Provided by: libssl-doc_3.0.13-0ubuntu3.4_all bug

NAME

       EVP_CIPHER_fetch, EVP_CIPHER_up_ref, EVP_CIPHER_free, EVP_CIPHER_CTX_new,
       EVP_CIPHER_CTX_reset, EVP_CIPHER_CTX_free, EVP_EncryptInit_ex, EVP_EncryptInit_ex2,
       EVP_EncryptUpdate, EVP_EncryptFinal_ex, EVP_DecryptInit_ex, EVP_DecryptInit_ex2,
       EVP_DecryptUpdate, EVP_DecryptFinal_ex, EVP_CipherInit_ex, EVP_CipherInit_ex2,
       EVP_CipherUpdate, EVP_CipherFinal_ex, EVP_CIPHER_CTX_set_key_length, EVP_CIPHER_CTX_ctrl,
       EVP_EncryptInit, EVP_EncryptFinal, EVP_DecryptInit, EVP_DecryptFinal, EVP_CipherInit,
       EVP_CipherFinal, EVP_Cipher, EVP_get_cipherbyname, EVP_get_cipherbynid,
       EVP_get_cipherbyobj, EVP_CIPHER_is_a, EVP_CIPHER_get0_name, EVP_CIPHER_get0_description,
       EVP_CIPHER_names_do_all, EVP_CIPHER_get0_provider, EVP_CIPHER_get_nid,
       EVP_CIPHER_get_params, EVP_CIPHER_gettable_params, EVP_CIPHER_get_block_size,
       EVP_CIPHER_get_key_length, EVP_CIPHER_get_iv_length, EVP_CIPHER_get_flags,
       EVP_CIPHER_get_mode, EVP_CIPHER_get_type, EVP_CIPHER_CTX_cipher,
       EVP_CIPHER_CTX_get0_cipher, EVP_CIPHER_CTX_get1_cipher, EVP_CIPHER_CTX_get0_name,
       EVP_CIPHER_CTX_get_nid, EVP_CIPHER_CTX_get_params, EVP_CIPHER_gettable_ctx_params,
       EVP_CIPHER_CTX_gettable_params, EVP_CIPHER_CTX_set_params, EVP_CIPHER_settable_ctx_params,
       EVP_CIPHER_CTX_settable_params, EVP_CIPHER_CTX_get_block_size,
       EVP_CIPHER_CTX_get_key_length, EVP_CIPHER_CTX_get_iv_length,
       EVP_CIPHER_CTX_get_tag_length, EVP_CIPHER_CTX_get_app_data, EVP_CIPHER_CTX_set_app_data,
       EVP_CIPHER_CTX_flags, EVP_CIPHER_CTX_set_flags, EVP_CIPHER_CTX_clear_flags,
       EVP_CIPHER_CTX_test_flags, EVP_CIPHER_CTX_get_type, EVP_CIPHER_CTX_get_mode,
       EVP_CIPHER_CTX_get_num, EVP_CIPHER_CTX_set_num, EVP_CIPHER_CTX_is_encrypting,
       EVP_CIPHER_param_to_asn1, EVP_CIPHER_asn1_to_param, EVP_CIPHER_CTX_set_padding,
       EVP_enc_null, EVP_CIPHER_do_all_provided, EVP_CIPHER_nid, EVP_CIPHER_name,
       EVP_CIPHER_block_size, EVP_CIPHER_key_length, EVP_CIPHER_iv_length, EVP_CIPHER_flags,
       EVP_CIPHER_mode, EVP_CIPHER_type, EVP_CIPHER_CTX_encrypting, EVP_CIPHER_CTX_nid,
       EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length, EVP_CIPHER_CTX_iv_length,
       EVP_CIPHER_CTX_tag_length, EVP_CIPHER_CTX_num, EVP_CIPHER_CTX_type, EVP_CIPHER_CTX_mode -
       EVP cipher routines

SYNOPSIS

        #include <openssl/evp.h>

        EVP_CIPHER *EVP_CIPHER_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
                                     const char *properties);
        int EVP_CIPHER_up_ref(EVP_CIPHER *cipher);
        void EVP_CIPHER_free(EVP_CIPHER *cipher);
        EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
        int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
        void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);

        int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                               ENGINE *impl, const unsigned char *key, const unsigned char *iv);
        int EVP_EncryptInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                                const unsigned char *key, const unsigned char *iv,
                                const OSSL_PARAM params[]);
        int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
                              int *outl, const unsigned char *in, int inl);
        int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);

        int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                               ENGINE *impl, const unsigned char *key, const unsigned char *iv);
        int EVP_DecryptInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                                const unsigned char *key, const unsigned char *iv,
                                const OSSL_PARAM params[]);
        int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
                              int *outl, const unsigned char *in, int inl);
        int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);

        int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                              ENGINE *impl, const unsigned char *key, const unsigned char *iv, int enc);
        int EVP_CipherInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                               const unsigned char *key, const unsigned char *iv,
                               int enc, const OSSL_PARAM params[]);
        int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
                             int *outl, const unsigned char *in, int inl);
        int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);

        int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                            const unsigned char *key, const unsigned char *iv);
        int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);

        int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                            const unsigned char *key, const unsigned char *iv);
        int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);

        int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                           const unsigned char *key, const unsigned char *iv, int enc);
        int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);

        int EVP_Cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
                       const unsigned char *in, unsigned int inl);

        int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
        int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
        int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int cmd, int p1, void *p2);
        int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
        void EVP_CIPHER_CTX_set_flags(EVP_CIPHER_CTX *ctx, int flags);
        void EVP_CIPHER_CTX_clear_flags(EVP_CIPHER_CTX *ctx, int flags);
        int EVP_CIPHER_CTX_test_flags(const EVP_CIPHER_CTX *ctx, int flags);

        const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
        const EVP_CIPHER *EVP_get_cipherbynid(int nid);
        const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a);

        int EVP_CIPHER_get_nid(const EVP_CIPHER *e);
        int EVP_CIPHER_is_a(const EVP_CIPHER *cipher, const char *name);
        int EVP_CIPHER_names_do_all(const EVP_CIPHER *cipher,
                                    void (*fn)(const char *name, void *data),
                                    void *data);
        const char *EVP_CIPHER_get0_name(const EVP_CIPHER *cipher);
        const char *EVP_CIPHER_get0_description(const EVP_CIPHER *cipher);
        const OSSL_PROVIDER *EVP_CIPHER_get0_provider(const EVP_CIPHER *cipher);
        int EVP_CIPHER_get_block_size(const EVP_CIPHER *e);
        int EVP_CIPHER_get_key_length(const EVP_CIPHER *e);
        int EVP_CIPHER_get_iv_length(const EVP_CIPHER *e);
        unsigned long EVP_CIPHER_get_flags(const EVP_CIPHER *e);
        unsigned long EVP_CIPHER_get_mode(const EVP_CIPHER *e);
        int EVP_CIPHER_get_type(const EVP_CIPHER *cipher);

        const EVP_CIPHER *EVP_CIPHER_CTX_get0_cipher(const EVP_CIPHER_CTX *ctx);
        EVP_CIPHER *EVP_CIPHER_CTX_get1_cipher(const EVP_CIPHER_CTX *ctx);
        int EVP_CIPHER_CTX_get_nid(const EVP_CIPHER_CTX *ctx);
        const char *EVP_CIPHER_CTX_get0_name(const EVP_CIPHER_CTX *ctx);

        int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]);
        int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]);
        int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]);
        const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher);
        const OSSL_PARAM *EVP_CIPHER_settable_ctx_params(const EVP_CIPHER *cipher);
        const OSSL_PARAM *EVP_CIPHER_gettable_ctx_params(const EVP_CIPHER *cipher);
        const OSSL_PARAM *EVP_CIPHER_CTX_settable_params(EVP_CIPHER_CTX *ctx);
        const OSSL_PARAM *EVP_CIPHER_CTX_gettable_params(EVP_CIPHER_CTX *ctx);
        int EVP_CIPHER_CTX_get_block_size(const EVP_CIPHER_CTX *ctx);
        int EVP_CIPHER_CTX_get_key_length(const EVP_CIPHER_CTX *ctx);
        int EVP_CIPHER_CTX_get_iv_length(const EVP_CIPHER_CTX *ctx);
        int EVP_CIPHER_CTX_get_tag_length(const EVP_CIPHER_CTX *ctx);
        void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
        void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
        int EVP_CIPHER_CTX_get_type(const EVP_CIPHER_CTX *ctx);
        int EVP_CIPHER_CTX_get_mode(const EVP_CIPHER_CTX *ctx);
        int EVP_CIPHER_CTX_get_num(const EVP_CIPHER_CTX *ctx);
        int EVP_CIPHER_CTX_set_num(EVP_CIPHER_CTX *ctx, int num);
        int EVP_CIPHER_CTX_is_encrypting(const EVP_CIPHER_CTX *ctx);

        int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
        int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);

        void EVP_CIPHER_do_all_provided(OSSL_LIB_CTX *libctx,
                                        void (*fn)(EVP_CIPHER *cipher, void *arg),
                                        void *arg);

