1=pod 2 3=head1 NAME 4 5EVP_MAC-KMAC, EVP_MAC-KMAC128, EVP_MAC-KMAC256 6- The KMAC EVP_MAC implementations 7 8=head1 DESCRIPTION 9 10Support for computing KMAC MACs through the B<EVP_MAC> API. 11 12=head2 Identity 13 14These implementations are identified with one of these names and 15properties, to be used with EVP_MAC_fetch(): 16 17=over 4 18 19=item "KMAC-128", "provider=default" or "provider=fips" 20 21=item "KMAC-256", "provider=default" or "provider=fips" 22 23=back 24 25=head2 Supported parameters 26 27The general description of these parameters can be found in 28L<EVP_MAC(3)/PARAMETERS>. 29 30All these parameters (except for "block-size") can be set with 31EVP_MAC_CTX_set_params(). 32Furthermore, the "size" parameter can be retrieved with 33EVP_MAC_CTX_get_params(), or with EVP_MAC_CTX_get_mac_size(). 34The length of the "size" parameter should not exceed that of a B<size_t>. 35Likewise, the "block-size" parameter can be retrieved with 36EVP_MAC_CTX_get_params(), or with EVP_MAC_CTX_get_block_size(). 37 38=over 4 39 40=item "key" (B<OSSL_MAC_PARAM_KEY>) <octet string> 41 42Sets the MAC key. 43Setting this parameter is identical to passing a I<key> to L<EVP_MAC_init(3)>. 44The length of the key (in bytes) must be in the range 4...512. 45 46=item "custom" (B<OSSL_MAC_PARAM_CUSTOM>) <octet string> 47 48Sets the customization string. 49It is an optional value with a length of at most 512 bytes, and is 50empty by default. 51 52=item "size" (B<OSSL_MAC_PARAM_SIZE>) <unsigned integer> 53 54Sets the MAC size. 55By default, it is 32 for C<KMAC-128> and 64 for C<KMAC-256>. 56 57=item "block-size" (B<OSSL_MAC_PARAM_BLOCK_SIZE>) <unsigned integer> 58 59Gets the MAC block size. 60It is 168 for C<KMAC-128> and 136 for C<KMAC-256>. 61 62=item "xof" (B<OSSL_MAC_PARAM_XOF>) <integer> 63 64The "xof" parameter value is expected to be 1 or 0. Use 1 to enable XOF mode. 65The default value is 0. 66 67=item "fips-indicator" (B<OSSL_MAC_PARAM_FIPS_APPROVED_INDICATOR>) <int> 68 69This settable parameter is described in L<provider-mac(7)>. 70 71=item "no-short-mac" (B<OSSL_MAC_PARAM_FIPS_NO_SHORT_MAC>) <integer> 72 73This settable parameter is described in L<provider-mac(7)>. It is used by 74the OpenSSL FIPS provider and the minimum length output for KMAC 75is defined by NIST's SP 800-185 8.4.2. 76 77=item "key-check" (B<OSSL_MAC_PARAM_FIPS_KEY_CHECK>) <integer> 78 79This settable parameter is described in L<provider-mac(7)>. 80 81=back 82 83The "custom" and "no-short-mac" parameters must be set as part of or before 84the EVP_MAC_init() call. 85The "xof" and "size" parameters can be set at any time before EVP_MAC_final(). 86The "key" parameter is set as part of the EVP_MAC_init() call, but can be 87set before it instead. 88 89=head1 EXAMPLES 90 91 #include <openssl/evp.h> 92 #include <openssl/params.h> 93 94 static int do_kmac(const unsigned char *in, size_t in_len, 95 const unsigned char *key, size_t key_len, 96 const unsigned char *custom, size_t custom_len, 97 int xof_enabled, unsigned char *out, int out_len) 98 { 99 EVP_MAC_CTX *ctx = NULL; 100 EVP_MAC *mac = NULL; 101 OSSL_PARAM params[4], *p; 102 int ret = 0; 103 size_t l = 0; 104 105 mac = EVP_MAC_fetch(NULL, "KMAC-128", NULL); 106 if (mac == NULL) 107 goto err; 108 ctx = EVP_MAC_CTX_new(mac); 109 /* The mac can be freed after it is used by EVP_MAC_CTX_new */ 110 EVP_MAC_free(mac); 111 if (ctx == NULL) 112 goto err; 113 114 /* 115 * Setup parameters required before calling EVP_MAC_init() 116 * The parameters OSSL_MAC_PARAM_XOF and OSSL_MAC_PARAM_SIZE may also be 117 * used at this point. 118 */ 119 p = params; 120 *p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY, 121 (void *)key, key_len); 122 if (custom != NULL && custom_len != 0) 123 *p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM, 124 (void *)custom, custom_len); 125 *p = OSSL_PARAM_construct_end(); 126 if (!EVP_MAC_CTX_set_params(ctx, params)) 127 goto err; 128 129 if (!EVP_MAC_init(ctx)) 130 goto err; 131 132 /* 133 * Note: the following optional parameters can be set any time 134 * before EVP_MAC_final(). 135 */ 136 p = params; 137 *p++ = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_XOF, &xof_enabled); 138 *p++ = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_SIZE, &out_len); 139 *p = OSSL_PARAM_construct_end(); 140 if (!EVP_MAC_CTX_set_params(ctx, params)) 141 goto err; 142 143 /* The update may be called multiple times here for streamed input */ 144 if (!EVP_MAC_update(ctx, in, in_len)) 145 goto err; 146 if (!EVP_MAC_final(ctx, out, &l, out_len)) 147 goto err; 148 ret = 1; 149 err: 150 EVP_MAC_CTX_free(ctx); 151 return ret; 152 } 153 154=head1 SEE ALSO 155 156L<EVP_MAC_CTX_get_params(3)>, L<EVP_MAC_CTX_set_params(3)>, 157L<EVP_MAC(3)/PARAMETERS>, L<OSSL_PARAM(3)>, 158L<SP 800-185 8.4.2|https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-185.pdf> 159 160=head1 COPYRIGHT 161 162Copyright 2018-2024 The OpenSSL Project Authors. All Rights Reserved. 163 164Licensed under the Apache License 2.0 (the "License"). You may not use 165this file except in compliance with the License. You can obtain a copy 166in the file LICENSE in the source distribution or at 167L<https://www.openssl.org/source/license.html>. 168 169=cut 170
