path: root/src/lib/libcrypto/man/EVP_CIPHER_meth_new.3

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.Dd $Mdocdate: March 16 2023 $
.Dt EVP_CIPHER_METH_NEW 3
.Os
.Sh NAME
.Nm EVP_CIPHER_meth_new ,
.Nm EVP_CIPHER_meth_dup ,
.Nm EVP_CIPHER_meth_free ,
.Nm EVP_CIPHER_meth_set_iv_length ,
.Nm EVP_CIPHER_meth_set_flags ,
.Nm EVP_CIPHER_meth_set_impl_ctx_size ,
.Nm EVP_CIPHER_meth_set_init ,
.Nm EVP_CIPHER_meth_set_do_cipher ,
.Nm EVP_CIPHER_meth_set_cleanup ,
.Nm EVP_CIPHER_meth_set_set_asn1_params ,
.Nm EVP_CIPHER_meth_set_get_asn1_params ,
.Nm EVP_CIPHER_meth_set_ctrl
.Nd Routines to build up EVP_CIPHER methods
.Sh SYNOPSIS
.In openssl/evp.h
.Ft EVP_CIPHER *
.Fo EVP_CIPHER_meth_new
.Fa "int cipher_type"
.Fa "int block_size"
.Fa "int key_len"
.Fc
.Ft EVP_CIPHER *
.Fo EVP_CIPHER_meth_dup
.Fa "const EVP_CIPHER *cipher"
.Fc
.Ft void
.Fo EVP_CIPHER_meth_free
.Fa "EVP_CIPHER *cipher"
.Fc
.Ft int
.Fo EVP_CIPHER_meth_set_iv_length
.Fa "EVP_CIPHER *cipher"
.Fa "int iv_len"
.Fc
.Ft int
.Fo EVP_CIPHER_meth_set_flags
.Fa "EVP_CIPHER *cipher"
.Fa "unsigned long flags"
.Fc
.Ft int
.Fo EVP_CIPHER_meth_set_impl_ctx_size
.Fa "EVP_CIPHER *cipher"
.Fa "int ctx_size"
.Fc
.Ft int
.Fo EVP_CIPHER_meth_set_init
.Fa "EVP_CIPHER *cipher"
.Fa "int (*init)(EVP_CIPHER_CTX *ctx, const unsigned char *key,\
 const unsigned char *iv, int enc)"
.Fc
.Ft int
.Fo EVP_CIPHER_meth_set_do_cipher
.Fa "EVP_CIPHER *cipher"
.Fa "int (*do_cipher)(EVP_CIPHER_CTX *ctx, unsigned char *out,\
 const unsigned char *in, size_t inl)"
.Fc
.Ft int
.Fo EVP_CIPHER_meth_set_cleanup
.Fa "EVP_CIPHER *cipher"
.Fa "int (*cleanup)(EVP_CIPHER_CTX *)"
.Fc
.Ft int
.Fo EVP_CIPHER_meth_set_set_asn1_params
.Fa "EVP_CIPHER *cipher"
.Fa "int (*set_asn1_parameters)(EVP_CIPHER_CTX *, ASN1_TYPE *)"
.Fc
.Ft int
.Fo EVP_CIPHER_meth_set_get_asn1_params
.Fa "EVP_CIPHER *cipher"
.Fa "int (*get_asn1_parameters)(EVP_CIPHER_CTX *, ASN1_TYPE *)"
.Fc
.Ft int
.Fo EVP_CIPHER_meth_set_ctrl
.Fa "EVP_CIPHER *cipher"
.Fa "int (*ctrl)(EVP_CIPHER_CTX *, int type, int arg, void *ptr)"
.Fc
.Sh DESCRIPTION
The
.Vt EVP_CIPHER
type is a structure holding function pointers for
a symmetric cipher implementation.
.Pp
.Fn EVP_CIPHER_meth_new
allocates a new
.Vt EVP_CIPHER
structure.
The cipher's NID (see
.Xr EVP_CIPHER_nid 3 )
is set to
.Fa cipher_type ,
the block size and key length are set to
.Fa block_size
and
.Fa key_len ,
respectively.
.Pp
.Fn EVP_CIPHER_meth_dup
creates a copy of
.Fa cipher .
.Pp
.Fn EVP_CIPHER_meth_free
frees an
.Vt EVP_CIPHER
structure.
.Pp
.Fn EVP_CIPHER_meth_set_iv_length
sets the length of the initialization vector.
This is only needed when the implemented cipher mode requires it.
.Pp
.Fn EVP_CIPHER_meth_set_flags
overwrites the flags to describe optional behaviours in
.Fa cipher
with
.Fa flags .
At most one of the following cipher modes can be set:
.Dv EVP_CIPH_STREAM_CIPHER ,
.Dv EVP_CIPH_ECB_MODE ,
.Dv EVP_CIPH_CBC_MODE ,
.Dv EVP_CIPH_CFB_MODE ,
.Dv EVP_CIPH_OFB_MODE ,
.Dv EVP_CIPH_CTR_MODE ,
.Dv EVP_CIPH_GCM_MODE ,
.Dv EVP_CIPH_CCM_MODE ,
.Dv EVP_CIPH_XTS_MODE ,
and
.Dv EVP_CIPH_WRAP_MODE .
The available flags are:
.Bl -tag -width Ds
.It EVP_CIPH_VARIABLE_LENGTH
This cipher is of variable length.
