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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 the EVP_KDF_CTX implementation documentation. 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
Specifies the secret key in hexadecimal form (two hex digits per byte). The key
length must conform to any restrictions of the KDF algorithm. A key must be
specified for most KDF algorithms.
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
Specifies the password in hexadecimal form (two hex digits per byte). The
password must be specified for PBKDF2 and scrypt.
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 2019-2022 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>.
3.0.2 2025-09-18 OPENSSL-KDF(1SSL)
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On Apache
Under GNU General Public License
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