Add the RFC 7539 ChaCha20-Poly1305 AEAD.
Change-Id: I07dfde7cc304d903c2253600905cc3e6257716c5
Reviewed-on: https://boringssl-review.googlesource.com/6101
Reviewed-by: Adam Langley <alangley@gmail.com>
diff --git a/crypto/cipher/e_chacha20poly1305.c b/crypto/cipher/e_chacha20poly1305.c
index 34446b4..29ada9b 100644
--- a/crypto/cipher/e_chacha20poly1305.c
+++ b/crypto/cipher/e_chacha20poly1305.c
@@ -67,18 +67,15 @@
OPENSSL_free(c20_ctx);
}
-static void poly1305_update_with_length(poly1305_state *poly1305,
- const uint8_t *data, size_t data_len) {
- size_t j = data_len;
+static void poly1305_update_length(poly1305_state *poly1305, size_t data_len) {
uint8_t length_bytes[8];
unsigned i;
for (i = 0; i < sizeof(length_bytes); i++) {
- length_bytes[i] = j;
- j >>= 8;
+ length_bytes[i] = data_len;
+ data_len >>= 8;
}
- CRYPTO_poly1305_update(poly1305, data, data_len);
CRYPTO_poly1305_update(poly1305, length_bytes, sizeof(length_bytes));
}
@@ -88,14 +85,34 @@
#define ALIGNED
#endif
-static int aead_chacha20_poly1305_seal(const EVP_AEAD_CTX *ctx, uint8_t *out,
- size_t *out_len, size_t max_out_len,
- const uint8_t *nonce, size_t nonce_len,
- const uint8_t *in, size_t in_len,
- const uint8_t *ad, size_t ad_len) {
- const struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state;
+typedef void (*aead_poly1305_update)(poly1305_state *ctx, const uint8_t *ad,
+ size_t ad_len, const uint8_t *ciphertext,
+ size_t ciphertext_len);
+
+/* aead_poly1305 fills |tag| with the authentication tag for the given
+ * inputs, using |update| to control the order and format that the inputs are
+ * signed/authenticated. */
+static void aead_poly1305(aead_poly1305_update update,
+ 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) {
uint8_t poly1305_key[32] ALIGNED;
- poly1305_state poly1305;
+ memset(poly1305_key, 0, sizeof(poly1305_key));
+ CRYPTO_chacha_20(poly1305_key, poly1305_key, sizeof(poly1305_key),
+ c20_ctx->key, nonce, 0);
+ poly1305_state ctx;
+ CRYPTO_poly1305_init(&ctx, poly1305_key);
+ update(&ctx, ad, ad_len, ciphertext, ciphertext_len);
+ CRYPTO_poly1305_finish(&ctx, tag);
+}
+
+static int seal(aead_poly1305_update poly1305_update, const EVP_AEAD_CTX *ctx,
+ uint8_t *out, size_t *out_len, size_t max_out_len,
+ const uint8_t nonce[12], const uint8_t *in, size_t in_len,
+ const uint8_t *ad, size_t ad_len) {
+ const struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state;
const uint64_t in_len_64 = in_len;
/* |CRYPTO_chacha_20| uses a 32-bit block counter. Therefore we disallow
@@ -119,40 +136,22 @@
return 0;
}
- if (nonce_len != 8) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_IV_TOO_LARGE);
- return 0;
- }
- uint8_t nonce_96[12];
- memset(nonce_96, 0, 4);
- memcpy(nonce_96 + 4, nonce, 8);
-
- memset(poly1305_key, 0, sizeof(poly1305_key));
- CRYPTO_chacha_20(poly1305_key, poly1305_key, sizeof(poly1305_key),
- c20_ctx->key, nonce_96, 0);
-
- CRYPTO_poly1305_init(&poly1305, poly1305_key);
- poly1305_update_with_length(&poly1305, ad, ad_len);
- CRYPTO_chacha_20(out, in, in_len, c20_ctx->key, nonce_96, 1);
- poly1305_update_with_length(&poly1305, out, in_len);
+ CRYPTO_chacha_20(out, in, in_len, c20_ctx->key, nonce, 1);
uint8_t tag[POLY1305_TAG_LEN] ALIGNED;
- CRYPTO_poly1305_finish(&poly1305, tag);
+ aead_poly1305(poly1305_update, tag, c20_ctx, nonce, ad, ad_len, out, in_len);
+
memcpy(out + in_len, tag, c20_ctx->tag_len);
*out_len = in_len + c20_ctx->tag_len;
return 1;
}
-static int aead_chacha20_poly1305_open(const EVP_AEAD_CTX *ctx, uint8_t *out,
- size_t *out_len, size_t max_out_len,
- const uint8_t *nonce, size_t nonce_len,
