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<title>10.8. Asymmetric encryption &#8212; PSA Crypto API 1.0.1 documentation</title>
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<div class="section" id="asymmetric-encryption">
<span id="pke"></span><h1>10.8. Asymmetric encryption</h1>
<div class="section" id="asymmetric-encryption-algorithms">
<span id="id1"></span><h2>10.8.1. Asymmetric encryption algorithms</h2>
<div class="section" id="PSA_ALG_RSA_PKCS1V15_CRYPT">
<span id="c.PSA_ALG_RSA_PKCS1V15_CRYPT"></span><h3><code class="docutils literal notranslate"><span class="pre">PSA_ALG_RSA_PKCS1V15_CRYPT</span></code> (macro)</h3>
<p>The RSA PKCS#1 v1.5 asymmetric encryption algorithm.</p>
<pre class="literal-block">#define <a class="reference internal" href="#c.PSA_ALG_RSA_PKCS1V15_CRYPT" title="PSA_ALG_RSA_PKCS1V15_CRYPT">PSA_ALG_RSA_PKCS1V15_CRYPT</a> ((<a class="reference internal" href="algorithms.html#c.psa_algorithm_t" title="psa_algorithm_t">psa_algorithm_t</a>)0x07000200)</pre>
<p>This encryption scheme is defined by <span><em>PKCS #1: RSA Cryptography Specifications Version 2.2</em> <a class="reference internal" href="../../about.html#citation-rfc8017"><span class="cite">[RFC8017]</span></a></span> <a class="reference external" href="https://tools.ietf.org/html/rfc8017.html#section-7.2">§7.2</a> under the name RSAES-PKCS-v1_5.</p>
</div>
<div class="section" id="PSA_ALG_RSA_OAEP">
<span id="c.PSA_ALG_RSA_OAEP"></span><h3><code class="docutils literal notranslate"><span class="pre">PSA_ALG_RSA_OAEP</span></code> (macro)</h3>
<p>The RSA OAEP asymmetric encryption algorithm.</p>
<pre class="literal-block">#define <a class="reference internal" href="#c.PSA_ALG_RSA_OAEP" title="PSA_ALG_RSA_OAEP">PSA_ALG_RSA_OAEP</a>(hash_alg) <em><a class="reference internal" href="../../overview/implementation.html#specification-defined-value"><span class="std std-ref">/* specification-defined value */</span></a></em></pre>
<p class="rubric">Parameters</p>
<dl class="simple">
<dt> <code class="docutils literal notranslate"><span class="pre">hash_alg</span></code></dt><dd><p>The hash algorithm (<code class="docutils literal notranslate"><span class="pre">PSA_ALG_XXX</span></code> value such that <a class="reference internal" href="algorithms.html#c.PSA_ALG_IS_HASH" title="PSA_ALG_IS_HASH"><code class="docutils literal notranslate"><span class="pre">PSA_ALG_IS_HASH</span></code></a><code class="docutils literal notranslate"><span class="pre">(</span></code><code class="docutils literal notranslate"><span class="pre">hash_alg</span></code><code class="docutils literal notranslate"><span class="pre">)</span></code> is true) to use for <em>MGF1</em>.</p>
</dd>
</dl>
<p class="rubric">Returns</p>
<p>The corresponding RSA OAEP encryption algorithm.</p>
<p>Unspecified if <code class="docutils literal notranslate"><span class="pre">hash_alg</span></code> is not a supported hash algorithm.</p>
<p class="rubric">Description</p>
<p>This encryption scheme is defined by <a class="reference internal" href="../../about.html#citation-rfc8017"><span class="cite">[RFC8017]</span></a> <a class="reference external" href="https://tools.ietf.org/html/rfc8017.html#section-7.1">§7.1</a> under the name RSAES-OAEP, with the mask generation function <em>MGF1</em> defined in <a class="reference internal" href="../../about.html#citation-rfc8017"><span class="cite">[RFC8017]</span></a> <a class="reference external" href="https://tools.ietf.org/html/rfc8017.html#appendix-B">Appendix B</a>.</p>
