Updated: 2022/Sep/29

Please read Privacy Policy. It's for your privacy.


EVP_PKEY_CTX_ctrl(3)                OpenSSL               EVP_PKEY_CTX_ctrl(3)



NAME
       EVP_PKEY_CTX_ctrl, EVP_PKEY_CTX_ctrl_str, EVP_PKEY_CTX_ctrl_uint64,
       EVP_PKEY_CTX_md, EVP_PKEY_CTX_set_signature_md,
       EVP_PKEY_CTX_get_signature_md, EVP_PKEY_CTX_set_mac_key,
       EVP_PKEY_CTX_set_group_name, EVP_PKEY_CTX_get_group_name,
       EVP_PKEY_CTX_set_rsa_padding, EVP_PKEY_CTX_get_rsa_padding,
       EVP_PKEY_CTX_set_rsa_pss_saltlen, EVP_PKEY_CTX_get_rsa_pss_saltlen,
       EVP_PKEY_CTX_set_rsa_keygen_bits, EVP_PKEY_CTX_set_rsa_keygen_pubexp,
       EVP_PKEY_CTX_set1_rsa_keygen_pubexp,
       EVP_PKEY_CTX_set_rsa_keygen_primes, EVP_PKEY_CTX_set_rsa_mgf1_md_name,
       EVP_PKEY_CTX_set_rsa_mgf1_md, EVP_PKEY_CTX_get_rsa_mgf1_md,
       EVP_PKEY_CTX_get_rsa_mgf1_md_name, EVP_PKEY_CTX_set_rsa_oaep_md_name,
       EVP_PKEY_CTX_set_rsa_oaep_md, EVP_PKEY_CTX_get_rsa_oaep_md,
       EVP_PKEY_CTX_get_rsa_oaep_md_name, EVP_PKEY_CTX_set0_rsa_oaep_label,
       EVP_PKEY_CTX_get0_rsa_oaep_label, EVP_PKEY_CTX_set_dsa_paramgen_bits,
       EVP_PKEY_CTX_set_dsa_paramgen_q_bits, EVP_PKEY_CTX_set_dsa_paramgen_md,
       EVP_PKEY_CTX_set_dsa_paramgen_md_props,
       EVP_PKEY_CTX_set_dsa_paramgen_gindex,
       EVP_PKEY_CTX_set_dsa_paramgen_type, EVP_PKEY_CTX_set_dsa_paramgen_seed,
       EVP_PKEY_CTX_set_dh_paramgen_prime_len,
       EVP_PKEY_CTX_set_dh_paramgen_subprime_len,
       EVP_PKEY_CTX_set_dh_paramgen_generator,
       EVP_PKEY_CTX_set_dh_paramgen_type, EVP_PKEY_CTX_set_dh_paramgen_gindex,
       EVP_PKEY_CTX_set_dh_paramgen_seed, EVP_PKEY_CTX_set_dh_rfc5114,
       EVP_PKEY_CTX_set_dhx_rfc5114, EVP_PKEY_CTX_set_dh_pad,
       EVP_PKEY_CTX_set_dh_nid, EVP_PKEY_CTX_set_dh_kdf_type,
       EVP_PKEY_CTX_get_dh_kdf_type, EVP_PKEY_CTX_set0_dh_kdf_oid,
       EVP_PKEY_CTX_get0_dh_kdf_oid, EVP_PKEY_CTX_set_dh_kdf_md,
       EVP_PKEY_CTX_get_dh_kdf_md, EVP_PKEY_CTX_set_dh_kdf_outlen,
       EVP_PKEY_CTX_get_dh_kdf_outlen, EVP_PKEY_CTX_set0_dh_kdf_ukm,
       EVP_PKEY_CTX_get0_dh_kdf_ukm, EVP_PKEY_CTX_set_ec_paramgen_curve_nid,
       EVP_PKEY_CTX_set_ec_param_enc, EVP_PKEY_CTX_set_ecdh_cofactor_mode,
       EVP_PKEY_CTX_get_ecdh_cofactor_mode, EVP_PKEY_CTX_set_ecdh_kdf_type,
       EVP_PKEY_CTX_get_ecdh_kdf_type, EVP_PKEY_CTX_set_ecdh_kdf_md,
       EVP_PKEY_CTX_get_ecdh_kdf_md, EVP_PKEY_CTX_set_ecdh_kdf_outlen,
       EVP_PKEY_CTX_get_ecdh_kdf_outlen, EVP_PKEY_CTX_set0_ecdh_kdf_ukm,
       EVP_PKEY_CTX_get0_ecdh_kdf_ukm, EVP_PKEY_CTX_set1_id,
       EVP_PKEY_CTX_get1_id, EVP_PKEY_CTX_get1_id_len, EVP_PKEY_CTX_set_kem_op
       - algorithm specific control operations

