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Title "EVP_PKEY_GETTABLE_PARAMS 3ossl" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
EVP_PKEY_gettable_params, EVP_PKEY_get_params, EVP_PKEY_get_int_param, EVP_PKEY_get_size_t_param, EVP_PKEY_get_bn_param, EVP_PKEY_get_utf8_string_param, EVP_PKEY_get_octet_string_param \- retrieve key parameters from a key Header "SYNOPSIS" .Vb 1 #include <openssl/evp.h> \& const OSSL_PARAM *EVP_PKEY_gettable_params(EVP_PKEY *pkey); int EVP_PKEY_get_params(const EVP_PKEY *pkey, OSSL_PARAM params[]); int EVP_PKEY_get_int_param(const EVP_PKEY *pkey, const char *key_name, int *out); int EVP_PKEY_get_size_t_param(const EVP_PKEY *pkey, const char *key_name, size_t *out); int EVP_PKEY_get_bn_param(const EVP_PKEY *pkey, const char *key_name, BIGNUM **bn); int EVP_PKEY_get_utf8_string_param(const EVP_PKEY *pkey, const char *key_name, char *str, size_t max_buf_sz, size_t *out_len); int EVP_PKEY_get_octet_string_param(const EVP_PKEY *pkey, const char *key_name, unsigned char *buf, size_t max_buf_sz, size_t *out_len); .Ve Header "DESCRIPTION" See \s-1OSSL_PARAM\s0\|(3) for information about parameters.

\fBEVP_PKEY_get_params() retrieves parameters from the key pkey, according to the contents of params.

\fBEVP_PKEY_gettable_params() returns a constant list of params indicating the names and types of key parameters that can be retrieved.

An \s-1OSSL_PARAM\s0\|(3) of type \s-1OSSL_PARAM_INTEGER\s0 or \fB\s-1OSSL_PARAM_UNSIGNED_INTEGER\s0 is of arbitrary length. Such a parameter can be obtained using any of the functions EVP_PKEY_get_int_param(), \fBEVP_PKEY_get_size_t_param() or EVP_PKEY_get_bn_param(). Attempting to obtain an integer value that does not fit into a native C int type will cause \fBEVP_PKEY_get_int_param() to fail. Similarly attempting to obtain an integer value that is negative or does not fit into a native C size_t type using \fBEVP_PKEY_get_size_t_param() will also fail.

\fBEVP_PKEY_get_int_param() retrieves a key pkey integer value *out associated with a name of key_name if it fits into \*(C`int\*(C' type. For parameters that do not fit into \*(C`int\*(C' use EVP_PKEY_get_bn_param().

\fBEVP_PKEY_get_size_t_param() retrieves a key pkey size_t value *out associated with a name of key_name if it fits into \*(C`size_t\*(C' type. For parameters that do not fit into \*(C`size_t\*(C' use EVP_PKEY_get_bn_param().

\fBEVP_PKEY_get_bn_param() retrieves a key pkey \s-1BIGNUM\s0 value **bn associated with a name of key_name. If *bn is \s-1NULL\s0 then the \s-1BIGNUM\s0 is allocated by the method.

\fBEVP_PKEY_get_utf8_string_param() get a key pkey \s-1UTF8\s0 string value into a buffer str of maximum size max_buf_sz associated with a name of \fIkey_name. The maximum size must be large enough to accommodate the string value including a terminating \s-1NUL\s0 byte, or this function will fail. If out_len is not \s-1NULL,\s0 *out_len is set to the length of the string not including the terminating \s-1NUL\s0 byte. The required buffer size not including the terminating \s-1NUL\s0 byte can be obtained from *out_len by calling the function with str set to \s-1NULL.\s0

\fBEVP_PKEY_get_octet_string_param() get a key pkey's octet string value into a buffer buf of maximum size max_buf_sz associated with a name of key_name. If out_len is not \s-1NULL,\s0 *out_len is set to the length of the contents. The required buffer size can be obtained from *out_len by calling the function with buf set to \s-1NULL.\s0

Header "NOTES" These functions only work for \s-1EVP_PKEY\s0s that contain a provider side key. Header "RETURN VALUES" \fBEVP_PKEY_gettable_params() returns \s-1NULL\s0 on error or if it is not supported.

All other methods return 1 if a value associated with the key's key_name was successfully returned, or 0 if there was an error. An error may be returned by methods EVP_PKEY_get_utf8_string_param() and \fBEVP_PKEY_get_octet_string_param() if max_buf_sz is not big enough to hold the value. If out_len is not \s-1NULL,\s0 *out_len will be assigned the required buffer size to hold the value.

Header "EXAMPLES" .Vb 1 #include <openssl/evp.h> \& char curve_name[64]; unsigned char pub[256]; BIGNUM *bn_priv = NULL; \& /* * NB: assumes \*(Aqkey\*(Aq is set up before the next step. In this example the key * is an EC key. */ \& if (!EVP_PKEY_get_utf8_string_param(key, OSSL_PKEY_PARAM_GROUP_NAME, curve_name, sizeof(curve_name), &len)) { /* Error */ } if (!EVP_PKEY_get_octet_string_param(key, OSSL_PKEY_PARAM_PUB_KEY, pub, sizeof(pub), &len)) { /* Error */ } if (!EVP_PKEY_get_bn_param(key, OSSL_PKEY_PARAM_PRIV_KEY, &bn_priv)) { /* Error */ } \& BN_clear_free(bn_priv); .Ve Header "SEE ALSO" \fBEVP_PKEY_CTX_new\|(3), provider-keymgmt\|(7), \s-1OSSL_PARAM\s0\|(3) Header "HISTORY" These functions were added in OpenSSL 3.0. Header "COPYRIGHT" Copyright 2020-2023 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.