</div>
</div>
<div class="section" id="asymmetric-encryption-functions">
<h2>10.8.2. Asymmetric encryption functions</h2>
<div class="section" id="psa_asymmetric_encrypt">
<span id="c.psa_asymmetric_encrypt"></span><h3><code class="docutils literal notranslate"><span class="pre">psa_asymmetric_encrypt</span></code> (function)</h3>
<p>Encrypt a short message with a public key.</p>
<pre class="literal-block"><a class="reference internal" href="../library/status.html#c.psa_status_t" title="psa_status_t">psa_status_t</a> <a class="reference internal" href="#c.psa_asymmetric_encrypt" title="psa_asymmetric_encrypt">psa_asymmetric_encrypt</a>(<a class="reference internal" href="../keys/ids.html#c.psa_key_id_t" title="psa_key_id_t">psa_key_id_t</a> key,
<a class="reference internal" href="algorithms.html#c.psa_algorithm_t" title="psa_algorithm_t">psa_algorithm_t</a> alg,
const uint8_t * input,
size_t input_length,
const uint8_t * salt,
size_t salt_length,
uint8_t * output,
size_t output_size,
size_t * output_length);</pre>
<p class="rubric">Parameters</p>
<dl class="simple">
<dt> <code class="docutils literal notranslate"><span class="pre">key</span></code></dt><dd><p>Identifer of the key to use for the operation. It must be a public key or an asymmetric key pair.
It must allow the usage <a class="reference internal" href="../keys/policy.html#c.PSA_KEY_USAGE_ENCRYPT" title="PSA_KEY_USAGE_ENCRYPT"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_KEY_USAGE_ENCRYPT</span></code></a>.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">alg</span></code></dt><dd><p>An asymmetric encryption algorithm that is compatible with the type of <code class="docutils literal notranslate"><span class="pre">key</span></code>.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">input</span></code></dt><dd><p>The message to encrypt.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">input_length</span></code></dt><dd><p>Size of the <code class="docutils literal notranslate"><span class="pre">input</span></code> buffer in bytes.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">salt</span></code></dt><dd><p>A salt or label, if supported by the encryption algorithm. If the algorithm does not support a salt, pass <code class="docutils literal notranslate"><span class="pre">NULL</span></code>. If the algorithm supports an optional salt, pass <code class="docutils literal notranslate"><span class="pre">NULL</span></code> to indicate that there is no salt.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">salt_length</span></code></dt><dd><p>Size of the <code class="docutils literal notranslate"><span class="pre">salt</span></code> buffer in bytes. If <code class="docutils literal notranslate"><span class="pre">salt</span></code> is <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, pass <code class="docutils literal notranslate"><span class="pre">0</span></code>.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">output</span></code></dt><dd><p>Buffer where the encrypted message is to be written.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">output_size</span></code></dt><dd><p>Size of the <code class="docutils literal notranslate"><span class="pre">output</span></code> buffer in bytes.