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/evp.h>

        int EVP_PKEY_CTX_ctrl(EVP_PKEY_CTX *ctx, int keytype, int optype,
                              int cmd, int p1, void *p2);
        int EVP_PKEY_CTX_ctrl_uint64(EVP_PKEY_CTX *ctx, int keytype, int optype,
                                     int cmd, uint64_t value);
        int EVP_PKEY_CTX_ctrl_str(EVP_PKEY_CTX *ctx, const char *type,
                                  const char *value);

        int EVP_PKEY_CTX_md(EVP_PKEY_CTX *ctx, int optype, int cmd, const char *md);

        int EVP_PKEY_CTX_set_signature_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
        int EVP_PKEY_CTX_get_signature_md(EVP_PKEY_CTX *ctx, const EVP_MD **pmd);

        int EVP_PKEY_CTX_set_mac_key(EVP_PKEY_CTX *ctx, const unsigned char *key,
                                     int len);
        int EVP_PKEY_CTX_set_group_name(EVP_PKEY_CTX *ctx, const char *name);
        int EVP_PKEY_CTX_get_group_name(EVP_PKEY_CTX *ctx, char *name, size_t namelen);

        int EVP_PKEY_CTX_set_kem_op(EVP_PKEY_CTX *ctx, const char *op);

        #include <openssl/rsa.h>

        int EVP_PKEY_CTX_set_rsa_padding(EVP_PKEY_CTX *ctx, int pad);
        int EVP_PKEY_CTX_get_rsa_padding(EVP_PKEY_CTX *ctx, int *pad);
        int EVP_PKEY_CTX_set_rsa_pss_saltlen(EVP_PKEY_CTX *ctx, int saltlen);
        int EVP_PKEY_CTX_get_rsa_pss_saltlen(EVP_PKEY_CTX *ctx, int *saltlen);
        int EVP_PKEY_CTX_set_rsa_keygen_bits(EVP_PKEY_CTX *ctx, int mbits);
        int EVP_PKEY_CTX_set1_rsa_keygen_pubexp(EVP_PKEY_CTX *ctx, BIGNUM *pubexp);
        int EVP_PKEY_CTX_set_rsa_keygen_primes(EVP_PKEY_CTX *ctx, int primes);
        int EVP_PKEY_CTX_set_rsa_mgf1_md_name(EVP_PKEY_CTX *ctx, const char *mdname,
                                            const char *mdprops);
        int EVP_PKEY_CTX_set_rsa_mgf1_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
        int EVP_PKEY_CTX_get_rsa_mgf1_md(EVP_PKEY_CTX *ctx, const EVP_MD **md);
        int EVP_PKEY_CTX_get_rsa_mgf1_md_name(EVP_PKEY_CTX *ctx, char *name,
                                              size_t namelen);
        int EVP_PKEY_CTX_set_rsa_oaep_md_name(EVP_PKEY_CTX *ctx, const char *mdname,
                                              const char *mdprops);
        int EVP_PKEY_CTX_set_rsa_oaep_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
        int EVP_PKEY_CTX_get_rsa_oaep_md(EVP_PKEY_CTX *ctx, const EVP_MD **md);
        int EVP_PKEY_CTX_get_rsa_oaep_md_name(EVP_PKEY_CTX *ctx, char *name,
                                              size_t namelen);
        int EVP_PKEY_CTX_set0_rsa_oaep_label(EVP_PKEY_CTX *ctx, void *label,
                                             int len);
        int EVP_PKEY_CTX_get0_rsa_oaep_label(EVP_PKEY_CTX *ctx, unsigned char **label);

        #include <openssl/dsa.h>

        int EVP_PKEY_CTX_set_dsa_paramgen_bits(EVP_PKEY_CTX *ctx, int nbits);
        int EVP_PKEY_CTX_set_dsa_paramgen_q_bits(EVP_PKEY_CTX *ctx, int qbits);
        int EVP_PKEY_CTX_set_dsa_paramgen_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
        int EVP_PKEY_CTX_set_dsa_paramgen_md_props(EVP_PKEY_CTX *ctx,
                                                   const char *md_name,
                                                   const char *md_properties);
        int EVP_PKEY_CTX_set_dsa_paramgen_type(EVP_PKEY_CTX *ctx, const char *name);
        int EVP_PKEY_CTX_set_dsa_paramgen_gindex(EVP_PKEY_CTX *ctx, int gindex);
        int EVP_PKEY_CTX_set_dsa_paramgen_seed(EVP_PKEY_CTX *ctx,
                                               const unsigned char *seed,
                                               size_t seedlen);