        #define EVP_CIPHER_nid EVP_CIPHER_get_nid
        #define EVP_CIPHER_name EVP_CIPHER_get0_name
        #define EVP_CIPHER_block_size EVP_CIPHER_get_block_size
        #define EVP_CIPHER_key_length EVP_CIPHER_get_key_length
        #define EVP_CIPHER_iv_length EVP_CIPHER_get_iv_length
        #define EVP_CIPHER_flags EVP_CIPHER_get_flags
        #define EVP_CIPHER_mode EVP_CIPHER_get_mode
        #define EVP_CIPHER_type EVP_CIPHER_get_type
        #define EVP_CIPHER_CTX_encrypting EVP_CIPHER_CTX_is_encrypting
        #define EVP_CIPHER_CTX_nid EVP_CIPHER_CTX_get_nid
        #define EVP_CIPHER_CTX_block_size EVP_CIPHER_CTX_get_block_size
        #define EVP_CIPHER_CTX_key_length EVP_CIPHER_CTX_get_key_length
        #define EVP_CIPHER_CTX_iv_length EVP_CIPHER_CTX_get_iv_length
        #define EVP_CIPHER_CTX_tag_length EVP_CIPHER_CTX_get_tag_length
        #define EVP_CIPHER_CTX_num EVP_CIPHER_CTX_get_num
        #define EVP_CIPHER_CTX_type EVP_CIPHER_CTX_get_type
        #define EVP_CIPHER_CTX_mode EVP_CIPHER_CTX_get_mode

       The following function has been deprecated since OpenSSL 3.0, and can be hidden entirely
       by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

        const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);

       The following function has been deprecated since OpenSSL 1.1.0, and can be hidden entirely
       by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

        int EVP_CIPHER_CTX_flags(const EVP_CIPHER_CTX *ctx);

DESCRIPTION

       The EVP cipher routines are a high-level interface to certain symmetric ciphers.

       The EVP_CIPHER type is a structure for cipher method implementation.

       EVP_CIPHER_fetch()
           Fetches the cipher implementation for the given algorithm from any provider offering
           it, within the criteria given by the properties.  See "ALGORITHM FETCHING" in
           crypto(7) for further information.

           The returned value must eventually be freed with EVP_CIPHER_free().

           Fetched EVP_CIPHER structures are reference counted.

       EVP_CIPHER_up_ref()
           Increments the reference count for an EVP_CIPHER structure.

       EVP_CIPHER_free()
           Decrements the reference count for the fetched EVP_CIPHER structure.  If the reference
           count drops to 0 then the structure is freed.

       EVP_CIPHER_CTX_new()
           Allocates and returns a cipher context.

       EVP_CIPHER_CTX_free()
           Clears all information from a cipher context and frees any allocated memory associated
           with it, including ctx itself. This function should be called after all operations
           using a cipher are complete so sensitive information does not remain in memory.

       EVP_CIPHER_CTX_ctrl()
           This is a legacy method. EVP_CIPHER_CTX_set_params() and EVP_CIPHER_CTX_get_params()
           is the mechanism that should be used to set and get parameters that are used by
           providers.

           Performs cipher-specific control actions on context ctx. The control command is
           indicated in cmd and any additional arguments in p1 and p2.  EVP_CIPHER_CTX_ctrl()
           must be called after EVP_CipherInit_ex2(). Other restrictions may apply depending on
           the control type and cipher implementation.

           If this function happens to be used with a fetched EVP_CIPHER, it will translate the
           controls that are known to OpenSSL into OSSL_PARAM(3) parameters with keys defined by
           OpenSSL and call EVP_CIPHER_CTX_get_params() or EVP_CIPHER_CTX_set_params() as is
           appropriate for each control command.

           See "CONTROLS" below for more information, including what translations are being done.

       EVP_CIPHER_get_params()
           Retrieves the requested list of algorithm params from a CIPHER cipher.  See
           "PARAMETERS" below for more information.

       EVP_CIPHER_CTX_get_params()
           Retrieves the requested list of params from CIPHER context ctx.  See "PARAMETERS"
           below for more information.

       EVP_CIPHER_CTX_set_params()
           Sets the list of params into a CIPHER context ctx.  See "PARAMETERS" below for more
           information.

       EVP_CIPHER_gettable_params()
           Get a constant OSSL_PARAM(3) array that describes the retrievable parameters that can
           be used with EVP_CIPHER_get_params().

       EVP_CIPHER_gettable_ctx_params() and EVP_CIPHER_CTX_gettable_params()
           Get a constant OSSL_PARAM(3) array that describes the retrievable parameters that can
           be used with EVP_CIPHER_CTX_get_params().  EVP_CIPHER_gettable_ctx_params() returns
           the parameters that can be retrieved from the algorithm, whereas
           EVP_CIPHER_CTX_gettable_params() returns the parameters that can be retrieved in the
           context's current state.

       EVP_CIPHER_settable_ctx_params() and EVP_CIPHER_CTX_settable_params()
           Get a constant OSSL_PARAM(3) array that describes the settable parameters that can be
           used with EVP_CIPHER_CTX_set_params().  EVP_CIPHER_settable_ctx_params() returns the
           parameters that can be set from the algorithm, whereas
           EVP_CIPHER_CTX_settable_params() returns the parameters that can be set in the
           context's current state.

       EVP_EncryptInit_ex2()
           Sets up cipher context ctx for encryption with cipher type. type is typically supplied
           by calling EVP_CIPHER_fetch(). type may also be set using legacy functions such as
           EVP_aes_256_cbc(), but this is not recommended for new applications. key is the
           symmetric key to use and iv is the IV to use (if necessary), the actual number of
           bytes used for the key and IV depends on the cipher. The parameters params will be set
           on the context after initialisation. It is possible to set all parameters to NULL
           except type in an initial call and supply the remaining parameters in subsequent
           calls, all of which have type set to NULL. This is done when the default cipher
           parameters are not appropriate.  For EVP_CIPH_GCM_MODE the IV will be generated
           internally if it is not specified.

       EVP_EncryptInit_ex()
           This legacy function is similar to EVP_EncryptInit_ex2() when impl is NULL.  The
           implementation of the type from the impl engine will be used if it exists.

       EVP_EncryptUpdate()
           Encrypts inl bytes from the buffer in and writes the encrypted version to out. The
           pointers out and in may point to the same location, in which case the encryption will
           be done in-place. If out and in point to different locations, the two buffers must be
           disjoint, otherwise the operation might fail or the outcome might be undefined.

           This function can be called multiple times to encrypt successive blocks of data. The
           amount of data written depends on the block alignment of the encrypted data.  For most
           ciphers and modes, the amount of data written can be anything from zero bytes to (inl
           + cipher_block_size - 1) bytes.  For wrap cipher modes, the amount of data written can
           be anything from zero bytes to (inl + cipher_block_size) bytes.  For stream ciphers,
           the amount of data written can be anything from zero bytes to inl bytes.  Thus, the
           buffer pointed to by out must contain sufficient room for the operation being
           performed.  The actual number of bytes written is placed in outl.

           If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts the "final"
           data, that is any data that remains in a partial block.  It uses standard block
           padding (aka PKCS padding) as described in the NOTES section, below. The encrypted
           final data is written to out which should have sufficient space for one cipher block.
           The number of bytes written is placed in outl. After this function is called the
           encryption operation is finished and no further calls to EVP_EncryptUpdate() should be
           made.

           If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more data and
           it will return an error if any data remains in a partial block: that is if the total
           data length is not a multiple of the block size.

