EVP_CIPHER_meth

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<ul id="index">
 <li><a href="#NAME">NAME</a></li>
 <li><a href="#SYNOPSIS">SYNOPSIS</a></li>
 <li><a href="#DESCRIPTION">DESCRIPTION</a></li>
 <li><a href="#RETURN-VALUES">RETURN VALUES</a></li>
 <li><a href="#SEE-ALSO">SEE ALSO</a></li>
 <li><a href="#HISTORY">HISTORY</a></li>
 <li><a href="#COPYRIGHT">COPYRIGHT</a></li>
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EVP_CIPHER_meth_new, EVP_CIPHER_meth_dup, EVP_CIPHER_meth_free, EVP_CIPHER_meth_set_iv_length, EVP_CIPHER_meth_set_flags, EVP_CIPHER_meth_set_impl_ctx_size, EVP_CIPHER_meth_set_init, EVP_CIPHER_meth_set_do_cipher, EVP_CIPHER_meth_set_cleanup, EVP_CIPHER_meth_set_set_asn1_params, EVP_CIPHER_meth_set_get_asn1_params, EVP_CIPHER_meth_set_ctrl, EVP_CIPHER_meth_get_init, EVP_CIPHER_meth_get_do_cipher, EVP_CIPHER_meth_get_cleanup, EVP_CIPHER_meth_get_set_asn1_params, EVP_CIPHER_meth_get_get_asn1_params, EVP_CIPHER_meth_get_ctrl - Routines to build up EVP_CIPHER methods

<h1 id="SYNOPSIS">SYNOPSIS</h1>

<pre><code> #include &lt;openssl/evp.h&gt;

EVP_CIPHER *EVP_CIPHER_meth_new(int cipher_type, int block_size, int key_len);
 EVP_CIPHER *EVP_CIPHER_meth_dup(const EVP_CIPHER *cipher);
 void EVP_CIPHER_meth_free(EVP_CIPHER *cipher);

int EVP_CIPHER_meth_set_iv_length(EVP_CIPHER *cipher, int iv_len);
 int EVP_CIPHER_meth_set_flags(EVP_CIPHER *cipher, unsigned long flags);
 int EVP_CIPHER_meth_set_impl_ctx_size(EVP_CIPHER *cipher, int ctx_size);
 int EVP_CIPHER_meth_set_init(EVP_CIPHER *cipher,
                              int (*init)(EVP_CIPHER_CTX *ctx,
                                          const unsigned char *key,
                                          const unsigned char *iv,
                                          int enc));
 int EVP_CIPHER_meth_set_do_cipher(EVP_CIPHER *cipher,
                                   int (*do_cipher)(EVP_CIPHER_CTX *ctx,
                                                    unsigned char *out,
                                                    const unsigned char *in,
                                                    size_t inl));
 int EVP_CIPHER_meth_set_cleanup(EVP_CIPHER *cipher,
                                 int (*cleanup)(EVP_CIPHER_CTX *));
 int EVP_CIPHER_meth_set_set_asn1_params(EVP_CIPHER *cipher,
                                         int (*set_asn1_parameters)(EVP_CIPHER_CTX *,
                                                                    ASN1_TYPE *));
 int EVP_CIPHER_meth_set_get_asn1_params(EVP_CIPHER *cipher,
                                         int (*get_asn1_parameters)(EVP_CIPHER_CTX *,
                                                                    ASN1_TYPE *));
 int EVP_CIPHER_meth_set_ctrl(EVP_CIPHER *cipher,
                              int (*ctrl)(EVP_CIPHER_CTX *, int type,
                                          int arg, void *ptr));

int (*EVP_CIPHER_meth_get_init(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *ctx,
 const unsigned char *key,
 const unsigned char *iv,
 int enc);
 int (*EVP_CIPHER_meth_get_do_cipher(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *ctx,
 unsigned char *out,
 const unsigned char *in,
 size_t inl);
 int (*EVP_CIPHER_meth_get_cleanup(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *);
 int (*EVP_CIPHER_meth_get_set_asn1_params(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *,
 ASN1_TYPE *);
 int (*EVP_CIPHER_meth_get_get_asn1_params(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *,
 ASN1_TYPE *);
 int (*EVP_CIPHER_meth_get_ctrl(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *,
 int type, int arg,
 void *ptr);</code></pre>

<h1 id="DESCRIPTION">DESCRIPTION</h1>

The EVP_CIPHER type is a structure for symmetric cipher method implementation.

