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crypto: Support Chacha20-Poly1305 with a nonce size of 8 bytes.

Browse Source 
This is useful for WireGuard which uses a nonce of 8 bytes rather
than the 12 bytes used for IPsec and TLS.

Note that this also fixes a (should be) harmless bug in ossl(4) where
the counter was incorrectly treated as a 64-bit counter instead of a
32-bit counter in terms of wrapping when using a 12 byte nonce.
However, this required a single message (TLS record) longer than 64 *
(2^32 - 1) bytes (about 256 GB) to trigger.

Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D32122
This commit is contained in:
John Baldwin 2021-10-06 14:08:49 -07:00
parent 668770dc7d
commit 42dcd39528
6 changed files with 42 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
share/man/man7/crypto.7
View File

@ -167,7 +167,7 @@ The following AEAD algorithms are supported:
AES Galois/Counter Mode
.It Dv CRYPTO_AES_CCM_16 Ta 12, 7-13 Ta 16, 24, 32 Ta 16 Ta
AES Counter with CBC-MAC
.It Dv CRYPTO_CHACHA20_POLY1305 Ta 12 Ta 32 Ta 16 Ta
.It Dv CRYPTO_CHACHA20_POLY1305 Ta 12, 8 Ta 32 Ta 16 Ta
ChaCha20-Poly1305
.El
.Sh SEE ALSO

14
sys/crypto/openssl/ossl_chacha20.c
View File

@ -161,7 +161,8 @@ ossl_chacha20_poly1305_encrypt(struct cryptop *crp,
for (i = 0; i < nitems(key); i++)
key[i] = CHACHA_U8TOU32(cipher_key + i * 4);
crypto_read_iv(crp, counter + 1);
memset(counter, 0, sizeof(counter));
crypto_read_iv(crp, counter + (CHACHA_CTR_SIZE - csp->csp_ivlen) / 4);
for (i = 1; i < nitems(counter); i++)
counter[i] = le32toh(counter[i]);
@ -223,7 +224,7 @@ ossl_chacha20_poly1305_encrypt(struct cryptop *crp,
/* Truncate if the 32-bit counter would roll over. */
next_counter = counter[0] + todo / CHACHA_BLK_SIZE;
if (next_counter < counter[0]) {
if (csp->csp_ivlen == 8 && next_counter < counter[0]) {
todo -= next_counter * CHACHA_BLK_SIZE;
next_counter = 0;
}
@ -232,7 +233,7 @@ ossl_chacha20_poly1305_encrypt(struct cryptop *crp,
Poly1305_Update(&auth_ctx, out, todo);
counter[0] = next_counter;
if (counter[0] == 0)
if (csp->csp_ivlen == 8 && counter[0] == 0)
counter[1]++;
if (out == block) {
@ -307,7 +308,8 @@ ossl_chacha20_poly1305_decrypt(struct cryptop *crp,
for (i = 0; i < nitems(key); i++)
key[i] = CHACHA_U8TOU32(cipher_key + i * 4);
crypto_read_iv(crp, counter + 1);
memset(counter, 0, sizeof(counter));
crypto_read_iv(crp, counter + (CHACHA_CTR_SIZE - csp->csp_ivlen) / 4);
for (i = 1; i < nitems(counter); i++)
counter[i] = le32toh(counter[i]);
@ -391,7 +393,7 @@ ossl_chacha20_poly1305_decrypt(struct cryptop *crp,
/* Truncate if the 32-bit counter would roll over. */
next_counter = counter[0] + todo / CHACHA_BLK_SIZE;
if (next_counter < counter[0]) {
if (csp->csp_ivlen == 8 && next_counter < counter[0]) {
todo -= next_counter * CHACHA_BLK_SIZE;
next_counter = 0;
}
@ -399,7 +401,7 @@ ossl_chacha20_poly1305_decrypt(struct cryptop *crp,
ChaCha20_ctr32(out, in, todo, key, counter);
counter[0] = next_counter;
if (counter[0] == 0)
if (csp->csp_ivlen == 8 && counter[0] == 0)
counter[1]++;
if (out == block) {

7
sys/opencrypto/crypto.c
View File

@ -852,10 +852,15 @@ check_csp(const struct crypto_session_params *csp)
return (false);
break;
case CRYPTO_AES_NIST_GCM_16:
case CRYPTO_CHACHA20_POLY1305:
if (csp->csp_auth_mlen > 16)
return (false);
break;
case CRYPTO_CHACHA20_POLY1305:
if (csp->csp_ivlen != 8 && csp->csp_ivlen != 12)
return (false);
if (csp->csp_auth_mlen > POLY1305_HASH_LEN)
return (false);
break;
}
break;
case CSP_MODE_ETA:

