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-rw-r--r--siv_nettle_int.c452
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diff --git a/siv_nettle_int.c b/siv_nettle_int.c
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+/* This is a single-file implementation of AES-SIV-CMAC-256 based on
+ a patch for GNU Nettle by Nikos Mavrogiannopoulos */
+
+/*
+ AES-CMAC-128 (rfc 4493)
+ Copyright (C) Stefan Metzmacher 2012
+ Copyright (C) Jeremy Allison 2012
+ Copyright (C) Michael Adam 2012
+ Copyright (C) 2017, Red Hat Inc.
+
+ This file is part of GNU Nettle.
+
+ GNU Nettle is free software: you can redistribute it and/or
+ modify it under the terms of either:
+
+ * the GNU Lesser General Public License as published by the Free
+ Software Foundation; either version 3 of the License, or (at your
+ option) any later version.
+
+ or
+
+ * the GNU General Public License as published by the Free
+ Software Foundation; either version 2 of the License, or (at your
+ option) any later version.
+
+ or both in parallel, as here.
+
+ GNU Nettle is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received copies of the GNU General Public License and
+ the GNU Lesser General Public License along with this program. If
+ not, see http://www.gnu.org/licenses/.
+*/
+/* siv-aes128.c, siv-cmac.c, siv.h
+
+ AES-SIV, RFC5297
+ SIV-CMAC, RFC5297
+
+ Copyright (C) 2017 Nikos Mavrogiannopoulos
+
+ This file is part of GNU Nettle.
+
+ GNU Nettle is free software: you can redistribute it and/or
+ modify it under the terms of either:
+
+ * the GNU Lesser General Public License as published by the Free
+ Software Foundation; either version 3 of the License, or (at your
+ option) any later version.
+
+ or
+
+ * the GNU General Public License as published by the Free
+ Software Foundation; either version 2 of the License, or (at your
+ option) any later version.
+
+ or both in parallel, as here.
+
+ GNU Nettle is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received copies of the GNU General Public License and
+ the GNU Lesser General Public License along with this program. If
+ not, see http://www.gnu.org/licenses/.
+*/
+/* cmac.h, siv-cmac.h, cmac-aes128.c
+
+ CMAC mode, as specified in RFC4493
+ SIV-CMAC mode, as specified in RFC5297
+ CMAC using AES128 as the underlying cipher.
+
+ Copyright (C) 2017 Red Hat, Inc.
+
+ Contributed by Nikos Mavrogiannopoulos
+
+ This file is part of GNU Nettle.
+
+ GNU Nettle is free software: you can redistribute it and/or
+ modify it under the terms of either:
+
+ * the GNU Lesser General Public License as published by the Free
+ Software Foundation; either version 3 of the License, or (at your
+ option) any later version.
+
+ or
+
+ * the GNU General Public License as published by the Free
+ Software Foundation; either version 2 of the License, or (at your
+ option) any later version.
+
+ or both in parallel, as here.
+
+ GNU Nettle is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received copies of the GNU General Public License and
+ the GNU Lesser General Public License along with this program. If
+ not, see http://www.gnu.org/licenses/.
+*/
+
+# include "config.h"
+
+#include <assert.h>
+#include <string.h>
+
+#include "nettle/aes.h"
+#include "nettle/ctr.h"
+#include "nettle/macros.h"
+#include "nettle/memxor.h"
+#include "nettle/memops.h"
+
+#include "nettle/nettle-types.h"
+
+/* For SIV, the block size of the block cipher shall be 128 bits. */
+#define SIV_BLOCK_SIZE 16
+#define SIV_DIGEST_SIZE 16
+#define SIV_MIN_NONCE_SIZE 1
+
+/*
+ * SIV mode requires the aad and plaintext when building the IV, which
+ * prevents streaming processing and it incompatible with the AEAD API.
