PKCS8(1)                            OpenSSL                           PKCS8(1)



NAME
       pkcs8 - PKCS#8 format private key conversion tool

LIBRARY
       libcrypto, -lcrypto

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

DESCRIPTION
       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.

COMMAND OPTIONS
       -topk8
           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).

       -nocrypt
           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.

       -nooct
           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.

       -embed
           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.

       -nsdb
           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.

       -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.

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

        -----BEGIN ENCRYPTED PRIVATE KEY-----
        -----END ENCRYPTED PRIVATE KEY-----

       The unencrypted form uses:

        -----BEGIN PRIVATE KEY-----
        -----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
       below.

       PBE-MD2-DES PBE-MD5-DES
           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-RC4-128 PBE-SHA1-RC4-40 PBE-SHA1-3DES PBE-SHA1-2DES
       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.

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

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

       Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
       (DES):

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

       Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
       (3DES):

        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

STANDARDS
       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.

BUGS
       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.

SEE ALSO
       openssl_dsa(1), openssl_rsa(1), openssl_genrsa(1), openssl_gendsa(1)



1.0.1i                            2009-07-20                          PKCS8(1)

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