        #include <openssl/dh.h>

        int EVP_PKEY_CTX_set_dh_paramgen_prime_len(EVP_PKEY_CTX *ctx, int len);
        int EVP_PKEY_CTX_set_dh_paramgen_subprime_len(EVP_PKEY_CTX *ctx, int len);
        int EVP_PKEY_CTX_set_dh_paramgen_generator(EVP_PKEY_CTX *ctx, int gen);
        int EVP_PKEY_CTX_set_dh_paramgen_type(EVP_PKEY_CTX *ctx, int type);
        int EVP_PKEY_CTX_set_dh_pad(EVP_PKEY_CTX *ctx, int pad);
        int EVP_PKEY_CTX_set_dh_nid(EVP_PKEY_CTX *ctx, int nid);
        int EVP_PKEY_CTX_set_dh_rfc5114(EVP_PKEY_CTX *ctx, int rfc5114);
        int EVP_PKEY_CTX_set_dhx_rfc5114(EVP_PKEY_CTX *ctx, int rfc5114);
        int EVP_PKEY_CTX_set_dh_paramgen_gindex(EVP_PKEY_CTX *ctx, int gindex);
        int EVP_PKEY_CTX_set_dh_paramgen_seed(EVP_PKEY_CTX *ctx,
                                               const unsigned char *seed,
                                               size_t seedlen);
        int EVP_PKEY_CTX_set_dh_kdf_type(EVP_PKEY_CTX *ctx, int kdf);
        int EVP_PKEY_CTX_get_dh_kdf_type(EVP_PKEY_CTX *ctx);
        int EVP_PKEY_CTX_set0_dh_kdf_oid(EVP_PKEY_CTX *ctx, ASN1_OBJECT *oid);
        int EVP_PKEY_CTX_get0_dh_kdf_oid(EVP_PKEY_CTX *ctx, ASN1_OBJECT **oid);
        int EVP_PKEY_CTX_set_dh_kdf_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
        int EVP_PKEY_CTX_get_dh_kdf_md(EVP_PKEY_CTX *ctx, const EVP_MD **md);
        int EVP_PKEY_CTX_set_dh_kdf_outlen(EVP_PKEY_CTX *ctx, int len);
        int EVP_PKEY_CTX_get_dh_kdf_outlen(EVP_PKEY_CTX *ctx, int *len);
        int EVP_PKEY_CTX_set0_dh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char *ukm, int len);

        #include <openssl/ec.h>

        int EVP_PKEY_CTX_set_ec_paramgen_curve_nid(EVP_PKEY_CTX *ctx, int nid);
        int EVP_PKEY_CTX_set_ec_param_enc(EVP_PKEY_CTX *ctx, int param_enc);
        int EVP_PKEY_CTX_set_ecdh_cofactor_mode(EVP_PKEY_CTX *ctx, int cofactor_mode);
        int EVP_PKEY_CTX_get_ecdh_cofactor_mode(EVP_PKEY_CTX *ctx);
        int EVP_PKEY_CTX_set_ecdh_kdf_type(EVP_PKEY_CTX *ctx, int kdf);
        int EVP_PKEY_CTX_get_ecdh_kdf_type(EVP_PKEY_CTX *ctx);
        int EVP_PKEY_CTX_set_ecdh_kdf_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
        int EVP_PKEY_CTX_get_ecdh_kdf_md(EVP_PKEY_CTX *ctx, const EVP_MD **md);
        int EVP_PKEY_CTX_set_ecdh_kdf_outlen(EVP_PKEY_CTX *ctx, int len);
        int EVP_PKEY_CTX_get_ecdh_kdf_outlen(EVP_PKEY_CTX *ctx, int *len);
        int EVP_PKEY_CTX_set0_ecdh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char *ukm, int len);

        int EVP_PKEY_CTX_set1_id(EVP_PKEY_CTX *ctx, void *id, size_t id_len);
        int EVP_PKEY_CTX_get1_id(EVP_PKEY_CTX *ctx, void *id);
        int EVP_PKEY_CTX_get1_id_len(EVP_PKEY_CTX *ctx, size_t *id_len);

       The following functions have 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):

        #include <openssl/rsa.h>

        int EVP_PKEY_CTX_set_rsa_keygen_pubexp(EVP_PKEY_CTX *ctx, BIGNUM *pubexp);

        #include <openssl/dh.h>

        int EVP_PKEY_CTX_get0_dh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char **ukm);

        #include <openssl/ec.h>

        int EVP_PKEY_CTX_get0_ecdh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char **ukm);

DESCRIPTION
       EVP_PKEY_CTX_ctrl() sends a control operation to the context ctx. The
       key type used must match keytype if it is not -1. The parameter optype
       is a mask indicating which operations the control can be applied to.
       The control command is indicated in cmd and any additional arguments in
       p1 and p2.

       For cmd = EVP_PKEY_CTRL_SET_MAC_KEY, p1 is the length of the MAC key,
       and p2 is the MAC key. This is used by Poly1305, SipHash, HMAC and
       CMAC.

       Applications will not normally call EVP_PKEY_CTX_ctrl() directly but
       will instead call one of the algorithm specific functions below.

       EVP_PKEY_CTX_ctrl_uint64() is a wrapper that directly passes a uint64
       value as p2 to EVP_PKEY_CTX_ctrl().

       EVP_PKEY_CTX_ctrl_str() allows an application to send an algorithm
       specific control operation to a context ctx in string form. This is
       intended to be used for options specified on the command line or in
       text files. The commands supported are documented in the openssl
       utility command line pages for the option -pkeyopt which is supported
       by the pkeyutl, genpkey and req commands.

