From: Tomas Mraz <tomas@openssl.org>
Date: Wed, 13 Dec 2023 09:06:59 +0000 (+0100)
Subject: AES: Document that the XTS, SIV, WRAP modes do not support streaming
X-Git-Tag: openssl-3.1.5~65
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9c2406600c39f1e87115732c6e118ae9502cdc20;p=thirdparty%2Fopenssl.git

AES: Document that the XTS, SIV, WRAP modes do not support streaming

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
(Merged from https://github.com/openssl/openssl/pull/23028)

(cherry picked from commit 8f0f814d791e0825b96c30494594de619da3e5a5)
---

diff --git a/doc/man7/EVP_CIPHER-AES.pod b/doc/man7/EVP_CIPHER-AES.pod
index 2c790d9cbd9..3313245f984 100644
--- a/doc/man7/EVP_CIPHER-AES.pod
+++ b/doc/man7/EVP_CIPHER-AES.pod
@@ -61,6 +61,19 @@ FIPS provider:
 This implementation supports the parameters described in
 L<EVP_EncryptInit(3)/PARAMETERS>.
 
+=head1 NOTES
+
+The AES-SIV and AES-WRAP mode implementations do not support streaming. That
+means to obtain correct results there can be only one L<EVP_EncryptUpdate(3)>
+or L<EVP_DecryptUpdate(3)> call after the initialization of the context.
+
+The AES-XTS implementations allow streaming to be performed, but each
+L<EVP_EncryptUpdate(3)> or L<EVP_DecryptUpdate(3)> call requires each input
+to be a multiple of the blocksize. Only the final EVP_EncryptUpdate() or
+EVP_DecryptUpdate() call can optionally have an input that is not a multiple
+of the blocksize but is larger than one block. In that case ciphertext
+stealing (CTS) is used to fill the block.
+
 =head1 SEE ALSO
 
 L<provider-cipher(7)>, L<OSSL_PROVIDER-FIPS(7)>, L<OSSL_PROVIDER-default(7)>