.It EVP_CIPH_CUSTOM_IV
Storing and initialising the IV is left entirely to the implementation.
.It EVP_CIPH_ALWAYS_CALL_INIT
Set this if the implementation's
.Fn init
function should be called even if
.Fa key
is
.Dv NULL .
.It EVP_CIPH_CTRL_INIT
Set this to have the implementation's
.Fn ctrl
function called with command code
.Dv EVP_CTRL_INIT
early in its setup.
.It EVP_CIPH_CUSTOM_KEY_LENGTH
Checking and setting the key length after creating the
.Vt EVP_CIPHER
is left to the implementation.
Whenever someone uses
.Xr EVP_CIPHER_CTX_set_key_length 3
on a
.Vt EVP_CIPHER
with this flag set, the implementation's
.Fn ctrl
function will be called with the control code
.Dv EVP_CTRL_SET_KEY_LENGTH
and the key length in
.Fa arg .
.It EVP_CIPH_NO_PADDING
Don't use standard block padding.
.It EVP_CIPH_RAND_KEY
Making a key with random content is left to the implementation.
This is done by calling the implementation's
.Fn ctrl
function with the control code
.Dv EVP_CTRL_RAND_KEY
and the pointer to the key memory storage in
.Fa ptr .
.It EVP_CIPH_CUSTOM_COPY
Set this to have the implementation's
.Fn ctrl
function called with command code
.Dv EVP_CTRL_COPY
at the end of
.Xr EVP_CIPHER_CTX_copy 3 .
The intended use is for further things to deal with after the
implementation specific data block has been copied.
The destination
.Vt EVP_CIPHER_CTX
object is passed to the control with the
.Fa ptr
parameter.
The implementation-specific data block is reached with
.Xr EVP_CIPHER_CTX_get_cipher_data 3 .
.It EVP_CIPH_FLAG_DEFAULT_ASN1
Use the default EVP routines to pass IV to and from ASN.1.
.It EVP_CIPH_FLAG_LENGTH_BITS
Signals that the length of the input buffer for encryption / decryption
is to be understood as the number of bits instead of bytes for this
implementation.
This is only useful for CFB1 ciphers.
.It EVP_CIPH_FLAG_CUSTOM_CIPHER
This indicates that the implementation takes care of everything,
including padding, buffering and finalization.
The EVP routines will simply give them control and do nothing more.
.It EVP_CIPH_FLAG_AEAD_CIPHER
This indicates that this is an AEAD cipher implementation.
.El
.Pp
.Fn EVP_CIPHER_meth_set_impl_ctx_size
sets the size of the EVP_CIPHER's implementation context so that it can
be automatically allocated.
.Pp
.Fn EVP_CIPHER_meth_set_init
sets the cipher init function for
.Fa cipher .
The cipher init function is called by
.Xr EVP_CipherInit 3 ,
.Xr EVP_CipherInit_ex 3 ,
.Xr EVP_EncryptInit 3 ,
.Xr EVP_EncryptInit_ex 3 ,
.Xr EVP_DecryptInit 3 ,
.Xr EVP_DecryptInit_ex 3 .
.Pp
.Fn EVP_CIPHER_meth_set_do_cipher
sets the cipher function for
.Fa cipher .
The cipher function is called by
.Xr EVP_CipherUpdate 3 ,
.Xr EVP_EncryptUpdate 3 ,
.Xr EVP_DecryptUpdate 3 ,
.Xr EVP_CipherFinal 3 ,
.Xr EVP_EncryptFinal 3 ,
.Xr EVP_EncryptFinal_ex 3 ,
.Xr EVP_DecryptFinal 3
and
.Xr EVP_DecryptFinal_ex 3 .
.Pp
.Fn EVP_CIPHER_meth_set_cleanup
sets the function for
.Fa cipher
to do extra cleanup before the method's private data structure is
cleaned out and freed.
Note that the cleanup function is passed a
.Sy EVP_CIPHER_CTX * ,
the private data structure is then available with
.Xr EVP_CIPHER_CTX_get_cipher_data 3 .
This cleanup function is called by
.Xr EVP_CIPHER_CTX_reset 3
and
.Xr EVP_CIPHER_CTX_free 3 .
.Pp
.Fn EVP_CIPHER_meth_set_set_asn1_params
sets the function for
.Fa cipher
to set the AlgorithmIdentifier "parameter" based on the passed cipher.
This function is called by
.Xr EVP_CIPHER_param_to_asn1 3 .
.Fn EVP_CIPHER_meth_set_get_asn1_params
sets the function for
.Fa cipher
that sets the cipher parameters based on an ASN.1 AlgorithmIdentifier
"parameter".
Both these functions are needed when there is a need for custom data
(more or other than the cipher IV). They are called by
.Xr EVP_CIPHER_param_to_asn1 3
and
.Xr EVP_CIPHER_asn1_to_param 3
respectively if defined.
.Pp
.Fn EVP_CIPHER_meth_set_ctrl
sets the control function for
.Fa cipher .
.Sh RETURN VALUES
.Fn EVP_CIPHER_meth_new
and
.Fn EVP_CIPHER_meth_dup
return a pointer to a newly created
.Vt EVP_CIPHER ,
or NULL on failure.
.Pp
All
.Fn EVP_CIPHER_meth_set_*
functions return 1.
.Sh SEE ALSO
.Xr EVP_EncryptInit 3
.Sh HISTORY
These functions first appeared in OpenSSL 1.1.0 and have been available since
.Ox 7.3 .