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- /* Copyright (c) 2014, Google Inc.
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
- * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
- * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
- * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
-
- #include <openssl/aead.h>
-
- #include <string.h>
-
- #include <openssl/chacha.h>
- #include <openssl/cipher.h>
- #include <openssl/cpu.h>
- #include <openssl/err.h>
- #include <openssl/mem.h>
- #include <openssl/poly1305.h>
- #include <openssl/type_check.h>
-
- #include "../fipsmodule/cipher/internal.h"
- #include "../internal.h"
-
-
- #define POLY1305_TAG_LEN 16
-
- struct aead_chacha20_poly1305_ctx {
- uint8_t key[32];
- };
-
- // For convenience (the x86_64 calling convention allows only six parameters in
- // registers), the final parameter for the assembly functions is both an input
- // and output parameter.
- union open_data {
- struct {
- alignas(16) uint8_t key[32];
- uint32_t counter;
- uint8_t nonce[12];
- } in;
- struct {
- uint8_t tag[POLY1305_TAG_LEN];
- } out;
- };
-
- union seal_data {
- struct {
- alignas(16) uint8_t key[32];
- uint32_t counter;
- uint8_t nonce[12];
- const uint8_t *extra_ciphertext;
- size_t extra_ciphertext_len;
- } in;
- struct {
- uint8_t tag[POLY1305_TAG_LEN];
- } out;
- };
-
- #if defined(OPENSSL_X86_64) && !defined(OPENSSL_NO_ASM) && \
- !defined(OPENSSL_WINDOWS)
- static int asm_capable(void) {
- const int sse41_capable = (OPENSSL_ia32cap_P[1] & (1 << 19)) != 0;
- return sse41_capable;
- }
-
- OPENSSL_COMPILE_ASSERT(sizeof(union open_data) == 48, wrong_open_data_size);
- OPENSSL_COMPILE_ASSERT(sizeof(union seal_data) == 48 + 8 + 8,
- wrong_seal_data_size);
-
- // chacha20_poly1305_open is defined in chacha20_poly1305_x86_64.pl. It decrypts
- // |plaintext_len| bytes from |ciphertext| and writes them to |out_plaintext|.
- // Additional input parameters are passed in |aead_data->in|. On exit, it will
- // write calculated tag value to |aead_data->out.tag|, which the caller must
- // check.
- extern void chacha20_poly1305_open(uint8_t *out_plaintext,
- const uint8_t *ciphertext,
- size_t plaintext_len, const uint8_t *ad,
- size_t ad_len, union open_data *aead_data);
-
- // chacha20_poly1305_open is defined in chacha20_poly1305_x86_64.pl. It encrypts
- // |plaintext_len| bytes from |plaintext| and writes them to |out_ciphertext|.
- // Additional input parameters are passed in |aead_data->in|. The calculated tag
- // value is over the computed ciphertext concatenated with |extra_ciphertext|
- // and written to |aead_data->out.tag|.
