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PKCS12

Section: OpenSSL (1)
Updated: 2001-09-07
Index

NAME

pkcs12 - PKCS#12 file utility

SYNOPSIS

openssl pkcs12[-export][-chain][-inkey filename][-certfile filename][-name name][-caname name][-in filename][-out filename][-noout][-nomacver][-nocerts][-clcerts][-cacerts][-nokeys][-info][-des][-des3][-idea][-nodes][-noiter][-maciter][-twopass][-descert][-certpbe][-keypbe][-keyex][-keysig][-password arg][-passin arg][-passout arg][-rand file(s)]

DESCRIPTION

The pkcs12 command allows PKCS#12 files (sometimes referred to asPFX files) to be created and parsed. PKCS#12 files are used by severalprograms including Netscape, MSIE and MS Outlook.

COMMAND OPTIONS

There are a lot of options the meaning of some depends of whether a PKCS#12 fileis being created or parsed. By default a PKCS#12 file is parsed a PKCS#12file can be created by using the -export option (see below).

PARSING OPTIONS

-in filename: This specifies filename of the PKCS#12 file to be parsed. Standard input is usedby default.
-out filename: The filename to write certificates and private keys to, standard output by default.They are all written in PEM format.
-pass arg, -passin arg: the PKCS#12 file (i.e. input file) password source. For more information about theformat of arg see the PASS PHRASE ARGUMENTS section inopenssl(1).
-passout arg: pass phrase source to encrypt any outputed private keys with. For more informationabout the format of arg see the PASS PHRASE ARGUMENTS section inopenssl(1).
-noout: this option inhibits output of the keys and certificates to the output file versionof the PKCS#12 file.
-clcerts: only output client certificates (not CA certificates).
-cacerts: only output CA certificates (not client certificates).
-nocerts: no certificates at all will be output.
-nokeys: no private keys will be output.
-info: output additional information about the PKCS#12 file structure, algorithms used anditeration counts.
-des: use DES to encrypt private keys before outputting.
-des3: use triple DES to encrypt private keys before outputting, this is the default.
-idea: use IDEA to encrypt private keys before outputting.
-nodes: don't encrypt the private keys at all.
-nomacver: don't attempt to verify the integrity MAC before reading the file.
-twopass: prompt for separate integrity and encryption passwords: most softwarealways assumes these are the same so this option will render suchPKCS#12 files unreadable.

FILE CREATION OPTIONS

-export: This option specifies that a PKCS#12 file will be created rather thanparsed.
-out filename: This specifies filename to write the PKCS#12 file to. Standard output is usedby default.
-in filename: The filename to read certificates and private keys from, standard input by default.They must all be in PEM format. The order doesn't matter but one private key andits corresponding certificate should be present. If additional certificates arepresent they will also be included in the PKCS#12 file.
-inkey filename: file to read private key from. If not present then a private key must be presentin the input file.
-name friendlyname: This specifies the ``friendly name'' for the certificate and private key. This nameis typically displayed in list boxes by software importing the file.
-certfile filename: A filename to read additional certificates from.
-caname friendlyname: This specifies the ``friendly name'' for other certificates. This option may beused multiple times to specify names for all certificates in the order theyappear. Netscape ignores friendly names on other certificates whereas MSIEdisplays them.
-pass arg, -passout arg: the PKCS#12 file (i.e. output file) password source. For more information aboutthe format of arg see the PASS PHRASE ARGUMENTS section inopenssl(1).
-passin password: pass phrase source to decrypt any input private keys with. For more informationabout the format of arg see the PASS PHRASE ARGUMENTS section inopenssl(1).
-chain: if this option is present then an attempt is made to include the entirecertificate chain of the user certificate. The standard CA store is usedfor this search. If the search fails it is considered a fatal error.
-descert: encrypt the certificate using triple DES, this may render the PKCS#12file unreadable by some ``export grade'' software. By default the privatekey is encrypted using triple DES and the certificate using 40 bit RC2.
-keypbe alg, -certpbe alg: these options allow the algorithm used to encrypt the private key andcertificates to be selected. Although any PKCS#5 v1.5 or PKCS#12 algorithmscan be selected it is advisable only to use PKCS#12 algorithms. See the listin the NOTES section for more information.
-keyex|-keysig: specifies that the private key is to be used for key exchange or just signing.This option is only interpreted by MSIE and similar MS software. Normally``export grade'' software will only allow 512 bit RSA keys to be used forencryption purposes but arbitrary length keys for signing. The -keysigoption marks the key for signing only. Signing only keys can be used forS/MIME signing, authenticode (ActiveX control signing) and SSL clientauthentication, however due to a bug only MSIE 5.0 and later supportthe use of signing only keys for SSL client authentication.
-nomaciter, -noiter: these options affect the iteration counts on the MAC and key algorithms.Unless you wish to produce files compatible with MSIE 4.0 you should leavethese options alone.
To discourage attacks by using large dictionaries of common passwords thealgorithm that derives keys from passwords can have an iteration count appliedto it: this causes a certain part of the algorithm to be repeated and slows itdown. The MAC is used to check the file integrity but since it will normallyhave the same password as the keys and certificates it could also be attacked.By default both MAC and encryption iteration counts are set to 2048, usingthese options the MAC and encryption iteration counts can be set to 1, sincethis reduces the file security you should not use these options unless youreally have to. Most software supports both MAC and key iteration counts.MSIE 4.0 doesn't support MAC iteration counts so it needs the -nomaciteroption.
-maciter: This option is included for compatibility with previous versions, it usedto be needed to use MAC iterations counts but they are now used by default.
-rand file(s): a file or files containing random data used to seed the random numbergenerator, or an EGD socket (see RAND_egd(3)).Multiple files can be specified separated by a OS-dependent character.The separator is ; for MS-Windows, , for OpenVMS, and : forall others.