       EVP_PKEY_CTX_md() sends a message digest control operation to the
       context ctx. The message digest is specified by its name md.

       EVP_PKEY_CTX_set_signature_md() sets the message digest type used in a
       signature. It can be used in the RSA, DSA and ECDSA algorithms.

       EVP_PKEY_CTX_get_signature_md()gets the message digest type used in a
       signature. It can be used in the RSA, DSA and ECDSA algorithms.

       Key generation typically involves setting up parameters to be used and
       generating the private and public key data. Some algorithm
       implementations allow private key data to be set explicitly using
       EVP_PKEY_CTX_set_mac_key().  In this case key generation is simply the
       process of setting up the parameters for the key and then setting the
       raw key data to the value explicitly.  Normally applications would call
       EVP_PKEY_new_raw_private_key(3) or similar functions instead.

       EVP_PKEY_CTX_set_mac_key() can be used with any of the algorithms
       supported by the EVP_PKEY_new_raw_private_key(3) function.

       EVP_PKEY_CTX_set_group_name() sets the group name to name for parameter
       and key generation. For example for EC keys this will set the curve
       name and for DH keys it will set the name of the finite field group.

       EVP_PKEY_CTX_get_group_name() finds the group name that's currently set
       with ctx, and writes it to the location that name points at, as long as
       its size namelen is large enough to store that name, including a
       terminating NUL byte.

   RSA parameters
       EVP_PKEY_CTX_set_rsa_padding() sets the RSA padding mode for ctx.  The
       pad parameter can take the value RSA_PKCS1_PADDING for PKCS#1 padding,
       RSA_NO_PADDING for no padding, RSA_PKCS1_OAEP_PADDING for OAEP padding
       (encrypt and decrypt only), RSA_X931_PADDING for X9.31 padding
       (signature operations only), RSA_PKCS1_PSS_PADDING (sign and verify
       only) and RSA_PKCS1_WITH_TLS_PADDING for TLS RSA ClientKeyExchange
       message padding (decryption only).

       Two RSA padding modes behave differently if
       EVP_PKEY_CTX_set_signature_md() is used. If this function is called for
       PKCS#1 padding the plaintext buffer is an actual digest value and is
       encapsulated in a DigestInfo structure according to PKCS#1 when signing
       and this structure is expected (and stripped off) when verifying. If
       this control is not used with RSA and PKCS#1 padding then the supplied
       data is used directly and not encapsulated. In the case of X9.31
       padding for RSA the algorithm identifier byte is added or checked and
       removed if this control is called. If it is not called then the first
       byte of the plaintext buffer is expected to be the algorithm identifier
       byte.

       EVP_PKEY_CTX_get_rsa_padding() gets the RSA padding mode for ctx.

       EVP_PKEY_CTX_set_rsa_pss_saltlen() sets the RSA PSS salt length to
       saltlen.  As its name implies it is only supported for PSS padding. If
       this function is not called then the maximum salt length is used when
       signing and auto detection when verifying. Three special values are
       supported:

       RSA_PSS_SALTLEN_DIGEST
           sets the salt length to the digest length.

       RSA_PSS_SALTLEN_MAX
           sets the salt length to the maximum permissible value.

       RSA_PSS_SALTLEN_AUTO
           causes the salt length to be automatically determined based on the
           PSS block structure when verifying.  When signing, it has the same
           meaning as RSA_PSS_SALTLEN_MAX.

       EVP_PKEY_CTX_get_rsa_pss_saltlen() gets the RSA PSS salt length for
       ctx.  The padding mode must already have been set to
       RSA_PKCS1_PSS_PADDING.

       EVP_PKEY_CTX_set_rsa_keygen_bits() sets the RSA key length for RSA key
       generation to bits. If not specified 2048 bits is used.

       EVP_PKEY_CTX_set1_rsa_keygen_pubexp() sets the public exponent value
       for RSA key generation to the value stored in pubexp. Currently it
       should be an odd integer. In accordance with the OpenSSL naming
       convention, the pubexp pointer must be freed independently of the
       EVP_PKEY_CTX (ie, it is internally copied).  If not specified 65537 is
       used.

       EVP_PKEY_CTX_set_rsa_keygen_pubexp() does the same as
       EVP_PKEY_CTX_set1_rsa_keygen_pubexp() except that there is no internal
       copy and therefore pubexp should not be modified or freed after the
       call.

       EVP_PKEY_CTX_set_rsa_keygen_primes() sets the number of primes for RSA
       key generation to primes. If not specified 2 is used.

       EVP_PKEY_CTX_set_rsa_mgf1_md_name() sets the MGF1 digest for RSA
       padding schemes to the digest named mdname. If the RSA algorithm
       implementation for the selected provider supports it then the digest
       will be fetched using the properties mdprops. If not explicitly set the
       signing digest is used. The padding mode must have been set to
       RSA_PKCS1_OAEP_PADDING or RSA_PKCS1_PSS_PADDING.