+ */
+
+/* AES_SIV_CMAC_256 */
+struct siv_cmac_aes128_ctx {
+ struct aes128_ctx cipher;
+ uint8_t s2vk[AES128_KEY_SIZE];
+};
+
+struct cmac128_ctx
+{
+ /* Key */
+ union nettle_block16 K1;
+ union nettle_block16 K2;
+
+ /* MAC state */
+ union nettle_block16 X;
+
+ /* Block buffer */
+ union nettle_block16 block;
+ size_t index;
+};
+
+/* shift one and XOR with 0x87. */
+static void
+_cmac128_block_mulx(union nettle_block16 *dst,
+ const union nettle_block16 *src)
+{
+ uint64_t b1 = READ_UINT64(src->b);
+ uint64_t b2 = READ_UINT64(src->b+8);
+
+ b1 = (b1 << 1) | (b2 >> 63);
+ b2 <<= 1;
+
+ if (src->b[0] & 0x80)
+ b2 ^= 0x87;
+
+ WRITE_UINT64(dst->b, b1);
+ WRITE_UINT64(dst->b+8, b2);
+}
+
+static void
+cmac128_set_key(struct cmac128_ctx *ctx, const void *cipher,
+ nettle_cipher_func *encrypt)
+{
+ static const uint8_t const_zero[] = {
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+ };
+ union nettle_block16 *L = &ctx->block;
+ memset(ctx, 0, sizeof(*ctx));
+
+ /* step 1 - generate subkeys k1 and k2 */
+ encrypt(cipher, 16, L->b, const_zero);
+
+ _cmac128_block_mulx(&ctx->K1, L);
+ _cmac128_block_mulx(&ctx->K2, &ctx->K1);
+}
+
+#define MIN(x,y) ((x)<(y)?(x):(y))
+
+static void
+cmac128_update(struct cmac128_ctx *ctx, const void *cipher,
+ nettle_cipher_func *encrypt,
+ size_t msg_len, const uint8_t *msg)
+{
+ union nettle_block16 Y;
+ /*
+ * check if we expand the block
+ */
+ if (ctx->index < 16)
+ {
+ size_t len = MIN(16 - ctx->index, msg_len);
+ memcpy(&ctx->block.b[ctx->index], msg, len);
+ msg += len;
+ msg_len -= len;
+ ctx->index += len;
+ }
+
+ if (msg_len == 0) {
+ /* if it is still the last block, we are done */
+ return;
+ }
+
+ /*
+ * now checksum everything but the last block
+ */
+ memxor3(Y.b, ctx->X.b, ctx->block.b, 16);
+ encrypt(cipher, 16, ctx->X.b, Y.b);
+
+ while (msg_len > 16)
+ {
+ memxor3(Y.b, ctx->X.b, msg, 16);
+ encrypt(cipher, 16, ctx->X.b, Y.b);
+ msg += 16;
+ msg_len -= 16;
+ }
+
+ /*
+ * copy the last block, it will be processed in
+ * cmac128_digest().
+ */
+ memcpy(ctx->block.b, msg, msg_len);
+ ctx->index = msg_len;
+}
+
+static void
+cmac128_digest(struct cmac128_ctx *ctx, const void *cipher,
+ nettle_cipher_func *encrypt,
+ unsigned length,
+ uint8_t *dst)
+{
+ union nettle_block16 Y;
+
+ memset(ctx->block.b+ctx->index, 0, sizeof(ctx->block.b)-ctx->index);
+
+ /* re-use ctx->block for memxor output */
+ if (ctx->index < 16)
+ {
+ ctx->block.b[ctx->index] = 0x80;
+ memxor(ctx->block.b, ctx->K2.b, 16);
+ }
+ else
+ {
+ memxor(ctx->block.b, ctx->K1.b, 16);
+ }
+
+ memxor3(Y.b, ctx->block.b, ctx->X.b, 16);
+
+ assert(length <= 16);
+ if (length == 16)
+ {
+ encrypt(cipher, 16, dst, Y.b);
+ }
+ else
+ {
+ encrypt(cipher, 16, ctx->block.b, Y.b);
+ memcpy(dst, ctx->block.b, length);
+ }
+
+ /* reset state for re-use */
+ memset(&ctx->X, 0, sizeof(ctx->X));
+ ctx->index = 0;
+}
+
+
+#define CMAC128_CTX(type) \
+ { struct cmac128_ctx ctx; type cipher; }
+
+/* NOTE: Avoid using NULL, as we don't include anything defining it. */
+#define CMAC128_SET_KEY(self, set_key, encrypt, cmac_key) \
+ do { \
+ (set_key)(&(self)->cipher, (cmac_key)); \
+ if (0) (encrypt)(&(self)->cipher, ~(size_t) 0, \
+ (uint8_t *) 0, (const uint8_t *) 0); \
+ cmac128_set_key(&(self)->ctx, &(self)->cipher, \
+ (nettle_cipher_func *) (encrypt)); \
+ } while (0)
+
+#define CMAC128_UPDATE(self, encrypt, length, src) \
+ cmac128_update(&(self)->ctx, &(self)->cipher, \
+ (nettle_cipher_func *)encrypt, (length), (src))
+
+#define CMAC128_DIGEST(self, encrypt, length, digest) \
+ (0 ? (encrypt)(&(self)->cipher, ~(size_t) 0, \
+ (uint8_t *) 0, (const uint8_t *) 0) \
+ : cmac128_digest(&(self)->ctx, &(self)->cipher, \
+ (nettle_cipher_func *) (encrypt), \
+ (length), (digest)))
+
+struct cmac_aes128_ctx CMAC128_CTX(struct aes128_ctx);
+
+static void
+cmac_aes128_set_key(struct cmac_aes128_ctx *ctx, const uint8_t *key)