EVP_CIPHER_meth_new() creates a new EVP_CIPHER structure.

EVP_CIPHER_meth_dup() creates a copy of cipher.

EVP_CIPHER_meth_free() destroys a EVP_CIPHER structure.

EVP_CIPHER_meth_set_iv_length() sets the length of the IV. This is only needed when the implemented cipher mode requires it.

EVP_CIPHER_meth_set_flags() sets the flags to describe optional behaviours in the particular cipher. With the exception of cipher modes, of which only one may be present, several flags can be or&#39;d together. The available flags are:

<dl>

<dt id="EVP_CIPH_STREAM_CIPHER-EVP_CIPH_ECB_MODE-EVP_CIPH_CBC_MODE-EVP_CIPH_CFB_MODE-EVP_CIPH_OFB_MODE-EVP_CIPH_CTR_MODE-EVP_CIPH_GCM_MODE-EVP_CIPH_CCM_MODE-EVP_CIPH_XTS_MODE-EVP_CIPH_WRAP_MODE-EVP_CIPH_OCB_MODE">EVP_CIPH_STREAM_CIPHER, EVP_CIPH_ECB_MODE EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE, EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE, EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE</dt>
<dd>

The cipher mode.

</dd>
<dt id="EVP_CIPH_VARIABLE_LENGTH">EVP_CIPH_VARIABLE_LENGTH</dt>
<dd>

This cipher is of variable length.

</dd>
<dt id="EVP_CIPH_CUSTOM_IV">EVP_CIPH_CUSTOM_IV</dt>
<dd>

Storing and initialising the IV is left entirely to the implementation.

</dd>
<dt id="EVP_CIPH_ALWAYS_CALL_INIT">EVP_CIPH_ALWAYS_CALL_INIT</dt>
<dd>

Set this if the implementation&#39;s init() function should be called even if key is NULL.

</dd>
<dt id="EVP_CIPH_CTRL_INIT">EVP_CIPH_CTRL_INIT</dt>
<dd>

Set this to have the implementation&#39;s ctrl() function called with command code EVP_CTRL_INIT early in its setup.

</dd>
<dt id="EVP_CIPH_CUSTOM_KEY_LENGTH">EVP_CIPH_CUSTOM_KEY_LENGTH</dt>
<dd>

Checking and setting the key length after creating the EVP_CIPHER is left to the implementation. Whenever someone uses EVP_CIPHER_CTX_set_key_length() on a EVP_CIPHER with this flag set, the implementation&#39;s ctrl() function will be called with the control code EVP_CTRL_SET_KEY_LENGTH and the key length in arg.

</dd>
<dt id="EVP_CIPH_NO_PADDING">EVP_CIPH_NO_PADDING</dt>
<dd>

Don&#39;t use standard block padding.

</dd>
<dt id="EVP_CIPH_RAND_KEY">EVP_CIPH_RAND_KEY</dt>
<dd>

Making a key with random content is left to the implementation. This is done by calling the implementation&#39;s ctrl() function with the control code EVP_CTRL_RAND_KEY and the pointer to the key memory storage in ptr.

</dd>
<dt id="EVP_CIPH_CUSTOM_COPY">EVP_CIPH_CUSTOM_COPY</dt>
<dd>

Set this to have the implementation&#39;s ctrl() function called with command code EVP_CTRL_COPY at the end of EVP_CIPHER_CTX_copy(). The intended use is for further things to deal with after the implementation specific data block has been copied. The destination EVP_CIPHER_CTX is passed to the control with the ptr parameter. The implementation specific data block is reached with EVP_CIPHER_CTX_get_cipher_data().

</dd>
<dt id="EVP_CIPH_FLAG_DEFAULT_ASN1">EVP_CIPH_FLAG_DEFAULT_ASN1</dt>
<dd>

Use the default EVP routines to pass IV to and from ASN.1.