       EVP_PKEY_CTX_set_rsa_mgf1_md() does the same as
       EVP_PKEY_CTX_set_rsa_mgf1_md_name() except that the name of the digest
       is inferred from the supplied md and it is not possible to specify any
       properties.

       EVP_PKEY_CTX_get_rsa_mgf1_md_name() gets the name of the MGF1 digest
       algorithm for ctx. If not explicitly set the signing digest is used.
       The padding mode must have been set to RSA_PKCS1_OAEP_PADDING or
       RSA_PKCS1_PSS_PADDING.

       EVP_PKEY_CTX_get_rsa_mgf1_md() does the same as
       EVP_PKEY_CTX_get_rsa_mgf1_md_name() except that it returns a pointer to
       an EVP_MD object instead. Note that only known, built-in EVP_MD objects
       will be returned. The EVP_MD object may be NULL if the digest is not
       one of these (such as a digest only implemented in a third party
       provider).

       EVP_PKEY_CTX_set_rsa_oaep_md_name() sets the message digest type used
       in RSA OAEP to the digest named mdname.  If the RSA algorithm
       implementation for the selected provider supports it then the digest
       will be fetched using the properties mdprops. The padding mode must
       have been set to RSA_PKCS1_OAEP_PADDING.

       EVP_PKEY_CTX_set_rsa_oaep_md() does the same as
       EVP_PKEY_CTX_set_rsa_oaep_md_name() except that the name of the digest
       is inferred from the supplied md and it is not possible to specify any
       properties.

       EVP_PKEY_CTX_get_rsa_oaep_md_name() gets the message digest algorithm
       name used in RSA OAEP and stores it in the buffer name which is of size
       namelen. The padding mode must have been set to RSA_PKCS1_OAEP_PADDING.
       The buffer should be sufficiently large for any expected digest
       algorithm names or the function will fail.

       EVP_PKEY_CTX_get_rsa_oaep_md() does the same as
       EVP_PKEY_CTX_get_rsa_oaep_md_name() except that it returns a pointer to
       an EVP_MD object instead. Note that only known, built-in EVP_MD objects
       will be returned. The EVP_MD object may be NULL if the digest is not
       one of these (such as a digest only implemented in a third party
       provider).

       EVP_PKEY_CTX_set0_rsa_oaep_label() sets the RSA OAEP label to binary
       data label and its length in bytes to len. If label is NULL or len is
       0, the label is cleared. The library takes ownership of the label so
       the caller should not free the original memory pointed to by label.
       The padding mode must have been set to RSA_PKCS1_OAEP_PADDING.

       EVP_PKEY_CTX_get0_rsa_oaep_label() gets the RSA OAEP label to label.
       The return value is the label length. The padding mode must have been
       set to RSA_PKCS1_OAEP_PADDING. The resulting pointer is owned by the
       library and should not be freed by the caller.

       RSA_PKCS1_WITH_TLS_PADDING is used when decrypting an RSA encrypted TLS
       pre-master secret in a TLS ClientKeyExchange message. It is the same as
       RSA_PKCS1_PADDING except that it additionally verifies that the result
       is the correct length and the first two bytes are the protocol version
       initially requested by the client. If the encrypted content is publicly
       invalid then the decryption will fail. However, if the padding checks
       fail then decryption will still appear to succeed but a random TLS
       premaster secret will be returned instead. This padding mode accepts
       two parameters which can be set using the EVP_PKEY_CTX_set_params(3)
       function. These are OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION and
       OSSL_ASYM_CIPHER_PARAM_TLS_NEGOTIATED_VERSION, both of which are
       expected to be unsigned integers. Normally only the first of these will
       be set and represents the TLS protocol version that was first requested
       by the client (e.g. 0x0303 for TLSv1.2, 0x0302 for TLSv1.1 etc).
       Historically some buggy clients would use the negotiated protocol
       version instead of the protocol version first requested. If this
       behaviour should be tolerated then
       OSSL_ASYM_CIPHER_PARAM_TLS_NEGOTIATED_VERSION should be set to the
       actual negotiated protocol version. Otherwise it should be left unset.

   DSA parameters
       EVP_PKEY_CTX_set_dsa_paramgen_bits() sets the number of bits used for
       DSA parameter generation to nbits. If not specified, 2048 is used.

       EVP_PKEY_CTX_set_dsa_paramgen_q_bits() sets the number of bits in the
       subprime parameter q for DSA parameter generation to qbits. If not
       specified, 224 is used. If a digest function is specified below, this
       parameter is ignored and instead, the number of bits in q matches the
       size of the digest.

       EVP_PKEY_CTX_set_dsa_paramgen_md() sets the digest function used for
       DSA parameter generation to md. If not specified, one of SHA-1,
       SHA-224, or SHA-256 is selected to match the bit length of q above.

