Branch data     Line data    Source code

       1                 :            : /*
       2                 :            :  * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
       3                 :            :  *
       4                 :            :  * Licensed under the Apache License, Version 2.0 (the "License").
       5                 :            :  * You may not use this file except in compliance with the License.
       6                 :            :  * A copy of the License is located at
       7                 :            :  *
       8                 :            :  *  http://aws.amazon.com/apache2.0
       9                 :            :  *
      10                 :            :  * or in the "license" file accompanying this file. This file is distributed
      11                 :            :  * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
      12                 :            :  * express or implied. See the License for the specific language governing
      13                 :            :  * permissions and limitations under the License.
      14                 :            :  */
      15                 :            : 
      16                 :            : #include "tls/s2n_kem_preferences.h"
      17                 :            : 
      18                 :            : #include "tls/s2n_kem.h"
      19                 :            : 
      20                 :            : /* Includes only IETF standard KEM Groups. */
      21                 :            : const struct s2n_kem_group *pq_kem_groups_ietf_2024_10[] = {
      22                 :            :     &s2n_x25519_mlkem_768,
      23                 :            :     &s2n_secp256r1_mlkem_768,
      24                 :            : };
      25                 :            : 
      26                 :            : const struct s2n_kem_group *pq_kem_groups_ietf_2025_07[] = {
      27                 :            :     &s2n_x25519_mlkem_768,
      28                 :            :     &s2n_secp256r1_mlkem_768,
      29                 :            :     &s2n_secp384r1_mlkem_1024,
      30                 :            : };
      31                 :            : 
      32                 :            : const struct s2n_kem_group *pq_kem_groups_cnsa2_2026_02[] = {
      33                 :            :     &s2n_pure_mlkem_1024,
      34                 :            : };
      35                 :            : 
      36                 :            : const struct s2n_kem_preferences kem_preferences_pq_tls_1_3_ietf_2024_10 = {
      37                 :            :     .kem_count = 0,
      38                 :            :     .kems = NULL,
      39                 :            :     .tls13_kem_group_count = s2n_array_len(pq_kem_groups_ietf_2024_10),
      40                 :            :     .tls13_kem_groups = pq_kem_groups_ietf_2024_10,
      41                 :            :     .tls13_pq_hybrid_draft_revision = 5
      42                 :            : };
      43                 :            : 
      44                 :            : const struct s2n_kem_preferences kem_preferences_pq_tls_1_3_ietf_2025_07 = {
      45                 :            :     .kem_count = 0,
      46                 :            :     .kems = NULL,
      47                 :            :     .tls13_kem_group_count = s2n_array_len(pq_kem_groups_ietf_2025_07),
      48                 :            :     .tls13_kem_groups = pq_kem_groups_ietf_2025_07,
      49                 :            :     .tls13_pq_hybrid_draft_revision = 5
      50                 :            : };
      51                 :            : 
      52                 :            : const struct s2n_kem_preferences kem_preferences_pq_tls_1_3_cnsa2_2026_02 = {
      53                 :            :     .kem_count = 0,
      54                 :            :     .kems = NULL,
      55                 :            :     .tls13_kem_group_count = s2n_array_len(pq_kem_groups_cnsa2_2026_02),
      56                 :            :     .tls13_kem_groups = pq_kem_groups_cnsa2_2026_02,
      57                 :            :     .tls13_pq_hybrid_draft_revision = 5
      58                 :            : };
      59                 :            : 
      60                 :            : const struct s2n_kem_preferences kem_preferences_all = {
      61                 :            :     .kem_count = 0,
      62                 :            :     .kems = NULL,
      63                 :            :     .tls13_kem_group_count = S2N_KEM_GROUPS_COUNT,
      64                 :            :     .tls13_kem_groups = ALL_SUPPORTED_KEM_GROUPS,
