man > openssl-kdf(1)

OPENSSL-KDF(1SSL)                              OpenSSL                             OPENSSL-KDF(1SSL)

NAME
       openssl-kdf - perform Key Derivation Function operations

SYNOPSIS
       openssl kdf [-help] [-cipher] [-digest] [-mac] [-kdfopt nm:v] [-keylen num] [-out filename]
       [-binary] [-provider name] [-provider-path path] [-propquery propq] kdf_name

DESCRIPTION
       The key derivation functions generate a derived key from either a secret or password.

OPTIONS
       -help
           Print a usage message.

       -keylen num
           The output size of the derived key. This field is required.

       -out filename
           Filename to output to, or standard output by default.

       -binary
           Output the derived key in binary form. Uses hexadecimal text format if not specified.

       -cipher name
           Specify  the  cipher  to  be used by the KDF.  Not all KDFs require a cipher and it is an
           error to use this option in such cases.

       -digest name
           Specify the digest to be used by the KDF.  Not all KDFs require a digest  and  it  is  an
           error  to  use  this  option  in  such  cases.  To see the list of supported digests, use
           "openssl list -digest-commands".

       -mac name
           Specify the MAC to be used by the KDF.  Not all KDFs require a MAC and it is an error  to
           use this option in such cases.

       -kdfopt nm:v
           Passes  options to the KDF algorithm.  A comprehensive list of parameters can be found in
           "PARAMETERS" in EVP_KDF(3).  Common parameter names used by EVP_KDF_CTX_set_params() are:

           key:string
               Specifies the secret key as an alphanumeric string (use if the key contains printable
               characters only).  The string length must conform to  any  restrictions  of  the  KDF
               algorithm.  A key must be specified for most KDF algorithms.

           hexkey:string
               Alternative  to the key: option where the secret key is specified in hexadecimal form
               (two hex digits per byte).

           pass:string
               Specifies the password as an  alphanumeric  string  (use  if  the  password  contains
               printable characters only).  The password must be specified for PBKDF2 and scrypt.

           hexpass:string
               Alternative  to  the pass: option where the password is specified in hexadecimal form
               (two hex digits per byte).

           salt:string
               Specifies a non-secret unique cryptographic salt as an alphanumeric string (use if it
               contains printable characters only).  The length must conform to any restrictions  of
               the  KDF algorithm.  A salt parameter is required for several KDF algorithms, such as
               EVP_KDF-PBKDF2(7).

           hexsalt:string
               Alternative to the salt: option where the salt is specified in hexadecimal form  (two
               hex digits per byte).

           info:string
               Some  KDF  implementations,  such  as  EVP_KDF-HKDF(7),  take an 'info' parameter for
               binding the derived key material to application-  and  context-specific  information.
               Specifies the info, fixed info, other info or shared info argument as an alphanumeric
               string  (use  if  it contains printable characters only).  The length must conform to
               any restrictions of the KDF algorithm.

           hexinfo:string
               Alternative to the info: option where the info is specified in hexadecimal form  (two
               hex digits per byte).

           digest:string
               This option is identical to the -digest option.

           cipher:string
               This option is identical to the -cipher option.

           mac:string
               This option is identical to the -mac option.

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

       kdf_name
           Specifies  the  name  of  a  supported  KDF  algorithm which will be used.  The supported
           algorithms  names  include  TLS1-PRF,  HKDF,   SSKDF,   PBKDF2,   SSHKDF,   X942KDF-ASN1,
           X942KDF-CONCAT, X963KDF and SCRYPT.

EXAMPLES
       Use TLS1-PRF to create a hex-encoded derived key from a secret key and seed:

           openssl kdf -keylen 16 -kdfopt digest:SHA2-256 -kdfopt key:secret \
                       -kdfopt seed:seed TLS1-PRF

       Use HKDF to create a hex-encoded derived key from a secret key, salt and info:

           openssl kdf -keylen 10 -kdfopt digest:SHA2-256 -kdfopt key:secret \
                       -kdfopt salt:salt -kdfopt info:label HKDF

       Use SSKDF with KMAC to create a hex-encoded derived key from a secret key, salt and info:

           openssl kdf -keylen 64 -kdfopt mac:KMAC-128 -kdfopt maclen:20 \
                       -kdfopt hexkey:b74a149a161545 -kdfopt hexinfo:348a37a2 \
                       -kdfopt hexsalt:3638271ccd68a2 SSKDF

       Use SSKDF with HMAC to create a hex-encoded derived key from a secret key, salt and info:

           openssl kdf -keylen 16 -kdfopt mac:HMAC -kdfopt digest:SHA2-256 \
                       -kdfopt hexkey:b74a149a -kdfopt hexinfo:348a37a2 \
                       -kdfopt hexsalt:3638271c SSKDF

       Use SSKDF with Hash to create a hex-encoded derived key from a secret key, salt and info:

           openssl kdf -keylen 14 -kdfopt digest:SHA2-256 \
                       -kdfopt hexkey:6dbdc23f045488 \
                       -kdfopt hexinfo:a1b2c3d4 SSKDF

       Use SSHKDF to create a hex-encoded derived key from a secret key, hash and session_id:

           openssl kdf -keylen 16 -kdfopt digest:SHA2-256 \
                       -kdfopt hexkey:0102030405 \
                       -kdfopt hexxcghash:06090A \
                       -kdfopt hexsession_id:01020304 \
                       -kdfopt type:A SSHKDF

       Use PBKDF2 to create a hex-encoded derived key from a password and salt:

           openssl kdf -keylen 32 -kdfopt digest:SHA256 -kdfopt pass:password \
                       -kdfopt salt:salt -kdfopt iter:2 PBKDF2

       Use scrypt to create a hex-encoded derived key from a password and salt:

           openssl kdf -keylen 64 -kdfopt pass:password -kdfopt salt:NaCl \
                       -kdfopt n:1024 -kdfopt r:8 -kdfopt p:16 \
                       -kdfopt maxmem_bytes:10485760 SCRYPT

NOTES
       The KDF mechanisms that are available will depend on the options used when building OpenSSL.

SEE ALSO
       openssl(1),    openssl-pkeyutl(1),    EVP_KDF(3),   EVP_KDF-SCRYPT(7),   EVP_KDF-TLS1_PRF(7),
       EVP_KDF-PBKDF2(7), EVP_KDF-HKDF(7), EVP_KDF-SS(7),  EVP_KDF-SSHKDF(7),  EVP_KDF-X942-ASN1(7),
       EVP_KDF-X942-CONCAT(7), EVP_KDF-X963(7)

HISTORY
       Added in OpenSSL 3.0

COPYRIGHT
       Copyright 2019-2023 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 <https://www.openssl.org/source/license.html>.

3.0.13                                       2026-07-29                            OPENSSL-KDF(1SSL)