Provided by: openssl_1.1.1-1ubuntu2_amd64

**NAME**

openssl-pkeyutl, pkeyutl - public key algorithm utility

**SYNOPSIS**

opensslpkeyutl[-help] [-infile] [-outfile] [-sigfilefile] [-inkeyfile] [-keyformPEM|DER|ENGINE] [-passinarg] [-peerkeyfile] [-peerformPEM|DER|ENGINE] [-pubin] [-certin] [-rev] [-sign] [-verify] [-verifyrecover] [-encrypt] [-decrypt] [-derive] [-kdfalgorithm] [-kdflenlength] [-pkeyoptopt:value] [-hexdump] [-asn1parse] [-randfile...] [-writerandfile] [-engineid] [-engine_impl]

**DESCRIPTION**

Thepkeyutlcommand can be used to perform low level public key operations using any supported algorithm.

**OPTIONS**

-helpPrint out a usage message.-infilenameThis specifies the input filename to read data from or standard input if this option is not specified.-outfilenameSpecifies the output filename to write to or standard output by default.-sigfilefileSignature file, required forverifyoperations only-inkeyfileThe input key file, by default it should be a private key.-keyformPEM|DER|ENGINEThe key format PEM, DER or ENGINE. Default is PEM.-passinargThe input key password source. For more information about the format ofargsee thePASSPHRASEARGUMENTSsection inopenssl(1).-peerkeyfileThe peer key file, used by key derivation (agreement) operations.-peerformPEM|DER|ENGINEThe peer key format PEM, DER or ENGINE. Default is PEM.-pubinThe input file is a public key.-certinThe input is a certificate containing a public key.-revReverse the order of the input buffer. This is useful for some libraries (such as CryptoAPI) which represent the buffer in little endian format.-signSign the input data (which must be a hash) and output the signed result. This requires a private key.-verifyVerify the input data (which must be a hash) against the signature file and indicate if the verification succeeded or failed.-verifyrecoverVerify the input data (which must be a hash) and output the recovered data.-encryptEncrypt the input data using a public key.-decryptDecrypt the input data using a private key.-deriveDerive a shared secret using the peer key.-kdfalgorithmUse key derivation functionalgorithm. The supported algorithms are at presentTLS1-PRFandHKDF. Note: additional parameters and the KDF output length will normally have to be set for this to work. SeeEVP_PKEY_CTX_set_hkdf_md(3) andEVP_PKEY_CTX_set_tls1_prf_md(3) for the supported string parameters of each algorithm.-kdflenlengthSet the output length for KDF.-pkeyoptopt:valuePublic key options specified as opt:value. See NOTES below for more details.-hexdumphex dump the output data.-asn1parseParse the ASN.1 output data, this is useful when combined with the-verifyrecoveroption when an ASN1 structure is signed.-randfile...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. [-writerandfile] Writes random data to the specifiedfileupon exit. This can be used with a subsequent-randflag.-engineidSpecifying an engine (by its uniqueidstring) will causepkeyutlto 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_implWhen used with the-engineoption, it specifies to also use engineidfor 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 thedigest:algoption which specifies the digest in use for sign, verify and verifyrecover operations. The valuealgshould represent a digest name as used in theEVP_get_digestbyname()function for examplesha1. 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 thepkeyutland for creating the structures that make up the signature (e.g.DigestInfoin 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 issha1the 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 additionalpkeyoptvalues are supported:rsa_padding_mode:modeThis sets the RSA padding mode. Acceptable values formodearepkcs1for PKCS#1 padding,sslv23for SSLv23 padding,nonefor no padding,oaepforOAEPmode,x931for X9.31 mode andpssfor PSS. In PKCS#1 padding if the message digest is not set then the supplied data is signed or verified directly instead of using aDigestInfostructure. If a digest is set then the aDigestInfostructure is used and its the length must correspond to the digest type. Foroaepmode only encryption and decryption is supported. Forx931if 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. Forpssmode only sign and verify are supported and the digest type must be specified.rsa_pss_saltlen:lenForpssmode 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 thePSSblock structure.rsa_mgf1_md:digestFor 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 additionalpkeyoptvalues are supported:rsa_padding_mode:mode,rsa_pss_saltlen:len,rsa_mgf1_md:digestThese have the same meaning as theRSAalgorithm with some additional restrictions. The padding mode can only be set topsswhich 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 options other thandigest. Only the SHA1 digest can be used and this digest is assumed by default.

**DH** **ALGORITHM**

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

**EC** **ALGORITHM**

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 thandigest. 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.

**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 digestSHA256and 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 2006-2018 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 <https://www.openssl.org/source/license.html>.