Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
PKCS8(1)			    OpenSSL			      PKCS8(1)

       pkcs8 - PKCS#8 format private key conversion tool

       openssl pkcs8 [-topk8] [-inform PEM|DER]	[-outform PEM|DER] [-in
       filename] [-passin arg] [-out filename] [-passout arg] [-noiter]
       [-nocrypt] [-nooct] [-embed] [-nsdb] [-v2 alg] [-v2prf alg] [-v1	alg]
       [-engine	id]

       The pkcs8 command processes private keys	in PKCS#8 format. It can
       handle both unencrypted PKCS#8 PrivateKeyInfo format and
       EncryptedPrivateKeyInfo format with a variety of	PKCS#5 (v1.5 and v2.0)
       and PKCS#12 algorithms.

	   Normally a PKCS#8 private key is expected on	input and a
	   traditional format private key will be written. With	the -topk8
	   option the situation	is reversed: it	reads a	traditional format
	   private key and writes a PKCS#8 format key.

       -inform DER|PEM
	   This	specifies the input format. If a PKCS#8	format key is expected
	   on input then either	a DER or PEM encoded version of	a PKCS#8 key
	   will	be expected. Otherwise the DER or PEM format of	the
	   traditional format private key is used.

       -outform	DER|PEM
	   This	specifies the output format, the options have the same meaning
	   as the -inform option.

       -in filename
	   This	specifies the input filename to	read a key from	or standard
	   input if this option	is not specified. If the key is	encrypted a
	   pass	phrase will be prompted	for.

       -passin arg
	   the input file password source. For more information	about the
	   format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).

       -out filename
	   This	specifies the output filename to write a key to	or standard
	   output by default. If any encryption	options	are set	then a pass
	   phrase will be prompted for.	The output filename should not be the
	   same	as the input filename.

       -passout	arg
	   the output file password source. For	more information about the
	   format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).

	   PKCS#8 keys generated or input are normally PKCS#8
	   EncryptedPrivateKeyInfo structures using an appropriate password
	   based encryption algorithm. With this option	an unencrypted
	   PrivateKeyInfo structure is expected	or output.  This option	does
	   not encrypt private keys at all and should only be used when
	   absolutely necessary. Certain software such as some versions	of
	   Java	code signing software used unencrypted private keys.

	   This	option generates RSA private keys in a broken format that some
	   software uses. Specifically the private key should be enclosed in a
	   OCTET STRING	but some software just includes	the structure itself
	   without the surrounding OCTET STRING.

	   This	option generates DSA keys in a broken format. The DSA
	   parameters are embedded inside the PrivateKey structure. In this
	   form	the OCTET STRING contains an ASN1 SEQUENCE consisting of two
	   structures: a SEQUENCE containing the parameters and	an ASN1
	   INTEGER containing the private key.

	   This	option generates DSA keys in a broken format compatible	with
	   Netscape private key	databases. The PrivateKey contains a SEQUENCE
	   consisting of the public and	private	keys respectively.

       -v2 alg
	   This	option enables the use of PKCS#5 v2.0 algorithms. Normally
	   PKCS#8 private keys are encrypted with the password based
	   encryption algorithm	called pbeWithMD5AndDES-CBC this uses 56 bit
	   DES encryption but it was the strongest encryption algorithm
	   supported in	PKCS#5 v1.5. Using the -v2 option PKCS#5 v2.0
	   algorithms are used which can use any encryption algorithm such as
	   168 bit triple DES or 128 bit RC2 however not many implementations
	   support PKCS#5 v2.0 yet. If you are just using private keys with
	   OpenSSL then	this doesn't matter.

	   The alg argument is the encryption algorithm	to use,	valid values
	   include des,	des3 and rc2. It is recommended	that des3 is used.

       -v2prf alg
	   This	option sets the	PRF algorithm to use with PKCS#5 v2.0. A
	   typical value values	would be hmacWithSHA256. If this option	isn't
	   set then the	default	for the	cipher is used or hmacWithSHA1 if
	   there is no default.

