1
0
mirror of https://github.com/moparisthebest/xeps synced 2024-12-12 19:02:16 -05:00

Fixed HMAC size for encryption

This commit is contained in:
Fabian Sauter 2021-12-27 12:09:33 +01:00 committed by GitHub
parent 7c43e4aaa8
commit 70d0ddf18a
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23

View File

@ -330,7 +330,7 @@
<ol>
<li>Use HKDF-SHA-256 to generate 80 bytes of output from the message key by providing mk as HKDF input, 256 zero-bits as HKDF salt and &quot;OMEMO Message Key Material&quot; as HKDF info.</li>
<li>Divide the HKDF output into a 32-byte encryption key, a 32-byte authentication key and a 16 byte IV.</li>
<li>Encrypt the plaintext (which consists of a 32 bytes key and a 32 bytes HMAC as specified in the section about <link url="#protocol-message_encryption">Message Encryption</link>) using AES-256-CBC with PKCS#7 padding, using the encryption key and IV derived in the previous step.</li>
<li>Encrypt the plaintext (which consists of a 32 bytes key and a 16 bytes HMAC as specified in the section about <link url="#protocol-message_encryption">Message Encryption</link>) using AES-256-CBC with PKCS#7 padding, using the encryption key and IV derived in the previous step.</li>
<li>Split the associated data as returned by <tt>CONCAT</tt> into the original ad and the <tt>OMEMOMessage.proto</tt> structure.</li>
<li>Add the ciphertext to the <tt>OMEMOMessage.proto</tt> structure.</li>
<li>Serialize the <tt>OMEMOMessage.proto</tt> structure into a parseable byte array. To avoid potential problems regarding non-uniqueness of the serialization, make sure to only serialize <em>once</em> and to use that exact byte sequence in the following steps.</li>