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OPENSSL-PKCS8(1ossl)                OpenSSL               OPENSSL-PKCS8(1ossl)


       openssl-pkcs8 - PKCS#8 format private key conversion command


       openssl pkcs8 [-help] [-topk8] [-inform DER|PEM] [-outform DER|PEM]
       [-in filename] [-passin arg] [-out filename] [-passout arg] [-iter
       count] [-noiter] [-nocrypt] [-traditional] [-v2 alg] [-v2prf alg] [-v1
       alg] [-scrypt] [-scrypt_N N] [-scrypt_r r] [-scrypt_p p] [-saltlen
       size] [-rand files] [-writerand file] [-engine id] [-provider name]
       [-provider-path path] [-propquery propq]


       This 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.


           Print out a usage message.

           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, -outform DER|PEM
           The input and formats; the default is PEM.  See
           openssl-format-options(1) for details.

           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

           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.

           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, -passout arg
           The password source for the input and output file.  For more
           information about the format of arg see

       -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.

       -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.

           When creating new PKCS#8 containers, use 1 as iteration count.

           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.

       -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

           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.

           Sets the length (in bytes) of the salt to use for the PBE
           algorithm.  If this value is not specified, the default for PBES2
           is 16 (128 bits) and 8 (64 bits) for PBES1.

       -rand files, -writerand file
           See "Random State Options" in openssl(1) for details.

       -engine id
           See "Engine Options" in openssl(1).  This option is deprecated.

       -provider name
       -provider-path path
       -propquery propq
           See "Provider Options" in openssl(1), provider(7), and property(7).


       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.

       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

           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

        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

        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

        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.


       openssl(1), openssl-dsa(1), openssl-rsa(1), openssl-genrsa(1),


       The -iter option was added in OpenSSL 1.1.0.

       The -engine option was deprecated in OpenSSL 3.0.


       Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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

3.2.0                             2023-11-23              OPENSSL-PKCS8(1ossl)

openssl 3.2.0 - Generated Wed Nov 29 07:39:16 CST 2023
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