439 lines
12 KiB
C
439 lines
12 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 "internal.h"
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#include "util.h"
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/*
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* Implements ChaCha20-Poly1305 according to RFC 8439, XChaCha20-Poly1305
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* according to draft-irtf-cfrg-xchacha-03.
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*/
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static int
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chacha20_xchacha20_keysetup(struct lc_cipher_ctx *cctx,
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uint8_t akey[LC_POLY1305_KEYLEN], void *initparams)
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{
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size_t i, olen, akeylen;
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for (i = 0; i < LC_POLY1305_KEYLEN; i++)
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akey[i] = 0;
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if (!lc_cipher_encrypt_init(cctx, initparams) ||
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!lc_cipher_encrypt_update(cctx, akey, &olen, akey,
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LC_POLY1305_KEYLEN))
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return 0;
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akeylen = olen;
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if (!lc_cipher_encrypt_final(cctx, akey + olen, &olen))
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return 0;
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akeylen += olen;
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return akeylen == LC_POLY1305_KEYLEN;
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}
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static int
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chacha20_poly1305_seal(uint8_t *out, size_t *outlen, void *initparams,
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const uint8_t *aad, size_t aadlen, const uint8_t *in, size_t inlen)
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{
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struct lc_chacha20_poly1305_params *params = initparams;
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struct lc_cipher_ctx *cctx = NULL;
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struct lc_auth_ctx *actx = NULL;
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struct lc_chacha20_params cparams;
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struct lc_poly1305_params aparams;
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uint8_t buf[sizeof(uint64_t) * 2];
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size_t i, olen;
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int ret = 0;
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*outlen = 0;
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/* inlen and aadlen are capped by design; enough space of tag. */
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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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return 0;
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/* Counter 0 is used for deriving Poly1305 key. */
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if (inlen > SIZE_MAX - (LC_CHACHA20_BLOCKLEN - 1) ||
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(inlen + LC_CHACHA20_BLOCKLEN - 1) / LC_CHACHA20_BLOCKLEN >
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CHACHA20_CTRMAX - 1)
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return 0;
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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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cctx = lc_cipher_ctx_new(lc_cipher_impl_chacha20());
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if (cctx == NULL)
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goto cleanup;
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actx = lc_auth_ctx_new(lc_auth_impl_poly1305());
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if (actx == NULL)
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goto cleanup;
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for (i = 0; i < sizeof(params->key); i++)
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cparams.key[i] = params->key[i];
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for (i = 0; i < sizeof(params->nonce); i++)
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cparams.nonce[i] = params->nonce[i];
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cparams.counter = 0;
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if (!chacha20_xchacha20_keysetup(cctx, aparams.key, &cparams))
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goto cleanup;
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if (!lc_auth_init(actx, &aparams) ||
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!lc_auth_update(actx, aad, aadlen))
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goto cleanup;
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if (aadlen % 16 != 0)
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if (!lc_auth_update(actx, zerobuf, 16 - (aadlen % 16)))
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goto cleanup;
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cparams.counter = 1;
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if (!lc_cipher_encrypt_init(cctx, &cparams) ||
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!lc_cipher_encrypt_update(cctx, out, &olen, in, inlen))
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goto cleanup;
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*outlen = olen;
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if (!lc_cipher_encrypt_final(cctx, out + olen, &olen))
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goto cleanup;
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*outlen += olen;
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if (*outlen != inlen)
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goto cleanup;
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if (!lc_auth_update(actx, out, inlen))
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goto cleanup;
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if (inlen % 16 != 0)
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if (!lc_auth_update(actx, zerobuf, 16 - (inlen % 16)))
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goto cleanup;
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store64le(&buf[0], aadlen);
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store64le(&buf[sizeof(uint64_t)], inlen);
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if (!lc_auth_update(actx, buf, sizeof(buf)) ||
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!lc_auth_final(actx, out + inlen, &olen))
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goto cleanup;
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*outlen += olen;
