The pkcs12 command allows PKCS#12 files (sometimes referred to as
PFX files) to be created and parsed. PKCS#12 files are used by several
programs including Netscape, MSIE and MS Outlook.
COMMAND OPTIONS
There are a lot of options the meaning of some depends of whether a PKCS#12 file
is being created or parsed. By default a PKCS#12 file is parsed a PKCS#12
file 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 used
by 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 the
format of arg see the PASSPHRASEARGUMENTS section in
openssl(1).
-passout arg
pass phrase source to encrypt any outputed private keys with. For more information
about the format of arg see the PASSPHRASEARGUMENTS section in
openssl(1).
-noout
this option inhibits output of the keys and certificates to the output file version
of 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 and
iteration 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 software
always assumes these are the same so this option will render such
PKCS#12 files unreadable.
FILE CREATION OPTIONS
-export
This option specifies that a PKCS#12 file will be created rather than
parsed.
-out filename
This specifies filename to write the PKCS#12 file to. Standard output is used
by 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 and
its corresponding certificate should be present. If additional certificates are
present 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 present
in the input file.
-name friendlyname
This specifies the ``friendly name'' for the certificate and private key. This name
is 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 be
used multiple times to specify names for all certificates in the order they
appear. Netscape ignores friendly names on other certificates whereas MSIE
displays them.
-pass arg, -passout arg
the PKCS#12 file (i.e. output file) password source. For more information about
the format of arg see the PASSPHRASEARGUMENTS section in
openssl(1).
-passin password
pass phrase source to decrypt any input private keys with. For more information
about the format of arg see the PASSPHRASEARGUMENTS section in
openssl(1).
-chain
if this option is present then an attempt is made to include the entire
certificate chain of the user certificate. The standard CA store is used
for this search. If the search fails it is considered a fatal error.
-descert
encrypt the certificate using triple DES, this may render the PKCS#12
file unreadable by some ``export grade'' software. By default the private
key 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 and
certificates to be selected. Although any PKCS#5 v1.5 or PKCS#12 algorithms
can be selected it is advisable only to use PKCS#12 algorithms. See the list
in 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 for
encryption purposes but arbitrary length keys for signing. The -keysig
option marks the key for signing only. Signing only keys can be used for
S/MIME signing, authenticode (ActiveX control signing) and SSL client
authentication, however due to a bug only MSIE 5.0 and later support
the 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 leave
these options alone.
To discourage attacks by using large dictionaries of common passwords the
algorithm that derives keys from passwords can have an iteration count applied
to it: this causes a certain part of the algorithm to be repeated and slows it
down. The MAC is used to check the file integrity but since it will normally
have 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, using
these options the MAC and encryption iteration counts can be set to 1, since
this reduces the file security you should not use these options unless you
really have to. Most software supports both MAC and key iteration counts.
MSIE 4.0 doesn't support MAC iteration counts so it needs the -nomaciter
option.
-maciter
This option is included for compatibility with previous versions, it used
to 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 number
generator, 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 : for
all others.
NOTES
Although there are a large number of options most of them are very rarely
used. For PKCS#12 file parsing only -in and -out need to be used
for PKCS#12 file creation -export and -name are also used.
If none of the -clcerts, -cacerts or -nocerts options are present
then all certificates will be output in the order they appear in the input
PKCS#12 files. There is no guarantee that the first certificate present is
the one corresponding to the private key. Certain software which requires
a private key and certificate and assumes the first certificate in the
file is the one corresponding to the private key: this may not always
be the case. Using the -clcerts option will solve this problem by only
outputting the certificate corresponding to the private key. If the CA
certificates are required then they can be output to a separate file using
the -nokeys -cacerts options to just output CA certificates.
The -keypbe and -certpbe algorithms allow the precise encryption
algorithms for private keys and certificates to be specified. Normally
the defaults are fine but occasionally software can't handle triple DES
encrypted private keys, then the option -keypbe PBE-SHA1-RC2-40 can
be used to reduce the private key encryption to 40 bit RC2. A complete
description of all algorithms is contained in the pkcs8 manual page.
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 generation
routines. Under rare circumstances this could produce a PKCS#12 file encrypted
with an invalid key. As a result some PKCS#12 files which triggered this bug
from other implementations (MSIE or Netscape) could not be decrypted
by OpenSSL and similarly OpenSSL could produce PKCS#12 files which could
not be decrypted by other implementations. The chances of producing such
a file are relatively small: less than 1 in 256.
A side effect of fixing this bug is that any old invalidly encrypted PKCS#12
files cannot no longer be parsed by the fixed version. Under such circumstances
the pkcs12 utility will report that the MAC is OK but fail with a decryption
error when extracting private keys.
This problem can be resolved by extracting the private keys and certificates
from the PKCS#12 file using an older version of OpenSSL and recreating the PKCS#12
file from the keys and certificates using a newer version of OpenSSL. For example:
