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:

    -----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

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


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