This must be appropriate for the selected algorithm and key:</p>
<ul class="simple">
<li><p>The required output size is <a class="reference internal" href="#c.PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE" title="PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE"><code class="docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE</span></code></a><code class="docutils literal notranslate"><span class="pre">(</span></code><code class="docutils literal notranslate"><span class="pre">key_type</span></code><code class="docutils literal notranslate"><span class="pre">,</span> </code><code class="docutils literal notranslate"><span class="pre">key_bits</span></code><code class="docutils literal notranslate"><span class="pre">,</span> </code><code class="docutils literal notranslate"><span class="pre">alg</span></code><code class="docutils literal notranslate"><span class="pre">)</span></code> where <code class="docutils literal notranslate"><span class="pre">key_type</span></code> and <code class="docutils literal notranslate"><span class="pre">key_bits</span></code> are the type and bit-size respectively of <code class="docutils literal notranslate"><span class="pre">key</span></code>.</p></li>
<li><p><a class="reference internal" href="#c.PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE" title="PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE</span></code></a> evaluates to the maximum output size of any supported asymmetric encryption.</p></li>
</ul>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">output_length</span></code></dt><dd><p>On success, the number of bytes that make up the returned output.</p>
</dd>
</dl>
<p class="rubric">Returns: <a class="reference internal" href="../library/status.html#c.psa_status_t" title="psa_status_t"><code class="docutils literal notranslate"><span class="pre">psa_status_t</span></code></a></p>
<dl class="simple">
<dt> <a class="reference internal" href="../library/status.html#c.PSA_SUCCESS" title="PSA_SUCCESS"><code class="docutils literal notranslate"><span class="pre">PSA_SUCCESS</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_INVALID_HANDLE" title="PSA_ERROR_INVALID_HANDLE"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_INVALID_HANDLE</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_NOT_PERMITTED" title="PSA_ERROR_NOT_PERMITTED"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_NOT_PERMITTED</span></code></a></dt><dd><p>The key does not have the <a class="reference internal" href="../keys/policy.html#c.PSA_KEY_USAGE_ENCRYPT" title="PSA_KEY_USAGE_ENCRYPT"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_KEY_USAGE_ENCRYPT</span></code></a> flag, or it does not permit the requested algorithm.</p>
</dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_BUFFER_TOO_SMALL" title="PSA_ERROR_BUFFER_TOO_SMALL"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_BUFFER_TOO_SMALL</span></code></a></dt><dd><p>The size of the <code class="docutils literal notranslate"><span class="pre">output</span></code> buffer is too small.
<a class="reference internal" href="#c.PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE" title="PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE()</span></code></a> or <a class="reference internal" href="#c.PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE" title="PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE</span></code></a> can be used to determine the required buffer size.</p>
</dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_NOT_SUPPORTED" title="PSA_ERROR_NOT_SUPPORTED"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_NOT_SUPPORTED</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_INVALID_ARGUMENT" title="PSA_ERROR_INVALID_ARGUMENT"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_INVALID_ARGUMENT</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_INSUFFICIENT_MEMORY" title="PSA_ERROR_INSUFFICIENT_MEMORY"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_INSUFFICIENT_MEMORY</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_COMMUNICATION_FAILURE" title="PSA_ERROR_COMMUNICATION_FAILURE"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_COMMUNICATION_FAILURE</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_HARDWARE_FAILURE" title="PSA_ERROR_HARDWARE_FAILURE"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_HARDWARE_FAILURE</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_CORRUPTION_DETECTED" title="PSA_ERROR_CORRUPTION_DETECTED"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_CORRUPTION_DETECTED</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