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if (*outlen != inlen + LC_POLY1305_TAGLEN)
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goto cleanup;
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ret = 1;
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cleanup:
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lc_scrub(buf, sizeof(buf));
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lc_scrub(&aparams, sizeof(aparams));
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lc_scrub(&cparams, sizeof(cparams));
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lc_auth_ctx_free(actx);
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lc_cipher_ctx_free(cctx);
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return ret;
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}
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static int
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xchacha20_poly1305_seal(uint8_t *out, size_t *outlen, void *initparams,
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const uint8_t *aad, size_t aadlen, const uint8_t *in, size_t inlen)
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{
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struct lc_xchacha20_poly1305_params *params = initparams;
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struct lc_cipher_ctx *cctx = NULL;
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struct lc_auth_ctx *actx = NULL;
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struct lc_xchacha20_params cparams;
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struct lc_poly1305_params aparams;
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uint8_t buf[sizeof(uint64_t) * 2];
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size_t i, olen;
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int ret = 0;
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*outlen = 0;
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/* inlen and aadlen are capped by design; enough space of tag. */
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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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return 0;
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/* Counter 0 is used for deriving Poly1305 key. */
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if (inlen > SIZE_MAX - (LC_CHACHA20_BLOCKLEN - 1) ||
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(inlen + LC_CHACHA20_BLOCKLEN - 1) / LC_CHACHA20_BLOCKLEN >
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CHACHA20_CTRMAX - 1)
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return 0;
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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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cctx = lc_cipher_ctx_new(lc_cipher_impl_xchacha20());
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if (cctx == NULL)
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goto cleanup;
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actx = lc_auth_ctx_new(lc_auth_impl_poly1305());
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if (actx == NULL)
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goto cleanup;
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for (i = 0; i < sizeof(params->key); i++)
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cparams.key[i] = params->key[i];
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for (i = 0; i < sizeof(params->nonce); i++)
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cparams.nonce[i] = params->nonce[i];
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cparams.counter = 0;
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if (!chacha20_xchacha20_keysetup(cctx, aparams.key, &cparams))
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goto cleanup;
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if (!lc_auth_init(actx, &aparams) ||
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!lc_auth_update(actx, aad, aadlen))
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goto cleanup;
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if (aadlen % 16 != 0)
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if (!lc_auth_update(actx, zerobuf, 16 - (aadlen % 16)))
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goto cleanup;
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cparams.counter = 1;
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if (!lc_cipher_encrypt_init(cctx, &cparams) ||
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!lc_cipher_encrypt_update(cctx, out, &olen, in, inlen))
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goto cleanup;
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*outlen = olen;
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if (!lc_cipher_encrypt_final(cctx, out + olen, &olen))
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goto cleanup;
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*outlen += olen;
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if (*outlen != inlen)
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goto cleanup;
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if (!lc_auth_update(actx, out, inlen))
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goto cleanup;
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if (inlen % 16 != 0)
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if (!lc_auth_update(actx, zerobuf, 16 - (inlen % 16)))
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goto cleanup;
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store64le(&buf[0], aadlen);
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store64le(&buf[sizeof(uint64_t)], inlen);
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if (!lc_auth_update(actx, buf, sizeof(buf)) ||
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!lc_auth_final(actx, out + inlen, &olen))
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goto cleanup;
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*outlen += olen;
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if (*outlen != inlen + LC_POLY1305_TAGLEN)
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goto cleanup;
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ret = 1;
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cleanup:
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lc_scrub(buf, sizeof(buf));
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lc_scrub(&aparams, sizeof(aparams));
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lc_scrub(&cparams, sizeof(cparams));
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lc_auth_ctx_free(actx);
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lc_cipher_ctx_free(cctx);
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return ret;
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}
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static int
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chacha20_poly1305_open(uint8_t *out, size_t *outlen, void *initparams,