- extern void chacha20_poly1305_seal(uint8_t *out_ciphertext,
- const uint8_t *plaintext,
- size_t plaintext_len, const uint8_t *ad,
- size_t ad_len, union seal_data *aead_data);
- #else
- static int asm_capable(void) { return 0; }
-
-
- static void chacha20_poly1305_open(uint8_t *out_plaintext,
- const uint8_t *ciphertext,
- size_t plaintext_len, const uint8_t *ad,
- size_t ad_len, union open_data *aead_data) {}
-
- static void chacha20_poly1305_seal(uint8_t *out_ciphertext,
- const uint8_t *plaintext,
- size_t plaintext_len, const uint8_t *ad,
- size_t ad_len, union seal_data *aead_data) {}
- #endif
-
- static int aead_chacha20_poly1305_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
- size_t key_len, size_t tag_len) {
- struct aead_chacha20_poly1305_ctx *c20_ctx;
-
- if (tag_len == 0) {
- tag_len = POLY1305_TAG_LEN;
- }
-
- if (tag_len > POLY1305_TAG_LEN) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
- return 0;
- }
-
- if (key_len != sizeof(c20_ctx->key)) {
- return 0; /* internal error - EVP_AEAD_CTX_init should catch this. */
- }
-
- c20_ctx = OPENSSL_malloc(sizeof(struct aead_chacha20_poly1305_ctx));
- if (c20_ctx == NULL) {
- return 0;
- }
-
- OPENSSL_memcpy(c20_ctx->key, key, key_len);
- ctx->aead_state = c20_ctx;
- ctx->tag_len = tag_len;
-
- return 1;
- }
-
- static void aead_chacha20_poly1305_cleanup(EVP_AEAD_CTX *ctx) {
- struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state;
- OPENSSL_cleanse(c20_ctx->key, sizeof(c20_ctx->key));
- OPENSSL_free(c20_ctx);
- }
-
- static void poly1305_update_length(poly1305_state *poly1305, size_t data_len) {
- uint8_t length_bytes[8];
-
- for (unsigned i = 0; i < sizeof(length_bytes); i++) {
- length_bytes[i] = data_len;
- data_len >>= 8;
- }
-
- CRYPTO_poly1305_update(poly1305, length_bytes, sizeof(length_bytes));
- }
-
- /* calc_tag fills |tag| with the authentication tag for the given inputs. */
- static void calc_tag(uint8_t tag[POLY1305_TAG_LEN],
- const struct aead_chacha20_poly1305_ctx *c20_ctx,
- const uint8_t nonce[12], const uint8_t *ad, size_t ad_len,
- const uint8_t *ciphertext, size_t ciphertext_len,
- const uint8_t *ciphertext_extra,
- size_t ciphertext_extra_len) {
- alignas(16) uint8_t poly1305_key[32];
- OPENSSL_memset(poly1305_key, 0, sizeof(poly1305_key));
- CRYPTO_chacha_20(poly1305_key, poly1305_key, sizeof(poly1305_key),
- c20_ctx->key, nonce, 0);
-
- static const uint8_t padding[16] = { 0 }; /* Padding is all zeros. */
- poly1305_state ctx;
- CRYPTO_poly1305_init(&ctx, poly1305_key);
- CRYPTO_poly1305_update(&ctx, ad, ad_len);
- if (ad_len % 16 != 0) {
- CRYPTO_poly1305_update(&ctx, padding, sizeof(padding) - (ad_len % 16));
- }
- CRYPTO_poly1305_update(&ctx, ciphertext, ciphertext_len);
- CRYPTO_poly1305_update(&ctx, ciphertext_extra, ciphertext_extra_len);
- const size_t ciphertext_total = ciphertext_len + ciphertext_extra_len;
- if (ciphertext_total % 16 != 0) {
- CRYPTO_poly1305_update(&ctx, padding,
- sizeof(padding) - (ciphertext_total % 16));
- }
- poly1305_update_length(&ctx, ad_len);
- poly1305_update_length(&ctx, ciphertext_total);
- CRYPTO_poly1305_finish(&ctx, tag);
- }
-
- static int aead_chacha20_poly1305_seal_scatter(
- const EVP_AEAD_CTX *ctx, uint8_t *out, uint8_t *out_tag,
- size_t *out_tag_len, size_t max_out_tag_len, const uint8_t *nonce,
- size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *extra_in,
- size_t extra_in_len, const uint8_t *ad, size_t ad_len) {
- const struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state;
-
- if (extra_in_len + ctx->tag_len < ctx->tag_len) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
- return 0;
- }
- if (max_out_tag_len < ctx->tag_len + extra_in_len) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
- return 0;
- }
- if (nonce_len != 12) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
- return 0;
- }
-
- /* |CRYPTO_chacha_20| uses a 32-bit block counter. Therefore we disallow
- * individual operations that work on more than 256GB at a time.
- * |in_len_64| is needed because, on 32-bit platforms, size_t is only
- * 32-bits and this produces a warning because it's always false.