_STORAGE_FAILURE" title="PSA_ERROR_STORAGE_FAILURE"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_STORAGE_FAILURE</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_DATA_CORRUPT" title="PSA_ERROR_DATA_CORRUPT"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_DATA_CORRUPT</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_DATA_INVALID" title="PSA_ERROR_DATA_INVALID"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_DATA_INVALID</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_INSUFFICIENT_ENTROPY" title="PSA_ERROR_INSUFFICIENT_ENTROPY"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_INSUFFICIENT_ENTROPY</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_BAD_STATE" title="PSA_ERROR_BAD_STATE"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_BAD_STATE</span></code></a></dt><dd><p>The library has not been previously initialized by <a class="reference internal" href="../library/library.html#c.psa_crypto_init" title="psa_crypto_init"><code class="xref any c c-func docutils literal notranslate"><span class="pre">psa_crypto_init()</span></code></a>. It is implementation-dependent whether a failure to initialize results in this error code.</p>
</dd>
</dl>
<p class="rubric">Description</p>
<ul class="simple">
<li><p>For <a class="reference internal" href="#c.PSA_ALG_RSA_PKCS1V15_CRYPT" title="PSA_ALG_RSA_PKCS1V15_CRYPT"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ALG_RSA_PKCS1V15_CRYPT</span></code></a>, no salt is supported.</p></li>
</ul>
</div>
<div class="section" id="psa_asymmetric_decrypt">
<span id="c.psa_asymmetric_decrypt"></span><h3><code class="docutils literal notranslate"><span class="pre">psa_asymmetric_decrypt</span></code> (function)</h3>
<p>Decrypt a short message with a private key.</p>
<pre class="literal-block"><a class="reference internal" href="../library/status.html#c.psa_status_t" title="psa_status_t">psa_status_t</a> <a class="reference internal" href="#c.psa_asymmetric_decrypt" title="psa_asymmetric_decrypt">psa_asymmetric_decrypt</a>(<a class="reference internal" href="../keys/ids.html#c.psa_key_id_t" title="psa_key_id_t">psa_key_id_t</a> key,
<a class="reference internal" href="algorithms.html#c.psa_algorithm_t" title="psa_algorithm_t">psa_algorithm_t</a> alg,
const uint8_t * input,
size_t input_length,
const uint8_t * salt,
size_t salt_length,
uint8_t * output,
size_t output_size,
size_t * output_length);</pre>
<p class="rubric">Parameters</p>
<dl class="simple">
<dt> <code class="docutils literal notranslate"><span class="pre">key</span></code></dt><dd><p>Identifier of the key to use for the operation. It must be an asymmetric key pair.
It must allow the usage <a class="reference internal" href="../keys/policy.html#c.PSA_KEY_USAGE_DECRYPT" title="PSA_KEY_USAGE_DECRYPT"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_KEY_USAGE_DECRYPT</span></code></a>.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">alg</span></code></dt><dd><p>An asymmetric encryption algorithm that is compatible with the type of <code class="docutils literal notranslate"><span class="pre">key</span></code>.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">input</span></code></dt><dd><p>The message to decrypt.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">input_length</span></code></dt><dd><p>Size of the <code class="docutils literal notranslate"><span class="pre">input</span></code> buffer in bytes.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">salt</span></code></dt><dd><p>A salt or label, if supported by the encryption algorithm. If the algorithm does not support a salt, pass <code class="docutils literal notranslate"><span class="pre">NULL</span></code>. If the algorithm supports an optional salt, pass <code class="docutils literal notranslate"><span class="pre">NULL</span></code> to indicate that there is no salt.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">salt_length</span></code></dt><dd><p>Size of the <code class="docutils literal notranslate"><span class="pre">salt</span></code> buffer in bytes. If <code class="docutils literal notranslate"><span class="pre">salt</span></code> is <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, pass <code class="docutils literal notranslate"><span class="pre">0</span></code>.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">output</span></code></dt><dd><p>Buffer where the decrypted message is to be written.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">output_size</span></code></dt><dd><p>Size of the <code class="docutils literal notranslate"><span class="pre">output</span></code> buffer in bytes.
