EVP_SIGNATURE-LMS(7ossl) OpenSSL EVP_SIGNATURE-LMS(7ossl)
NAME
EVP_SIGNATURE-LMS - The EVP_PKEY LMS signature implementation
DESCRIPTION
The LMS EVP_PKEY implementation supports Leighton-Micali Signatures (LMS)
described in [RFC 8554](https://datatracker.ietf.org/doc/html/rfc8854)
and [SP 800-208](https://csrc.nist.gov/pubs/sp/800/208/final). The
OpenSSL providers only support LMS signature verification, as this is a
[SP 800-208](https://csrc.nist.gov/pubs/sp/800/208/final) requirement for
FIPS software modules.
EVP_PKEY_verify_message_init() and EVP_PKEY_verify() are the only
supported functions used for LMS signatures. Streaming is not currently
supported, and since the signature data contains data related to the
digest used, functions that specify the digest name are not necessary.
FIPS indicator
The following parameter can be retrieved using
EVP_PKEY_CTX_get_params(3):
"fips-indicator" (OSSL_SIGNATURE_PARAM_FIPS_APPROVED_INDICATOR) <integer>
The OpenSSL FIPS provider returns 1 if the operation is FIPS
approved, or 0 otherwise. See "FIPS indicators" in fips_module(7)
for more information.
NOTES
LMS support is disabled by default at compile-time. To enable, specify
the enable-lms build configuration option.
LMS should only be used for older deployments. New deployments should
use either EVP_SIGNATURE-ML-DSA(7) or <L/EVP_SIGNATURE-SLH-DSA(7)>.
EXAMPLES
Error checking has been omitted from the following examples
LMS signature verification
/* See L<EVP_PKEY-LMS(7)/EXAMPLES for an example of loading a LMS |pub| key */
ctx = EVP_PKEY_CTX_new_from_pkey(libctx, pub, propq);
sig = EVP_SIGNATURE_fetch(libctx, "LMS", propq);
EVP_PKEY_verify_message_init(ctx, sig, NULL);
/*
* EVP_PKEY_verify_message_update() and EVP_PKEY_verify_message_final()
* are not supported
*/
ret = EVP_PKEY_verify(ctx, sigdata, sigdata_len, msg, msglen);
/*
* ret == 1 indicates success, 0 verify failure and < 0 for some
* other error.
*/
SEE ALSO
EVP_PKEY-LMS(7), provider-signature(7),
HISTORY
This functionality was added in OpenSSL 3.6.
COPYRIGHT
Copyright 2025-2026 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>.
3.6.5 2026-09-29 EVP_SIGNATURE-LMS(7ossl)
openssl 3.6.5 - Generated Sat Oct 3 10:07:54 CDT 2026