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]
[-provparam [name:]key=value] [-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
-provparam [name:]key=value
-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>.
3.5.4 2025-09-30 OPENSSL-KDF(1SSL)
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