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 can be set with EVP_MAC_CTX_set_params(). 31Furthermore, the "size" parameter can be retrieved with 32EVP_MAC_CTX_get_params(), or with EVP_MAC_CTX_get_mac_size(). 33The length of the "size" parameter should not exceed that of a B<size_t>. 34Likewise, the "block-size" parameter can be retrieved with 35EVP_MAC_CTX_get_params(), or with EVP_MAC_CTX_get_block_size(). 36 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 custom value. 49It is an optional value with a length of at most 512 bytes, and is empty by default. 50 51=item "size" (B<OSSL_MAC_PARAM_SIZE>) <unsigned integer> 52 53Sets the MAC size. 54By default, it is 16 for C<KMAC-128> and 32 for C<KMAC-256>. 55 56=item "block-size" (B<OSSL_MAC_PARAM_SIZE>) <unsigned integer> 57 58Gets the MAC block size. 59By default, it is 168 for C<KMAC-128> and 136 for C<KMAC-256>. 60 61=item "xof" (B<OSSL_MAC_PARAM_XOF>) <integer> 62 63The "xof" parameter value is expected to be 1 or 0. Use 1 to enable XOF mode. 64The default value is 0. 65 66=back 67 68The "custom" parameter must be set as part of or before the EVP_MAC_init() call. 69The "xof" and "size" parameters can be set at any time before EVP_MAC_final(). 70The "key" parameter is set as part of the EVP_MAC_init() call, but can be 71set before it instead. 72 73=head1 EXAMPLES 74 75 #include <openssl/evp.h> 76 #include <openssl/params.h> 77 78 static int do_kmac(const unsigned char *in, size_t in_len, 79 const unsigned char *key, size_t key_len, 80 const unsigned char *custom, size_t custom_len, 81 int xof_enabled, unsigned char *out, int out_len) 82 { 83 EVP_MAC_CTX *ctx = NULL; 84 EVP_MAC *mac = NULL; 85 OSSL_PARAM params[4], *p; 86 int ret = 0; 87 size_t l = 0; 88 89 mac = EVP_MAC_fetch(NULL, "KMAC-128", NULL); 90 if (mac == NULL) 91 goto err; 92 ctx = EVP_MAC_CTX_new(mac); 93 /* The mac can be freed after it is used by EVP_MAC_CTX_new */ 94 EVP_MAC_free(mac); 95 if (ctx == NULL) 96 goto err; 97 98 /* 99 * Setup parameters required before calling EVP_MAC_init() 100 * The parameters OSSL_MAC_PARAM_XOF and OSSL_MAC_PARAM_SIZE may also be 101 * used at this point. 102 */ 103 p = params; 104 *p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY, 105 (void *)key, key_len); 106 if (custom != NULL && custom_len != 0) 107 *p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM, 108 (void *)custom, custom_len); 109 *p = OSSL_PARAM_construct_end(); 110 if (!EVP_MAC_CTX_set_params(ctx, params)) 111 goto err; 112 113 if (!EVP_MAC_init(ctx)) 114 goto err; 115 116 /* 117 * Note: the following optional parameters can be set any time 118 * before EVP_MAC_final(). 119 */ 120 p = params; 121 *p++ = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_XOF, &xof_enabled); 122 *p++ = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_SIZE, &out_len); 123 *p = OSSL_PARAM_construct_end(); 124 if (!EVP_MAC_CTX_set_params(ctx, params)) 125 goto err; 126 127 /* The update may be called multiple times here for streamed input */ 128 if (!EVP_MAC_update(ctx, in, in_len)) 129 goto err; 130 if (!EVP_MAC_final(ctx, out, &l, out_len)) 131 goto err; 132 ret = 1; 133 err: 134 EVP_MAC_CTX_free(ctx); 135 return ret; 136 } 137 138=head1 SEE ALSO 139 140L<EVP_MAC_CTX_get_params(3)>, L<EVP_MAC_CTX_set_params(3)>, 141L<EVP_MAC(3)/PARAMETERS>, L<OSSL_PARAM(3)> 142 143=head1 COPYRIGHT 144 145Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved. 146 147Licensed under the Apache License 2.0 (the "License"). You may not use 148this file except in compliance with the License. You can obtain a copy 149in the file LICENSE in the source distribution or at 150L<https://www.openssl.org/source/license.html>. 151 152=cut 153