+{
+ CMAC128_SET_KEY(ctx, aes128_set_encrypt_key, aes128_encrypt, key);
+}
+
+static void
+cmac_aes128_update (struct cmac_aes128_ctx *ctx,
+ size_t length, const uint8_t *data)
+{
+ CMAC128_UPDATE (ctx, aes128_encrypt, length, data);
+}
+
+static void
+cmac_aes128_digest(struct cmac_aes128_ctx *ctx,
+ size_t length, uint8_t *digest)
+{
+ CMAC128_DIGEST(ctx, aes128_encrypt, length, digest);
+}
+
+static const uint8_t const_one[] = {
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01
+};
+
+static const uint8_t const_zero[] = {
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+static
+void _siv_s2v(nettle_set_key_func *cmac_set_key,
+ nettle_hash_update_func *cmac_update,
+ nettle_hash_digest_func *cmac_digest,
+ size_t cmac_ctx_size,
+ const uint8_t *s2vk, size_t alength, const uint8_t *adata,
+ size_t nlength, const uint8_t *nonce,
+ size_t plength, const uint8_t *pdata,
+ uint8_t *v)
+{
+ uint8_t ctx[sizeof(struct cmac128_ctx)+sizeof(struct aes_ctx)];
+ union nettle_block16 D, S, T;
+
+ assert(cmac_ctx_size <= sizeof (ctx));
+
+ cmac_set_key(ctx, s2vk);
+
+ if (nlength == 0 && alength == 0) {
+ cmac_update(ctx, 16, const_one);
+ cmac_digest(ctx, 16, v);
+ return;
+ }
+
+ cmac_update(ctx, 16, const_zero);
+ cmac_digest(ctx, 16, D.b);
+
+ if (1) {
+ _cmac128_block_mulx(&D, &D);
+ cmac_update(ctx, alength, adata);
+ cmac_digest(ctx, 16, S.b);
+
+ memxor(D.b, S.b, 16);
+ }
+
+ if (nlength > 0) {
+ _cmac128_block_mulx(&D, &D);
+ cmac_update(ctx, nlength, nonce);
+ cmac_digest(ctx, 16, S.b);
+
+ memxor(D.b, S.b, 16);
+ }
+
+ /* Sn */
+ if (plength >= 16) {
+ cmac_update(ctx, plength-16, pdata);
+
+ pdata += plength-16;
+
+ memxor3(T.b, pdata, D.b, 16);
+ } else {
+ union nettle_block16 pad;
+
+ _cmac128_block_mulx(&T, &D);
+ memcpy(pad.b, pdata, plength);
+ pad.b[plength] = 0x80;
+ if (plength+1 < 16)
+ memset(&pad.b[plength+1], 0, 16-plength-1);
+
+ memxor(T.b, pad.b, 16);
+ }
+
+ cmac_update(ctx, 16, T.b);
+ cmac_digest(ctx, 16, v);
+}
+
+static void
+siv_cmac_aes128_set_key(struct siv_cmac_aes128_ctx *ctx, const uint8_t *key)
+{
+ memcpy(ctx->s2vk, key, 16);
+ aes128_set_encrypt_key(&ctx->cipher, key+16);
+}
+
+static void
+siv_cmac_aes128_encrypt_message(struct siv_cmac_aes128_ctx *ctx,
+ size_t nlength, const uint8_t *nonce,
+ size_t alength, const uint8_t *adata,
+ size_t clength, uint8_t *dst, const uint8_t *src)
+{
+ union nettle_block16 siv;
+ size_t slength;
+
+ assert (clength >= SIV_DIGEST_SIZE);
+ slength = clength - SIV_DIGEST_SIZE;
+
+ /* create CTR nonce */
+ _siv_s2v((nettle_set_key_func*)cmac_aes128_set_key,
+ (nettle_hash_update_func*)cmac_aes128_update,
+ (nettle_hash_digest_func*)cmac_aes128_digest,
+ sizeof(struct cmac_aes128_ctx), ctx->s2vk, alength, adata,
+ nlength, nonce, slength, src, siv.b);
+ memcpy(dst, siv.b, SIV_DIGEST_SIZE);
+ siv.b[8] &= ~0x80;
+ siv.b[12] &= ~0x80;
+
+ ctr_crypt(&ctx->cipher, (nettle_cipher_func *)aes128_encrypt, AES_BLOCK_SIZE,
+ siv.b, slength, dst+SIV_DIGEST_SIZE, src);
+}
+
+static int
+siv_cmac_aes128_decrypt_message(struct siv_cmac_aes128_ctx *ctx,
+ size_t nlength, const uint8_t *nonce,
+ size_t alength, const uint8_t *adata,
+ size_t mlength, uint8_t *dst, const uint8_t *src)
+{
+ union nettle_block16 siv;
+ union nettle_block16 ctr;
+
+ memcpy(ctr.b, src, SIV_DIGEST_SIZE);
+ ctr.b[8] &= ~0x80;
+ ctr.b[12] &= ~0x80;
+
+ ctr_crypt(&ctx->cipher, (nettle_cipher_func *)aes128_encrypt, AES_BLOCK_SIZE,
+ ctr.b, mlength, dst, src+SIV_DIGEST_SIZE);
+
+ /* create CTR nonce */
+ _siv_s2v((nettle_set_key_func*)cmac_aes128_set_key,
+ (nettle_hash_update_func*)cmac_aes128_update,
+ (nettle_hash_digest_func*)cmac_aes128_digest,
+ sizeof(struct cmac_aes128_ctx), ctx->s2vk, alength, adata,
+ nlength, nonce, mlength, dst, siv.b);
+
+ return memeql_sec(siv.b, src, SIV_DIGEST_SIZE);
+}
+
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