OpenBSD manual page server

Manual Page Search Parameters

EVP_PKEY_CTX_CTRL(3) Library Functions Manual 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_rsa_pss_saltlen, EVP_PKEY_CTX_set_rsa_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_ec_paramgen_curve_nidalgorithm specific control operations

#include <openssl/evp.h>

EVP_PKEY_CTX_ctrl(EVP_PKEY_CTX *ctx, int keytype, int optype, int cmd, int p1, void *p2);

EVP_PKEY_CTX_ctrl_str(EVP_PKEY_CTX *ctx, const char *type, const char *value);

#include <openssl/rsa.h>

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

EVP_PKEY_CTX_set_rsa_padding(EVP_PKEY_CTX *ctx, int pad);

EVP_PKEY_CTX_set_rsa_pss_saltlen(EVP_PKEY_CTX *ctx, int len);

EVP_PKEY_CTX_set_rsa_rsa_keygen_bits(EVP_PKEY_CTX *ctx, int mbits);

EVP_PKEY_CTX_set_rsa_keygen_pubexp(EVP_PKEY_CTX *ctx, BIGNUM *pubexp);

#include <openssl/dsa.h>

EVP_PKEY_CTX_set_dsa_paramgen_bits(EVP_PKEY_CTX *ctx, int nbits);

#include <openssl/dh.h>

EVP_PKEY_CTX_set_dh_paramgen_prime_len(EVP_PKEY_CTX *ctx, int len);

EVP_PKEY_CTX_set_dh_paramgen_generator(EVP_PKEY_CTX *ctx, int gen);

#include <openssl/ec.h>

EVP_PKEY_CTX_set_ec_paramgen_curve_nid(EVP_PKEY_CTX *ctx, int nid);

The function () 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 () directly but will instead call one of the algorithm specific macros below.

The function () 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(1) 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 () macro sets the message digest type used in a signature. It can be used with any public key algorithm supporting signature operations.

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

The () 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 freed after the call. If this macro is not called, then 65537 is used.

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

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

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

The () 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_decrypt(3), EVP_PKEY_derive(3), EVP_PKEY_encrypt(3), EVP_PKEY_get_default_digest_nid(3), EVP_PKEY_keygen(3), EVP_PKEY_sign(3), EVP_PKEY_verify(3), EVP_PKEY_verify_recover(3)

These functions were first added to OpenSSL 1.0.0.

December 25, 2016 OpenBSD-6.1