mirror of https://github.com/openssl/openssl
251 lines
9.7 KiB
Plaintext
251 lines
9.7 KiB
Plaintext
=pod
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=head1 NAME
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EVP_CIPHER_meth_new, EVP_CIPHER_meth_dup, EVP_CIPHER_meth_free,
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EVP_CIPHER_meth_set_iv_length, EVP_CIPHER_meth_set_flags,
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EVP_CIPHER_meth_set_impl_ctx_size, EVP_CIPHER_meth_set_init,
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EVP_CIPHER_meth_set_do_cipher, EVP_CIPHER_meth_set_cleanup,
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EVP_CIPHER_meth_set_set_asn1_params, EVP_CIPHER_meth_set_get_asn1_params,
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EVP_CIPHER_meth_set_ctrl, EVP_CIPHER_meth_get_init,
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EVP_CIPHER_meth_get_do_cipher, EVP_CIPHER_meth_get_cleanup,
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EVP_CIPHER_meth_get_set_asn1_params, EVP_CIPHER_meth_get_get_asn1_params,
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EVP_CIPHER_meth_get_ctrl
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- Routines to build up EVP_CIPHER methods
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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EVP_CIPHER *EVP_CIPHER_meth_new(int cipher_type, int block_size, int key_len);
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EVP_CIPHER *EVP_CIPHER_meth_dup(const EVP_CIPHER *cipher);
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void EVP_CIPHER_meth_free(EVP_CIPHER *cipher);
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int EVP_CIPHER_meth_set_iv_length(EVP_CIPHER *cipher, int iv_len);
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int EVP_CIPHER_meth_set_flags(EVP_CIPHER *cipher, unsigned long flags);
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int EVP_CIPHER_meth_set_impl_ctx_size(EVP_CIPHER *cipher, int ctx_size);
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int EVP_CIPHER_meth_set_init(EVP_CIPHER *cipher,
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int (*init)(EVP_CIPHER_CTX *ctx,
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const unsigned char *key,
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const unsigned char *iv,
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int enc));
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int EVP_CIPHER_meth_set_do_cipher(EVP_CIPHER *cipher,
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int (*do_cipher)(EVP_CIPHER_CTX *ctx,
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unsigned char *out,
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const unsigned char *in,
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size_t inl));
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int EVP_CIPHER_meth_set_cleanup(EVP_CIPHER *cipher,
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int (*cleanup)(EVP_CIPHER_CTX *));
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int EVP_CIPHER_meth_set_set_asn1_params(EVP_CIPHER *cipher,
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int (*set_asn1_parameters)(EVP_CIPHER_CTX *,
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ASN1_TYPE *));
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int EVP_CIPHER_meth_set_get_asn1_params(EVP_CIPHER *cipher,
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int (*get_asn1_parameters)(EVP_CIPHER_CTX *,
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ASN1_TYPE *));
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int EVP_CIPHER_meth_set_ctrl(EVP_CIPHER *cipher,
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int (*ctrl)(EVP_CIPHER_CTX *, int type,
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int arg, void *ptr));
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int (*EVP_CIPHER_meth_get_init(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *ctx,
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const unsigned char *key,
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const unsigned char *iv,
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int enc);
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int (*EVP_CIPHER_meth_get_do_cipher(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *ctx,
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unsigned char *out,
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const unsigned char *in,
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size_t inl);
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int (*EVP_CIPHER_meth_get_cleanup(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *);
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int (*EVP_CIPHER_meth_get_set_asn1_params(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *,
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ASN1_TYPE *);
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int (*EVP_CIPHER_meth_get_get_asn1_params(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *,
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ASN1_TYPE *);
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int (*EVP_CIPHER_meth_get_ctrl(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *,
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int type, int arg,
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void *ptr);
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=head1 DESCRIPTION
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The B<EVP_CIPHER> type is a structure for symmetric cipher method
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implementation.
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EVP_CIPHER_meth_new() creates a new B<EVP_CIPHER> structure.
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EVP_CIPHER_meth_dup() creates a copy of B<cipher>.
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EVP_CIPHER_meth_free() destroys a B<EVP_CIPHER> structure.
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EVP_CIPHER_meth_set_iv_length() sets the length of the IV.
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This is only needed when the implemented cipher mode requires it.
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EVP_CIPHER_meth_set_flags() sets the flags to describe optional
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behaviours in the particular B<cipher>.
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With the exception of cipher modes, of which only one may be present,
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several flags can be or'd together.
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The available flags are:
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=over 4
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=item EVP_CIPH_STREAM_CIPHER, EVP_CIPH_ECB_MODE EVP_CIPH_CBC_MODE,
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EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE, EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE,
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EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE, EVP_CIPH_WRAP_MODE,
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EVP_CIPH_OCB_MODE, EVP_CIPH_SIV_MODE
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The cipher mode.
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=item EVP_CIPH_VARIABLE_LENGTH
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This cipher is of variable length.
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=item EVP_CIPH_CUSTOM_IV
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Storing and initialising the IV is left entirely to the
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implementation.
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=item EVP_CIPH_ALWAYS_CALL_INIT
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Set this if the implementation's init() function should be called even
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if B<key> is B<NULL>.
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=item EVP_CIPH_CTRL_INIT
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Set this to have the implementation's ctrl() function called with
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command code B<EVP_CTRL_INIT> early in its setup.