This must be appropriate for the selected algorithm and key:</p>
<ul class="simple">
<li><p>The required output size is <a class="reference internal" href="#c.PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE" title="PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE"><code class="docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE</span></code></a><code class="docutils literal notranslate"><span class="pre">(</span></code><code class="docutils literal notranslate"><span class="pre">key_type</span></code><code class="docutils literal notranslate"><span class="pre">,</span> </code><code class="docutils literal notranslate"><span class="pre">key_bits</span></code><code class="docutils literal notranslate"><span class="pre">,</span> </code><code class="docutils literal notranslate"><span class="pre">alg</span></code><code class="docutils literal notranslate"><span class="pre">)</span></code> where <code class="docutils literal notranslate"><span class="pre">key_type</span></code> and <code class="docutils literal notranslate"><span class="pre">key_bits</span></code> are the type and bit-size respectively of <code class="docutils literal notranslate"><span class="pre">key</span></code>.</p></li>
<li><p><a class="reference internal" href="#c.PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE" title="PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE</span></code></a> evaluates to the maximum output size of any supported asymmetric decryption.</p></li>
</ul>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">output_length</span></code></dt><dd><p>On success, the number of bytes that make up the returned output.</p>
</dd>
</dl>
<p class="rubric">Returns: <a class="reference internal" href="../library/status.html#c.psa_status_t" title="psa_status_t"><code class="docutils literal notranslate"><span class="pre">psa_status_t</span></code></a></p>
<dl class="simple">
<dt> <a class="reference internal" href="../library/status.html#c.PSA_SUCCESS" title="PSA_SUCCESS"><code class="docutils literal notranslate"><span class="pre">PSA_SUCCESS</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_INVALID_HANDLE" title="PSA_ERROR_INVALID_HANDLE"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_INVALID_HANDLE</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_NOT_PERMITTED" title="PSA_ERROR_NOT_PERMITTED"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_NOT_PERMITTED</span></code></a></dt><dd><p>The key does not have the <a class="reference internal" href="../keys/policy.html#c.PSA_KEY_USAGE_DECRYPT" title="PSA_KEY_USAGE_DECRYPT"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_KEY_USAGE_DECRYPT</span></code></a> flag, or it does not permit the requested algorithm.</p>
</dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_BUFFER_TOO_SMALL" title="PSA_ERROR_BUFFER_TOO_SMALL"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_BUFFER_TOO_SMALL</span></code></a></dt><dd><p>The size of the <code class="docutils literal notranslate"><span class="pre">output</span></code> buffer is too small.
<a class="reference internal" href="#c.PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE" title="PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE()</span></code></a> or <a class="reference internal" href="#c.PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE" title="PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE</span></code></a> can be used to determine the required buffer size.</p>
</dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_NOT_SUPPORTED" title="PSA_ERROR_NOT_SUPPORTED"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_NOT_SUPPORTED</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_INVALID_ARGUMENT" title="PSA_ERROR_INVALID_ARGUMENT"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_INVALID_ARGUMENT</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_INSUFFICIENT_MEMORY" title="PSA_ERROR_INSUFFICIENT_MEMORY"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_INSUFFICIENT_MEMORY</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_COMMUNICATION_FAILURE" title="PSA_ERROR_COMMUNICATION_FAILURE"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_COMMUNICATION_FAILURE</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_HARDWARE_FAILURE" title="PSA_ERROR_HARDWARE_FAILURE"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_HARDWARE_FAILURE</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_CORRUPTION_DETECTED" title="PSA_ERROR_CORRUPTION_DETECTED"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_CORRUPTION_DETECTED</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_STORAGE_FAILURE" title="PSA_ERROR_STORAGE_FAILURE"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_STORAGE_FAILURE</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_DATA_CORRUPT" title="PSA_ERROR_DATA_CORRUPT"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_DATA_CORRUPT</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_DATA_INVALID" title="PSA_ERROR_DATA_INVALID"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_DATA_INVALID</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_INSUFFICIENT_ENTROPY" title="PSA_ERROR_INSUFFICIENT_ENTROPY"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_INSUFFICIENT_ENTROPY</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_INVALID_PADDING" title="PSA_ERROR_INVALID_PADDING"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_INVALID_PADDING</span></code></a></dt><dd></dd>