      65                 :            :     .tls13_pq_hybrid_draft_revision = 5
      66                 :            : };
      67                 :            : 
      68                 :            : const struct s2n_kem_preferences kem_preferences_null = {
      69                 :            :     .kem_count = 0,
      70                 :            :     .kems = NULL,
      71                 :            :     .tls13_kem_group_count = 0,
      72                 :            :     .tls13_kem_groups = NULL,
      73                 :            :     .tls13_pq_hybrid_draft_revision = 0
      74                 :            : };
      75                 :            : 
      76                 :            : /* Determines if query_iana_id corresponds to a tls13_kem_group for these KEM preferences. */
      77                 :            : bool s2n_kem_preferences_includes_tls13_kem_group(const struct s2n_kem_preferences *kem_preferences,
      78                 :            :         uint16_t query_iana_id)
      79                 :         11 : {
      80         [ -  + ]:         11 :     if (kem_preferences == NULL) {
      81                 :          0 :         return false;
      82                 :          0 :     }
      83                 :            : 
      84         [ +  + ]:         20 :     for (size_t i = 0; i < kem_preferences->tls13_kem_group_count; i++) {
      85         [ +  + ]:         14 :         if (query_iana_id == kem_preferences->tls13_kem_groups[i]->iana_id) {
      86                 :          5 :             return true;
      87                 :          5 :         }
      88                 :         14 :     }
      89                 :            : 
      90                 :          6 :     return false;
      91                 :         11 : }
      92                 :            : 
      93                 :            : /* Whether the client must include the length prefix in the PQ TLS 1.3 KEM KeyShares that it sends. Draft 0 of
      94                 :            :  * the PQ TLS 1.3 standard required length prefixing, and drafts 1-5 removed this length prefix. To not break
      95                 :            :  * backwards compatibility, we check what revision of the draft standard is configured to determine whether to send it. */
      96                 :            : bool s2n_tls13_client_must_use_hybrid_kem_length_prefix(const struct s2n_kem_preferences *kem_pref)
      97                 :         41 : {
      98 [ +  - ][ -  + ]:         41 :     return kem_pref && (kem_pref->tls13_pq_hybrid_draft_revision == 0);
      99                 :         41 : }
     100                 :            : 
     101                 :            : S2N_RESULT s2n_kem_preferences_groups_available(const struct s2n_kem_preferences *kem_preferences, uint32_t *groups_available)
     102                 :       6622 : {
     103 [ #  # ][ -  + ]:       6622 :     RESULT_ENSURE_REF(kem_preferences);
     104 [ -  + ][ #  # ]:       6622 :     RESULT_ENSURE_REF(groups_available);
     105                 :            : 
     106                 :       6622 :     uint32_t count = 0;
     107         [ +  + ]:      18349 :     for (int i = 0; i < kem_preferences->tls13_kem_group_count; i++) {
     108         [ -  + ]:      11727 :         if (s2n_kem_group_is_available(kem_preferences->tls13_kem_groups[i])) {
     109                 :          0 :             count++;
     110                 :          0 :         }
     111                 :      11727 :     }
     112                 :       6622 :     *groups_available = count;
     113                 :       6622 :     return S2N_RESULT_OK;
     114                 :       6622 : }
     115                 :            : 
     116                 :            : const struct s2n_kem_group *s2n_kem_preferences_get_highest_priority_group(const struct s2n_kem_preferences *kem_preferences)
     117                 :          1 : {
     118 [ -  + ][ #  # ]:          1 :     PTR_ENSURE_REF(kem_preferences);
     119         [ +  + ]:          5 :     for (size_t i = 0; i < kem_preferences->tls13_kem_group_count; i++) {
     120         [ -  + ]:          4 :         if (s2n_kem_group_is_available(kem_preferences->tls13_kem_groups[i])) {
     121                 :          0 :             return kem_preferences->tls13_kem_groups[i];
     122                 :          0 :         }
     123                 :          4 :     }
     124                 :          1 :     return NULL;
     125                 :          1 : }