openssl-pkeyutl, pkeyutl - public key algorithm utility
openssl pkeyutl [-help] [-in file] [-out
file] [-sigfile file] [-inkey file] [-keyform
PEM|DER|ENGINE] [-passin arg] [-peerkey file] [-peerform
PEM|DER|ENGINE] [-pubin] [-certin] [-rev]
[-sign] [-verify] [-verifyrecover] [-encrypt]
[-decrypt] [-derive] [-kdf algorithm] [-kdflen
length] [-pkeyopt opt:value] [-hexdump] [-asn1parse]
[-rand file...] [-writerand file] [-engine id]
The pkeyutl command can be used to perform low-level public key
operations using any supported algorithm.
The operations and options supported vary according to the key algorithm and its
implementation. The OpenSSL operations and options are indicated below.
- 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
- 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
- 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
- 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
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.
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
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
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 input.
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 values are
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
additional pkeyopt 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
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
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 used.
- Sets the digest used for the OAEP hash function. If not explicitly set
then SHA1 is used.
The DSA algorithm supports signing and verification operations only. Currently
there are no additional -pkeyopt options other than digest. The
SHA1 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. SHA1 is assumed by default
for the -pkeyopt digest option.
The X25519 and X448 algorithms support key derivation only. Currently there are
no additional options.
Sign some data using a private key:
- 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.
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
Decrypt some data using a private key with OAEP padding using
openssl pkeyutl -decrypt -in file -inkey key.pem -out secret \
-pkeyopt rsa_padding_mode:oaep -pkeyopt rsa_oaep_md:sha256
genpkey(1), pkey(1), rsautl(1) dgst(1),
rsa(1), genrsa(1), EVP_PKEY_CTX_set_hkdf_md(3),
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Licensed under the OpenSSL license (the "License"). You
may not use this file except in compliance with the License. You can obtain
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