NOTES

Although there are a large number of options most of them are very rarelyused. For PKCS#12 file parsing only -in and -out need to be usedfor PKCS#12 file creation -export and -name are also used.

If none of the -clcerts, -cacerts or -nocerts options are presentthen all certificates will be output in the order they appear in the inputPKCS#12 files. There is no guarantee that the first certificate present isthe one corresponding to the private key. Certain software which requiresa private key and certificate and assumes the first certificate in thefile is the one corresponding to the private key: this may not alwaysbe the case. Using the -clcerts option will solve this problem by onlyoutputting the certificate corresponding to the private key. If the CAcertificates are required then they can be output to a separate file usingthe -nokeys -cacerts options to just output CA certificates.

The -keypbe and -certpbe algorithms allow the precise encryptionalgorithms for private keys and certificates to be specified. Normallythe defaults are fine but occasionally software can't handle triple DESencrypted private keys, then the option -keypbe PBE-SHA1-RC2-40 canbe used to reduce the private key encryption to 40 bit RC2. A completedescription of all algorithms is contained in the pkcs8 manual page.

EXAMPLES

Parse a PKCS#12 file and output it to a file:

 openssl pkcs12 -in file.p12 -out file.pem

Output only client certificates to a file:

 openssl pkcs12 -in file.p12 -clcerts -out file.pem

Don't encrypt the private key:

 openssl pkcs12 -in file.p12 -out file.pem -nodes

Print some info about a PKCS#12 file:

 openssl pkcs12 -in file.p12 -info -noout

Create a PKCS#12 file:

 openssl pkcs12 -export -in file.pem -out file.p12 -name "My Certificate"

Include some extra certificates:

 openssl pkcs12 -export -in file.pem -out file.p12 -name "My Certificate" \  -certfile othercerts.pem

BUGS

Some would argue that the PKCS#12 standard is one big bug :-)

Versions of OpenSSL before 0.9.6a had a bug in the PKCS#12 key generationroutines. Under rare circumstances this could produce a PKCS#12 file encryptedwith an invalid key. As a result some PKCS#12 files which triggered this bugfrom other implementations (MSIE or Netscape) could not be decryptedby OpenSSL and similarly OpenSSL could produce PKCS#12 files which couldnot be decrypted by other implementations. The chances of producing sucha file are relatively small: less than 1 in 256.

A side effect of fixing this bug is that any old invalidly encrypted PKCS#12files cannot no longer be parsed by the fixed version. Under such circumstancesthe pkcs12 utility will report that the MAC is OK but fail with a decryptionerror when extracting private keys.

This problem can be resolved by extracting the private keys and certificatesfrom the PKCS#12 file using an older version of OpenSSL and recreating the PKCS#12file from the keys and certificates using a newer version of OpenSSL. For example:

 old-openssl -in bad.p12 -out keycerts.pem openssl -in keycerts.pem -export -name "My PKCS#12 file" -out fixed.p12

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