| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Generic authenticated encryption interface |
| 4 | * |
| 5 | * (c) 2018 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 9 | * |
| 10 | * This file is part of Catacomb. |
| 11 | * |
| 12 | * Catacomb is free software: you can redistribute it and/or modify it |
| 13 | * under the terms of the GNU Library General Public License as published |
| 14 | * by the Free Software Foundation; either version 2 of the License, or |
| 15 | * (at your option) any later version. |
| 16 | * |
| 17 | * Catacomb is distributed in the hope that it will be useful, but |
| 18 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 20 | * Library General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU Library General Public |
| 23 | * License along with Catacomb. If not, write to the Free Software |
| 24 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, |
| 25 | * USA. |
| 26 | */ |
| 27 | |
| 28 | /*----- Header files ------------------------------------------------------*/ |
| 29 | |
| 30 | #include "gaead.h" |
| 31 | |
| 32 | /*----- Main code ---------------------------------------------------------*/ |
| 33 | |
| 34 | /* --- @gaead_encrypt@ --- * |
| 35 | * |
| 36 | * Arguments: @const gaead_key *k@ = the AEAD key, already prepared |
| 37 | * @const void *n@, @size_t nsz@ = nonce |
| 38 | * @const void *h@, @size_t hsz@ = additional `header' data |
| 39 | * @const void *m@, @size_t msz@ = message input |
| 40 | * @void *c@, @size_t *csz_input@ = ciphertext output |
| 41 | * @void *t@, @size_t tsz@ = tag output |
| 42 | * |
| 43 | * Returns: Zero on success, @-1@ if the output buffer is too small. |
| 44 | * |
| 45 | * Use: Encrypts and authenticates a message in a single operation. |
| 46 | * This just saves a bunch of messing about with the various |
| 47 | * @gaead_...@ objects. |
| 48 | * |
| 49 | * On entry, @*csz_inout@ should be the capacity of the |
| 50 | * ciphertext buffer; on exit, it will be updated with the |
| 51 | * actual size of ciphertext produced. The function will not |
| 52 | * fail if @*csz_inout >= msz + k->c->ohd@. |
| 53 | */ |
| 54 | |
| 55 | int gaead_encrypt(const gaead_key *k, const void *n, size_t nsz, |
| 56 | const void *h, size_t hsz, |
| 57 | const void *m, size_t msz, |
| 58 | void *c, size_t *csz_inout, |
| 59 | void *t, size_t tsz) |
| 60 | { |
| 61 | gaead_enc *e = 0; |
| 62 | gaead_aad *a = 0; |
| 63 | buf b; |
| 64 | int rc; |
| 65 | |
| 66 | buf_init(&b, c, *csz_inout); |
| 67 | e = GAEAD_ENC(k, n, nsz, hsz, msz, tsz); if (!e) { rc = -1; goto end; } |
| 68 | if (hsz) { a = GAEAD_AAD(e); GAEAD_HASH(a, h, hsz); } |
| 69 | rc = GAEAD_ENCRYPT(e, m, msz, &b); if (rc) goto end; |
| 70 | rc = GAEAD_DONE(e, a, &b, t, tsz); |
| 71 | end: |
| 72 | if (rc >= 0) *csz_inout = BLEN(&b); |
| 73 | if (e) GAEAD_DESTROY(e); |
| 74 | if (a) GAEAD_DESTROY(a); |
| 75 | return (rc); |
| 76 | } |
| 77 | |
| 78 | /* --- @gaead_decrypt@ --- * |
| 79 | * |
| 80 | * Arguments: @const gaead_key *k@ = the AEAD key, already prepared |
| 81 | * @const void *n@, @size_t nsz@ = nonce |
| 82 | * @const void *h@, @size_t hsz@ = additional `header' data |
| 83 | * @const void *c@, @size_t csz@ = ciphertext input |
| 84 | * @void *m@, @size_t *msz_inout@ = message output |
| 85 | * @const void *t@, @size_t tsz@ = tag input |
| 86 | * |
| 87 | * Returns: @+1@ if everything is good; zero for authentication failure, |
| 88 | * @-1@ for other problems. |
| 89 | * |
| 90 | * Use: Decrypts and verifies a message in a single operation. |
| 91 | * This just saves a bunch of messing about with the various |
| 92 | * @gaead_...@ objects. |
| 93 | * |
| 94 | * On entry, @*msz_inout@ should be the capacity of the |
| 95 | * message buffer; on exit, it will be updated with the |
| 96 | * actual size of message produced. The function will not |
| 97 | * fail if @*msz_inout >= csz@. |
| 98 | */ |
| 99 | |
| 100 | int gaead_decrypt(const gaead_key *k, const void *n, size_t nsz, |
| 101 | const void *h, size_t hsz, |
| 102 | const void *c, size_t csz, |
| 103 | void *m, size_t *msz_inout, |
| 104 | const void *t, size_t tsz) |
| 105 | { |
| 106 | gaead_dec *d = 0; |
| 107 | gaead_aad *a = 0; |
| 108 | buf b; |
| 109 | int rc; |
| 110 | |
| 111 | buf_init(&b, m, *msz_inout); |
| 112 | d = GAEAD_DEC(k, n, nsz, hsz, csz, tsz); if (!d) { rc = -1; goto end; } |
| 113 | if (hsz) { a = GAEAD_AAD(d); GAEAD_HASH(a, h, hsz); } |
| 114 | rc = GAEAD_DECRYPT(d, c, csz, &b); if (rc) goto end; |
| 115 | rc = GAEAD_DONE(d, a, &b, t, tsz); |
| 116 | end: |
| 117 | if (rc >= 0) *msz_inout = BLEN(&b); |
| 118 | if (d) GAEAD_DESTROY(d); |
| 119 | if (a) GAEAD_DESTROY(a); |
| 120 | return (rc); |
| 121 | } |
| 122 | |
| 123 | /*----- That's all, folks -------------------------------------------------*/ |