Updated: 2021/Apr/14


PKEYUTL(1)                          OpenSSL                         PKEYUTL(1)



NAME
       openssl-pkeyutl, pkeyutl - public key algorithm utility

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
       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] [-engine_impl]

DESCRIPTION
       The pkeyutl command can be used to perform low-level public key
       operations using any supported algorithm.

OPTIONS
       -help
           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 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 the PASS PHRASE ARGUMENTS section 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.

       -pubin
           The input file is a public key.

       -certin
           The input is a certificate containing a public key.

       -rev
           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
           Sign the input data (which must be a hash) and output the signed
           result. This requires a private key.

       -verify
           Verify the input data (which must be a hash) against the signature
           file and indicate if the verification succeeded or failed.

       -verifyrecover
           Verify the input data (which must be a hash) and output the
           recovered data.

       -encrypt
           Encrypt the input data using a public key.

       -decrypt
           Decrypt the input data using a private key.

       -derive
           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.

       -hexdump
           hex dump the output data.

       -asn1parse
           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.

       -engine_impl
           When used with the -engine option, it specifies to also use engine
           id for crypto operations.

NOTES
       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 input.

RSA ALGORITHM
       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 supported:

       rsa_padding_mode:mode
           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.

       rsa_pss_saltlen:len
           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.

       rsa_mgf1_md:digest
           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.

RSA-PSS ALGORITHM
       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:

       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 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.

DSA ALGORITHM
       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.

DH ALGORITHM
       The DH algorithm only supports the derivation operation and no
       additional -pkeyopt options.

EC ALGORITHM
       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.

X25519 and X448 ALGORITHMS
       The X25519 and X448 algorithms support key derivation only. Currently
       there are no additional options.

EXAMPLES
       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

SEE ALSO
       genpkey(1), pkey(1), rsautl(1) dgst(1), rsa(1), genrsa(1),
       EVP_PKEY_CTX_set_hkdf_md(3), EVP_PKEY_CTX_set_tls1_prf_md(3)

COPYRIGHT
       Copyright 2006-2020 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
       <https://www.openssl.org/source/license.html>.



1.1.1i                            2020-12-10                        PKEYUTL(1)