EVP_PKEY-ML-DSA(7SSL) OpenSSL EVP_PKEY-ML-DSA(7SSL)
NAME
EVP_PKEY-ML-DSA, EVP_KEYMGMT-ML-DSA, EVP_PKEY-ML-DSA-44,
EVP_PKEY-ML-DSA-65, EVP_PKEY-ML-DSA-87 - EVP_PKEY ML-DSA keytype and
algorithm support
DESCRIPTION
ML-DSA implements the algorithms ML-DSA-44, ML-DSA-65 and ML-DSA-87.
The key types EVP_PKEY_ML_DSA_44, EVP_PKEY_ML_DSA_65 and
EVP_PKEY_ML_DSA_87 are implemented in OpenSSL's default and FIPS
providers. These implementations support the associated key, containing
the public key pub and the private key priv.
Each of the different key types has an associated security category.
This value is one of 2, 3 or 5 for key types ML-DSA-44, ML-DSA-65 and
ML-DSA-87 respectively, which correspond to security strengths of 128,
192 and 256 repsectively.
Keygen Parameters
"seed" (OSSL_PKEY_PARAM_ML_DSA_SEED) <octet string>
The seed can be used to generate the private and public key
components in a deterministic manner. The length of the value
supplied must be 32 bytes. When this value is not supplied the seed
is generated randomly using a DRBG.
Generated keys default to retaining the seed used. The seed is also
by default retained when keys are loaded from PKCS#8 files in the
seed format. When available, the seed parameter is also used during
key export and import, with keys (by default) regenerated from the
seed even when also provided on import. See "Provider configuration
parameters" below for related controls.
When the seed is retained, it is also available as a gettable
parameter, and private key output to PKCS#8 files will by default
include the seed. When the seed was not initially known, or was not
retained, PKCS#8 private key files will contain only the private key
in FIPS 204 "sk" format.
"properties" (OSSL_PKEY_PARAM_PROPERTIES) <UTF8 string>
Sets properties to be used when fetching algorithm implementations
used for ML-DSA hashing operations.
Use EVP_PKEY_CTX_set_params(3) after calling EVP_PKEY_keygen_init(3).
Common ML-DSA parameters
In addition to the common parameters that all keytypes should support
(see "Common Information Parameters" in provider-keymgmt(7), the
implementation of these key types support the parameters listed below.
These are gettable using EVP_PKEY_get_octet_string_param(3) or
EVP_PKEY_get_params(3). They can be initialised via
EVP_PKEY_fromdata(3), and are returned by EVP_PKEY_todata(3) given a
suitable selection. Once a public or private key is configured, it can
no longer be modified, nor can another key component be added.
"pub" (OSSL_PKEY_PARAM_PUB_KEY) <octet string>
The encoded public key value of size 1312, 1952 or 2592 bytes
depending on the respective key type of ML-DSA-44, ML-DSA-65 or
ML-DSA-87.
"priv" (OSSL_PKEY_PARAM_PRIV_KEY) <octet string>
The encoded private key value of size 2560, 4032 or 4896 bytes
depending on the respective key type of ML-DSA-44, ML-DSA-65 or
ML-DSA-87.
Provider configuration parameters
See the description of the -provparam option in openssl(1) to learn how
to set provider configuration parameters in the command line tools. See
OSSL_PROVIDER_add_conf_parameter(3) to learn how to set provider
configuration options programmatically.
"ml-dsa.retain_seed" (OSSL_PKEY_PARAM_ML_DSA_RETAIN_SEED) <UTF8 string>
When set to a string representing a false boolean value (see
OSSL_PROVIDER_conf_get_bool(3)), the seed will not be retained after
key generation or key import from a seed value. If the resulting
key is then written to a PKCS#8 object, it will contain only the
FIPS 204 "sk" key.
"ml-dsa.prefer_seed" (OSSL_PKEY_PARAM_ML_DSA_PREFER_SEED) <UTF8 string>
When decoding PKCS#8 objects that contain both a seed and the FIPS
204 "sk" private key, the seed is by default used to regenerate the
key, and the companion private key is ignored. When this
configuration parameter is set to a string representing a false
boolean value (see OSSL_PROVIDER_conf_get_bool(3)), the seed is
ignored (neither used to regenerate the key, nor retained), and the
companion key is used instead.
"ml-dsa.input_formats" (OSSL_PKEY_PARAM_ML_DSA_INPUT_FORMATS) <UTF8
string>
List of enabled private key input formats when parsing PKCS#8
objects. List elements are separated by commas, spaces or tabs.
The list of enabled formats can be specified in the configuration
file, as seen in the "EXAMPLES" section below, or the via the
-provparam command-line option (see also
OSSL_PROVIDER_add_conf_parameter(3)).
Values specified on the command-line override any configuration file
settings. By default all the supported formats are enabled. The
supported formats are:
"seed-priv":
This format represents PKCS#8 objects in which both the FIPS 204
32-byte ξ seed and the secret key sk are present in the private
key as part of the DER encoding of the ASN.1 sequence:
ML-DSA-PrivateKey ::= CHOICE {
seed [0] IMPLICIT OCTET STRING (SIZE (32)),
expandedKey OCTET STRING (SIZE (2560 | 4032 | 4896)),
both SEQUENCE {
seed OCTET STRING (SIZE (32)),
expandedKey OCTET STRING (SIZE (2560 | 4032 | 4896)) } }
If the "seed-priv" format is not included in the list, this
format will not be recognised on input.