- * Casting to uint64_t inside the conditional is not sufficient to stop
- * the warning. */
- const uint64_t in_len_64 = in_len;
- if (in_len_64 >= (UINT64_C(1) << 32) * 64 - 64) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
- return 0;
- }
-
- if (max_out_tag_len < ctx->tag_len) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
- return 0;
- }
-
- /* The the extra input is given, it is expected to be very short and so is
- * encrypted byte-by-byte first. */
- if (extra_in_len) {
- static const size_t kChaChaBlockSize = 64;
- uint32_t block_counter = 1 + (in_len / kChaChaBlockSize);
- size_t offset = in_len % kChaChaBlockSize;
- uint8_t block[64 /* kChaChaBlockSize */];
-
- for (size_t done = 0; done < extra_in_len; block_counter++) {
- memset(block, 0, sizeof(block));
- CRYPTO_chacha_20(block, block, sizeof(block), c20_ctx->key, nonce,
- block_counter);
- for (size_t i = offset; i < sizeof(block) && done < extra_in_len;
- i++, done++) {
- out_tag[done] = extra_in[done] ^ block[i];
- }
- offset = 0;
- }
- }
-
- union seal_data data;
- if (asm_capable()) {
- OPENSSL_memcpy(data.in.key, c20_ctx->key, 32);
- data.in.counter = 0;
- OPENSSL_memcpy(data.in.nonce, nonce, 12);
- data.in.extra_ciphertext = out_tag;
- data.in.extra_ciphertext_len = extra_in_len;
- chacha20_poly1305_seal(out, in, in_len, ad, ad_len, &data);
- } else {
- CRYPTO_chacha_20(out, in, in_len, c20_ctx->key, nonce, 1);
- calc_tag(data.out.tag, c20_ctx, nonce, ad, ad_len, out, in_len, out_tag,
- extra_in_len);
- }
-
- OPENSSL_memcpy(out_tag + extra_in_len, data.out.tag, ctx->tag_len);
- *out_tag_len = extra_in_len + ctx->tag_len;
- return 1;
- }
-
- static int aead_chacha20_poly1305_open_gather(
- const EVP_AEAD_CTX *ctx, uint8_t *out, const uint8_t *nonce,
- size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *in_tag,
- size_t in_tag_len, const uint8_t *ad, size_t ad_len) {
- const struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state;
-
- if (nonce_len != 12) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
- return 0;
- }
-
- if (in_tag_len != ctx->tag_len) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
- return 0;
- }
-
- /* |CRYPTO_chacha_20| uses a 32-bit block counter. Therefore we disallow
- * individual operations that work on more than 256GB at a time.
- * |in_len_64| is needed because, on 32-bit platforms, size_t is only
- * 32-bits and this produces a warning because it's always false.
- * Casting to uint64_t inside the conditional is not sufficient to stop
- * the warning. */
- const uint64_t in_len_64 = in_len;
- if (in_len_64 >= (UINT64_C(1) << 32) * 64 - 64) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
- return 0;
- }
-
- union open_data data;
- if (asm_capable()) {
- OPENSSL_memcpy(data.in.key, c20_ctx->key, 32);
- data.in.counter = 0;
- OPENSSL_memcpy(data.in.nonce, nonce, 12);
- chacha20_poly1305_open(out, in, in_len, ad, ad_len, &data);
- } else {
- calc_tag(data.out.tag, c20_ctx, nonce, ad, ad_len, in, in_len, NULL, 0);
- CRYPTO_chacha_20(out, in, in_len, c20_ctx->key, nonce, 1);
- }
-
- if (CRYPTO_memcmp(data.out.tag, in_tag, ctx->tag_len) != 0) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
- return 0;
- }
-
- return 1;
- }
-
- static const EVP_AEAD aead_chacha20_poly1305 = {
- 32, /* key len */
- 12, /* nonce len */
- POLY1305_TAG_LEN, /* overhead */
- POLY1305_TAG_LEN, /* max tag length */
- 1, /* seal_scatter_supports_extra_in */
-
- aead_chacha20_poly1305_init,
- NULL, /* init_with_direction */
- aead_chacha20_poly1305_cleanup,
- NULL /* open */,
- aead_chacha20_poly1305_seal_scatter,
- aead_chacha20_poly1305_open_gather,
- NULL, /* get_iv */
- NULL, /* tag_len */
- };
-
- const EVP_AEAD *EVP_aead_chacha20_poly1305(void) {
- return &aead_chacha20_poly1305;
- }
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