diff options
| author | slontis <shane.lontis@oracle.com> | 2022-06-22 15:21:13 +1000 |
|---|---|---|
| committer | Tomas Mraz <tomas@openssl.org> | 2022-08-17 16:17:42 +0200 |
| commit | b7cf9dd2393de8e90a15e83466d9b8b781b18385 (patch) | |
| tree | 36efb3c6c4e7f451e21b8e2407960aa40a86e401 /doc/man7 | |
| parent | 2f1112b22a826dc8854b41b60a422c987f8ddafb (diff) | |
SHAKE documentation updates for default output length.
Fixes #18586
In order to not break existing applications the OpenSSL documentation
related to SHAKE has been updated.
Background:
All digests algorithms (including XOF's) use the bitlen as the default output length.
This results in a security strength of bitlen / 2.
This means that SHAKE128 will by default have an output length of 16
bytes and a security strength of 64 bits.
For SHAKE256 the default output length is 32 bytes and has a security
strength of 128 bits.
This behaviour was present in 1.1.1 and has been duplicated in the
provider SHAKE algorithms for 3.0.
The SHAKE XOF algorithms have a security strength of
min(bitlen, output xof length in bits / 2).
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18622)
Diffstat (limited to 'doc/man7')
| -rw-r--r-- | doc/man7/EVP_MD-SHAKE.pod | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/doc/man7/EVP_MD-SHAKE.pod b/doc/man7/EVP_MD-SHAKE.pod index 2426d5a4a2..8a31cd53a8 100644 --- a/doc/man7/EVP_MD-SHAKE.pod +++ b/doc/man7/EVP_MD-SHAKE.pod @@ -15,18 +15,20 @@ implementation (see L<EVP_MAC-KMAC(7)>). =head2 Identities -This implementation is only available with the default provider, and -includes the following varieties: +This implementation is available in the FIPS provider as well as the default +provider, and includes the following varieties: =over 4 =item KECCAK-KMAC-128 Known names are "KECCAK-KMAC-128" and "KECCAK-KMAC128" +This is used by L<EVP_MAC-KMAC128(7)> =item KECCAK-KMAC-256 Known names are "KECCAK-KMAC-256" and "KECCAK-KMAC256" +This is used by L<EVP_MAC-KMAC256(7)> =item SHAKE-128 @@ -55,6 +57,14 @@ settable for an B<EVP_MD_CTX> with L<EVP_MD_CTX_set_params(3)>: Sets the digest length for extendable output functions. The length of the "xoflen" parameter should not exceed that of a B<size_t>. +For backwards compatibility reasons the default xoflen length for SHAKE-128 is +16 (bytes) which results in a security strength of only 64 bits. To ensure the +maximum security strength of 128 bits, the xoflen should be set to at least 32. + +For backwards compatibility reasons the default xoflen length for SHAKE-256 is +32 (bytes) which results in a security strength of only 128 bits. To ensure the +maximum security strength of 256 bits, the xoflen should be set to at least 64. + =back =head1 SEE ALSO @@ -63,7 +73,7 @@ L<EVP_MD_CTX_set_params(3)>, L<provider-digest(7)>, L<OSSL_PROVIDER-default(7)> =head1 COPYRIGHT -Copyright 2020 The OpenSSL Project Authors. All Rights Reserved. +Copyright 2020-2022 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 |