"seed-only":
This format represents PKCS#8 objects in which only the 32-byte
FIPS 204 ξ seed is present in the above sequence. If the
"seed-only" format is not included in the list, this format will
not be recognised on input.
"priv-only":
This format represents PKCS#8 objects in which only the FIPS 204
private key sk is present in the above sequence. If the
"priv-only" format is not included in the list, this format will
not be recognised on input.
"oqskeypair":
This format represents PKCS#8 objects in which the private key
is a DER encoding of an octet string containing the concatenaton
of the FIPS 204 private key sk and the public key pk. This
encoding is used in some builds of the "oqsprovider". If the
"oqskeypair" format is not included in the list, this format
will not be recognised on input.
"bare-seed":
This format represents PKCS#8 objects in which the private key
contains the 32-byte FIPS 204 seed ξ without any ASN.1
encapsulation. If the "bare-seed" format is not included in the
list, this format will not be recognised on input.
"bare-priv":
This format represents PKCS#8 objects in which the private key
contains the FIPS 204 secret key sk without any ASN.1
encapsulation. If the "bare-priv" format is not included in the
list, this format will not be recognised on input.
"ml-dsa.output_formats" (OSSL_PKEY_PARAM_ML_DSA_OUTPUT_FORMATS) <UTF8
string>
Ordered list of enabled private key output formats when writing
PKCS#8 files. List elements are separated by commas, spaces or
tabs. The list of enabled formats can be specified in the
configuration file, as seen in the "EXAMPLES" section below, or the
via the -provparam command-line option.
This supports the same set of formats as described under
"ml-dsa.input_formats" above. The order in which elements are
listed is important, the selected format will be the first one that
is possible to output. If the key seed is known, the first listed
format will be selected. If the key seed is not known, the first
format that omits the seed will be selected. The default order is
equivalent to "seed-priv" first and "priv-only" second, with both
seed and key output when the seed is available, and just the key
otherwise. If "seed-only" is listed first, then the seed will be
output without the key when available, otherwise the output will
have just the key. If "priv-only" is listed first, then just the
key is output regardless of whether the seed is present. The legacy
"oqskeypair", "bare-seed" and "bare-priv" formats can also be
output, by listing those first.
CONFORMING TO
FIPS 204
EXAMPLES
An EVP_PKEY context can be obtained by calling:
EVP_PKEY_CTX *pctx =
EVP_PKEY_CTX_new_from_name(NULL, "ML-DSA-44", NULL);
An ML-DSA-44 key can be generated like this:
pkey = EVP_PKEY_Q_keygen(NULL, NULL, "ML-DSA-44");
The key pair components can be extracted from a key by calling:
/* Sizes large enough for ML-DSA-87 */
uint8_t pub[2592], priv[4896], seed[32]:
size_t priv_len, pub_len, seed_len;
EVP_PKEY_get_octet_string_param(pkey, OSSL_PKEY_PARAM_ML_DSA_SEED,
seed, sizeof(seed), &seed_len);
EVP_PKEY_get_octet_string_param(pkey, OSSL_PKEY_PARAM_PRIV_KEY,
priv, sizeof(priv), &priv_len);
EVP_PKEY_get_octet_string_param(pkey, OSSL_PKEY_PARAM_PUB_KEY,
pub, sizeof(pub), &pub_len));
An ML-DSA private key in seed format can be converted to a key in the
FIPS 204 sk format by running:
$ openssl pkey -provparam ml-dsa.retain_seed=no \
-in seed-only.pem -out priv-only.pem
To generate an, e.g., ML-DSA-65 key, in FIPS 204 sk format, you can run:
$ openssl genpkey -provparam ml-dsa.retain_seed=no \
-algorithm ml-dsa-65 -out priv-only.pem
If you have a PKCS#8 file with both a seed and a key, and prefer to
import the companion key rather than the seed, you can run:
$ openssl pkey -provparam ml-dsa.prefer_seed=no \
-in seed-priv.pem -out priv-only.pem
In the openssl.cnf file, this looks like:
openssl_conf = openssl_init
[openssl_init]
providers = providers_sect
# Can be referenced in one or more provider sections
[ml_dsa_sect]
prefer_seed = yes
retain_seed = yes
# OQS legacy formats disabled
input_formats = seed-priv, seed-only, priv-only
# Output either the seed alone, or else the key alone
output_formats = seed-only, priv-only
[providers_sect]
default = default_sect
# Or perhaps just: base = default_sect
base = base_sect
[default_sect]
ml-dsa = ml_dsa_sect
[base_sect]
ml-dsa = ml_dsa_sect
SEE ALSO
EVP_KEYMGMT(3), EVP_PKEY(3), provider-keymgmt(7),
EVP_PKEY_get_raw_private_key(3), EVP_PKEY_get_raw_public_key(3),
EVP_PKEY_get1_encoded_public_key(3),
OSSL_PROVIDER_add_conf_parameter(3), provider-keymgmt(7),
EVP_SIGNATURE-ML-DSA(7)
HISTORY
This functionality was added in OpenSSL 3.5.
COPYRIGHT
Copyright 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>.
3.5.4 2025-09-30 EVP_PKEY-ML-DSA(7SSL)
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