plucky (1) openssl-pkeyutl.1ssl.gz

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NAME
       openssl-pkeyutl - asymmetric key command


SYNOPSIS
       openssl pkeyutl [-help] [-in file] [-rawin] [-digest algorithm] [-out file] [-secret file] [-sigfile
       file] [-inkey filename|uri] [-keyform DER|PEM|P12|ENGINE] [-passin arg] [-pubin] [-certin] [-rev] [-sign]
       [-verify] [-verifyrecover] [-encrypt] [-decrypt] [-derive] [-peerkey file] [-peerform DER|PEM|P12|ENGINE]
       [-encap] [-decap] [-kdf algorithm] [-kdflen length] [-kemop operation] [-pkeyopt opt:value]
       [-pkeyopt_passin opt[:passarg]] [-hexdump] [-asn1parse] [-engine id] [-engine_impl] [-rand files]
       [-writerand file] [-provider name] [-provider-path path] [-propquery propq] [-config configfile]


DESCRIPTION
       This command can be used to perform low-level operations on asymmetric (public or private) keys using any
       supported algorithm.

       By default the signing operation (see -sign option) is assumed.


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.

       -rawin
           This indicates that the signature or verification input data is raw data, which is not hashed by any
           message digest algorithm.  Except with EdDSA, the user can specify a digest algorithm by using the
           -digest option.  For signature algorithms like RSA, DSA and ECDSA, the default digest algorithm is
           SHA256. For SM2, it is SM3.

           This option can only be used with -sign and -verify.  For EdDSA (the Ed25519 and Ed448 algorithms)
           this option is required.

       -digest algorithm
           This option can only be used with -sign and -verify.  It specifies the digest algorithm that is used
           to hash the input data before signing or verifying it with the input key. This option could be
           omitted if the signature algorithm does not require preprocessing the input through a pluggable hash
           function before signing (for instance, EdDSA). If this option is omitted but the signature algorithm
           requires one and the -rawin option is given, a default value will be used (see -rawin for details).
           If this option is present, then the -rawin option is required.

           At this time, HashEdDSA (the ph or "prehash" variant of EdDSA) is not supported, so the -digest
           option cannot be used with EdDSA.

       -out filename
           Specifies the output filename to write to or standard output by default.

       -secret filename
           Specifies the output filename to write the secret to on -encap.

       -sigfile file
           Signature file, required and allowed for -verify operations only.

       -inkey filename|uri
           The input key, by default it should be a private key.

       -keyform DER|PEM|P12|ENGINE
           The key format; unspecified by default.  See openssl-format-options(1) for details.

       -passin arg
           The input key password source. For more information about the format of arg see
           openssl-passphrase-options(1).

       -pubin
           By default a private key is read from the key input.  With this option a public key is read instead.
           If the input contains no public key but a private key, its public part is used.

       -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.  This cannot be used in conjunction with -rawin.

       -sign
           Sign the input data and output the signed result. This requires a private key.  Using a message
           digest operation along with this is recommended, when applicable, see the -rawin and -digest options
           for details.  Otherwise, the input data given with the -in option is assumed to already be a digest,
           but this may then require an additional -pkeyopt "digest:"md in some cases (e.g., RSA with the
           default PKCS#1 padding mode).  Even for other algorithms like ECDSA, where the additional -pkeyopt
           option does not affect signature output, it is recommended, as it enables checking that the input
           length is consistent with the intended digest.

       -verify
           Verify the input data against the signature given with the -sigfile option and indicate if the
           verification succeeded or failed.  The input data given with the -in option is assumed to be a hash
           value unless the -rawin option is specified or implied.  With raw data, when a digest algorithm is
           applicable, though it may be inferred from the signature or take a default value, it should also be
           specified.

       -verifyrecover
           Verify the given signature and output the recovered data (signature payload).  For example, in case
           of RSA PKCS#1 the recovered data is the EMSA-PKCS-v1_5 DER encoding of the digest algorithm OID and
           value as specified in RFC8017 Section 9.2
           <https://datatracker.ietf.org/doc/html/rfc8017#section-9.2>.

           Note that here the input given with the -in option is not a signature input (as with the -sign and
           -verify options) but a signature output value, typically produced using the -sign option.

           This option is available only for use with RSA keys.

       -encrypt
           Encrypt the input data using a public key.

       -decrypt
           Decrypt the input data using a private key.

       -derive
           Derive a shared secret using own private (EC)DH key and peer key.

       -peerkey file
           File containing the peer public or private (EC)DH key to use with the key derivation (agreement)
           operation.  Its type must match the type of the own private key given with -inkey.

       -peerform DER|PEM|P12|ENGINE
           The peer key format; unspecified by default.  See openssl-format-options(1) for details.

       -encap
           Encapsulate a generated secret using a private key.  The encapsulated result (binary data) is written
           to standard output by default, or else to the file specified with -out.  The -secret option must also
           be provided to specify the output file for the secret value generated in the encapsulation process.

       -decap
           Decapsulate the secret using a private key.  The result (binary data) is written to standard output
           by default, or else to the file specified with -out.

       -kemop operation
           This option is used for -encap/-decap commands and specifies the KEM operation specific for the key
           algorithm when there is no default KEM operation.  If the algorithm has the default KEM operation,
           this option can be omitted.

           See EVP_PKEY_CTX_set_kem_op(3) and algorithm-specific KEM documentation e.g.  EVP_KEM-RSA(7),
           EVP_KEM-EC(7), EVP_KEM-X25519(7), and EVP_KEM-X448(7).