       EVP_DecryptInit_ex2(), EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex()
           These functions are the corresponding decryption operations.  EVP_DecryptFinal() will
           return an error code if padding is enabled and the final block is not correctly
           formatted. The parameters and restrictions are identical to the encryption operations
           except that if padding is enabled the decrypted data buffer out passed to
           EVP_DecryptUpdate() should have sufficient room for (inl + cipher_block_size) bytes
           unless the cipher block size is 1 in which case inl bytes is sufficient.

       EVP_CipherInit_ex2(), EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex()
           These functions can be used for decryption or encryption. The operation performed
           depends on the value of the enc parameter. It should be set to 1 for encryption, 0 for
           decryption and -1 to leave the value unchanged (the actual value of 'enc' being
           supplied in a previous call).

       EVP_CIPHER_CTX_reset()
           Clears all information from a cipher context and free up any allocated memory
           associated with it, except the ctx itself. This function should be called anytime ctx
           is reused by another EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal() series
           of calls.

       EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit()
           Behave in a similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
           EVP_CipherInit_ex() except if the type is not a fetched cipher they use the default
           implementation of the type.

       EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal()
           Identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and EVP_CipherFinal_ex(). In
           previous releases they also cleaned up the ctx, but this is no longer done and
           EVP_CIPHER_CTX_cleanup() must be called to free any context resources.

       EVP_Cipher()
           Encrypts or decrypts a maximum inl amount of bytes from in and leaves the result in
           out.

           For legacy ciphers - If the cipher doesn't have the flag EVP_CIPH_FLAG_CUSTOM_CIPHER
           set, then inl must be a multiple of EVP_CIPHER_get_block_size().  If it isn't, the
           result is undefined.  If the cipher has that flag set, then inl can be any size.

           Due to the constraints of the API contract of this function it shouldn't be used in
           applications, please consider using EVP_CipherUpdate() and EVP_CipherFinal_ex()
           instead.

       EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
           Returns an EVP_CIPHER structure when passed a cipher name, a cipher NID or an
           ASN1_OBJECT structure respectively.

           EVP_get_cipherbyname() will return NULL for algorithms such as "AES-128-SIV",
           "AES-128-CBC-CTS" and "CAMELLIA-128-CBC-CTS" which were previously only accessible via
           low level interfaces.

           The EVP_get_cipherbyname() function is present for backwards compatibility with
           OpenSSL prior to version 3 and is different to the EVP_CIPHER_fetch() function since
           it does not attempt to "fetch" an implementation of the cipher.  Additionally, it only
           knows about ciphers that are built-in to OpenSSL and have an associated NID. Similarly
           EVP_get_cipherbynid() and EVP_get_cipherbyobj() also return objects without an
           associated implementation.

           When the cipher objects returned by these functions are used (such as in a call to
           EVP_EncryptInit_ex()) an implementation of the cipher will be implicitly fetched from
           the loaded providers. This fetch could fail if no suitable implementation is
           available. Use EVP_CIPHER_fetch() instead to explicitly fetch the algorithm and an
           associated implementation from a provider.

           See "ALGORITHM FETCHING" in crypto(7) for more information about fetching.

           The cipher objects returned from these functions do not need to be freed with
           EVP_CIPHER_free().

       EVP_CIPHER_get_nid() and EVP_CIPHER_CTX_get_nid()
           Return the NID of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX structure.  The
           actual NID value is an internal value which may not have a corresponding OBJECT
           IDENTIFIER.

       EVP_CIPHER_CTX_set_flags(), EVP_CIPHER_CTX_clear_flags() and EVP_CIPHER_CTX_test_flags()
           Sets, clears and tests ctx flags.  See "FLAGS" below for more information.

           For provided ciphers EVP_CIPHER_CTX_set_flags() should be called only after the
           fetched cipher has been assigned to the ctx. It is recommended to use "PARAMETERS"
           instead.

       EVP_CIPHER_CTX_set_padding()
           Enables or disables padding. This function should be called after the context is set
           up for encryption or decryption with EVP_EncryptInit_ex2(), EVP_DecryptInit_ex2() or
           EVP_CipherInit_ex2(). By default encryption operations are padded using standard block
           padding and the padding is checked and removed when decrypting. If the pad parameter
           is zero then no padding is performed, the total amount of data encrypted or decrypted
           must then be a multiple of the block size or an error will occur.

       EVP_CIPHER_get_key_length() and EVP_CIPHER_CTX_get_key_length()
           Return the key length of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX
           structure. The constant EVP_MAX_KEY_LENGTH is the maximum key length for all ciphers.
           Note: although EVP_CIPHER_get_key_length() is fixed for a given cipher, the value of
           EVP_CIPHER_CTX_get_key_length() may be different for variable key length ciphers.

       EVP_CIPHER_CTX_set_key_length()
           Sets the key length of the cipher context.  If the cipher is a fixed length cipher
           then attempting to set the key length to any value other than the fixed value is an
           error.

       EVP_CIPHER_get_iv_length() and EVP_CIPHER_CTX_get_iv_length()
           Return the IV length of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX. It will
           return zero if the cipher does not use an IV.  The constant EVP_MAX_IV_LENGTH is the
           maximum IV length for all ciphers.

       EVP_CIPHER_CTX_get_tag_length()
           Returns the tag length of an AEAD cipher when passed a EVP_CIPHER_CTX. It will return
           zero if the cipher does not support a tag. It returns a default value if the tag
           length has not been set.

       EVP_CIPHER_get_block_size() and EVP_CIPHER_CTX_get_block_size()
           Return the block size of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX
           structure. The constant EVP_MAX_BLOCK_LENGTH is also the maximum block length for all
           ciphers.

       EVP_CIPHER_get_type() and EVP_CIPHER_CTX_get_type()
           Return the type of the passed cipher or context. This "type" is the actual NID of the
           cipher OBJECT IDENTIFIER and as such it ignores the cipher parameters (40 bit RC2 and
           128 bit RC2 have the same NID). If the cipher does not have an object identifier or
           does not have ASN1 support this function will return NID_undef.

       EVP_CIPHER_is_a()
           Returns 1 if cipher is an implementation of an algorithm that's identifiable with
           name, otherwise 0. If cipher is a legacy cipher (it's the return value from the likes
           of EVP_aes128() rather than the result of an EVP_CIPHER_fetch()), only cipher names
           registered with the default library context (see OSSL_LIB_CTX(3)) will be considered.

       EVP_CIPHER_get0_name() and EVP_CIPHER_CTX_get0_name()
           Return the name of the passed cipher or context.  For fetched ciphers with multiple
           names, only one of them is returned. See also EVP_CIPHER_names_do_all().

       EVP_CIPHER_names_do_all()
           Traverses all names for the cipher, and calls fn with each name and data.  This is
           only useful with fetched EVP_CIPHERs.

       EVP_CIPHER_get0_description()
           Returns a description of the cipher, meant for display and human consumption.  The
           description is at the discretion of the cipher implementation.

       EVP_CIPHER_get0_provider()
           Returns an OSSL_PROVIDER pointer to the provider that implements the given EVP_CIPHER.

       EVP_CIPHER_CTX_get0_cipher()
           Returns the EVP_CIPHER structure when passed an EVP_CIPHER_CTX structure.
           EVP_CIPHER_CTX_get1_cipher() is the same except the ownership is passed to the caller.

       EVP_CIPHER_get_mode() and EVP_CIPHER_CTX_get_mode()
           Return the block cipher mode: 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 or EVP_CIPH_SIV_MODE.  If the
           cipher is a stream cipher then EVP_CIPH_STREAM_CIPHER is returned.

       EVP_CIPHER_get_flags()
           Returns any flags associated with the cipher. See "FLAGS" for a list of currently
           defined flags.

       EVP_CIPHER_CTX_get_num() and EVP_CIPHER_CTX_set_num()
           Gets or sets the cipher specific "num" parameter for the associated ctx.  Built-in
           ciphers typically use this to track how much of the current underlying block has been
           "used" already.

       EVP_CIPHER_CTX_is_encrypting()
           Reports whether the ctx is being used for encryption or decryption.

       EVP_CIPHER_CTX_flags()
           A deprecated macro calling "EVP_CIPHER_get_flags(EVP_CIPHER_CTX_get0_cipher(ctx))".
           Do not use.

       EVP_CIPHER_param_to_asn1()
           Sets the AlgorithmIdentifier "parameter" based on the passed cipher. This will
           typically include any parameters and an IV. The cipher IV (if any) must be set when
           this call is made. This call should be made before the cipher is actually "used"
           (before any EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example).  This
           function may fail if the cipher does not have any ASN1 support.

