From 3aa8b1dd6e0f504ef83da99f8c9cdb2532f948f5 Mon Sep 17 00:00:00 2001
From: Rob Austein <sra@hactrn.net>
Date: Sun, 13 Sep 2020 23:10:21 +0000
Subject: Initial conversion pass

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+```
+#!htmlcomment
+
+This page is maintained automatically by a script.  Don't modify this page by hand,
+your changes will just be overwritten the next time the script runs.  Talk to your
+Friendly Neighborhood Repository Maintainer if you need to change something here.
+
+```
+
+```
+#!html
+<h1>keywrap</h1>
+
+<h2>Introduction</h2>
+
+<p>This core implememts AES KEY WRAP as defined in <a href="https://tools.ietf.org/html/rfc3394">RFC
+3394</a> and the keywrap with padding
+according to <a href="https://tools.ietf.org/html/rfc5649">RFC 5694</a></p>
+
+<p>The core supports wrap/unwrap of objects up to 64 kByte in size.
+The core supports 128 and 256 bit wrapping keys.</p>
+
+<h2>Status</h2>
+
+<p>First complete version developed. The core does work.</p>
+
+<p>The core has been simulated with two different simulators and
+linted. The core has been used on the Cryptech Alpha and verified to
+work.</p>
+
+<h2>API</h2>
+
+<p>Objects to be processed are written in word order (MSB words). The
+caller writes the calculated magic value to the A regsisters in word
+order. The caller also needs to write the number of blocks (excluding
+magic block) into the RLEN register. Finally the caller needs to write
+the wrapping key.</p>
+
+<p>Due to address space limitations in the Cryptech cores (with 8-bit
+address space) the object storage is divided into banks [0 .. 127]. Each
+bank supports 128 32-bit words or 4096 bits. For objects lager than 4096
+bits, it is the callers responsibilty to switch banks when reading and
+writing to the storage.</p>
+
+<h2>Implementation details</h2>
+
+<h3>Key Wrap</h3>
+
+<p>The core implements the wrap block processing part of the AES Key Wrap
+as specified in chapter 2.1.1 of RFC 3394:</p>
+
+<p>For j = 0 to 5
+           For i=1 to n
+               B = AES(K, A | R[i])
+               A = MSB(64, B) ^ t where t = (n*j)+i
+               R[i] = LSB(64, B)</p>
+
+<p>The core does not perform the calculation of the magic value, which is
+the initial value of A. The core also does not perform padding om the
+message to an even 8 byte block.</p>
+
+<p>This means that SW needs to generate the 64-bit initial value of A and
+perform padding as meeded.</p>
+
+<p>(Similarly, the core implements the unwrap processng as specifie in
+chapter 2.2.2 of RFC 3394.)</p>
+
+<h2>Implementation results</h2>
+
+<p>The core has been implemented for Xilinx Artix7-t200 using ISE with the
+following results:</p>
+
+<p>Regs:    2906 (1%)
+Slices:  1991 (5%)
+RamB36E: 32 (8%)
+Clock:   100+ MH</p>
+```
+
+[[RepositoryIndex(format=table,glob=core/util/keywrap)]]
+
+| Clone `https://git.cryptech.is/core/util/keywrap.git` |
+|---|
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