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const uint8_t *aad, size_t aadlen, const uint8_t *in, size_t inlen)
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{
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struct lc_chacha20_poly1305_params *params = initparams;
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struct lc_cipher_ctx *cctx = NULL;
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struct lc_auth_ctx *actx = NULL;
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struct lc_chacha20_params cparams;
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struct lc_poly1305_params aparams;
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uint8_t tag[LC_POLY1305_TAGLEN];
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uint8_t buf[sizeof(uint64_t) * 2];
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size_t i, olen, ctlen;
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int ret = 0;
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*outlen = 0;
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/* inlen includes the tag; inlen and aadlen are capped by design. */
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if (inlen < LC_POLY1305_TAGLEN ||
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inlen > UINT64_MAX || aadlen > UINT64_MAX)
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return 0;
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/* Counter 0 is used for deriving Poly1305 key. */
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if (inlen > SIZE_MAX - (LC_CHACHA20_BLOCKLEN - 1) ||
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(inlen + LC_CHACHA20_BLOCKLEN - 1) / LC_CHACHA20_BLOCKLEN >
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CHACHA20_CTRMAX - 1) {
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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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cctx = lc_cipher_ctx_new(lc_cipher_impl_chacha20());
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if (cctx == NULL)
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goto cleanup;
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actx = lc_auth_ctx_new(lc_auth_impl_poly1305());
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if (actx == NULL)
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goto cleanup;
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for (i = 0; i < sizeof(params->key); i++)
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cparams.key[i] = params->key[i];
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for (i = 0; i < sizeof(params->nonce); i++)
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cparams.nonce[i] = params->nonce[i];
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cparams.counter = 0;
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if (!chacha20_xchacha20_keysetup(cctx, aparams.key, &cparams))
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goto cleanup;
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if (!lc_auth_init(actx, &aparams) ||
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!lc_auth_update(actx, aad, aadlen))
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goto cleanup;
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if (aadlen % 16 != 0)
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if (!lc_auth_update(actx, zerobuf, 16 - (aadlen % 16)))
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goto cleanup;
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ctlen = inlen - LC_POLY1305_TAGLEN;
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if (!lc_auth_update(actx, in, ctlen))
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goto cleanup;
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if (ctlen % 16 != 0)
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if (!lc_auth_update(actx, zerobuf, 16 - (ctlen % 16)))
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goto cleanup;
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store64le(&buf[0], aadlen);
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store64le(&buf[sizeof(uint64_t)], ctlen);
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if (!lc_auth_update(actx, buf, sizeof(buf)) ||
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!lc_auth_final(actx, tag, &olen))
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goto cleanup;
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if (olen != LC_POLY1305_TAGLEN)
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goto cleanup;
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if (!lc_ct_cmp(tag, in + ctlen, LC_POLY1305_TAGLEN))
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goto cleanup;
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cparams.counter = 1;
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if (!lc_cipher_decrypt_init(cctx, &cparams) ||
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!lc_cipher_decrypt_update(cctx, out, &olen, in, ctlen))
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goto cleanup;
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*outlen = olen;
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if (!lc_cipher_decrypt_final(cctx, out + olen, &olen))
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goto cleanup;
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*outlen += olen;
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if (*outlen != ctlen)
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goto cleanup;
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ret = 1;
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cleanup:
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lc_scrub(buf, sizeof(buf));
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lc_scrub(&aparams, sizeof(aparams));
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lc_scrub(&cparams, sizeof(cparams));
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lc_scrub(tag, sizeof(tag));
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lc_auth_ctx_free(actx);
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lc_cipher_ctx_free(cctx);
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return ret;
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}
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static int
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xchacha20_poly1305_open(uint8_t *out, size_t *outlen, void *initparams,
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const uint8_t *aad, size_t aadlen, const uint8_t *in, size_t inlen)
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{
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struct lc_xchacha20_poly1305_params *params = initparams;
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struct lc_cipher_ctx *cctx = NULL;
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struct lc_auth_ctx *actx = NULL;
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struct lc_xchacha20_params cparams;
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struct lc_poly1305_params aparams;