       EVP_PKEY_CTX_set_dsa_paramgen_md_props() sets the digest function used
       for DSA parameter generation using md_name and md_properties to
       retrieve the digest from a provider.  If not specified, md_name will be
       set to one of SHA-1, SHA-224, or SHA-256 depending on the bit length of
       q above. md_properties is a property query string that has a default
       value of '' if not specified.

       EVP_PKEY_CTX_set_dsa_paramgen_gindex() sets the gindex used by the
       generator G. The default value is -1 which uses unverifiable g,
       otherwise a positive value uses verifiable g. This value must be saved
       if key validation of g is required, since it is not part of a persisted
       key.

       EVP_PKEY_CTX_set_dsa_paramgen_seed() sets the seed to use for
       generation rather than using a randomly generated value for the seed.
       This is useful for testing purposes only and can fail if the seed does
       not produce primes for both p & q on its first iteration. This value
       must be saved if key validation of p, q, and verifiable g are required,
       since it is not part of a persisted key.

       EVP_PKEY_CTX_set_dsa_paramgen_type() sets the generation type to use
       FIPS186-4 generation if name is "fips186_4", or FIPS186-2 generation if
       name is "fips186_2". The default value for the default provider is
       "fips186_2". The default value for the FIPS provider is "fips186_4".

   DH parameters
       EVP_PKEY_CTX_set_dh_paramgen_prime_len() sets the length of the DH
       prime parameter p for DH parameter generation. If this function is not
       called then 2048 is used. Only accepts lengths greater than or equal to
       256.

       EVP_PKEY_CTX_set_dh_paramgen_subprime_len() sets the length of the DH
       optional subprime parameter q for DH parameter generation. The default
       is 256 if the prime is at least 2048 bits long or 160 otherwise. The DH
       paramgen type must have been set to "fips186_4".

       EVP_PKEY_CTX_set_dh_paramgen_generator() sets DH generator to gen for
       DH parameter generation. If not specified 2 is used.

       EVP_PKEY_CTX_set_dh_paramgen_type() sets the key type for DH parameter
       generation. The supported parameters are:

       DH_PARAMGEN_TYPE_GROUP
           Use a named group. If only the safe prime parameter p is set this
           can be used to select a ffdhe safe prime group of the correct size.

       DH_PARAMGEN_TYPE_FIPS_186_4
           FIPS186-4 FFC parameter generator.

       DH_PARAMGEN_TYPE_FIPS_186_2
           FIPS186-2 FFC parameter generator (X9.42 DH).

       DH_PARAMGEN_TYPE_GENERATOR
           Uses a safe prime generator g (PKCS#3 format).

       The default in the default provider is DH_PARAMGEN_TYPE_GENERATOR for
       the "DH" keytype, and DH_PARAMGEN_TYPE_FIPS_186_2 for the "DHX"
       keytype. In the FIPS provider the default value is
       DH_PARAMGEN_TYPE_GROUP for the "DH" keytype and
       <DH_PARAMGEN_TYPE_FIPS_186_4 for the "DHX" keytype.

       EVP_PKEY_CTX_set_dh_paramgen_gindex() sets the gindex used by the
       generator G.  The default value is -1 which uses unverifiable g,
       otherwise a positive value uses verifiable g. This value must be saved
       if key validation of g is required, since it is not part of a persisted
       key.

       EVP_PKEY_CTX_set_dh_paramgen_seed() sets the seed to use for generation
       rather than using a randomly generated value for the seed. This is
       useful for testing purposes only and can fail if the seed does not
       produce primes for both p & q on its first iteration. This value must
       be saved if key validation of p, q, and verifiable g are required,
       since it is not part of a persisted key.

       EVP_PKEY_CTX_set_dh_pad() sets the DH padding mode.  If pad is 1 the
       shared secret is padded with zeros up to the size of the DH prime p.
       If pad is zero (the default) then no padding is performed.

       EVP_PKEY_CTX_set_dh_nid() sets the DH parameters to values
       corresponding to nid as defined in RFC7919 or RFC3526. The nid
       parameter must be NID_ffdhe2048, NID_ffdhe3072, NID_ffdhe4096,
       NID_ffdhe6144, NID_ffdhe8192, NID_modp_1536, NID_modp_2048,
       NID_modp_3072, NID_modp_4096, NID_modp_6144, NID_modp_8192 or NID_undef
       to clear the stored value. This function can be called during parameter
       or key generation.  The nid parameter and the rfc5114 parameter are
       mutually exclusive.

       EVP_PKEY_CTX_set_dh_rfc5114() and EVP_PKEY_CTX_set_dhx_rfc5114() both
       set the DH parameters to the values defined in RFC5114. The rfc5114
       parameter must be 1, 2 or 3 corresponding to RFC5114 sections 2.1, 2.2
       and 2.3. or 0 to clear the stored value. This macro can be called
       during parameter generation. The ctx must have a key type of
       EVP_PKEY_DHX.  The rfc5114 parameter and the nid parameter are mutually
       exclusive.

