Section: OpenSSL (1)
openssl-pkeyutl, pkeyutl - public key algorithm utility
command can be used to perform low-level public key operations
using any supported algorithm.
Print out a usage message.
- -in filename
This specifies the input filename to read data from or standard input
if this option is not specified.
- -out filename
Specifies the output filename to write to or standard output by
- -sigfile file
Signature file, required for verify operations only
- -inkey file
The input key file, by default it should be a private key.
- -keyform PEM|DER|ENGINE
The key format PEM, DER or ENGINE. Default is PEM.
- -passin arg
The input key password source. For more information about the format of arg
see ``Pass Phrase Options'' in openssl(1).
- -peerkey file
The peer key file, used by key derivation (agreement) operations.
- -peerform PEM|DER|ENGINE
The peer key format PEM, DER or ENGINE. Default is PEM.
The input file is a public key.
The input is a certificate containing a public key.
Reverse the order of the input buffer. This is useful for some libraries
(such as CryptoAPI) which represent the buffer in little endian format.
Sign the input data (which must be a hash) and output the signed result. This
requires a private key.
Verify the input data (which must be a hash) against the signature file and
indicate if the verification succeeded or failed.
Verify the input data (which must be a hash) and output the recovered data.
Encrypt the input data using a public key.
Decrypt the input data using a private key.
Derive a shared secret using the peer key.
- -kdf algorithm
Use key derivation function algorithm. The supported algorithms are
at present TLS1-PRF and HKDF.
Note: additional parameters and the KDF output length will normally have to be
set for this to work.
See EVP_PKEY_CTX_set_hkdf_md(3) and EVP_PKEY_CTX_set_tls1_prf_md(3)
for the supported string parameters of each algorithm.
- -kdflen length
Set the output length for KDF.
- -pkeyopt opt:value
Public key options specified as opt:value. See NOTES below for more details.
hex dump the output data.
Parse the ASN.1 output data, this is useful when combined with the
-verifyrecover option when an ASN1 structure is signed.
- -rand file...
A file or files containing random data used to seed the random number
Multiple files can be specified separated by an OS-dependent character.
The separator is ; for MS-Windows, , for OpenVMS, and : for
- [-writerand file]
Writes random data to the specified file upon exit.
This can be used with a subsequent -rand flag.
- -engine id
Specifying an engine (by its unique id string) will cause pkeyutl
to attempt to obtain a functional reference to the specified engine,
thus initialising it if needed. The engine will then be set as the default
for all available algorithms.
When used with the -engine option, it specifies to also use
engine id for crypto operations.
The operations and options supported vary according to the key algorithm
and its implementation. The OpenSSL operations and options are indicated below.
Unless otherwise mentioned all algorithms support the digest:alg option
which specifies the digest in use for sign, verify and verifyrecover operations.
The value alg should represent a digest name as used in the
EVP_get_digestbyname() function for example sha1. This value is not used to
hash the input data. It is used (by some algorithms) for sanity-checking the
lengths of data passed in to the pkeyutl and for creating the structures that
make up the signature (e.g. DigestInfo in RSASSA PKCS#1 v1.5 signatures).
This utility does not hash the input data but rather it will use the data
directly as input to the signature algorithm. Depending on the key type,
signature type, and mode of padding, the maximum acceptable lengths of input
data differ. The signed data can't be longer than the key modulus with RSA. In
case of ECDSA and DSA the data shouldn't be longer than the field
size, otherwise it will be silently truncated to the field size. In any event
the input size must not be larger than the largest supported digest size.
In other words, if the value of digest is sha1 the input should be the 20
bytes long binary encoding of the SHA-1 hash function output.
The Ed25519 and Ed448 signature algorithms are not supported by this utility.
They accept non-hashed input, but this utility can only be used to sign hashed
algorithm generally supports the encrypt, decrypt, sign,
verify and verifyrecover operations. However, some padding modes
support only a subset of these operations. The following additional
values are supported:
This sets the RSA padding mode. Acceptable values for mode are pkcs1 for
PKCS#1 padding, sslv23 for SSLv23 padding, none for no padding, oaep
for OAEP mode, x931 for X9.31 mode and pss for PSS.
In PKCS#1 padding if the message digest is not set then the supplied data is
signed or verified directly instead of using a DigestInfo structure. If a
digest is set then the a DigestInfo structure is used and its the length
must correspond to the digest type.
For oaep mode only encryption and decryption is supported.
For x931 if the digest type is set it is used to format the block data
otherwise the first byte is used to specify the X9.31 digest ID. Sign,
verify and verifyrecover are can be performed in this mode.
For pss mode only sign and verify are supported and the digest type must be
For pss mode only this option specifies the salt length. Three special
values are supported: ``digest'' sets the salt length to the digest length,
``max'' sets the salt length to the maximum permissible value. When verifying
``auto'' causes the salt length to be automatically determined based on the
PSS block structure.
For PSS and OAEP padding sets the MGF1 digest. If the MGF1 digest is not
explicitly set in PSS mode then the signing digest is used.
The RSA-PSS algorithm is a restricted version of the RSA
algorithm which only
supports the sign and verify operations with PSS
padding. The following
values are supported:
- rsa_padding_mode:mode, rsa_pss_saltlen:len, rsa_mgf1_md:digest
These have the same meaning as the RSA algorithm with some additional
restrictions. The padding mode can only be set to pss which is the
If the key has parameter restrictions than the digest, MGF1
digest and salt length are set to the values specified in the parameters.
The digest and MG cannot be changed and the salt length cannot be set to a
value less than the minimum restriction.
algorithm supports signing and verification operations only. Currently
there are no additional -pkeyopt
options other than digest
. The SHA1
digest is assumed by default.
algorithm only supports the derivation operation and no additional
algorithm supports sign, verify and derive operations. The sign and
verify operations use ECDSA
and derive uses ECDH. SHA1
is assumed by default for
the -pkeyopt digest
X25519 and X448 ALGORITHMS
The X25519 and X448 algorithms support key derivation only. Currently there are
no additional options.
Sign some data using a private key:
openssl pkeyutl -sign -in file -inkey key.pem -out sig
Recover the signed data (e.g. if an RSA key is used):
openssl pkeyutl -verifyrecover -in sig -inkey key.pem
Verify the signature (e.g. a DSA key):
openssl pkeyutl -verify -in file -sigfile sig -inkey key.pem
Sign data using a message digest value (this is currently only valid for RSA):
openssl pkeyutl -sign -in file -inkey key.pem -out sig -pkeyopt digest:sha256
Derive a shared secret value:
openssl pkeyutl -derive -inkey key.pem -peerkey pubkey.pem -out secret
Hexdump 48 bytes of TLS1 PRF using digest SHA256 and shared secret and
seed consisting of the single byte 0xFF:
openssl pkeyutl -kdf TLS1-PRF -kdflen 48 -pkeyopt md:SHA256 \
-pkeyopt hexsecret:ff -pkeyopt hexseed:ff -hexdump
Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (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