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