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=item EVP_CIPH_CUSTOM_KEY_LENGTH
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Checking and setting the key length after creating the B<EVP_CIPHER>
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is left to the implementation.
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Whenever someone uses EVP_CIPHER_CTX_set_key_length() on a
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B<EVP_CIPHER> with this flag set, the implementation's ctrl() function
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will be called with the control code B<EVP_CTRL_SET_KEY_LENGTH> and
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the key length in B<arg>.
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=item EVP_CIPH_NO_PADDING
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Don't use standard block padding.
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=item EVP_CIPH_RAND_KEY
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Making a key with random content is left to the implementation.
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This is done by calling the implementation's ctrl() function with the
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control code B<EVP_CTRL_RAND_KEY> and the pointer to the key memory
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storage in B<ptr>.
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=item EVP_CIPH_CUSTOM_COPY
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Set this to have the implementation's ctrl() function called with
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command code B<EVP_CTRL_COPY> at the end of EVP_CIPHER_CTX_copy().
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The intended use is for further things to deal with after the
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implementation specific data block has been copied.
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The destination B<EVP_CIPHER_CTX> is passed to the control with the
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B<ptr> parameter.
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The implementation specific data block is reached with
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EVP_CIPHER_CTX_get_cipher_data().
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=item EVP_CIPH_FLAG_DEFAULT_ASN1
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Use the default EVP routines to pass IV to and from ASN.1.
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=item EVP_CIPH_FLAG_LENGTH_BITS
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Signals that the length of the input buffer for encryption /
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decryption is to be understood as the number of bits instead of
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bytes for this implementation.
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This is only useful for CFB1 ciphers.
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=item EVP_CIPH_FLAG_CTS
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Indicates that the cipher uses ciphertext stealing. This is currently
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used to indicate that the cipher is a one shot that only allows a single call to
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EVP_CipherUpdate().
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=item EVP_CIPH_FLAG_CUSTOM_CIPHER
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This indicates that the implementation takes care of everything,
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including padding, buffering and finalization.
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The EVP routines will simply give them control and do nothing more.
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=item EVP_CIPH_FLAG_AEAD_CIPHER
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This indicates that this is an AEAD cipher implementation.
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=item EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK
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Allow interleaving of crypto blocks, a particular optimization only applicable
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to certain TLS ciphers.
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=back
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EVP_CIPHER_meth_set_impl_ctx_size() sets the size of the EVP_CIPHER's
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implementation context so that it can be automatically allocated.
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EVP_CIPHER_meth_set_init() sets the cipher init function for
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B<cipher>.
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The cipher init function is called by EVP_CipherInit(),
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EVP_CipherInit_ex(), EVP_EncryptInit(), EVP_EncryptInit_ex(),
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EVP_DecryptInit(), EVP_DecryptInit_ex().
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EVP_CIPHER_meth_set_do_cipher() sets the cipher function for
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B<cipher>.
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The cipher function is called by EVP_CipherUpdate(),
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EVP_EncryptUpdate(), EVP_DecryptUpdate(), EVP_CipherFinal(),
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EVP_EncryptFinal(), EVP_EncryptFinal_ex(), EVP_DecryptFinal() and
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EVP_DecryptFinal_ex().
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EVP_CIPHER_meth_set_cleanup() sets the function for B<cipher> to do
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extra cleanup before the method's private data structure is cleaned
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out and freed.
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Note that the cleanup function is passed a B<EVP_CIPHER_CTX *>, the
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private data structure is then available with
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EVP_CIPHER_CTX_get_cipher_data().
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This cleanup function is called by EVP_CIPHER_CTX_reset() and
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EVP_CIPHER_CTX_free().
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EVP_CIPHER_meth_set_set_asn1_params() sets the function for B<cipher>
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to set the AlgorithmIdentifier "parameter" based on the passed cipher.
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This function is called by EVP_CIPHER_param_to_asn1().
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EVP_CIPHER_meth_set_get_asn1_params() sets the function for B<cipher>
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that sets the cipher parameters based on an ASN.1 AlgorithmIdentifier
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"parameter".
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Both these functions are needed when there is a need for custom data
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(more or other than the cipher IV).
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They are called by EVP_CIPHER_param_to_asn1() and
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EVP_CIPHER_asn1_to_param() respectively if defined.
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EVP_CIPHER_meth_set_ctrl() sets the control function for B<cipher>.
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EVP_CIPHER_meth_get_init(), EVP_CIPHER_meth_get_do_cipher(),
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EVP_CIPHER_meth_get_cleanup(), EVP_CIPHER_meth_get_set_asn1_params(),
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EVP_CIPHER_meth_get_get_asn1_params() and EVP_CIPHER_meth_get_ctrl()
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are all used to retrieve the method data given with the
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EVP_CIPHER_meth_set_*() functions above.
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=head1 RETURN VALUES
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EVP_CIPHER_meth_new() and EVP_CIPHER_meth_dup() return a pointer to a
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newly created B<EVP_CIPHER>, or NULL on failure.
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All EVP_CIPHER_meth_set_*() functions return 1.
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All EVP_CIPHER_meth_get_*() functions return pointers to their
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respective B<cipher> function.
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=head1 SEE ALSO
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L<EVP_EncryptInit(3)>
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=head1 HISTORY
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The functions described here were added in OpenSSL 1.1.0.
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The B<EVP_CIPHER> structure created with these functions became reference
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counted in OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2016-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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