EVP_SIGNATURE-SLH-DSA(7ossl) OpenSSL EVP_SIGNATURE-SLH-DSA(7ossl)
NAME
EVP_SIGNATURE-SLH-DSA, EVP_SIGNATURE-SLH-DSA-SHA2-128s,
EVP_SIGNATURE-SLH-DSA-SHA2-128f, EVP_SIGNATURE-SLH-DSA-SHA2-192s,
EVP_SIGNATURE-SLH-DSA-SHA2-192f, EVP_SIGNATURE-SLH-DSA-SHA2-256s,
EVP_SIGNATURE-SLH-DSA-SHA2-256f, EVP_SIGNATURE-SLH-DSA-SHAKE-128s,
EVP_SIGNATURE-SLH-DSA-SHAKE-128f, EVP_SIGNATURE-SLH-DSA-SHAKE-192s,
EVP_SIGNATURE-SLH-DSA-SHAKE-192f, EVP_SIGNATURE-SLH-DSA-SHAKE-256s,
EVP_SIGNATURE-SLH-DSA-SHAKE-256f - EVP_PKEY SLH-DSA support
DESCRIPTION
The SLH-DSA-SHA2-128s, EVP_PKEY-SLH-DSA-SHA2-128f, SLH-DSA-SHA2-192s,
EVP_PKEY-SLH-DSA-SHA2-192f, SLH-DSA-SHA2-256s,
EVP_PKEY-SLH-DSA-SHA2-256f, SLH-DSA-SHAKE-128s,
EVP_PKEY-SLH-DSA-SHAKE-128f, SLH-DSA-SHAKE-192s,
EVP_PKEY-SLH-DSA-SHAKE-192f, SLH-DSA-SHAKE-256s and
EVP_PKEY-SLH-DSA-SHAKE-256f EVP_PKEY implementations supports key
generation, one-shot sign and verify using the SLH-DSA signature
schemes described in FIPS 205.
The different algorithms names correspond to the parameter sets defined
in FIPS 205 Section 11 Table 2. "s" types have smaller signature
sizes, and the "f" variants are faster, (The signatures range from ~8K
to ~50K depending on the type chosen). There are 3 different security
categories also depending on the type.
EVP_SIGNATURE_fetch(3) can be used to explicitely fetch one of the 12
algorithms which can then be used with EVP_PKEY_sign_message_init(3),
EVP_PKEY_sign(3), EVP_PKEY_verify_message_init(3), and
EVP_PKEY_verify(3) to perform one-shot message signing or verification.
The normal signing process (called Pure SLH-DSA Signature Generation)
encodes the message internally as 0x00 || len(ctx) || ctx || message.
where ctx is some optional value of size 0x00..0xFF. OpenSSL also
allows the message to not be encoded which is required for testing.
OpenSSL does not support Pre Hash SLH-DSA Signature Generation, but
this may be done by the user by doing Pre hash encoding externally and
then chosing the option to not encode the message.
SLH-DSA Signature Parameters
The "context-string" parameter, described below, can be used for both
signing and verification. It may be set by passing an OSSL_PARAM array
to EVP_PKEY_sign_init_ex2(3) or EVP_PKEY_verify_init_ex2(3)
"context-string" (OSSL_SIGNATURE_PARAM_CONTEXT_STRING) <octet string>
A string of octets with length at most 255. By default it is the
empty string.
The following parameters can be used when signing: They can be set by
passing an OSSL_PARAM array to EVP_PKEY_sign_init_ex2(3).
"message-encoding" (OSSL_SIGNATURE_PARAM_MESSAGE_ENCODING) <integer>
The default value of 1 uses 'Pure SLH-DSA Signature Generation' as
described above. Setting it to 0 does not encode the message, which
is used for testing, but can also be used for 'Pre Hash SLH-DSA
Signature Generation'.
"test-entropy" (OSSL_SIGNATURE_PARAM_TEST_ENTROPY <octet string
Used for testing to pass a optional random value.
"deterministic" (OSSL_SIGNATURE_PARAM_DETERMINISTIC) <integer>
The default value of 0 generates a random value (using a DRBG) this
is used when processing the message. Setting this to 1 causes the
private key seed to be used instead. This value is ignored if
"test-entropy" is set.
See EVP_PKEY-SLH-DSA(7) for information related to SLH-DSA keys.
NOTES
For backwards compatibility reasons EVP_DigestSignInit_ex(),
EVP_DigestSign(), EVP_DigestVerifyInit_ex() and EVP_DigestVerify() may
also be used, but the digest passed in mdname must be NULL.
EXAMPLES
To sign a message using an SLH-DSA EVP_PKEY structure:
void do_sign(EVP_PKEY *key, unsigned char *msg, size_t msg_len)
{
size_t sig_len;
unsigned char *sig = NULL;
const OSSL_PARAM params[] = {
OSSL_PARAM_octet_string("context-string", (unsigned char *)"A context string", 33),
OSSL_PARAM_END
};
EVP_PKEY_CTX *sctx = EVP_PKEY_CTX_new_from_pkey(NULL, pkey, NULL);
EVP_SIGNATURE *sig_alg = EVP_SIGNATURE_fetch(NULL, "SLH-DSA-SHA2-128s", NULL);
EVP_PKEY_sign_message_init(sctx, sig_alg, params);
/* Calculate the required size for the signature by passing a NULL buffer. */
EVP_PKEY_sign(sctx, NULL, &sig_len, msg, msg_len);
sig = OPENSSL_zalloc(sig_len);
EVP_PKEY_sign(sctx, sig, &sig_len, msg, msg_len);
...
OPENSSL_free(sig);
EVP_SIGNATURE_free(sig_alg);
EVP_PKEY_CTX_free(sctx);
}
SEE ALSO
EVP_PKEY-SLH-DSA(7) provider-signature(7), EVP_PKEY_sign(3),
EVP_PKEY_verify(3),
HISTORY
This functionality was added in OpenSSL 3.5.
COPYRIGHT
Copyright 2024-2025 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_SIGNATURE-SLH-DSA(7ossl)
openssl3 3.5.4 - Generated Wed Oct 15 18:29:47 CDT 2025