| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | EVP_PKEY_gettable_params, EVP_PKEY_get_params,
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| 6 | EVP_PKEY_get_int_param, EVP_PKEY_get_size_t_param,
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| 7 | EVP_PKEY_get_bn_param, EVP_PKEY_get_utf8_string_param,
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| 8 | EVP_PKEY_get_octet_string_param
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| 9 | - retrieve key parameters from a key
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| 10 |
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| 11 | =head1 SYNOPSIS
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| 12 |
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| 13 | #include <openssl/evp.h>
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| 14 |
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| 15 | const OSSL_PARAM *EVP_PKEY_gettable_params(EVP_PKEY *pkey);
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| 16 | int EVP_PKEY_get_params(const EVP_PKEY *pkey, OSSL_PARAM params[]);
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| 17 | int EVP_PKEY_get_int_param(const EVP_PKEY *pkey, const char *key_name,
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| 18 | int *out);
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| 19 | int EVP_PKEY_get_size_t_param(const EVP_PKEY *pkey, const char *key_name,
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| 20 | size_t *out);
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| 21 | int EVP_PKEY_get_bn_param(const EVP_PKEY *pkey, const char *key_name,
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| 22 | BIGNUM **bn);
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| 23 | int EVP_PKEY_get_utf8_string_param(const EVP_PKEY *pkey, const char *key_name,
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| 24 | char *str, size_t max_buf_sz,
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| 25 | size_t *out_len);
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| 26 | int EVP_PKEY_get_octet_string_param(const EVP_PKEY *pkey, const char *key_name,
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| 27 | unsigned char *buf, size_t max_buf_sz,
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| 28 | size_t *out_len);
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| 29 |
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| 30 | =head1 DESCRIPTION
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| 31 |
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| 32 | EVP_PKEY_get_params() retrieves parameters from the key I<pkey>, according to
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| 33 | the contents of I<params>.
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| 34 | See L<OSSL_PARAM(3)> for information about parameters.
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| 35 |
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| 36 | EVP_PKEY_gettable_params() returns a constant list of I<params> indicating
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| 37 | the names and types of key parameters that can be retrieved.
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| 38 | See L<OSSL_PARAM(3)> for information about parameters.
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| 39 |
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| 40 | EVP_PKEY_get_int_param() retrieves a key I<pkey> integer value I<*out>
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| 41 | associated with a name of I<key_name>.
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| 42 |
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| 43 | EVP_PKEY_get_size_t_param() retrieves a key I<pkey> size_t value I<*out>
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| 44 | associated with a name of I<key_name>.
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| 45 |
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| 46 | EVP_PKEY_get_bn_param() retrieves a key I<pkey> BIGNUM value I<**bn>
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| 47 | associated with a name of I<key_name>. If I<*bn> is NULL then the BIGNUM
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| 48 | is allocated by the method.
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| 49 |
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| 50 | EVP_PKEY_get_utf8_string_param() get a key I<pkey> UTF8 string value into a
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| 51 | buffer I<str> of maximum size I<max_buf_sz> associated with a name of
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| 52 | I<key_name>. The maximum size must be large enough to accomodate the string
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| 53 | value including a terminating NUL byte, or this function will fail.
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| 54 | If I<out_len> is not NULL, I<*out_len> is set to the length of the string
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| 55 | not including the terminating NUL byte. The required buffer size not including
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| 56 | the terminating NUL byte can be obtained from I<*out_len> by calling the
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| 57 | function with I<str> set to NULL.
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| 58 |
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| 59 | EVP_PKEY_get_octet_string_param() get a key I<pkey>'s octet string value into a
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| 60 | buffer I<buf> of maximum size I<max_buf_sz> associated with a name of I<key_name>.
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| 61 | If I<out_len> is not NULL, I<*out_len> is set to the length of the contents.
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| 62 | The required buffer size can be obtained from I<*out_len> by calling the
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| 63 | function with I<buf> set to NULL.
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| 64 |
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| 65 | =head1 NOTES
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| 66 |
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| 67 | These functions only work for B<EVP_PKEY>s that contain a provider side key.
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| 68 |
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| 69 | =head1 RETURN VALUES
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| 70 |
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| 71 | EVP_PKEY_gettable_params() returns NULL on error or if it is not supported,
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| 72 |
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| 73 | All other methods return 1 if a value associated with the key's I<key_name> was
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| 74 | successfully returned, or 0 if there was an error.
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| 75 | An error may be returned by methods EVP_PKEY_get_utf8_string_param() and
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| 76 | EVP_PKEY_get_octet_string_param() if I<max_buf_sz> is not big enough to hold the
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| 77 | value. If I<out_len> is not NULL, I<*out_len> will be assigned the required
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| 78 | buffer size to hold the value.
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| 79 |
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| 80 | =head1 EXAMPLES
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| 81 |
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| 82 | #include <openssl/evp.h>
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| 83 |
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| 84 | char *curve_name[64];
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| 85 | unsigned char pub[256];
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| 86 | BIGNUM *bn_priv = NULL;
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| 87 |
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| 88 | /*
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| 89 | * NB: assumes 'key' is set up before the next step. In this example the key
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| 90 | * is an EC key.
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| 91 | */
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| 92 |
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| 93 | if (!EVP_PKEY_get_utf8_string_param(key, OSSL_PKEY_PARAM_GROUP_NAME,
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| 94 | curve_name, sizeof(curve_name), &len)) {
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| 95 | /* Error */
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| 96 | }
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| 97 | if (!EVP_PKEY_get_octet_string_param(key, OSSL_PKEY_PARAM_PUB_KEY,
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| 98 | pub, sizeof(pub), &len)) {
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| 99 | /* Error */
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| 100 | }
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| 101 | if (!EVP_PKEY_get_bn_param(key, OSSL_PKEY_PARAM_PRIV_KEY, &bn_priv)) {
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| 102 | /* Error */
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| 103 | }
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| 104 |
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| 105 |
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| 106 | BN_clear_free(bn_priv);
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| 107 |
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| 108 | =head1 SEE ALSO
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| 109 |
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| 110 | L<EVP_PKEY_CTX_new(3)>, L<provider-keymgmt(7)>, L<OSSL_PARAM(3)>
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| 111 |
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| 112 | =head1 HISTORY
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| 113 |
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| 114 | These functions were added in OpenSSL 3.0.
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| 115 |
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| 116 | =head1 COPYRIGHT
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| 117 |
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| 118 | Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
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| 119 |
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| 120 | Licensed under the Apache License 2.0 (the "License"). You may not use
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| 121 | this file except in compliance with the License. You can obtain a copy
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| 122 | in the file LICENSE in the source distribution or at
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| 123 | L<https://www.openssl.org/source/license.html>.
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| 124 |
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| 125 | =cut
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| 126 |
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