openssl-pkcs8, pkcs8 - PKCS#8 format private key conversion tool
openssl pkcs8 [-help] [-topk8] [-inform
  PEM|DER] [-outform PEM|DER] [-in filename] [-passin
  arg] [-out filename] [-passout arg] [-iter count]
  [-noiter] [-rand file...] [-writerand file]
  [-nocrypt] [-traditional] [-v2 alg] [-v2prf alg]
  [-v1 alg] [-engine id] [-scrypt] [-scrypt_N N]
  [-scrypt_r r] [-scrypt_p p]
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.
  - -help
- Print out a usage message.
- -topk8
- Normally a PKCS#8 private key is expected on input and a private key will
      be written to the output file. With the -topk8 option the situation
      is reversed: it reads a private key and writes a PKCS#8 format key.
- -inform DER|PEM
- This specifies the input format: see "KEY FORMATS" for more
      details. The default format is PEM.
- -outform DER|PEM
- This specifies the output format: see "KEY FORMATS" for more
      details. The default format is PEM.
- -traditional
- When this option is present and -topk8 is not a traditional format
      private key is written.
- -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).
- -iter count
- When creating new PKCS#8 containers, use a given number of iterations on
      the password in deriving the encryption key for the PKCS#8 output. High
      values increase the time required to brute-force a PKCS#8 container.
- -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.
- -rand file...
- A file or files containing random data used to seed the random number
      generator. Multiple files can be specified separated by an OS-dependent
      character. The separator is ; for MS-Windows, , for OpenVMS,
      and : for all others.
- [-writerand file]
- Writes random data to the specified file upon exit. This can be
      used with a subsequent -rand flag.
- -v2 alg
- This option sets the PKCS#5 v2.0 algorithm.
    The alg argument is the encryption algorithm to use,
        valid values include aes128, aes256 and des3. If
        this option isn't specified then aes256 is used. 
- -v2prf alg
- This option sets the PRF algorithm to use with PKCS#5 v2.0. A typical
      value value would be hmacWithSHA256. If this option isn't set then
      the default for the cipher is used or hmacWithSHA256 if there is no
      default.
    Some implementations may not support custom PRF algorithms and
        may require the hmacWithSHA1 option to work. 
- -v1 alg
- This option indicates a PKCS#5 v1.5 or PKCS#12 algorithm should be used.
      Some older implementations may not support PKCS#5 v2.0 and may require
      this option. If not specified PKCS#5 v2.0 form is used.
- -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.
- -scrypt
- Uses the scrypt algorithm for private key encryption using default
      parameters: currently N=16384, r=8 and p=1 and AES in CBC mode with a 256
      bit key. These parameters can be modified using the -scrypt_N,
      -scrypt_r, -scrypt_p and -v2 options.
- -scrypt_N N -scrypt_r r -scrypt_p p
- Sets the scrypt N, r or p parameters.
Various different formats are used by the pkcs8 utility. These are detailed
  below.If a key is being converted from PKCS#8 form (i.e. the
    -topk8 option is not used) then the input file must be in PKCS#8
    format. An encrypted key is expected unless -nocrypt is included.
If -topk8 is not used and PEM mode is set the output
    file will be an unencrypted private key in PKCS#8 format. If the
    -traditional option is used then a traditional format private key is
    written instead.
If -topk8 is not used and DER mode is set the output
    file will be an unencrypted private key in traditional DER format.
If -topk8 is used then any supported private key can be
    used for the input file in a format specified by -inform. The output
    file will be encrypted PKCS#8 format using the specified encryption
    parameters unless -nocrypt is included.
By default, when converting a key to PKCS#8 format, PKCS#5 v2.0 using 256 bit
  AES with HMAC and SHA256 is used.
Some older implementations do not support PKCS#5 v2.0 format and
    require the older PKCS#5 v1.5 form instead, possibly also requiring insecure
    weak encryption algorithms such as 56 bit DES.
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.
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.
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.
Convert a private key to PKCS#8 format using default parameters (AES with 256
  bit key and hmacWithSHA256):
 openssl pkcs8 -in key.pem -topk8 -out enckey.pem
Convert a private key to PKCS#8 unencrypted format:
 openssl pkcs8 -in key.pem -topk8 -nocrypt -out enckey.pem
Convert a private key 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#5 v2.0 format using AES with 256
    bits in CBC mode and hmacWithSHA512 PRF:
 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA512 -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 -v1 PBE-MD5-DES -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 encrypted format to
    traditional format:
 openssl pkcs8 -in pk8.pem -traditional -out key.pem
Convert a private key to PKCS#8 format, encrypting with AES-256
    and with one million iterations of the password:
 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -iter 1000000 -out pk8.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.
dsa(1), rsa(1), genrsa(1), gendsa(1)
The -iter option was added in OpenSSL 1.1.0.
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Licensed under the OpenSSL license (the "License"). You
    may not use this file except in compliance with the License. You can obtain
    a copy in the file LICENSE in the source distribution or at
    <https://www.openssl.org/source/license.html>.