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EVP_PKEY_CTX_ctrl(3)                OpenSSL               EVP_PKEY_CTX_ctrl(3)



NAME
       EVP_PKEY_CTX_ctrl, EVP_PKEY_CTX_ctrl_str,
       EVP_PKEY_CTX_set_signature_md, EVP_PKEY_CTX_get_signature_md,
       EVP_PKEY_CTX_set_mac_key, EVP_PKEY_CTX_set_rsa_padding,
       EVP_PKEY_CTX_set_rsa_pss_saltlen, EVP_PKEY_CTX_set_rsa_keygen_bits,
       EVP_PKEY_CTX_set_rsa_keygen_pubexp, EVP_PKEY_CTX_set_dsa_paramgen_bits,
       EVP_PKEY_CTX_set_dh_paramgen_prime_len,
       EVP_PKEY_CTX_set_dh_paramgen_generator, EVP_PKEY_CTX_set_dh_pad,
       EVP_PKEY_CTX_set_dh_nid, EVP_PKEY_CTX_set_ec_paramgen_curve_nid,
       EVP_PKEY_CTX_set_ec_param_enc, EVP_PKEY_CTX_set1_id,
       EVP_PKEY_CTX_get1_id, EVP_PKEY_CTX_get1_id_len - 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_str(EVP_PKEY_CTX *ctx, const char *type,
                                  const char *value);

        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, unsigned char *key, int len);

        #include <openssl/rsa.h>

        int EVP_PKEY_CTX_set_rsa_padding(EVP_PKEY_CTX *ctx, int pad);
        int EVP_PKEY_CTX_set_rsa_pss_saltlen(EVP_PKEY_CTX *ctx, int len);
        int EVP_PKEY_CTX_set_rsa_keygen_bits(EVP_PKEY_CTX *ctx, int mbits);
        int EVP_PKEY_CTX_set_rsa_keygen_pubexp(EVP_PKEY_CTX *ctx, BIGNUM *pubexp);

        #include <openssl/dsa.h>
        int EVP_PKEY_CTX_set_dsa_paramgen_bits(EVP_PKEY_CTX *ctx, int nbits);

        #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_generator(EVP_PKEY_CTX *ctx, int gen);
        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);

        #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_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);

DESCRIPTION
       The function 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 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 macros below.

       The function 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.

       All the remaining "functions" are implemented as macros.

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

       The EVP_PKEY_CTX_get_signature_md() macro 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 the
       EVP_PKEY_CTX_set_mac_key() macro. 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 provided by that macro.
       Normally applications would call EVP_PKEY_new_raw_private_key(3) or
       similar functions instead of this macro.

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

       The macro 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_SSLV23_PADDING for SSLv23 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)
       and RSA_PKCS1_PSS_PADDING (sign and verify only).

       Two RSA padding modes behave differently if
       EVP_PKEY_CTX_set_signature_md() is used. If this macro 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.

       The EVP_PKEY_CTX_set_rsa_pss_saltlen() macro sets the RSA PSS salt
       length to len as its name implies it is only supported for PSS padding.
       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. When verifying
       RSA_PSS_SALTLEN_AUTO causes the salt length to be automatically
       determined based on the PSS block structure. If this macro is not
       called maximum salt length is used when signing and auto detection when
       verifying is used by default.

       The EVP_PKEY_CTX_set_rsa_keygen_bits() macro sets the RSA key length
       for RSA key generation to bits. If not specified 1024 bits is used.

       The EVP_PKEY_CTX_set_rsa_keygen_pubexp() macro sets the public exponent
       value for RSA key generation to pubexp currently it should be an odd
       integer. The pubexp pointer is used internally by this function so it
       should not be modified or free after the call. If this macro is not
       called then 65537 is used.

       The macro EVP_PKEY_CTX_set_dsa_paramgen_bits() sets the number of bits
       used for DSA parameter generation to bits. If not specified 1024 is
       used.

       The macro EVP_PKEY_CTX_set_dh_paramgen_prime_len() sets the length of
       the DH prime parameter p for DH parameter generation. If this macro is
       not called then 1024 is used.

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

       The EVP_PKEY_CTX_set_dh_pad() macro sets the DH padding mode. If pad is
       1 the shared secret is padded with zeroes 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. The nid parameter must be NID_ffdhe2048,
       NID_ffdhe3072, NID_ffdhe4096, NID_ffdhe6144 or NID_ffdhe8192.  This
       macro can be called during parameter or key generation.

       The EVP_PKEY_CTX_set_ec_paramgen_curve_nid() sets the EC curve for EC
       parameter generation to nid. For EC parameter generation this macro
       must be called or an error occurs because there is no default curve.
       This function can also be called to set the curve explicitly when
       generating an EC key.

       The 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 only added
       to OpenSSL 1.1.0; previous versions should use 0 instead.

       The EVP_PKEY_CTX_set1_id(), EVP_PKEY_CTX_get1_id() and
       EVP_PKEY_CTX_get1_id_len() macros 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. The
       EVP_PKEY_CTX_get1_id_len() macro 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().
       The EVP_PKEY_CTX_get1_id() macro 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().

RETURN VALUES
       EVP_PKEY_CTX_ctrl() and its macros 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_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)

HISTORY
       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 first added to OpenSSL 1.0.0.

COPYRIGHT
       Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (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>.



1.1.1                             2018-09-17              EVP_PKEY_CTX_ctrl(3)