   DH key derivation function parameters
       Note that all of the following functions require that the ctx parameter
       has a private key type of EVP_PKEY_DHX. When using key derivation, the
       output of EVP_PKEY_derive() is the output of the KDF instead of the DH
       shared secret.  The KDF output is typically used as a Key Encryption
       Key (KEK) that in turn encrypts a Content Encryption Key (CEK).

       EVP_PKEY_CTX_set_dh_kdf_type() sets the key derivation function type to
       kdf for DH key derivation. Possible values are EVP_PKEY_DH_KDF_NONE and
       EVP_PKEY_DH_KDF_X9_42 which uses the key derivation specified in
       RFC2631 (based on the keying algorithm described in X9.42). When using
       key derivation, the kdf_oid, kdf_md and kdf_outlen parameters must also
       be specified.

       EVP_PKEY_CTX_get_dh_kdf_type() gets the key derivation function type
       for ctx used for DH key derivation. Possible values are
       EVP_PKEY_DH_KDF_NONE and EVP_PKEY_DH_KDF_X9_42.

       EVP_PKEY_CTX_set0_dh_kdf_oid() sets the key derivation function object
       identifier to oid for DH key derivation. This OID should identify the
       algorithm to be used with the Content Encryption Key.  The library
       takes ownership of the object identifier so the caller should not free
       the original memory pointed to by oid.

       EVP_PKEY_CTX_get0_dh_kdf_oid() gets the key derivation function oid for
       ctx used for DH key derivation. The resulting pointer is owned by the
       library and should not be freed by the caller.

       EVP_PKEY_CTX_set_dh_kdf_md() sets the key derivation function message
       digest to md for DH key derivation. Note that RFC2631 specifies that
       this digest should be SHA1 but OpenSSL tolerates other digests.

       EVP_PKEY_CTX_get_dh_kdf_md() gets the key derivation function message
       digest for ctx used for DH key derivation.

       EVP_PKEY_CTX_set_dh_kdf_outlen() sets the key derivation function
       output length to len for DH key derivation.

       EVP_PKEY_CTX_get_dh_kdf_outlen() gets the key derivation function
       output length for ctx used for DH key derivation.

       EVP_PKEY_CTX_set0_dh_kdf_ukm() sets the user key material to ukm and
       its length to len for DH key derivation. This parameter is optional and
       corresponds to the partyAInfo field in RFC2631 terms. The specification
       requires that it is 512 bits long but this is not enforced by OpenSSL.
       The library takes ownership of the user key material so the caller
       should not free the original memory pointed to by ukm.

       EVP_PKEY_CTX_get0_dh_kdf_ukm() gets the user key material for ctx.  The
       return value is the user key material length. The resulting pointer is
       owned by the library and should not be freed by the caller.

   EC parameters
       Use EVP_PKEY_CTX_set_group_name() (described above) to set the curve
       name to name for parameter and key generation.

       EVP_PKEY_CTX_set_ec_paramgen_curve_nid() does the same as
       EVP_PKEY_CTX_set_group_name(), but is specific to EC and uses a nid
       rather than a name string.

       For EC parameter generation, one of EVP_PKEY_CTX_set_group_name() or
       EVP_PKEY_CTX_set_ec_paramgen_curve_nid() must be called or an error
       occurs because there is no default curve.  These function can also be
       called to set the curve explicitly when generating an EC key.

       EVP_PKEY_CTX_get_group_name() (described above) can be used to obtain
       the curve name that's currently set with ctx.

       EVP_PKEY_CTX_set_ec_param_enc() sets the EC parameter encoding to
       param_enc when generating EC parameters or an EC key. The encoding can
       be OPENSSL_EC_EXPLICIT_CURVE for explicit parameters (the default in
       versions of OpenSSL before 1.1.0) or OPENSSL_EC_NAMED_CURVE to use
       named curve form.  For maximum compatibility the named curve form
       should be used. Note: the OPENSSL_EC_NAMED_CURVE value was added in
       OpenSSL 1.1.0; previous versions should use 0 instead.

   ECDH parameters
       EVP_PKEY_CTX_set_ecdh_cofactor_mode() sets the cofactor mode to
       cofactor_mode for ECDH key derivation. Possible values are 1 to enable
       cofactor key derivation, 0 to disable it and -1 to clear the stored
       cofactor mode and fallback to the private key cofactor mode.

       EVP_PKEY_CTX_get_ecdh_cofactor_mode() returns the cofactor mode for ctx
       used for ECDH key derivation. Possible values are 1 when cofactor key
       derivation is enabled and 0 otherwise.

   ECDH key derivation function parameters
       EVP_PKEY_CTX_set_ecdh_kdf_type() sets the key derivation function type
       to kdf for ECDH key derivation. Possible values are
       EVP_PKEY_ECDH_KDF_NONE and EVP_PKEY_ECDH_KDF_X9_63 which uses the key
       derivation specified in X9.63.  When using key derivation, the kdf_md
       and kdf_outlen parameters must also be specified.