       EVP_CIPHER_asn1_to_param()
           Sets the cipher parameters based on an ASN1 AlgorithmIdentifier "parameter".  The
           precise effect depends on the cipher. In the case of RC2, for example, it will set the
           IV and effective key length.  This function should be called after the base cipher
           type is set but before the key is set. For example EVP_CipherInit() will be called
           with the IV and key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
           EVP_CipherInit() again with all parameters except the key set to NULL. It is possible
           for this function to fail if the cipher does not have any ASN1 support or the
           parameters cannot be set (for example the RC2 effective key length is not supported.

       EVP_CIPHER_CTX_rand_key()
           Generates a random key of the appropriate length based on the cipher context.  The
           EVP_CIPHER can provide its own random key generation routine to support keys of a
           specific form. key must point to a buffer at least as big as the value returned by
           EVP_CIPHER_CTX_get_key_length().

       EVP_CIPHER_do_all_provided()
           Traverses all ciphers implemented by all activated providers in the given library
           context libctx, and for each of the implementations, calls the given function fn with
           the implementation method and the given arg as argument.

PARAMETERS

       See OSSL_PARAM(3) for information about passing parameters.

   Gettable EVP_CIPHER parameters
       When EVP_CIPHER_fetch() is called it internally calls EVP_CIPHER_get_params() and caches
       the results.

       EVP_CIPHER_get_params() can be used with the following OSSL_PARAM(3) keys:

       "mode" (OSSL_CIPHER_PARAM_MODE) <unsigned integer>
           Gets the mode for the associated cipher algorithm cipher.  See "EVP_CIPHER_get_mode()
           and EVP_CIPHER_CTX_get_mode()" for a list of valid modes.  Use EVP_CIPHER_get_mode()
           to retrieve the cached value.

       "keylen" (OSSL_CIPHER_PARAM_KEYLEN) <unsigned integer>
           Gets the key length for the associated cipher algorithm cipher.  Use
           EVP_CIPHER_get_key_length() to retrieve the cached value.

       "ivlen" (OSSL_CIPHER_PARAM_IVLEN) <unsigned integer>
           Gets the IV length for the associated cipher algorithm cipher.  Use
           EVP_CIPHER_get_iv_length() to retrieve the cached value.

       "blocksize" (OSSL_CIPHER_PARAM_BLOCK_SIZE) <unsigned integer>
           Gets the block size for the associated cipher algorithm cipher.  The block size should
           be 1 for stream ciphers.  Note that the block size for a cipher may be different to
           the block size for the underlying encryption/decryption primitive.  For example AES in
           CTR mode has a block size of 1 (because it operates like a stream cipher), even though
           AES has a block size of 16.  Use EVP_CIPHER_get_block_size() to retrieve the cached
           value.

       "aead" (OSSL_CIPHER_PARAM_AEAD) <integer>
           Gets 1 if this is an AEAD cipher algorithm, otherwise it gets 0.  Use
           (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_AEAD_CIPHER) to retrieve the cached
           value.

       "custom-iv" (OSSL_CIPHER_PARAM_CUSTOM_IV) <integer>
           Gets 1 if the cipher algorithm cipher has a custom IV, otherwise it gets 0.  Storing
           and initializing the IV is left entirely to the implementation, if a custom IV is
           used.  Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_CUSTOM_IV) to retrieve the cached
           value.

       "cts" (OSSL_CIPHER_PARAM_CTS) <integer>
           Gets 1 if the cipher algorithm cipher uses ciphertext stealing, otherwise it gets 0.
           This is currently used to indicate that the cipher is a one shot that only allows a
           single call to EVP_CipherUpdate().  Use (EVP_CIPHER_get_flags(cipher) &
           EVP_CIPH_FLAG_CTS) to retrieve the cached value.

       "tls-multi" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK) <integer>
           Gets 1 if the cipher algorithm cipher supports interleaving of crypto blocks,
           otherwise it gets 0. The interleaving is an optimization only applicable to certain
           TLS ciphers.  Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK) to
           retrieve the cached value.

       "has-randkey" (OSSL_CIPHER_PARAM_HAS_RANDKEY) <integer>
           Gets 1 if the cipher algorithm cipher supports the gettable EVP_CIPHER_CTX parameter
           OSSL_CIPHER_PARAM_RANDOM_KEY. Only DES and 3DES set this to 1, all other OpenSSL
           ciphers return 0.

   Gettable and Settable EVP_CIPHER_CTX parameters
       The following OSSL_PARAM(3) keys can be used with both EVP_CIPHER_CTX_get_params() and
       EVP_CIPHER_CTX_set_params().

       "padding" (OSSL_CIPHER_PARAM_PADDING) <unsigned integer>
           Gets or sets the padding mode for the cipher context ctx.  Padding is enabled if the
           value is 1, and disabled if the value is 0.  See also EVP_CIPHER_CTX_set_padding().

       "num" (OSSL_CIPHER_PARAM_NUM) <unsigned integer>
           Gets or sets the cipher specific "num" parameter for the cipher context ctx.  Built-in
           ciphers typically use this to track how much of the current underlying block has been
           "used" already.  See also EVP_CIPHER_CTX_get_num() and EVP_CIPHER_CTX_set_num().

       "keylen" (OSSL_CIPHER_PARAM_KEYLEN) <unsigned integer>
           Gets or sets the key length for the cipher context ctx.  The length of the "keylen"
           parameter should not exceed that of a size_t.  See also
           EVP_CIPHER_CTX_get_key_length() and EVP_CIPHER_CTX_set_key_length().

       "tag" (OSSL_CIPHER_PARAM_AEAD_TAG) <octet string>
           Gets or sets the AEAD tag for the associated cipher context ctx.  See "AEAD Interface"
           in EVP_EncryptInit(3).

       "keybits" (OSSL_CIPHER_PARAM_RC2_KEYBITS) <unsigned integer>
           Gets or sets the effective keybits used for a RC2 cipher.  The length of the "keybits"
           parameter should not exceed that of a size_t.

       "rounds" (OSSL_CIPHER_PARAM_ROUNDS) <unsigned integer>
           Gets or sets the number of rounds to be used for a cipher.  This is used by the RC5
           cipher.

       "alg_id_param" (OSSL_CIPHER_PARAM_ALGORITHM_ID_PARAMS) <octet string>
           Used to pass the DER encoded AlgorithmIdentifier parameter to or from the cipher
           implementation.  Functions like EVP_CIPHER_param_to_asn1(3) and
           EVP_CIPHER_asn1_to_param(3) use this parameter for any implementation that has the
           flag EVP_CIPH_FLAG_CUSTOM_ASN1 set.

       "cts_mode" (OSSL_CIPHER_PARAM_CTS_MODE) <UTF8 string>
           Gets or sets the cipher text stealing mode. For all modes the output size is the same
           as the input size. The input length must be greater than or equal to the block size.
           (The block size for AES and CAMELLIA is 16 bytes).

           Valid values for the mode are:

           "CS1"
               The NIST variant of cipher text stealing.  For input lengths that are multiples of
               the block size it is equivalent to using a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC"
               cipher otherwise the second last cipher text block is a partial block.

           "CS2"
               For input lengths that are multiples of the block size it is equivalent to using a
               "AES-XXX-CBC" or "CAMELLIA-XXX-CBC" cipher, otherwise it is the same as "CS3"
               mode.

           "CS3"
               The Kerberos5 variant of cipher text stealing which always swaps the last cipher
               text block with the previous block (which may be a partial or full block depending
               on the input length). If the input length is exactly one full block then this is
               equivalent to using a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC" cipher.

           The default is "CS1".  This is only supported for "AES-128-CBC-CTS",
           "AES-192-CBC-CTS", "AES-256-CBC-CTS", "CAMELLIA-128-CBC-CTS", "CAMELLIA-192-CBC-CTS"
           and "CAMELLIA-256-CBC-CTS".

       "tls1multi_interleave" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE) <unsigned integer>
           Sets or gets the number of records being sent in one go for a tls1 multiblock cipher
           operation (either 4 or 8 records).