</dd>
<dt id="EVP_CIPH_FLAG_LENGTH_BITS">EVP_CIPH_FLAG_LENGTH_BITS</dt>
<dd>

Signals that the length of the input buffer for encryption / decryption is to be understood as the number of bits instead of bytes for this implementation. This is only useful for CFB1 ciphers.

</dd>
<dt id="EVP_CIPH_FLAG_CUSTOM_CIPHER">EVP_CIPH_FLAG_CUSTOM_CIPHER</dt>
<dd>

This indicates that the implementation takes care of everything, including padding, buffering and finalization. The EVP routines will simply give them control and do nothing more.

</dd>
<dt id="EVP_CIPH_FLAG_AEAD_CIPHER">EVP_CIPH_FLAG_AEAD_CIPHER</dt>
<dd>

This indicates that this is an AEAD cipher implementation.

</dd>
<dt id="EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK">EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK</dt>
<dd>

Allow interleaving of crypto blocks, a particular optimization only applicable to certain TLS ciphers.

</dd>
</dl>

EVP_CIPHER_meth_set_impl_ctx_size() sets the size of the EVP_CIPHER&#39;s implementation context so that it can be automatically allocated.

EVP_CIPHER_meth_set_init() sets the cipher init function for cipher. The cipher init function is called by EVP_CipherInit(), EVP_CipherInit_ex(), EVP_EncryptInit(), EVP_EncryptInit_ex(), EVP_DecryptInit(), EVP_DecryptInit_ex().

EVP_CIPHER_meth_set_do_cipher() sets the cipher function for cipher. The cipher function is called by EVP_CipherUpdate(), EVP_EncryptUpdate(), EVP_DecryptUpdate(), EVP_CipherFinal(), EVP_EncryptFinal(), EVP_EncryptFinal_ex(), EVP_DecryptFinal() and EVP_DecryptFinal_ex().

EVP_CIPHER_meth_set_cleanup() sets the function for cipher to do extra cleanup before the method&#39;s private data structure is cleaned out and freed. Note that the cleanup function is passed a EVP_CIPHER_CTX *, the private data structure is then available with EVP_CIPHER_CTX_get_cipher_data(). This cleanup function is called by EVP_CIPHER_CTX_reset() and EVP_CIPHER_CTX_free().

EVP_CIPHER_meth_set_set_asn1_params() sets the function for cipher to set the AlgorithmIdentifier &quot;parameter&quot; based on the passed cipher. This function is called by EVP_CIPHER_param_to_asn1(). EVP_CIPHER_meth_set_get_asn1_params() sets the function for cipher that sets the cipher parameters based on an ASN.1 AlgorithmIdentifier &quot;parameter&quot;. Both these functions are needed when there is a need for custom data (more or other than the cipher IV). They are called by EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() respectively if defined.

EVP_CIPHER_meth_set_ctrl() sets the control function for cipher.

EVP_CIPHER_meth_get_init(), EVP_CIPHER_meth_get_do_cipher(), EVP_CIPHER_meth_get_cleanup(), EVP_CIPHER_meth_get_set_asn1_params(), EVP_CIPHER_meth_get_get_asn1_params() and EVP_CIPHER_meth_get_ctrl() are all used to retrieve the method data given with the EVP_CIPHER_meth_set_*() functions above.

<h1 id="RETURN-VALUES">RETURN VALUES</h1>

EVP_CIPHER_meth_new() and EVP_CIPHER_meth_dup() return a pointer to a newly created EVP_CIPHER, or NULL on failure. All EVP_CIPHER_meth_set_*() functions return 1. All EVP_CIPHER_meth_get_*() functions return pointers to their respective cipher function.

<a href="/../man3/EVP_EncryptInit.html">EVP_EncryptInit</a>

<h1 id="HISTORY">HISTORY</h1>

The functions described here were added in OpenSSL 1.1.0.

<h1 id="COPYRIGHT">COPYRIGHT</h1>

Licensed under the OpenSSL license (the &quot;License&quot;). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.

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