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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>kcapi_aead_decrypt</title><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="index.html" title="Linux Kernel Crypto API User Space Interface Library"><link rel="up" href="ch03s08.html" title="Synchronous AEAD Cipher API - One Shot"><link rel="prev" href="API-kcapi-aead-encrypt.html" title="kcapi_aead_encrypt"><link rel="next" href="ch03s09.html" title="Aynchronous AEAD Cipher API - One Shot"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span class="phrase">kcapi_aead_decrypt</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-kcapi-aead-encrypt.html">Prev</a> </td><th width="60%" align="center">Synchronous AEAD Cipher API - One Shot</th><td width="20%" align="right"> <a accesskey="n" href="ch03s09.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-kcapi-aead-decrypt"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>kcapi_aead_decrypt —
synchronously decrypt AEAD data (one shot)
</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int32_t <b class="fsfunc">kcapi_aead_decrypt </b>(</code></td><td>struct kcapi_handle * <var class="pdparam">handle</var>, </td></tr><tr><td> </td><td>const uint8_t * <var class="pdparam">in</var>, </td></tr><tr><td> </td><td>uint32_t <var class="pdparam">inlen</var>, </td></tr><tr><td> </td><td>const uint8_t * <var class="pdparam">iv</var>, </td></tr><tr><td> </td><td>uint8_t * <var class="pdparam">out</var>, </td></tr><tr><td> </td><td>uint32_t <var class="pdparam">outlen</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">access</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm2380"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>handle</code></em></span></dt><dd><p>
[in] cipher handle
</p></dd><dt><span class="term"><em class="parameter"><code>in</code></em></span></dt><dd><p>
[in] ciphertext data buffer
</p></dd><dt><span class="term"><em class="parameter"><code>inlen</code></em></span></dt><dd><p>
[in] length of in buffer
</p></dd><dt><span class="term"><em class="parameter"><code>iv</code></em></span></dt><dd><p>
[in] IV to be used for cipher operation
</p></dd><dt><span class="term"><em class="parameter"><code>out</code></em></span></dt><dd><p>
[out] plaintext data buffer
</p></dd><dt><span class="term"><em class="parameter"><code>outlen</code></em></span></dt><dd><p>
[in] length of out buffer
</p></dd><dt><span class="term"><em class="parameter"><code>access</code></em></span></dt><dd><p>
[in] kernel access type (KCAPI_ACCESS_HEURISTIC - use internal
heuristic for fastest kernel access; KCAPI_ACCESS_VMSPLICE
use vmsplice access; KCAPI_ACCESS_SENDMSG sendmsg access)
</p></dd></dl></div></div><div class="refsect1"><a name="idm2418"></a><h2>Description</h2><p>
The AEAD cipher operation requires the furnishing of the associated
authentication data. In case such data is not required, it can be set to
NULL and length value must be set to zero.
</p><p>
It is perfectly legal to use the same buffer as the plaintext and
ciphertext pointers. That would mean that after the encryption operation,
the ciphertext is overwritten with the plaintext.
</p><p>
The memory should be aligned at the page boundary using
posix_memalign(sysconf(_SC_PAGESIZE)), If it is not aligned at the page
boundary, the vmsplice call may not send all data to the kernel.
</p><p>
The IV buffer must be exactly <code class="function">kcapi_cipher_ivsize</code> bytes in size.
</p><p>
To catch authentication errors (i.e. integrity violations) during
the decryption operation, the return value of this call should be
checked. If this function returns -EBADMSG, an authentication error
was detected.
</p></div><div class="refsect1"><a name="idm2426"></a><h2>IMPORTANT NOTE</h2><p>
The kernel will only process
sysconf(_SC_PAGESIZE) * ALG_MAX_PAGES at one time. Longer input data cannot
be handled by the kernel.
</p><p>
<em class="parameter"><code>return</code></em> number of bytes decrypted upon success;
a negative errno-style error code if an error occurred
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