Document EVP_AEAD_DEFAULT_TAG_LENGTH and EVP_AEAD_MAX_TAG_LENGTH,

making some adjacent wordings slightly more precise.

diff --git a/lib/libcrypto/man/EVP_AEAD_CTX_init.3 b/lib/libcrypto/man/EVP_AEAD_CTX_init.3
index ad37842..02f6e27 100644 (file)
--- a/lib/libcrypto/man/EVP_AEAD_CTX_init.3
+++ b/lib/libcrypto/man/EVP_AEAD_CTX_init.3
@@ -1,8 +1,9 @@
-.\" $OpenBSD: EVP_AEAD_CTX_init.3,v 1.13 2023/08/24 04:33:08 tb Exp $
+.\" $OpenBSD: EVP_AEAD_CTX_init.3,v 1.14 2023/09/12 13:29:38 schwarze Exp $
 .\"
 .\" Copyright (c) 2014, Google Inc.
 .\" Parts of the text were written by Adam Langley and David Benjamin.
 .\" Copyright (c) 2015 Reyk Floeter <reyk@openbsd.org>
+.\" Copyright (c) 2023 Ingo Schwarze <schwarze@openbsd.org>
 .\"
 .\" Permission to use, copy, modify, and/or distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above
@@ -16,7 +17,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: August 24 2023 $
+.Dd $Mdocdate: September 12 2023 $
 .Dt EVP_AEAD_CTX_INIT 3
 .Os
 .Sh NAME
@@ -147,7 +148,11 @@ argument must be
 for the default implementation;
 other values are currently not supported.
 Authentication tags may be truncated by passing a tag length.
-A tag length of zero indicates the default tag length should be used.
+A
+.Fa tag_len
+argument of
+.Dv EVP_AEAD_DEFAULT_TAG_LENGTH ,
+which has the value 0, causes the default tag length to be used.
 .Pp
 .Fn EVP_AEAD_CTX_cleanup
 frees any data allocated for the context
@@ -241,6 +246,18 @@ and
 provide information about the AEAD algorithm
 .Fa aead .
 .Pp
+.Fn EVP_AEAD_max_tag_len
+returns the maximum tag length that can be used with the given
+.Fa aead .
+This is the largest value that can be passed as the
+.Fa tag_len
+argument to
+.Fn EVP_AEAD_CTX_init .
+No built-in
+.Vt EVP_AEAD
+object has a maximum tag length larger than the constant
+.Dv EVP_AEAD_MAX_TAG_LENGTH .
+.Pp
 All cipher algorithms have a fixed key length unless otherwise stated.
 The following ciphers are available:
 .Bl -tag -width Ds -offset indent
@@ -310,8 +327,6 @@ sealing data with the AEAD.
 .Pp
 .Fn EVP_AEAD_max_tag_len
 returns the maximum tag length when using this AEAD.
-This is the largest value that can be passed as a tag length to
-.Fn EVP_AEAD_CTX_init .
 .Pp
 .Fn EVP_AEAD_nonce_length
 returns the length of the per-message nonce.