       -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.

       -pkeyopt_passin opt[:passarg]
           Allows reading a public key option opt from stdin or a password source.  If only opt is specified,
           the user will be prompted to enter a password on stdin.  Alternatively, passarg can be specified
           which can be any value supported by openssl-passphrase-options(1).

       -hexdump
           hex dump the output data.

       -asn1parse
           Parse the ASN.1 output data to check its DER encoding and print any errors.  When combined with the
           -verifyrecover option, this may be useful in case an ASN.1 DER-encoded structure had been signed
           directly (without hashing it) and when checking a signature in PKCS#1 v1.5 format, which has a DER
           encoding.

       -engine id
           See "Engine Options" in openssl(1).  This option is deprecated.

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

       -rand files, -writerand file
           See "Random State Options" in openssl(1) for details.

       -provider name
       -provider-path path
       -propquery propq
           See "Provider Options" in openssl(1), provider(7), and property(7).

       -config configfile
           See "Configuration Option" in openssl(1).


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, the -pkeyopt option supports for all public-key types the "digest:"alg
       argument, which specifies the digest in use for the signing and verification operations.  The value alg
       should represent a digest name as used in the EVP_get_digestbyname() function for example sha256. 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 and for creating the structures that make up the signature (e.g., DigestInfo in RSASSA
       PKCS#1 v1.5 signatures).

       For instance, if the value of the -pkeyopt option "digest" argument is sha256, the signature or
       verification input should be the 32 bytes long binary value of the SHA256 hash function output.

       Unless -rawin is used or implied, this command 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 sensible lengths of input data differ. With RSA the signed data cannot be longer
       than the key modulus. In case of ECDSA and DSA the data should not 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 output size EVP_MAX_MD_SIZE, which currently is 64 bytes.


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, 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 DigestInfo structure
           is used and its length must correspond to the digest type.

           Note, for pkcs1 padding, as a protection against the Bleichenbacher attack, the decryption will not
           fail in case of padding check failures. Use none and manual inspection of the decrypted message to
           verify if the decrypted value has correct PKCS#1 v1.5 padding.

           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_oaep_md:digest
           Sets the digest used for the OAEP hash function. If not explicitly set then SHA256 is used.

       rsa_pkcs1_implicit_rejection:flag
           Disables (when set to 0) or enables (when set to 1) the use of implicit rejection with PKCS#1 v1.5
           decryption. When enabled (the default), as a protection against Bleichenbacher attack, the library
           will generate a deterministic random plaintext that it will return to the caller in case of padding
           check failure.  When disabled, it's the callers' responsibility to handle the returned errors in a
           side-channel free manner.


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 then 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 SHA256 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. SHA256 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.


ED25519 AND ED448 ALGORITHMS
       These algorithms only support signing and verifying. OpenSSL only implements the "pure" variants of these
       algorithms so raw data can be passed directly to them without hashing them first. OpenSSL only supports
       "oneshot" operation with these algorithms. This means that the entire file to be signed/verified must be
       read into memory before processing it. Signing or Verifying very large files should be avoided.
       Additionally the size of the file must be known for this to work. If the size of the file cannot be
       determined (for example if the input is stdin) then the sign or verify operation will fail.


SM2
       The SM2 algorithm supports sign, verify, encrypt and decrypt operations. For the sign and verify
       operations, SM2 requires an Distinguishing ID string to be passed in. The following -pkeyopt value is
       supported:

       distid:string
           This sets the ID string used in SM2 sign or verify operations. While verifying an SM2 signature, the
           ID string must be the same one used when signing the data.  Otherwise the verification will fail.

       hexdistid:hex_string
           This sets the ID string used in SM2 sign or verify operations. While verifying an SM2 signature, the
           ID string must be the same one used when signing the data.  Otherwise the verification will fail. The
           ID string provided with this option should be a valid hexadecimal value.


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

       Derive a key using scrypt where the password is read from command line:

        openssl pkeyutl -kdf scrypt -kdflen 16 -pkeyopt_passin pass \
           -pkeyopt hexsalt:aabbcc -pkeyopt N:16384 -pkeyopt r:8 -pkeyopt p:1

       Derive using the same algorithm, but read key from environment variable MYPASS:

        openssl pkeyutl -kdf scrypt -kdflen 16 -pkeyopt_passin pass:env:MYPASS \
           -pkeyopt hexsalt:aabbcc -pkeyopt N:16384 -pkeyopt r:8 -pkeyopt p:1

       Sign some data using an SM2(7) private key and a specific ID:

        openssl pkeyutl -sign -in file -inkey sm2.key -out sig -rawin -digest sm3 \
           -pkeyopt distid:someid

       Verify some data using an SM2(7) certificate and a specific ID:

        openssl pkeyutl -verify -certin -in file -inkey sm2.cert -sigfile sig \
           -rawin -digest sm3 -pkeyopt distid:someid

       Decrypt some data using a private key with OAEP padding using SHA256:

        openssl pkeyutl -decrypt -in file -inkey key.pem -out secret \
           -pkeyopt rsa_padding_mode:oaep -pkeyopt rsa_oaep_md:sha256


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


HISTORY
       The -engine option was deprecated in OpenSSL 3.0.


       Copyright 2006-2025 The OpenSSL Project Authors. All Rights Reserved.

       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
       <https://www.openssl.org/source/license.html>.