<dt> <a class="reference internal" href="../library/status.html#c.PSA_ERROR_BAD_STATE" title="PSA_ERROR_BAD_STATE"><code class="docutils literal notranslate"><span class="pre">PSA_ERROR_BAD_STATE</span></code></a></dt><dd><p>The library has not been previously initialized by <a class="reference internal" href="../library/library.html#c.psa_crypto_init" title="psa_crypto_init"><code class="xref any c c-func docutils literal notranslate"><span class="pre">psa_crypto_init()</span></code></a>. It is implementation-dependent whether a failure to initialize results in this error code.</p>
</dd>
</dl>
<p class="rubric">Description</p>
<ul class="simple">
<li><p>For <a class="reference internal" href="#c.PSA_ALG_RSA_PKCS1V15_CRYPT" title="PSA_ALG_RSA_PKCS1V15_CRYPT"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ALG_RSA_PKCS1V15_CRYPT</span></code></a>, no salt is supported.</p></li>
</ul>
</div>
</div>
<div class="section" id="support-macros">
<h2>10.8.3. Support macros</h2>
<div class="section" id="PSA_ALG_IS_RSA_OAEP">
<span id="c.PSA_ALG_IS_RSA_OAEP"></span><h3><code class="docutils literal notranslate"><span class="pre">PSA_ALG_IS_RSA_OAEP</span></code> (macro)</h3>
<p>Whether the specified algorithm is an RSA OAEP encryption algorithm.</p>
<pre class="literal-block">#define <a class="reference internal" href="#c.PSA_ALG_IS_RSA_OAEP" title="PSA_ALG_IS_RSA_OAEP">PSA_ALG_IS_RSA_OAEP</a>(alg) <em><a class="reference internal" href="../../overview/implementation.html#specification-defined-value"><span class="std std-ref">/* specification-defined value */</span></a></em></pre>
<p class="rubric">Parameters</p>
<dl class="simple">
<dt> <code class="docutils literal notranslate"><span class="pre">alg</span></code></dt><dd><p>An algorithm identifier (value of type <a class="reference internal" href="algorithms.html#c.psa_algorithm_t" title="psa_algorithm_t"><code class="xref any c c-type docutils literal notranslate"><span class="pre">psa_algorithm_t</span></code></a>).</p>
</dd>
</dl>
<p class="rubric">Returns</p>
<p><code class="docutils literal notranslate"><span class="pre">1</span></code> if <code class="docutils literal notranslate"><span class="pre">alg</span></code> is an RSA OAEP algorithm, <code class="docutils literal notranslate"><span class="pre">0</span></code> otherwise.</p>
<p>This macro can return either <code class="docutils literal notranslate"><span class="pre">0</span></code> or <code class="docutils literal notranslate"><span class="pre">1</span></code> if <code class="docutils literal notranslate"><span class="pre">alg</span></code> is not a supported algorithm identifier.</p>
</div>
<div class="section" id="PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE">
<span id="c.PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE"></span><h3><code class="docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE</span></code> (macro)</h3>
<p>Sufficient output buffer size for <a class="reference internal" href="#c.psa_asymmetric_encrypt" title="psa_asymmetric_encrypt"><code class="xref any c c-func docutils literal notranslate"><span class="pre">psa_asymmetric_encrypt()</span></code></a>.</p>
<pre class="literal-block">#define <a class="reference internal" href="#c.PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE" title="PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE">PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE</a>(key_type, key_bits, alg) \
<em><a class="reference internal" href="../../overview/implementation.html#implementation-defined-value"><span class="std std-ref">/* implementation-defined value */</span></a></em></pre>
<p class="rubric">Parameters</p>
<dl class="simple">
<dt> <code class="docutils literal notranslate"><span class="pre">key_type</span></code></dt><dd><p>An asymmetric key type, either a key pair or a public key.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">key_bits</span></code></dt><dd><p>The size of the key in bits.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">alg</span></code></dt><dd><p>The asymmetric encryption algorithm.</p>
</dd>
</dl>
<p class="rubric">Returns</p>
<p>If the parameters are valid and supported, return a buffer size in bytes that guarantees that <a class="reference internal" href="#c.psa_asymmetric_encrypt" title="psa_asymmetric_encrypt"><code class="xref any c c-func docutils literal notranslate"><span class="pre">psa_asymmetric_encrypt()</span></code></a> will not fail with <a class="reference internal" href="../library/status.html#c.PSA_ERROR_BUFFER_TOO_SMALL" title="PSA_ERROR_BUFFER_TOO_SMALL"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ERROR_BUFFER_TOO_SMALL</span></code></a>. If the parameters are a valid combination that is not supported by the implementation, this macro must return either a sensible size or <code class="docutils literal notranslate"><span class="pre">0</span></code>. If the parameters are not valid, the return value is unspecified.</p>
