kris/boringssl
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Clarify the ChaCha20-Poly1305 assembly functions' final parameters.

Browse Source 
The memcpy of a pointer looks like a typo, though it isn't. Instead,
transcribe what the functions expect into a union and let C fill it in.

Change-Id: Iba4c824295e8908c5bda68ac35673040a8cff116
Reviewed-on: https://boringssl-review.googlesource.com/18744
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
This commit is contained in:
David Benjamin 2017-08-01 15:02:26 -04:00 committed by CQ bot account: commit-bot@chromium.org
parent b0c761eb76
commit 8d200744b4
1 changed files with 65 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

104
crypto/cipher_extra/e_chacha20poly1305.c
View File

@ -22,6 +22,7 @@
#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"
@ -30,7 +31,34 @@
#define POLY1305_TAG_LEN 16
struct aead_chacha20_poly1305_ctx {
unsigned char key[32];
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) && \
@ -40,42 +68,42 @@ static int asm_capable(void) {
return sse41_capable;
}
// chacha20_poly1305_open is defined in chacha20_poly1305_x86_64.pl. It
// decrypts |plaintext_len| bytes from |ciphertext| and writes them to
// |out_plaintext|. On entry, |aead_data| must contain the final 48 bytes of
// the initial ChaCha20 block, i.e. the key, followed by four zeros, followed
// by the nonce. On exit, it will contain the calculated tag value, which the
// caller must check.
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, uint8_t *aead_data);
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|. On entry, |aead_data| must contain the final 48 bytes of
// the initial ChaCha20 block, i.e. the key, followed by four zeros, followed
// by the nonce. On exit, it will contain the calculated tag value, which the
// caller must append to the ciphertext.
// 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, uint8_t *aead_data);
size_t ad_len, union seal_data *aead_data);
#else
static int asm_capable(void) {
return 0;
}
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, uint8_t *aead_data) {}
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, uint8_t *aead_data) {}
size_t ad_len, union seal_data *aead_data) {}
#endif
static int aead_chacha20_poly1305_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
@ -212,22 +240,21 @@ static int aead_chacha20_poly1305_seal_scatter(
}
}
alignas(16) uint8_t tag[48 + 8 + 8];
union seal_data data;
if (asm_capable()) {
OPENSSL_memcpy(tag, c20_ctx->key, 32);
OPENSSL_memset(tag + 32, 0, 4);
OPENSSL_memcpy(tag + 32 + 4, nonce, 12);
OPENSSL_memcpy(tag + 48, &out_tag, sizeof(out_tag));
OPENSSL_memcpy(tag + 56, &extra_in_len, sizeof(extra_in_len));
chacha20_poly1305_seal(out, in, in_len, ad, ad_len, tag);
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(tag, c20_ctx, nonce, ad, ad_len, out, in_len,
out_tag, extra_in_len);
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, tag, ctx->tag_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;
}
@ -260,19 +287,18 @@ static int aead_chacha20_poly1305_open_gather(
return 0;
}
alignas(16) uint8_t tag[48];
union open_data data;
if (asm_capable()) {
OPENSSL_memcpy(tag, c20_ctx->key, 32);
OPENSSL_memset(tag + 32, 0, 4);
OPENSSL_memcpy(tag + 32 + 4, nonce, 12);
chacha20_poly1305_open(out, in, in_len, ad, ad_len, tag);
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(tag, c20_ctx, nonce, ad, ad_len, in, in_len, NULL, 0);
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(tag, in_tag, ctx->tag_len) != 0) {
if (CRYPTO_memcmp(data.out.tag, in_tag, ctx->tag_len) != 0) {
OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
return 0;
}