       -v1 alg
	   This	option specifies a PKCS#5 v1.5 or PKCS#12 algorithm to use. A
	   complete list of possible algorithms	is included below.

       -engine id
	   specifying an engine	(by its	unique id string) will cause pkcs8 to
	   attempt to obtain a functional reference to the specified engine,
	   thus	initialising it	if needed. The engine will then	be set as the
	   default for all available algorithms.

       The encrypted form of a PEM encode PKCS#8 files uses the	following
       headers and footers:


       The unencrypted form uses:

	-----END PRIVATE KEY-----

       Private keys encrypted using PKCS#5 v2.0	algorithms and high iteration
       counts are more secure that those encrypted using the traditional
       SSLeay compatible formats. So if	additional security is considered
       important the keys should be converted.

       The default encryption is only 56 bits because this is the encryption
       that most current implementations of PKCS#8 will	support.

       Some software may use PKCS#12 password based encryption algorithms with
       PKCS#8 format private keys: these are handled automatically but there
       is no option to produce them.

       It is possible to write out DER encoded encrypted private keys in
       PKCS#8 format because the encryption details are	included at an ASN1
       level whereas the traditional format includes them at a PEM level.

PKCS#5 v1.5 and	PKCS#12	algorithms.
       Various algorithms can be used with the -v1 command line	option,
       including PKCS#5	v1.5 and PKCS#12. These	are described in more detail

	   These algorithms were included in the original PKCS#5 v1.5
	   specification.  They	only offer 56 bits of protection since they
	   both	use DES.

       PBE-SHA1-RC2-64 PBE-MD2-RC2-64 PBE-MD5-RC2-64 PBE-SHA1-DES
	   These algorithms are	not mentioned in the original PKCS#5 v1.5
	   specification but they use the same key derivation algorithm	and
	   are supported by some software. They	are mentioned in PKCS#5	v2.0.
	   They	use either 64 bit RC2 or 56 bit	DES.

       PBE-SHA1-RC2-128	PBE-SHA1-RC2-40
	   These algorithms use	the PKCS#12 password based encryption
	   algorithm and allow strong encryption algorithms like triple	DES or
	   128 bit RC2 to be used.

       Convert a private from traditional to PKCS#5 v2.0 format	using triple

	openssl	pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem

       Convert a private from traditional to PKCS#5 v2.0 format	using AES with
       256 bits	in CBC mode and	hmacWithSHA256 PRF:

	openssl	pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf	hmacWithSHA256 -out enckey.pem

       Convert a private key to	PKCS#8 using a PKCS#5 1.5 compatible algorithm

	openssl	pkcs8 -in key.pem -topk8 -out enckey.pem

       Convert a private key to	PKCS#8 using a PKCS#12 compatible algorithm

	openssl	pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES

       Read a DER unencrypted PKCS#8 format private key:

	openssl	pkcs8 -inform DER -nocrypt -in key.der -out key.pem

       Convert a private key from any PKCS#8 format to traditional format:

	openssl	pkcs8 -in pk8.pem -out key.pem

       Test vectors from this PKCS#5 v2.0 implementation were posted to	the
       pkcs-tng	mailing	list using triple DES, DES and RC2 with	high iteration
       counts, several people confirmed	that they could	decrypt	the private
       keys produced and Therefore it can be assumed that the PKCS#5 v2.0
       implementation is reasonably accurate at	least as far as	these
       algorithms are concerned.

       The format of PKCS#8 DSA	(and other) private keys is not	well
       documented: it is hidden	away in	PKCS#11	v2.01, section 11.9. OpenSSL's
       default DSA PKCS#8 private key format complies with this	standard.

       There should be an option that prints out the encryption	algorithm in
       use and other details such as the iteration count.

       PKCS#8 using triple DES and PKCS#5 v2.0 should be the default private
       key format for OpenSSL: for compatibility several of the	utilities use
       the old format at present.

       dsa(1), rsa(1), genrsa(1), gendsa(1)

1.0.2h				  2016-05-03			      PKCS8(1)


Want to link to this manual page? Use this URL:

home | help