OPENSSL-PKEYUTL(1) | OpenSSL | OPENSSL-PKEYUTL(1) |
openssl-pkeyutl - asymmetric key command
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 mode] [-pkeyopt opt:value] [-pkeyopt_passin opt[:passarg]] [-hexdump] [-asn1parse] [-engine id] [-engine_impl] [-rand files] [-writerand file] [-provider name] [-provider-path path] [-provparam [name:]key=value] [-propquery propq] [-config configfile]
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.
This option can only be used with -sign and -verify. For EdDSA (the Ed25519 and Ed448 algorithms) this option is implied since OpenSSL 3.5, and required in earlier versions.
The -digest option implies -rawin since OpenSSL 3.5.
At this time, HashEdDSA (the ph or "prehash" variant of EdDSA) is not supported, so the -digest option cannot be used with EdDSA.
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.
At the API level, encapsulation and decapsulation are also supported for a few hybrid ECDHE (no DHKEM) plus ML-KEM algorithms, but these are intended primarily for use with TLS and should not be used standalone. There are in any case no standard public and private key formats for the hybrid algorithms, so it is not possible to provide the required key material.
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.
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:
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.
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:
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.
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.
The DH algorithm only supports the derivation operation and no additional -pkeyopt options.
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.
The X25519 and X448 algorithms support key derivation only. Currently there are no additional options.
The SLH-DSA algorithms (SLH-DSA-SHA2-128s, SLH-DSA-SHA2-128f, SLH-DSA-SHA2-192s, SLH-DSA-SHA2-192f, SLH-DSA-SHA2-256s, SLH-DSA-SHA2-256f) are post-quantum signature algorithms. When using SLH-DSA with pkeyutl, the following options are available:
$ openssl pkeyutl -sign -in file.txt -inkey slhdsa.pem -out sig
$ openssl pkeyutl -verify -in file.txt -inkey slhdsa.pem -sigfile sig
See EVP_PKEY-SLH-DSA(7) and EVP_SIGNATURE-SLH-DSA(7) for additional details about the SLH-DSA algorithm and its implementation.
The ML-DSA algorithms are post-quantum signature algorithms that support signing and verification of "raw" messages. No preliminary hashing is performed. When using ML-DSA with pkeyutl, the following options are available:
$ openssl pkeyutl -sign -in file.txt -inkey mldsa65.pem -out sig
$ openssl pkeyutl -verify -in file.txt -inkey mldsa65.pem -sigfile sig
$ openssl pkeyutl -sign -in file.txt -inkey mldsa65.pem -out sig -pkeyopt message-encoding:1
$ openssl pkeyutl -sign -in file.txt -inkey mldsa65.pem -out sig -pkeyopt test-entropy:abcdefghijklmnopqrstuvwxyz012345
$ openssl pkeyutl -sign -in file.txt -inkey mldsa65.pem -out sig -pkeyopt hextest-entropy:000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f
$ openssl pkeyutl -sign -in file.txt -inkey mldsa65.pem -out sig -pkeyopt deterministic:1
$ echo -n "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef" >file.txt $ openssl pkeyutl -sign -in file.txt -inkey mldsa65.pem -out sig -pkeyopt mu:1
$ openssl pkeyutl -sign -in file.txt -inkey mldsa65.pem -out sig -pkeyopt context-string:mycontext $ openssl pkeyutl -verify -in file.txt -inkey mldsa65.pem -sigfile sig -pkeyopt context-string:mycontext
$ openssl pkeyutl -sign -in file.txt -inkey mldsa65.pem -out sig -pkeyopt hexcontext-string:6d79636f6e74657874
The signing operation supports a deterministic:bool option, with bool set to 1 if a deterministic signature is to be generated with a fixed all zero random input. By default, or if the bool is 0 a random entropy value is used. A deterministic result can also be obtained by specifying an explicit entropy value via the hextest-entropy:value parameter. Deterministic ML-DSA signing should only be used in tests.
See EVP_SIGNATURE-ML-DSA(7) for additional details about the ML-DSA algorithms and their implementation.
The ML-KEM algorithms support encapsulation and decapsulation only. The encapsulation operation supports a hexikme:entropy option, with entropy the 64 hexadecimal digit encoding of a 32-byte value. This should only be used in tests, known or leaked values of the option may compromise the generated shared secret.
See EVP_KEM-ML-KEM(7) for additional detail.
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.
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:
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
Create an ML-DSA key pair and sign data with a specific context string:
$ openssl genpkey -algorithm ML-DSA-65 -out mldsa65.pem $ openssl pkeyutl -sign -in file.txt -inkey mldsa65.pem -out sig -pkeyopt context-string:example
Verify a signature using ML-DSA with the same context string:
$ openssl pkeyutl -verify -in file.txt -inkey mldsa65.pem -sigfile sig -pkeyopt context-string:example
Generate an ML-KEM key pair and use it for encapsulation:
$ openssl genpkey -algorithm ML-KEM-768 -out mlkem768.pem $ openssl pkey -in mlkem768.pem -pubout -out mlkem768_pub.pem $ openssl pkeyutl -encap -inkey mlkem768_pub.pem -pubin -out ciphertext -secret shared_secret.bin
Decapsulate a shared secret using an ML-KEM private key:
$ openssl pkeyutl -decap -inkey mlkem768.pem -in ciphertext -secret decapsulated_secret.bin
Create an SLH-DSA key pair and sign data:
$ openssl genpkey -algorithm SLH-DSA-SHA2-128s -out slh-dsa.pem $ openssl pkeyutl -sign -in file.txt -inkey slh-dsa.pem -out sig
Verify a signature using SLH-DSA:
$ openssl pkeyutl -verify -in file.txt -inkey slh-dsa.pem -sigfile sig
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),
Since OpenSSL 3.5, the -digest option implies -rawin, and these two options are no longer required when signing or verifying with an Ed25519 or Ed448 key.
Also since OpenSSL 3.5, the -kemop option is no longer required for any of the supported algorithms, the only supported mode is now the default.
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>.
2025-07-18 | 3.5.1 |