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aead: implement ChaCha20-Poly1305 open

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This commit is contained in:
Lucas Gabriel Vuotto 2024-05-31 16:46:05 +00:00
parent 8f8924bfdf
commit 217145edc0
1 changed files with 80 additions and 1 deletions
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81
aead_chacha20_poly1305.c
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@ -101,10 +101,89 @@ chacha20_poly1305_seal(const uint8_t *key, size_t keylen, const uint8_t *iv,
return 1;
}
static int
chacha20_poly1305_open(const uint8_t *key, size_t keylen, const uint8_t *iv,
size_t ivlen, uint8_t *out, size_t *outlen, const uint8_t *aad,
size_t aadlen, const uint8_t *in, size_t inlen)
{
const uint8_t *tagp;
struct chacha20_ctx cctx;
struct poly1305_ctx pctx;
uint8_t poly1305_key[LC_POLY1305_KEYLEN];
uint8_t tag[LC_POLY1305_TAGLEN];
uint8_t buf[sizeof(uint64_t) * 2];
size_t i, olen, ctlen;
if (inlen < LC_POLY1305_TAGLEN ||
inlen > UINT64_MAX || aadlen > UINT64_MAX ||
inlen > SIZE_MAX - LC_POLY1305_TAGLEN ||
inlen > SIZE_MAX - CHACHA20_CHUNK + 1 ||
(inlen + CHACHA20_CHUNK - 1) / CHACHA20_CHUNK >
CHACHA20_CTRMAX - 1) {
if (out == NULL)
*outlen = 0;
return 0;
}
if (out == NULL) {
*outlen = inlen - LC_POLY1305_TAGLEN;
return 1;
}
*outlen = 0;
ctlen = inlen - LC_POLY1305_TAGLEN;
tagp = in + ctlen;
for (i = 0; i < LC_POLY1305_KEYLEN; i++)
poly1305_key[i] = 0;
if (!chacha20_x_init(&cctx, key, keylen, iv, ivlen) ||
!chacha20_x_update(&cctx, poly1305_key, &olen, poly1305_key,
LC_POLY1305_KEYLEN))
return 0;
for (i = 0; i < LC_POLY1305_KEYLEN / sizeof(uint32_t); i++)
store32le(&poly1305_key[i * 4], cctx.s[i]);
if (!poly1305_init(&pctx, poly1305_key, LC_POLY1305_KEYLEN) ||
!poly1305_update(&pctx, aad, aadlen))
return 0;
if (aadlen % 16 != 0)
if (!poly1305_update(&pctx, zeropad, 16 - (aadlen % 16)))
return 0;
if (!poly1305_update(&pctx, in, ctlen))
return 0;
if (ctlen % 16 != 0)
if (!poly1305_update(&pctx, zeropad, 16 - (ctlen % 16)))
return 0;
store64le(&buf[0], aadlen);
store64le(&buf[sizeof(uint64_t)], ctlen);
if (!poly1305_update(&pctx, buf, sizeof(buf)) ||
!poly1305_final(&pctx, tag, &olen))
return 0;
if (lc_ct_cmp(tag, tagp, LC_POLY1305_TAGLEN) != 0)
return 0;
lc_scrub(buf, sizeof(buf));
lc_scrub(poly1305_key, sizeof(poly1305_key));
if (!chacha20_x_init_from(&cctx, key, keylen, iv, ivlen, 1))
return 0;
if (!chacha20_x_update(&cctx, out, &olen, in, ctlen))
return 0;
*outlen = olen;
if (!chacha20_x_final(&cctx, out + olen, &olen))
return 0;
*outlen += olen;
return 1;
}
static struct lc_aead_impl chacha20_poly1305_impl = {
.seal = &chacha20_poly1305_seal,
.open = NULL, //&chacha20_poly1305_open,
.open = &chacha20_poly1305_open,
};
const struct lc_aead_impl *