   Gettable EVP_CIPHER_CTX parameters
       The following OSSL_PARAM(3) keys can be used with EVP_CIPHER_CTX_get_params():

       "ivlen" (OSSL_CIPHER_PARAM_IVLEN and <OSSL_CIPHER_PARAM_AEAD_IVLEN) <unsigned integer>
           Gets the IV length for the cipher context ctx.  The length of the "ivlen" parameter
           should not exceed that of a size_t.  See also EVP_CIPHER_CTX_get_iv_length().

       "iv" (OSSL_CIPHER_PARAM_IV) <octet string OR octet ptr>
           Gets the IV used to initialize the associated cipher context ctx.  See also
           EVP_CIPHER_CTX_get_original_iv().

       "updated-iv" (OSSL_CIPHER_PARAM_UPDATED_IV) <octet string OR octet ptr>
           Gets the updated pseudo-IV state for the associated cipher context, e.g., the previous
           ciphertext block for CBC mode or the iteratively encrypted IV value for OFB mode.
           Note that octet pointer access is deprecated and is provided only for backwards
           compatibility with historical libcrypto APIs.  See also
           EVP_CIPHER_CTX_get_updated_iv().

       "randkey" (OSSL_CIPHER_PARAM_RANDOM_KEY) <octet string>
           Gets an implementation specific randomly generated key for the associated cipher
           context ctx. This is currently only supported by DES and 3DES (which set the key to
           odd parity).

       "taglen" (OSSL_CIPHER_PARAM_AEAD_TAGLEN) <unsigned integer>
           Gets the tag length to be used for an AEAD cipher for the associated cipher context
           ctx. It gets a default value if it has not been set.  The length of the "taglen"
           parameter should not exceed that of a size_t.  See also
           EVP_CIPHER_CTX_get_tag_length().

       "tlsaadpad" (OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD) <unsigned integer>
           Gets the length of the tag that will be added to a TLS record for the AEAD tag for the
           associated cipher context ctx.  The length of the "tlsaadpad" parameter should not
           exceed that of a size_t.

       "tlsivgen" (OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN) <octet string>
           Gets the invocation field generated for encryption.  Can only be called after
           "tlsivfixed" is set.  This is only used for GCM mode.

       "tls1multi_enclen" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN) <unsigned integer>
           Get the total length of the record returned from the "tls1multi_enc" operation.

       "tls1multi_maxbufsz" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE) <unsigned integer>
           Gets the maximum record length for a TLS1 multiblock cipher operation.  The length of
           the "tls1multi_maxbufsz" parameter should not exceed that of a size_t.

       "tls1multi_aadpacklen" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN) <unsigned integer>
           Gets the result of running the "tls1multi_aad" operation.

       "tls-mac" (OSSL_CIPHER_PARAM_TLS_MAC) <octet ptr>
           Used to pass the TLS MAC data.

   Settable EVP_CIPHER_CTX parameters
       The following OSSL_PARAM(3) keys can be used with EVP_CIPHER_CTX_set_params():

       "mackey" (OSSL_CIPHER_PARAM_AEAD_MAC_KEY) <octet string>
           Sets the MAC key used by composite AEAD ciphers such as AES-CBC-HMAC-SHA256.

       "speed" (OSSL_CIPHER_PARAM_SPEED) <unsigned integer>
           Sets the speed option for the associated cipher context. This is only supported by AES
           SIV ciphers which disallow multiple operations by default.  Setting "speed" to 1
           allows another encrypt or decrypt operation to be performed. This is used for
           performance testing.

       "use-bits" (OSSL_CIPHER_PARAM_USE_BITS) <unsigned integer>
           Determines if the input length inl passed to EVP_EncryptUpdate(), EVP_DecryptUpdate()
           and EVP_CipherUpdate() is the number of bits or number of bytes.  Setting "use-bits"
           to 1 uses bits. The default is in bytes.  This is only used for CFB1 ciphers.

           This can be set using EVP_CIPHER_CTX_set_flags(ctx, EVP_CIPH_FLAG_LENGTH_BITS).

       "tls-version" (OSSL_CIPHER_PARAM_TLS_VERSION) <integer>
           Sets the TLS version.

       "tls-mac-size" (OSSL_CIPHER_PARAM_TLS_MAC_SIZE) <unsigned integer>
           Set the TLS MAC size.

       "tlsaad" (OSSL_CIPHER_PARAM_AEAD_TLS1_AAD) <octet string>
           Sets TLSv1.2 AAD information for the associated cipher context ctx.  TLSv1.2 AAD
           information is always 13 bytes in length and is as defined for the "additional_data"
           field described in section 6.2.3.3 of RFC5246.

       "tlsivfixed" (OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED) <octet string>
           Sets the fixed portion of an IV for an AEAD cipher used in a TLS record encryption/
           decryption for the associated cipher context.  TLS record encryption/decryption always
           occurs "in place" so that the input and output buffers are always the same memory
           location.  AEAD IVs in TLSv1.2 consist of an implicit "fixed" part and an explicit
           part that varies with every record.  Setting a TLS fixed IV changes a cipher to
           encrypt/decrypt TLS records.  TLS records are encrypted/decrypted using a single
           OSSL_FUNC_cipher_cipher call per record.  For a record decryption the first bytes of
           the input buffer will be the explicit part of the IV and the final bytes of the input
           buffer will be the AEAD tag.  The length of the explicit part of the IV and the tag
           length will depend on the cipher in use and will be defined in the RFC for the
           relevant ciphersuite.  In order to allow for "in place" decryption the plaintext
           output should be written to the same location in the output buffer that the ciphertext
           payload was read from, i.e. immediately after the explicit IV.

           When encrypting a record the first bytes of the input buffer should be empty to allow
           space for the explicit IV, as will the final bytes where the tag will be written.  The
           length of the input buffer will include the length of the explicit IV, the payload,
           and the tag bytes.  The cipher implementation should generate the explicit IV and
           write it to the beginning of the output buffer, do "in place" encryption of the
           payload and write that to the output buffer, and finally add the tag onto the end of
           the output buffer.

           Whether encrypting or decrypting the value written to *outl in the
           OSSL_FUNC_cipher_cipher call should be the length of the payload excluding the
           explicit IV length and the tag length.

       "tlsivinv" (OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV) <octet string>
           Sets the invocation field used for decryption.  Can only be called after "tlsivfixed"
           is set.  This is only used for GCM mode.

       "tls1multi_enc" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC) <octet string>
           Triggers a multiblock TLS1 encrypt operation for a TLS1 aware cipher that supports
           sending 4 or 8 records in one go.  The cipher performs both the MAC and encrypt stages
           and constructs the record headers itself.  "tls1multi_enc" supplies the output buffer
           for the encrypt operation, "tls1multi_encin" & "tls1multi_interleave" must also be set
           in order to supply values to the encrypt operation.

       "tls1multi_encin" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN) <octet string>
           Supplies the data to encrypt for a TLS1 multiblock cipher operation.

       "tls1multi_maxsndfrag" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT) <unsigned
       integer>
           Sets the maximum send fragment size for a TLS1 multiblock cipher operation.  It must
           be set before using "tls1multi_maxbufsz".  The length of the "tls1multi_maxsndfrag"
           parameter should not exceed that of a size_t.

       "tls1multi_aad" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD) <octet string>
           Sets the authenticated additional data used by a TLS1 multiblock cipher operation.
           The supplied data consists of 13 bytes of record data containing: Bytes 0-7: The
           sequence number of the first record Byte 8: The record type Byte 9-10: The protocol
           version Byte 11-12: Input length (Always 0)

           "tls1multi_interleave" must also be set for this operation.

CONTROLS

       The Mappings from EVP_CIPHER_CTX_ctrl() identifiers to PARAMETERS are listed in the
       following section. See the "PARAMETERS" section for more details.

       EVP_CIPHER_CTX_ctrl() can be used to send the following standard controls:

       EVP_CTRL_AEAD_SET_IVLEN and EVP_CTRL_GET_IVLEN
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() and
           EVP_CIPHER_CTX_get_params() get called with an OSSL_PARAM(3) item with the key "ivlen"
           (OSSL_CIPHER_PARAM_IVLEN).

       EVP_CTRL_AEAD_SET_IV_FIXED
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() gets called with an
           OSSL_PARAM(3) item with the key "tlsivfixed" (OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED).

       EVP_CTRL_AEAD_SET_MAC_KEY
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() gets called with an
           OSSL_PARAM(3) item with the key "mackey" (OSSL_CIPHER_PARAM_AEAD_MAC_KEY).

