EVP_PKEY_CTX_ctrl(3)         OpenSSL         EVP_PKEY_CTX_ctrl(3)


     EVP_PKEY_CTX_ctrl, EVP_PKEY_CTX_ctrl_str,
     EVP_PKEY_CTX_set_signature_md, EVP_PKEY_CTX_set_rsa_padding,
     EVP_PKEY_CTX_set_ec_paramgen_curve_nid - algorithm specific
     control operations


      #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_get_default_digest_nid(EVP_PKEY *pkey, int *pnid);

      #include <openssl/rsa.h>

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

      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_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);

      #include <openssl/ec.h>
      int EVP_PKEY_CTX_set_ec_paramgen_curve_nid(EVP_PKEY_CTX *ctx, int nid);


     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.

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

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EVP_PKEY_CTX_ctrl(3)         OpenSSL         EVP_PKEY_CTX_ctrl(3)

     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 with any
     public key algorithm supporting signature operations.

     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

     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.  Two special values are
     supported: -1 sets the salt length to the digest length.
     When signing -2 sets the salt length to the maximum
     permissible value. When verifying -2 causes the salt length
     to be automatically determined based on the PSS block
     structure. If this macro is not called a salt length value
     of -2 is used by default.

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

1.0.2t               Last change: 2019-09-10                    2

EVP_PKEY_CTX_ctrl(3)         OpenSSL         EVP_PKEY_CTX_ctrl(3)

     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_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.


     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.


     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)


     These functions were first added to OpenSSL 1.0.0.

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