openssl-pkeyutl, pkeyutl - public key algorithm utility
] [ -in file
] [ -out
] [ -sigfile file
] [ -inkey file
] [ -keyform
] [ -passin arg
] [ -peerkey file
] [ -pubin
] [ -certin
] [ -sign
] [ -verify
] [ -verifyrecover
] [ -decrypt
] [ -derive
] [ -kdf algorithm
[ -kdflen length
] [ -pkeyopt opt:value
] [ -hexdump
] [ -rand file...
] [ -writerand file
] [ -engine_impl
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 default.
- -sigfile file
- Signature file, required for verify operations
- -inkey file
- The input key file, by default it should be a private
- -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 the PASS PHRASE ARGUMENTS section in
- -peerkey file
- The peer key file, used by key derivation (agreement)
- -peerform PEM|DER|ENGINE
- The peer key format PEM, DER or ENGINE. Default is
- 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
- 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
- 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
- -rand file...
- A file or files containing random data used to seed the
random number generator. Multiple files can be specified separated by an
OS-dependent character. The separator is ; for MS-Windows, ,
for OpenVMS, and : for all others.
- [-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
which specifies the digest in use for sign, verify and verifyrecover
operations. The value alg
should represent a digest name as used in the
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
creating the structures that make up the signature (e.g. DigestInfo
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
The RSA 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 pkeyopt
- 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 specified.
- 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
- 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
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:
- 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 default value.
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.
The DSA algorithm supports signing and verification operations only. Currently
there are no additional options other than digest
. Only the SHA1 digest
can be used and this digest is assumed by default.
The DH algorithm only supports the derivation operation and no additional
The EC algorithm supports sign, verify and derive operations. The sign and
verify operations use ECDSA and derive uses ECDH. Currently there are no
additional options other than digest
. Only the SHA1 digest can be used
and this digest is assumed by default.
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 2006-2018 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