115 lines
3.2 KiB
C
115 lines
3.2 KiB
C
/*
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* Copyright (c) 2024 Lucas Gabriel Vuotto <lucas@lgv5.net>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "lilcrypto.h"
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#include "aead.h"
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#include "auth_poly1305.h"
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#include "cipher_chacha20.h"
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#include "impl_chacha20.h"
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#include "impl_poly1305.h"
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#include "util.h"
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/*
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* Implements ChaCha20-Poly1305 according to RFC 8439.
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*/
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static uint8_t zeropad[16];
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static int
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chacha20_poly1305_seal(const uint8_t *key, size_t keylen, const uint8_t *iv,
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size_t ivlen, uint8_t *out, size_t *outlen, const uint8_t *aad,
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size_t aadlen, const uint8_t *in, size_t inlen)
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{
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struct chacha20_ctx cctx;
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struct poly1305_ctx pctx;
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uint8_t poly1305_key[LC_POLY1305_KEYLEN];
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uint8_t buf[sizeof(uint64_t) * 2];
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size_t i, olen;
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if (inlen > UINT64_MAX || aadlen > UINT64_MAX ||
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inlen > SIZE_MAX - LC_POLY1305_TAGLEN ||
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inlen > SIZE_MAX - CHACHA20_CHUNK + 1 ||
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(inlen + CHACHA20_CHUNK - 1) / CHACHA20_CHUNK >
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CHACHA20_CTRMAX - 1) {
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if (out == NULL)
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*outlen = 0;
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return 0;
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}
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if (out == NULL) {
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*outlen = inlen + LC_POLY1305_TAGLEN;
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return 1;
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}
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*outlen = 0;
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for (i = 0; i < LC_POLY1305_KEYLEN; i++)
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poly1305_key[i] = 0;
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if (!chacha20_x_init(&cctx, key, keylen, iv, ivlen) ||
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!chacha20_x_update(&cctx, poly1305_key, &olen, poly1305_key,
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LC_POLY1305_KEYLEN))
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return 0;
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for (i = 0; i < LC_POLY1305_KEYLEN / sizeof(uint32_t); i++)
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store32le(&poly1305_key[i * 4], cctx.s[i]);
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if (!poly1305_init(&pctx, poly1305_key, LC_POLY1305_KEYLEN) ||
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!poly1305_update(&pctx, aad, aadlen))
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return 0;
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if (aadlen % 16 != 0)
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if (!poly1305_update(&pctx, zeropad, 16 - (aadlen % 16)))
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return 0;
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if (!chacha20_x_init_from(&cctx, key, keylen, iv, ivlen, 1))
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return 0;
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if (!chacha20_x_update(&cctx, out, &olen, in, inlen))
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return 0;
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*outlen = olen;
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if (!chacha20_x_final(&cctx, out + olen, &olen))
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return 0;
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if (!poly1305_update(&pctx, out, inlen))
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return 0;
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if (inlen % 16 != 0)
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if (!poly1305_update(&pctx, zeropad, 16 - (inlen % 16)))
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return 0;
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store64le(&buf[0], aadlen);
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store64le(&buf[sizeof(uint64_t)], inlen);
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if (!poly1305_update(&pctx, buf, sizeof(buf)) ||
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!poly1305_final(&pctx, out + inlen, &olen))
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return 0;
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lc_scrub(buf, sizeof(buf));
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lc_scrub(poly1305_key, sizeof(poly1305_key));
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*outlen = inlen + LC_POLY1305_TAGLEN;
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return 1;
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}
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static struct lc_aead_impl chacha20_poly1305_impl = {
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.seal = &chacha20_poly1305_seal,
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.open = NULL, //&chacha20_poly1305_open,
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};
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const struct lc_aead_impl *
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lc_aead_impl_chacha20_poly1305(void)
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{
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return &chacha20_poly1305_impl;
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}
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