Manual: openssl-kdf

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

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
.

3.5.5 2026-01-27 OPENSSL-KDF(1SSL)

← Back to Index

Manual: openssl-kdf

Related Commands: