The peer key file, used by key derivation (agreement) operations.

The input file is a public key.

hex dump the output data.

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 and for creating the structures that make up the signature (e.g. DigestInfo in RSASSA PKCS#1 v1.5 signatures).

This command does not hash the input data (except where -rawin is used) 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.

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.

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. The option -rawin must be used with these algorithms with no -digest specified. Additionally 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