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uint8_t tag[LC_POLY1305_TAGLEN];
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uint8_t buf[sizeof(uint64_t) * 2];
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size_t i, olen, ctlen;
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int ret = 0;
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*outlen = 0;
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/* inlen includes the tag; inlen and aadlen are capped by design. */
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if (inlen < LC_POLY1305_TAGLEN ||
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inlen > UINT64_MAX || aadlen > UINT64_MAX)
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return 0;
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/* Counter 0 is used for deriving Poly1305 key. */
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if (inlen > SIZE_MAX - (LC_CHACHA20_BLOCKLEN - 1) ||
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(inlen + LC_CHACHA20_BLOCKLEN - 1) / LC_CHACHA20_BLOCKLEN >
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CHACHA20_CTRMAX - 1) {
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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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cctx = lc_cipher_ctx_new(lc_cipher_impl_xchacha20());
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if (cctx == NULL)
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goto cleanup;
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actx = lc_auth_ctx_new(lc_auth_impl_poly1305());
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if (actx == NULL)
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goto cleanup;
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for (i = 0; i < sizeof(params->key); i++)
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cparams.key[i] = params->key[i];
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for (i = 0; i < sizeof(params->nonce); i++)
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cparams.nonce[i] = params->nonce[i];
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cparams.counter = 0;
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if (!chacha20_xchacha20_keysetup(cctx, aparams.key, &cparams))
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goto cleanup;
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if (!lc_auth_init(actx, &aparams) ||
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!lc_auth_update(actx, aad, aadlen))
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goto cleanup;
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if (aadlen % 16 != 0)
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if (!lc_auth_update(actx, zerobuf, 16 - (aadlen % 16)))
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goto cleanup;
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ctlen = inlen - LC_POLY1305_TAGLEN;
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if (!lc_auth_update(actx, in, ctlen))
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goto cleanup;
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if (ctlen % 16 != 0)
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if (!lc_auth_update(actx, zerobuf, 16 - (ctlen % 16)))
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goto cleanup;
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store64le(&buf[0], aadlen);
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store64le(&buf[sizeof(uint64_t)], ctlen);
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if (!lc_auth_update(actx, buf, sizeof(buf)) ||
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!lc_auth_final(actx, tag, &olen))
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goto cleanup;
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if (olen != LC_POLY1305_TAGLEN)
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goto cleanup;
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if (!lc_ct_cmp(tag, in + ctlen, LC_POLY1305_TAGLEN))
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goto cleanup;
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cparams.counter = 1;
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if (!lc_cipher_decrypt_init(cctx, &cparams) ||
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!lc_cipher_decrypt_update(cctx, out, &olen, in, ctlen))
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goto cleanup;
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*outlen = olen;
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if (!lc_cipher_decrypt_final(cctx, out + olen, &olen))
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goto cleanup;
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*outlen += olen;
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if (*outlen != ctlen)
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goto cleanup;
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ret = 1;
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cleanup:
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lc_scrub(buf, sizeof(buf));
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lc_scrub(&aparams, sizeof(aparams));
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lc_scrub(&cparams, sizeof(cparams));
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lc_scrub(tag, sizeof(tag));
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lc_auth_ctx_free(actx);
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lc_cipher_ctx_free(cctx);
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return ret;
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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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static struct lc_aead_impl chacha20_poly1305_impl = {
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.seal = &chacha20_poly1305_seal,
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.open = &chacha20_poly1305_open,
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.blocklen = LC_CHACHA20_BLOCKLEN,
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};
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return &chacha20_poly1305_impl;
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}
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const struct lc_aead_impl *
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lc_aead_impl_xchacha20_poly1305(void)
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{
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static struct lc_aead_impl xchacha20_poly1305_impl = {
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.seal = &xchacha20_poly1305_seal,
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.open = &xchacha20_poly1305_open,
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.blocklen = LC_XCHACHA20_BLOCKLEN,
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};
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return &xchacha20_poly1305_impl;
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}
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