTOM EXTENSIONS.
+
+Currently there are three types of supported extensions.
+
+String extensions are simple strings where the value is placed directly in the
+extensions, and the string returned is printed out.
+
+Multi value extensions are passed a STACK_OF(CONF_VALUE) name and value pairs
+or return a STACK_OF(CONF_VALUE).
+
+Raw extensions are just passed a BIO or a value and it is the extensions
+responsibility to handle all the necessary printing.
+
+There are two ways to add an extension. One is simply as an alias to an already
+existing extension. An alias is an extension that is identical in ASN1 structure
+to an existing extension but has a different OBJECT IDENTIFIER. This can be
+done by calling:
+
+int X509V3_EXT_add_alias(int nid_to, int nid_from);
+
+'nid_to' is the new extension NID and 'nid_from' is the already existing
+extension NID.
+
+Alternatively an extension can be written from scratch. This involves writing
+the ASN1 code to encode and decode the extension and functions to print out and
+generate the extension from strings. The relevant functions are then placed in
+a X509V3_EXT_METHOD structure and int X509V3_EXT_add(X509V3_EXT_METHOD *ext);
+called.
+
+The X509V3_EXT_METHOD structure is described below.
+
+struct {
+int ext_nid;
+int ext_flags;
+X509V3_EXT_NEW ext_new;
+X509V3_EXT_FREE ext_free;
+X509V3_EXT_D2I d2i;
+X509V3_EXT_I2D i2d;
+X509V3_EXT_I2S i2s;
+X509V3_EXT_S2I s2i;
+X509V3_EXT_I2V i2v;
+X509V3_EXT_V2I v2i;
+X509V3_EXT_R2I r2i;
+X509V3_EXT_I2R i2r;
+
+void *usr_data;
+};
+
+The elements have the following meanings.
+
+ext_nid is the NID of the object identifier of the extension.
+
+ext_flags is set of flags. Currently the only external flag is
+ X509V3_EXT_MULTILINE which means a multi valued extensions
+ should be printed on separate lines.
+
+usr_data is an extension specific pointer to any relevant data. This
+ allows extensions to share identical code but have different
+ uses. An example of this is the bit string extension which uses
+ usr_data to contain a list of the bit names.
+
+All the remaining elements are function pointers.
+
+ext_new is a pointer to a function that allocates memory for the
+ extension ASN1 structure: for example ASN1_OBJECT_new().
+
+ext_free is a pointer to a function that free up memory of the extension
+ ASN1 structure: for example ASN1_OBJECT_free().
+
+d2i is the standard ASN1 function that converts a DER buffer into
+ the internal ASN1 structure: for example d2i_ASN1_IA5STRING().
+
+i2d is the standard ASN1 function that converts the internal
+ structure into the DER representation: for example
+ i2d_ASN1_IA5STRING().
+
+The remaining functions are depend on the type of extension. One i2X and
+one X2i should be set and the rest set to NULL. The types set do not need
+to match up, for example the extension could be set using the multi valued
+v2i function and printed out using the raw i2r.
+
+All functions have the X509V3_EXT_METHOD passed to them in the 'method'
+parameter and an X509V3_CTX structure. Extension code can then access the
+parent structure via the 'method' parameter to for example make use of the value
+of usr_data. If the code needs to use detail relating to the request it can
+use the 'ctx' parameter.
+
+A note should be given here about the 'flags' member of the 'ctx' parameter.
+If it has the value CTX_TEST then the configuration syntax is being checked
+and no actual certificate or CRL exists. Therefore any attempt in the config
+file to access such information should silently succeed. If the syntax is OK
+then it should simply return a (possibly bogus) extension, otherwise it
+should return NULL.
+
+char *i2s(struct v3_ext_method *method, void *ext);
+
+This function takes the internal structure in the ext parameter and returns
+a Malloc'ed string representing its value.
+
+void * s2i(struct v3_ext_method *method, struct v3_ext_ctx *ctx, char *str);
+
+This function takes the string representation in the ext parameter and returns
+an allocated internal structure: ext_free() will be used on this internal
+structure after use.
+
+i2v and v2i handle a STACK_OF(CONF_VALUE):
+
+typedef struct
+{
+ char *section;
+ char *name;
+ char *value;
+} CONF_VALUE;
+
+Only the name and value members are currently used.
+
+STACK_OF(CONF_VALUE) * i2v(struct v3_ext_method *method, void *ext);
+
+This function is passed the internal structure in the ext parameter and
+returns a STACK of CONF_VALUE structures. The values of name, value,
+section and the structure itself will be freed up with Free after use.
+Several helper functions are available to add values to this STACK.
+
+void * v2i(struct v3_ext_method *method, struct v3_ext_ctx *ctx,
+ STACK_OF(CONF_VALUE) *values);
+
+This function takes a STACK_OF(CONF_VALUE) structures and should set the
+values of the external structure. This typically uses the name element to
+determine which structure element to set and the value element to determine
+what to set it to. Several helper functions are available for this
+purpose (see above).
+
+int i2r(struct v3_ext_method *method, void *ext, BIO *out, int indent);
+
+This function is passed the internal extension structure in the ext parameter
+and sends out a human readable version of the extension to out. The 'indent'
+parameter should be noted to determine the necessary amount of indentation
+needed on the output.
+
+void * r2i(struct v3_ext_method *method, struct v3_ext_ctx *ctx, char *str);
+
+This is just passed the string representation of the extension. It is intended
+to be used for more elaborate extensions where the standard single and multi
+valued options are insufficient. They can use the 'ctx' parameter to parse the
+configuration database themselves. See the context functions section for details
+of how to do this.
+
+Note: although this type takes the same parameters as the "r2s" function there
+is a subtle difference. Whereas an "r2i" function can access a configuration
+database an "s2i" function MUST NOT. This is so the internal code can safely
+assume that an "s2i" function will work without a configuration database.
+
==============================================================================
PKCS#12 Library
==============================================================================
This is the same but for a FILE pointer.
-3. Parsing and creation functions.
+3. High level functions.
3.1 Parsing with PKCS12_parse().
i2d_PKCS12_fp(fp, p12);
PKCS12_free(p12);
+3.3 Changing a PKCS#12 structure password.
+
+int PKCS12_newpass(PKCS12 *p12, char *oldpass, char *newpass);
+
+This changes the password of an already existing PKCS#12 structure. oldpass
+is the old password and newpass is the new one. An error occurs if the old
+password is incorrect.
+
LOW LEVEL FUNCTIONS.
In some cases the high level functions do not provide the necessary
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