       EVP_CTRL_AEAD_SET_TAG and EVP_CTRL_AEAD_GET_TAG
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() and
           EVP_CIPHER_CTX_get_params() get called with an OSSL_PARAM(3) item with the key "tag"
           (OSSL_CIPHER_PARAM_AEAD_TAG).

       EVP_CTRL_CCM_SET_L
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() gets called with an
           OSSL_PARAM(3) item with the key "ivlen" (OSSL_CIPHER_PARAM_IVLEN) with a value of (15
           - L)

       EVP_CTRL_COPY
           There is no OSSL_PARAM mapping for this. Use EVP_CIPHER_CTX_copy() instead.

       EVP_CTRL_GCM_SET_IV_INV
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() gets called with an
           OSSL_PARAM(3) item with the key "tlsivinv" (OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV).

       EVP_CTRL_RAND_KEY
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() gets called with an
           OSSL_PARAM(3) item with the key "randkey" (OSSL_CIPHER_PARAM_RANDOM_KEY).

       EVP_CTRL_SET_KEY_LENGTH
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() gets called with an
           OSSL_PARAM(3) item with the key "keylen" (OSSL_CIPHER_PARAM_KEYLEN).

       EVP_CTRL_SET_RC2_KEY_BITS and EVP_CTRL_GET_RC2_KEY_BITS
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() and
           EVP_CIPHER_CTX_get_params() get called with an OSSL_PARAM(3) item with the key
           "keybits" (OSSL_CIPHER_PARAM_RC2_KEYBITS).

       EVP_CTRL_SET_RC5_ROUNDS and EVP_CTRL_GET_RC5_ROUNDS
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() and
           EVP_CIPHER_CTX_get_params() get called with an OSSL_PARAM(3) item with the key
           "rounds" (OSSL_CIPHER_PARAM_ROUNDS).

       EVP_CTRL_SET_SPEED
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() gets called with an
           OSSL_PARAM(3) item with the key "speed" (OSSL_CIPHER_PARAM_SPEED).

       EVP_CTRL_GCM_IV_GEN
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_get_params() gets called with an
           OSSL_PARAM(3) item with the key "tlsivgen" (OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN).

       EVP_CTRL_AEAD_TLS1_AAD
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() get called with an
           OSSL_PARAM(3) item with the key "tlsaad" (OSSL_CIPHER_PARAM_AEAD_TLS1_AAD) followed by
           EVP_CIPHER_CTX_get_params() with a key of "tlsaadpad"
           (OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD).

       EVP_CTRL_TLS1_1_MULTIBLOCK_MAX_BUFSIZE
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() gets called with an
           OSSL_PARAM(3) item with the key OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT
           followed by EVP_CIPHER_CTX_get_params() with a key of "tls1multi_maxbufsz"
           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE).

       EVP_CTRL_TLS1_1_MULTIBLOCK_AAD
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() gets called with
           OSSL_PARAM(3) items with the keys "tls1multi_aad"
           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD) and "tls1multi_interleave"
           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE) followed by EVP_CIPHER_CTX_get_params()
           with keys of "tls1multi_aadpacklen" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN)
           and "tls1multi_interleave" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE).

       EVP_CTRL_TLS1_1_MULTIBLOCK_ENCRYPT
           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params() gets called with
           OSSL_PARAM(3) items with the keys "tls1multi_enc"
           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC), "tls1multi_encin"
           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN) and "tls1multi_interleave"
           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE), followed by
           EVP_CIPHER_CTX_get_params() with a key of "tls1multi_enclen"
           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN).

FLAGS

       EVP_CIPHER_CTX_set_flags(), EVP_CIPHER_CTX_clear_flags() and EVP_CIPHER_CTX_test_flags().
       can be used to manipulate and test these EVP_CIPHER_CTX flags:

       EVP_CIPH_NO_PADDING
           Used by EVP_CIPHER_CTX_set_padding().

           See also "Gettable and Settable EVP_CIPHER_CTX parameters" "padding"

       EVP_CIPH_FLAG_LENGTH_BITS
           See "Settable EVP_CIPHER_CTX parameters" "use-bits".

       EVP_CIPHER_CTX_FLAG_WRAP_ALLOW
           Used for Legacy purposes only. This flag needed to be set to indicate the cipher
           handled wrapping.

       EVP_CIPHER_flags() uses the following flags that have mappings to "Gettable EVP_CIPHER
       parameters":

       EVP_CIPH_FLAG_AEAD_CIPHER
           See "Gettable EVP_CIPHER parameters" "aead".

       EVP_CIPH_CUSTOM_IV
           See "Gettable EVP_CIPHER parameters" "custom-iv".

       EVP_CIPH_FLAG_CTS
           See "Gettable EVP_CIPHER parameters" "cts".

       EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK;
           See "Gettable EVP_CIPHER parameters" "tls-multi".

       EVP_CIPH_RAND_KEY
           See "Gettable EVP_CIPHER parameters" "has-randkey".

       EVP_CIPHER_flags() uses the following flags for legacy purposes only:

       EVP_CIPH_VARIABLE_LENGTH
       EVP_CIPH_FLAG_CUSTOM_CIPHER
       EVP_CIPH_ALWAYS_CALL_INIT
       EVP_CIPH_CTRL_INIT
       EVP_CIPH_CUSTOM_KEY_LENGTH
       EVP_CIPH_CUSTOM_COPY
       EVP_CIPH_FLAG_DEFAULT_ASN1
           See EVP_CIPHER_meth_set_flags(3) for further information related to the above flags.

RETURN VALUES

       EVP_CIPHER_fetch() returns a pointer to a EVP_CIPHER for success and NULL for failure.

       EVP_CIPHER_up_ref() returns 1 for success or 0 otherwise.

       EVP_CIPHER_CTX_new() returns a pointer to a newly created EVP_CIPHER_CTX for success and
       NULL for failure.

       EVP_EncryptInit_ex2(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex() return 1 for success
       and 0 for failure.

       EVP_DecryptInit_ex2() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
       EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.

       EVP_CipherInit_ex2() and EVP_CipherUpdate() return 1 for success and 0 for failure.
       EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.

       EVP_Cipher() returns 1 on success or 0 on failure, if the flag EVP_CIPH_FLAG_CUSTOM_CIPHER
       is not set for the cipher.  EVP_Cipher() returns the number of bytes written to out for
       encryption / decryption, or the number of bytes authenticated in a call specifying AAD for
       an AEAD cipher, if the flag EVP_CIPH_FLAG_CUSTOM_CIPHER is set for the cipher.

       EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.

       EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() return an
       EVP_CIPHER structure or NULL on error.

       EVP_CIPHER_get_nid() and EVP_CIPHER_CTX_get_nid() return a NID.

       EVP_CIPHER_get_block_size() and EVP_CIPHER_CTX_get_block_size() return the block size.

       EVP_CIPHER_get_key_length() and EVP_CIPHER_CTX_get_key_length() return the key length.

       EVP_CIPHER_CTX_set_padding() always returns 1.

       EVP_CIPHER_get_iv_length() and EVP_CIPHER_CTX_get_iv_length() return the IV length or zero
       if the cipher does not use an IV.

       EVP_CIPHER_CTX_get_tag_length() return the tag length or zero if the cipher does not use a
       tag.

       EVP_CIPHER_get_type() and EVP_CIPHER_CTX_get_type() return the NID of the cipher's OBJECT
       IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.

       EVP_CIPHER_CTX_cipher() returns an EVP_CIPHER structure.

       EVP_CIPHER_CTX_get_num() returns a nonnegative num value or EVP_CTRL_RET_UNSUPPORTED if
       the implementation does not support the call or on any other error.

       EVP_CIPHER_CTX_set_num() returns 1 on success and 0 if the implementation does not support
       the call or on any other error.

       EVP_CIPHER_CTX_is_encrypting() returns 1 if the ctx is set up for encryption 0 otherwise.

       EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater than zero for
       success and zero or a negative number on failure.

       EVP_CIPHER_CTX_rand_key() returns 1 for success and zero or a negative number for failure.

       EVP_CIPHER_names_do_all() returns 1 if the callback was called for all names.  A return
       value of 0 means that the callback was not called for any names.

CIPHER LISTING

       All algorithms have a fixed key length unless otherwise stated.

       Refer to "SEE ALSO" for the full list of ciphers available through the EVP interface.

       EVP_enc_null()
           Null cipher: does nothing.