3
sys/opencrypto/cryptosoft.c
View File

@ -1393,9 +1393,6 @@ swcr_setup_chacha20_poly1305(struct swcr_session *ses,
struct swcr_auth *swa;
const struct auth_hash *axf;
if (csp->csp_ivlen != CHACHA20_POLY1305_IV_LEN)
return (EINVAL);
/* First, setup the auth side. */
swa = &ses->swcr_auth;
axf = &auth_hash_chacha20_poly1305;

31
sys/opencrypto/xform_chacha20_poly1305.c
View File

@ -34,6 +34,7 @@
struct chacha20_poly1305_cipher_ctx {
const void *key;
uint32_t ic;
bool ietf;
char nonce[CHACHA20_POLY1305_IV_LEN];
};
@ -58,7 +59,8 @@ chacha20_poly1305_reinit(void *vctx, const uint8_t *iv, size_t ivlen)
("%s: invalid nonce length", __func__));
/* Block 0 is used for the poly1305 key. */
memcpy(ctx->nonce, iv, sizeof(ctx->nonce));
memcpy(ctx->nonce, iv, ivlen);
ctx->ietf = (ivlen == CHACHA20_POLY1305_IV_LEN);
ctx->ic = 1;
}
@ -68,8 +70,12 @@ chacha20_poly1305_crypt(void *vctx, const uint8_t *in, uint8_t *out)
struct chacha20_poly1305_cipher_ctx *ctx = vctx;
int error;
error = crypto_stream_chacha20_ietf_xor_ic(out, in,
CHACHA20_NATIVE_BLOCK_LEN, ctx->nonce, ctx->ic, ctx->key);
if (ctx->ietf)
error = crypto_stream_chacha20_ietf_xor_ic(out, in,
CHACHA20_NATIVE_BLOCK_LEN, ctx->nonce, ctx->ic, ctx->key);
else
error = crypto_stream_chacha20_xor_ic(out, in,
CHACHA20_NATIVE_BLOCK_LEN, ctx->nonce, ctx->ic, ctx->key);
KASSERT(error == 0, ("%s failed: %d", __func__, error));
ctx->ic++;
}
@ -82,8 +88,12 @@ chacha20_poly1305_crypt_last(void *vctx, const uint8_t *in, uint8_t *out,
int error;
error = crypto_stream_chacha20_ietf_xor_ic(out, in, len, ctx->nonce,
ctx->ic, ctx->key);
if (ctx->ietf)
error = crypto_stream_chacha20_ietf_xor_ic(out, in, len,
ctx->nonce, ctx->ic, ctx->key);
else
error = crypto_stream_chacha20_xor_ic(out, in, len, ctx->nonce,
ctx->ic, ctx->key);
KASSERT(error == 0, ("%s failed: %d", __func__, error));
}
@ -129,7 +139,16 @@ chacha20_poly1305_Reinit(void *vctx, const uint8_t *nonce, u_int noncelen)
struct chacha20_poly1305_auth_ctx *ctx = vctx;
char block[CHACHA20_NATIVE_BLOCK_LEN];
crypto_stream_chacha20_ietf(block, sizeof(block), nonce, ctx->key);
switch (noncelen) {
case 8:
crypto_stream_chacha20(block, sizeof(block), nonce, ctx->key);
break;
case CHACHA20_POLY1305_IV_LEN:
crypto_stream_chacha20_ietf(block, sizeof(block), nonce, ctx->key);
break;
default:
__assert_unreachable();
}
crypto_onetimeauth_poly1305_init(&ctx->state, block);
explicit_bzero(block, sizeof(block));
}

4
tools/tools/crypto/cryptocheck.c
View File

@ -126,7 +126,7 @@
* aes-ccm 128-bit AES-CCM
* aes-ccm192 192-bit AES-CCM
* aes-ccm256 256-bit AES-CCM
* chacha20-poly1305 Chacha20 (96 bit nonce) with Poly1305 per RFC 8439
* chacha20-poly1305 Chacha20 with Poly1305 per RFC 8439
*/
#include <sys/param.h>
@ -233,7 +233,7 @@ static const struct alg {
.evp_cipher = EVP_aes_256_ccm },
{ .name = "chacha20-poly1305", .cipher = CRYPTO_CHACHA20_POLY1305,
.type = T_AEAD, .tag_len = POLY1305_HASH_LEN,
.iv_sizes = { CHACHA20_POLY1305_IV_LEN },
.iv_sizes = { CHACHA20_POLY1305_IV_LEN, 8 },
.evp_cipher = EVP_chacha20_poly1305 },
};