<p class="rubric">Description</p>
<p>This macro returns a sufficient buffer size for a ciphertext produced using a key of the specified type and size, with the specified algorithm. Note that the actual size of the ciphertext might be smaller, depending on the algorithm.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This function might evaluate its arguments multiple times or zero times. Providing arguments that have side effects will result in implementation-specific behavior, and is non-portable.</p>
</div>
<p>See also <a class="reference internal" href="#c.PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE" title="PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE</span></code></a>.</p>
</div>
<div class="section" id="PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE">
<span id="c.PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE"></span><h3><code class="docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE</span></code> (macro)</h3>
<p>A sufficient output buffer size for <a class="reference internal" href="#c.psa_asymmetric_encrypt" title="psa_asymmetric_encrypt"><code class="xref any c c-func docutils literal notranslate"><span class="pre">psa_asymmetric_encrypt()</span></code></a>, for any supported asymmetric encryption.</p>
<pre class="literal-block">#define <a class="reference internal" href="#c.PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE" title="PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE">PSA_ASYMMETRIC_ENCRYPT_OUTPUT_MAX_SIZE</a> \
<em><a class="reference internal" href="../../overview/implementation.html#implementation-defined-value"><span class="std std-ref">/* implementation-defined value */</span></a></em></pre>
<p>See also <a class="reference internal" href="#c.PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE" title="PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE()</span></code></a>.</p>
</div>
<div class="section" id="PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE">
<span id="c.PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE"></span><h3><code class="docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE</span></code> (macro)</h3>
<p>Sufficient output buffer size for <a class="reference internal" href="#c.psa_asymmetric_decrypt" title="psa_asymmetric_decrypt"><code class="xref any c c-func docutils literal notranslate"><span class="pre">psa_asymmetric_decrypt()</span></code></a>.</p>
<pre class="literal-block">#define <a class="reference internal" href="#c.PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE" title="PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE">PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE</a>(key_type, key_bits, alg) \
<em><a class="reference internal" href="../../overview/implementation.html#implementation-defined-value"><span class="std std-ref">/* implementation-defined value */</span></a></em></pre>
<p class="rubric">Parameters</p>
<dl class="simple">
<dt> <code class="docutils literal notranslate"><span class="pre">key_type</span></code></dt><dd><p>An asymmetric key type, either a key pair or a public key.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">key_bits</span></code></dt><dd><p>The size of the key in bits.</p>
</dd>
<dt> <code class="docutils literal notranslate"><span class="pre">alg</span></code></dt><dd><p>The asymmetric encryption algorithm.</p>
</dd>
</dl>
<p class="rubric">Returns</p>
<p>If the parameters are valid and supported, return a buffer size in bytes that guarantees that <a class="reference internal" href="#c.psa_asymmetric_decrypt" title="psa_asymmetric_decrypt"><code class="xref any c c-func docutils literal notranslate"><span class="pre">psa_asymmetric_decrypt()</span></code></a> will not fail with <a class="reference internal" href="../library/status.html#c.PSA_ERROR_BUFFER_TOO_SMALL" title="PSA_ERROR_BUFFER_TOO_SMALL"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ERROR_BUFFER_TOO_SMALL</span></code></a>. If the parameters are a valid combination that is not supported by the implementation, this macro must return either a sensible size or <code class="docutils literal notranslate"><span class="pre">0</span></code>. If the parameters are not valid, the return value is unspecified.</p>
<p class="rubric">Description</p>
<p>This macro returns a sufficient buffer size for a plaintext produced using a key of the specified type and size, with the specified algorithm. Note that the actual size of the plaintext might be smaller, depending on the algorithm.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This function might evaluate its arguments multiple times or zero times. Providing arguments that have side effects will result in implementation-specific behavior, and is non-portable.</p>
</div>