AEAD INTERFACE

       The EVP interface for Authenticated Encryption with Associated Data (AEAD) modes are
       subtly altered and several additional ctrl operations are supported depending on the mode
       specified.

       To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(),
       EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output parameter out
       set to NULL. In this case, on success, the parameter outl is set to the number of bytes
       authenticated.

       When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal() indicates
       whether the operation was successful. If it does not indicate success, the authentication
       operation has failed and any output data MUST NOT be used as it is corrupted.

   GCM and OCB Modes
       The following ctrls are supported in GCM and OCB modes.

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
           Sets the IV length. This call can only be made before specifying an IV. If not called
           a default IV length is used.

           For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the maximum is
           15.

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
           Writes "taglen" bytes of the tag value to the buffer indicated by "tag".  This call
           can only be made when encrypting data and after all data has been processed (e.g.
           after an EVP_EncryptFinal() call).

           For OCB, "taglen" must either be 16 or the value previously set via
           EVP_CTRL_AEAD_SET_TAG.

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
           When decrypting, this call sets the expected tag to "taglen" bytes from "tag".
           "taglen" must be between 1 and 16 inclusive.  The tag must be set prior to any call to
           EVP_DecryptFinal() or EVP_DecryptFinal_ex().

           For GCM, this call is only valid when decrypting data.

           For OCB, this call is valid when decrypting data to set the expected tag, and when
           encrypting to set the desired tag length.

           In OCB mode, calling this when encrypting with "tag" set to "NULL" sets the tag
           length. The tag length can only be set before specifying an IV. If this is not called
           prior to setting the IV during encryption, then a default tag length is used.

           For OCB AES, the default tag length is 16 (i.e. 128 bits).  It is also the maximum tag
           length for OCB.

   CCM Mode
       The EVP interface for CCM mode is similar to that of the GCM mode but with a few
       additional requirements and different ctrl values.

       For CCM mode, the total plaintext or ciphertext length MUST be passed to
       EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output and input
       parameters (in and out) set to NULL and the length passed in the inl parameter.

       The following ctrls are supported in CCM mode.

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
           This call is made to set the expected CCM tag value when decrypting or the length of
           the tag (with the "tag" parameter set to NULL) when encrypting.  The tag length is
           often referred to as M. If not set a default value is used (12 for AES). When
           decrypting, the tag needs to be set before passing in data to be decrypted, but as in
           GCM and OCB mode, it can be set after passing additional authenticated data (see "AEAD
           INTERFACE").

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)
           Sets the CCM L value. If not set a default is used (8 for AES).

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
           Sets the CCM nonce (IV) length. This call can only be made before specifying a nonce
           value. The nonce length is given by 15 - L so it is 7 by default for AES.

   SIV Mode
       For SIV mode ciphers the behaviour of the EVP interface is subtly altered and several
       additional ctrl operations are supported.

       To specify any additional authenticated data (AAD) and/or a Nonce, a call to
       EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the
       output parameter out set to NULL.

       RFC5297 states that the Nonce is the last piece of AAD before the actual encrypt/decrypt
       takes place. The API does not differentiate the Nonce from other AAD.

       When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal() indicates if
       the operation was successful. If it does not indicate success the authentication operation
       has failed and any output data MUST NOT be used as it is corrupted.

       The API does not store the the SIV (Synthetic Initialization Vector) in the cipher text.
       Instead, it is stored as the tag within the EVP_CIPHER_CTX.  The SIV must be retrieved
       from the context after encryption, and set into the context before decryption.

       This differs from RFC5297 in that the cipher output from encryption, and the cipher input
       to decryption, does not contain the SIV. This also means that the plain text and cipher
       text lengths are identical.

       The following ctrls are supported in SIV mode, and are used to get and set the Synthetic
       Initialization Vector:

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
           Writes taglen bytes of the tag value (the Synthetic Initialization Vector) to the
           buffer indicated by tag. This call can only be made when encrypting data and after all
           data has been processed (e.g. after an EVP_EncryptFinal() call). For SIV mode the
           taglen must be 16.

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
           Sets the expected tag (the Synthetic Initialization Vector) to taglen bytes from tag.
           This call is only legal when decrypting data and must be made before any data is
           processed (e.g. before any EVP_DecryptUpdate() calls). For SIV mode the taglen must be
           16.

       SIV mode makes two passes over the input data, thus, only one call to EVP_CipherUpdate(),
       EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with out set to a non-NULL
       value. A call to EVP_DecryptFinal() or EVP_CipherFinal() is not required, but will
       indicate if the update operation succeeded.

   ChaCha20-Poly1305
       The following ctrls are supported for the ChaCha20-Poly1305 AEAD algorithm.

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
           Sets the nonce length. This call is now redundant since the only valid value is the
           default length of 12 (i.e. 96 bits).  Prior to OpenSSL 3.0 a nonce of less than 12
           bytes could be used to automatically pad the iv with leading 0 bytes to make it 12
           bytes in length.

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
           Writes "taglen" bytes of the tag value to the buffer indicated by "tag".  This call
           can only be made when encrypting data and after all data has been processed (e.g.
           after an EVP_EncryptFinal() call).

           "taglen" specified here must be 16 (POLY1305_BLOCK_SIZE, i.e. 128-bits) or less.

       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
           Sets the expected tag to "taglen" bytes from "tag".  The tag length can only be set
           before specifying an IV.  "taglen" must be between 1 and 16 (POLY1305_BLOCK_SIZE)
           inclusive.  This call is only valid when decrypting data.

NOTES

       Where possible the EVP interface to symmetric ciphers should be used in preference to the
       low-level interfaces. This is because the code then becomes transparent to the cipher used
       and much more flexible. Additionally, the EVP interface will ensure the use of platform
       specific cryptographic acceleration such as AES-NI (the low-level interfaces do not
       provide the guarantee).

       PKCS padding works by adding n padding bytes of value n to make the total length of the
       encrypted data a multiple of the block size. Padding is always added so if the data is
       already a multiple of the block size n will equal the block size. For example if the block
       size is 8 and 11 bytes are to be encrypted then 5 padding bytes of value 5 will be added.

       When decrypting the final block is checked to see if it has the correct form.

       Although the decryption operation can produce an error if padding is enabled, it is not a
       strong test that the input data or key is correct. A random block has better than 1 in 256
       chance of being of the correct format and problems with the input data earlier on will not
       produce a final decrypt error.

       If padding is disabled then the decryption operation will always succeed if the total
       amount of data decrypted is a multiple of the block size.

       The functions EVP_EncryptInit(), EVP_EncryptInit_ex(), EVP_EncryptFinal(),
       EVP_DecryptInit(), EVP_DecryptInit_ex(), EVP_CipherInit(), EVP_CipherInit_ex() and
       EVP_CipherFinal() are obsolete but are retained for compatibility with existing code. New
       code should use EVP_EncryptInit_ex2(), EVP_EncryptFinal_ex(), EVP_DecryptInit_ex2(),
       EVP_DecryptFinal_ex(), EVP_CipherInit_ex2() and EVP_CipherFinal_ex() because they can
       reuse an existing context without allocating and freeing it up on each call.

       There are some differences between functions EVP_CipherInit() and EVP_CipherInit_ex(),
       significant in some circumstances. EVP_CipherInit() fills the passed context object with
       zeros.  As a consequence, EVP_CipherInit() does not allow step-by-step initialization of
       the ctx when the key and iv are passed in separate calls. It also means that the flags set
       for the CTX are removed, and it is especially important for the
       EVP_CIPHER_CTX_FLAG_WRAP_ALLOW flag treated specially in EVP_CipherInit_ex().

       Ignoring failure returns of the EVP_CIPHER_CTX initialization functions can lead to
       subsequent undefined behavior when calling the functions that update or finalize the
       context. The only valid calls on the EVP_CIPHER_CTX when initialization fails are calls
       that attempt another initialization of the context or release the context.

       EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.

BUGS

       EVP_MAX_KEY_LENGTH and EVP_MAX_IV_LENGTH only refer to the internal ciphers with default
       key lengths. If custom ciphers exceed these values the results are unpredictable. This is
       because it has become standard practice to define a generic key as a fixed unsigned char
       array containing EVP_MAX_KEY_LENGTH bytes.

       The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested for certain
       common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.