       EVP_PKEY_CTX_get_ecdh_kdf_type() returns the key derivation function
       type for ctx used for ECDH key derivation. Possible values are
       EVP_PKEY_ECDH_KDF_NONE and EVP_PKEY_ECDH_KDF_X9_63.

       EVP_PKEY_CTX_set_ecdh_kdf_md() sets the key derivation function message
       digest to md for ECDH key derivation. Note that X9.63 specifies that
       this digest should be SHA1 but OpenSSL tolerates other digests.

       EVP_PKEY_CTX_get_ecdh_kdf_md() gets the key derivation function message
       digest for ctx used for ECDH key derivation.

       EVP_PKEY_CTX_set_ecdh_kdf_outlen() sets the key derivation function
       output length to len for ECDH key derivation.

       EVP_PKEY_CTX_get_ecdh_kdf_outlen() gets the key derivation function
       output length for ctx used for ECDH key derivation.

       EVP_PKEY_CTX_set0_ecdh_kdf_ukm() sets the user key material to ukm for
       ECDH key derivation. This parameter is optional and corresponds to the
       shared info in X9.63 terms. The library takes ownership of the user key
       material so the caller should not free the original memory pointed to
       by ukm.

       EVP_PKEY_CTX_get0_ecdh_kdf_ukm() gets the user key material for ctx.
       The return value is the user key material length. The resulting pointer
       is owned by the library and should not be freed by the caller.

   Other parameters
       EVP_PKEY_CTX_set1_id(), EVP_PKEY_CTX_get1_id() and
       EVP_PKEY_CTX_get1_id_len() are used to manipulate the special
       identifier field for specific signature algorithms such as SM2. The
       EVP_PKEY_CTX_set1_id() sets an ID pointed by id with the length id_len
       to the library. The library takes a copy of the id so that the caller
       can safely free the original memory pointed to by id.
       EVP_PKEY_CTX_get1_id_len() returns the length of the ID set via a
       previous call to EVP_PKEY_CTX_set1_id(). The length is usually used to
       allocate adequate memory for further calls to EVP_PKEY_CTX_get1_id().
       EVP_PKEY_CTX_get1_id() returns the previously set ID value to caller in
       id. The caller should allocate adequate memory space for the id before
       calling EVP_PKEY_CTX_get1_id().

       EVP_PKEY_CTX_set_kem_op() sets the KEM operation to run. This can be
       set after EVP_PKEY_encapsulate_init() or EVP_PKEY_decapsulate_init() to
       select the kem operation. RSA is the only key type that supports
       encapsulation currently, and as there is no default operation for the
       RSA type, this function must be called before EVP_PKEY_encapsulate() or
       EVP_PKEY_decapsulate().

RETURN VALUES
       All other functions described on this page return a positive value for
       success and 0 or a negative value for failure. In particular a return
       value of -2 indicates the operation is not supported by the public key
       algorithm.

SEE ALSO
       EVP_PKEY_CTX_set_params(3), EVP_PKEY_CTX_new(3), EVP_PKEY_encrypt(3),
       EVP_PKEY_decrypt(3), EVP_PKEY_sign(3), EVP_PKEY_verify(3),
       EVP_PKEY_verify_recover(3), EVP_PKEY_derive(3), EVP_PKEY_keygen(3)
       EVP_PKEY_encapsulate(3) EVP_PKEY_decapsulate(3)

HISTORY
       EVP_PKEY_CTX_get_rsa_oaep_md_name(),
       EVP_PKEY_CTX_get_rsa_mgf1_md_name(),
       EVP_PKEY_CTX_set_rsa_mgf1_md_name(),
       EVP_PKEY_CTX_set_rsa_oaep_md_name(),
       EVP_PKEY_CTX_set_dsa_paramgen_md_props(),
       EVP_PKEY_CTX_set_dsa_paramgen_gindex(),
       EVP_PKEY_CTX_set_dsa_paramgen_type(),
       EVP_PKEY_CTX_set_dsa_paramgen_seed(), EVP_PKEY_CTX_set_group_name() and
       EVP_PKEY_CTX_get_group_name() were added in OpenSSL 3.0.

       The EVP_PKEY_CTX_set1_id(), EVP_PKEY_CTX_get1_id() and
       EVP_PKEY_CTX_get1_id_len() macros were added in 1.1.1, other functions
       were added in OpenSSL 1.0.0.

       In OpenSSL 1.1.1 and below the functions were mostly macros.  From
       OpenSSL 3.0 they are all functions.

       EVP_PKEY_CTX_set_rsa_keygen_pubexp(), EVP_PKEY_CTX_get0_dh_kdf_ukm(),
       and EVP_PKEY_CTX_get0_ecdh_kdf_ukm() were deprecated in OpenSSL 3.0.

COPYRIGHT
       Copyright 2006-2021 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>.



3.0.12                            2023-05-07              EVP_PKEY_CTX_ctrl(3)