<p>See also <a class="reference internal" href="#c.PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE" title="PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE</span></code></a>.</p>
</div>
<div class="section" id="PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE">
<span id="c.PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE"></span><h3><code class="docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE</span></code> (macro)</h3>
<p>A sufficient output buffer size for <a class="reference internal" href="#c.psa_asymmetric_decrypt" title="psa_asymmetric_decrypt"><code class="xref any c c-func docutils literal notranslate"><span class="pre">psa_asymmetric_decrypt()</span></code></a>, for any supported asymmetric decryption.</p>
<pre class="literal-block">#define <a class="reference internal" href="#c.PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE" title="PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE">PSA_ASYMMETRIC_DECRYPT_OUTPUT_MAX_SIZE</a> \
<em><a class="reference internal" href="../../overview/implementation.html#implementation-defined-value"><span class="std std-ref">/* implementation-defined value */</span></a></em></pre>
<p>See also <a class="reference internal" href="#c.PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE" title="PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE"><code class="xref any c c-macro docutils literal notranslate"><span class="pre">PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE()</span></code></a>.</p>
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<div class="sphinxsidebarwrapper"><h3><a href="../../index.html"><b>PSA Crypto API</b></a></h3>
IHI 0086<br/>
Non-confidential<br/>
Version 1.0.1
<span style="color: red; font-weight: bold;"></span>
<ul>
<li class="toctree-l1"><a class="reference internal" href="../../about.html">About this document</a></li>
</ul>
<ul class="current">
<li class="toctree-l1"><a class="reference internal" href="../../overview/intro.html">1. Introduction</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../overview/goals.html">2. Design goals</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../overview/functionality.html">3. Functionality overview</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../overview/sample-arch.html">4. Sample architectures</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../overview/conventions.html">5. Library conventions</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../overview/implementation.html">6. Implementation considerations</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../overview/usage.html">7. Usage considerations</a></li>
<li class="toctree-l1"><a class="reference internal" href="../library/index.html">8. Library management reference</a></li>
<li class="toctree-l1"><a class="reference internal" href="../keys/index.html">9. Key management reference</a></li>
<li class="toctree-l1 current"><a class="reference internal" href="index.html">10. Cryptographic operation reference</a><ul class="current">
<li class="toctree-l2"><a class="reference internal" href="algorithms.html">10.1. Algorithms</a></li>
<li class="toctree-l2"><a class="reference internal" href="hashes.html">10.2. Message digests</a></li>
<li class="toctree-l2"><a class="reference internal" href="macs.html">10.3. Message authentication codes (MAC)</a></li>
<li class="toctree-l2"><a class="reference internal" href="ciphers.html">10.4. Unauthenticated ciphers</a></li>
<li class="toctree-l2"><a class="reference internal" href="aead.html">10.5. Authenticated encryption with associated data (AEAD)</a></li>
<li class="toctree-l2"><a class="reference internal" href="kdf.html">10.6. Key derivation</a></li>
<li class="toctree-l2"><a class="reference internal" href="sign.html">10.7. Asymmetric signature</a></li>
<li class="toctree-l2 current"><a class="current reference internal" href="#">10.8. Asymmetric encryption</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#asymmetric-encryption-algorithms">10.8.1. Asymmetric encryption algorithms</a></li>
<li class="toctree-l3"><a class="reference internal" href="#asymmetric-encryption-functions">10.8.2. Asymmetric encryption functions</a></li>
<li class="toctree-l3"><a class="reference internal" href="#support-macros">10.8.3. Support macros</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="ka.html">10.9. Key agreement</a></li>
<li class="toctree-l2"><a class="reference internal" href="rng.html">10.10. Other cryptographic services</a></li>
</ul>
</li>
</ul>
<ul>
<li class="toctree-l1"><a class="reference internal" href="../../appendix/example_header.html">Example header file</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../appendix/specdef_values.html">Example macro implementations</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../appendix/history.html">Changes to the API</a></li>
</ul>
<ul>
<li class="toctree-l1"><a class="reference internal" href="../../psa_c-identifiers.html">Index of API elements</a></li>
</ul>
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