EXAMPLES

       Encrypt a string using IDEA:

        int do_crypt(char *outfile)
        {
            unsigned char outbuf[1024];
            int outlen, tmplen;
            /*
             * Bogus key and IV: we'd normally set these from
             * another source.
             */
            unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
            unsigned char iv[] = {1,2,3,4,5,6,7,8};
            char intext[] = "Some Crypto Text";
            EVP_CIPHER_CTX *ctx;
            FILE *out;

            ctx = EVP_CIPHER_CTX_new();
            if (!EVP_EncryptInit_ex2(ctx, EVP_idea_cbc(), key, iv, NULL)) {
                /* Error */
                EVP_CIPHER_CTX_free(ctx);
                return 0;
            }

            if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
                /* Error */
                EVP_CIPHER_CTX_free(ctx);
                return 0;
            }
            /*
             * Buffer passed to EVP_EncryptFinal() must be after data just
             * encrypted to avoid overwriting it.
             */
            if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
                /* Error */
                EVP_CIPHER_CTX_free(ctx);
                return 0;
            }
            outlen += tmplen;
            EVP_CIPHER_CTX_free(ctx);
            /*
             * Need binary mode for fopen because encrypted data is
             * binary data. Also cannot use strlen() on it because
             * it won't be NUL terminated and may contain embedded
             * NULs.
             */
            out = fopen(outfile, "wb");
            if (out == NULL) {
                /* Error */
                return 0;
            }
            fwrite(outbuf, 1, outlen, out);
            fclose(out);
            return 1;
        }

       The ciphertext from the above example can be decrypted using the openssl utility with the
       command line (shown on two lines for clarity):

        openssl idea -d \
            -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename

       General encryption and decryption function example using FILE I/O and AES128 with a
       128-bit key:

        int do_crypt(FILE *in, FILE *out, int do_encrypt)
        {
            /* Allow enough space in output buffer for additional block */
            unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
            int inlen, outlen;
            EVP_CIPHER_CTX *ctx;
            /*
             * Bogus key and IV: we'd normally set these from
             * another source.
             */
            unsigned char key[] = "0123456789abcdeF";
            unsigned char iv[] = "1234567887654321";

            /* Don't set key or IV right away; we want to check lengths */
            ctx = EVP_CIPHER_CTX_new();
            if (!EVP_CipherInit_ex2(ctx, EVP_aes_128_cbc(), NULL, NULL,
                                    do_encrypt, NULL)) {
                /* Error */
                EVP_CIPHER_CTX_free(ctx);
                return 0;
            }
            OPENSSL_assert(EVP_CIPHER_CTX_get_key_length(ctx) == 16);
            OPENSSL_assert(EVP_CIPHER_CTX_get_iv_length(ctx) == 16);

            /* Now we can set key and IV */
            if (!EVP_CipherInit_ex2(ctx, NULL, key, iv, do_encrypt, NULL)) {
                /* Error */
                EVP_CIPHER_CTX_free(ctx);
                return 0;
            }

            for (;;) {
                inlen = fread(inbuf, 1, 1024, in);
                if (inlen <= 0)
                    break;
                if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
                    /* Error */
                    EVP_CIPHER_CTX_free(ctx);
                    return 0;
                }
                fwrite(outbuf, 1, outlen, out);
            }
            if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
                /* Error */
                EVP_CIPHER_CTX_free(ctx);
                return 0;
            }
            fwrite(outbuf, 1, outlen, out);

            EVP_CIPHER_CTX_free(ctx);
            return 1;
        }

       Encryption using AES-CBC with a 256-bit key with "CS1" ciphertext stealing.

        int encrypt(const unsigned char *key, const unsigned char *iv,
                    const unsigned char *msg, size_t msg_len, unsigned char *out)
        {
           /*
            * This assumes that key size is 32 bytes and the iv is 16 bytes.
            * For ciphertext stealing mode the length of the ciphertext "out" will be
            * the same size as the plaintext size "msg_len".
            * The "msg_len" can be any size >= 16.
            */
            int ret = 0, encrypt = 1, outlen, len;
            EVP_CIPHER_CTX *ctx = NULL;
            EVP_CIPHER *cipher = NULL;
            OSSL_PARAM params[2];

            ctx = EVP_CIPHER_CTX_new();
            cipher = EVP_CIPHER_fetch(NULL, "AES-256-CBC-CTS", NULL);
            if (ctx == NULL || cipher == NULL)
                goto err;

            /*
             * The default is "CS1" so this is not really needed,
             * but would be needed to set either "CS2" or "CS3".
             */
            params[0] = OSSL_PARAM_construct_utf8_string(OSSL_CIPHER_PARAM_CTS_MODE,
                                                         "CS1", 0);
            params[1] = OSSL_PARAM_construct_end();

            if (!EVP_CipherInit_ex2(ctx, cipher, key, iv, encrypt, params))
                goto err;

            /* NOTE: CTS mode does not support multiple calls to EVP_CipherUpdate() */
            if (!EVP_CipherUpdate(ctx, out, &outlen, msg, msg_len))
                goto err;
             if (!EVP_CipherFinal_ex(ctx, out + outlen, &len))
                goto err;
            ret = 1;
        err:
            EVP_CIPHER_free(cipher);
            EVP_CIPHER_CTX_free(ctx);
            return ret;
        }

SEE ALSO

       evp(7), property(7), "ALGORITHM FETCHING" in crypto(7), provider-cipher(7),
       life_cycle-cipher(7)

       Supported ciphers are listed in:

       EVP_aes_128_gcm(3), EVP_aria_128_gcm(3), EVP_bf_cbc(3), EVP_camellia_128_ecb(3),
       EVP_cast5_cbc(3), EVP_chacha20(3), EVP_des_cbc(3), EVP_desx_cbc(3), EVP_idea_cbc(3),
       EVP_rc2_cbc(3), EVP_rc4(3), EVP_rc5_32_12_16_cbc(3), EVP_seed_cbc(3), EVP_sm4_cbc(3),

HISTORY

       Support for OCB mode was added in OpenSSL 1.1.0.

       EVP_CIPHER_CTX was made opaque in OpenSSL 1.1.0.  As a result, EVP_CIPHER_CTX_reset()
       appeared and EVP_CIPHER_CTX_cleanup() disappeared.  EVP_CIPHER_CTX_init() remains as an
       alias for EVP_CIPHER_CTX_reset().

       The EVP_CIPHER_CTX_cipher() function was deprecated in OpenSSL 3.0; use
       EVP_CIPHER_CTX_get0_cipher() instead.

       The EVP_EncryptInit_ex2(), EVP_DecryptInit_ex2(), EVP_CipherInit_ex2(),
       EVP_CIPHER_fetch(), EVP_CIPHER_free(), EVP_CIPHER_up_ref(), EVP_CIPHER_CTX_get0_cipher(),
       EVP_CIPHER_CTX_get1_cipher(), EVP_CIPHER_get_params(), EVP_CIPHER_CTX_set_params(),
       EVP_CIPHER_CTX_get_params(), EVP_CIPHER_gettable_params(),
       EVP_CIPHER_settable_ctx_params(), EVP_CIPHER_gettable_ctx_params(),
       EVP_CIPHER_CTX_settable_params() and EVP_CIPHER_CTX_gettable_params() functions were added
       in 3.0.

       The EVP_CIPHER_nid(), EVP_CIPHER_name(), EVP_CIPHER_block_size(), EVP_CIPHER_key_length(),
       EVP_CIPHER_iv_length(), EVP_CIPHER_flags(), EVP_CIPHER_mode(), EVP_CIPHER_type(),
       EVP_CIPHER_CTX_nid(), EVP_CIPHER_CTX_block_size(), EVP_CIPHER_CTX_key_length(),
       EVP_CIPHER_CTX_iv_length(), EVP_CIPHER_CTX_tag_length(), EVP_CIPHER_CTX_num(),
       EVP_CIPHER_CTX_type(), and EVP_CIPHER_CTX_mode() functions were renamed to include "get"
       or "get0" in their names in OpenSSL 3.0, respectively. The old names are kept as non-
       deprecated alias macros.

       The EVP_CIPHER_CTX_encrypting() function was renamed to EVP_CIPHER_CTX_is_encrypting() in
       OpenSSL 3.0. The old name is kept as non-deprecated alias macro.

       The EVP_CIPHER_CTX_flags() macro was deprecated in OpenSSL 1.1.0.

COPYRIGHT

       Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  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 <https://www.openssl.org/source/license.html>.