- const uint8_t *in, size_t in_len,
- const uint8_t *ad, size_t ad_len) {
+static int open(aead_poly1305_update poly1305_update, const EVP_AEAD_CTX *ctx,
+ uint8_t *out, size_t *out_len, size_t max_out_len,
+ const uint8_t nonce[12], const uint8_t *in, size_t in_len,
+ const uint8_t *ad, size_t ad_len) {
const struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state;
- uint8_t mac[POLY1305_TAG_LEN];
- uint8_t poly1305_key[32] ALIGNED;
size_t plaintext_len;
- poly1305_state poly1305;
const uint64_t in_len_64 = in_len;
if (in_len < c20_ctx->tag_len) {
@@ -171,43 +170,68 @@
return 0;
}
- if (nonce_len != 8) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_IV_TOO_LARGE);
- return 0;
- }
- uint8_t nonce_96[12];
- memset(nonce_96, 0, 4);
- memcpy(nonce_96 + 4, nonce, 8);
-
plaintext_len = in_len - c20_ctx->tag_len;
-
- if (max_out_len < plaintext_len) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
- return 0;
- }
-
- memset(poly1305_key, 0, sizeof(poly1305_key));
- CRYPTO_chacha_20(poly1305_key, poly1305_key, sizeof(poly1305_key),
- c20_ctx->key, nonce_96, 0);
-
- CRYPTO_poly1305_init(&poly1305, poly1305_key);
- poly1305_update_with_length(&poly1305, ad, ad_len);
- poly1305_update_with_length(&poly1305, in, plaintext_len);
- CRYPTO_poly1305_finish(&poly1305, mac);
-
- if (CRYPTO_memcmp(mac, in + plaintext_len, c20_ctx->tag_len) != 0) {
+ uint8_t tag[POLY1305_TAG_LEN] ALIGNED;
+ aead_poly1305(poly1305_update, tag, c20_ctx, nonce, ad, ad_len, in,
+ plaintext_len);
+ if (CRYPTO_memcmp(tag, in + plaintext_len, c20_ctx->tag_len) != 0) {
OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
return 0;
}
- CRYPTO_chacha_20(out, in, plaintext_len, c20_ctx->key, nonce_96, 1);
+ CRYPTO_chacha_20(out, in, plaintext_len, c20_ctx->key, nonce, 1);
*out_len = plaintext_len;
return 1;
}
+static void poly1305_update_padded_16(poly1305_state *poly1305,
+ const uint8_t *data, size_t data_len) {
+ static const uint8_t padding[16] = { 0 }; /* Padding is all zeros. */
+
+ CRYPTO_poly1305_update(poly1305, data, data_len);
+ if (data_len % 16 != 0) {
+ CRYPTO_poly1305_update(poly1305, padding, sizeof(padding) - (data_len % 16));
+ }
+}
+
+static void poly1305_update(poly1305_state *ctx, const uint8_t *ad,
+ size_t ad_len, const uint8_t *ciphertext,
+ size_t ciphertext_len) {
+ poly1305_update_padded_16(ctx, ad, ad_len);
+ poly1305_update_padded_16(ctx, ciphertext, ciphertext_len);
+ poly1305_update_length(ctx, ad_len);
+ poly1305_update_length(ctx, ciphertext_len);
+}
+
+static int aead_chacha20_poly1305_seal(const EVP_AEAD_CTX *ctx, uint8_t *out,
+ size_t *out_len, size_t max_out_len,
+ const uint8_t *nonce, size_t nonce_len,
+ const uint8_t *in, size_t in_len,
+ const uint8_t *ad, size_t ad_len) {
+ if (nonce_len != 12) {
+ OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
+ return 0;
+ }
+ return seal(poly1305_update, ctx, out, out_len, max_out_len, nonce, in,
+ in_len, ad, ad_len);
+}
+
+static int aead_chacha20_poly1305_open(const EVP_AEAD_CTX *ctx, uint8_t *out,
+ size_t *out_len, size_t max_out_len,
+ const uint8_t *nonce, size_t nonce_len,
+ const uint8_t *in, size_t in_len,
+ const uint8_t *ad, size_t ad_len) {
+ if (nonce_len != 12) {
+ OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
+ return 0;
+ }
+ return open(poly1305_update, ctx, out, out_len, max_out_len, nonce, in,
+ in_len, ad, ad_len);
+}
+
static const EVP_AEAD aead_chacha20_poly1305 = {
32, /* key len */
- 8, /* nonce len */
+ 12, /* nonce len */
POLY1305_TAG_LEN, /* overhead */
POLY1305_TAG_LEN, /* max tag length */
aead_chacha20_poly1305_init,
@@ -221,3 +245,59 @@
const EVP_AEAD *EVP_aead_chacha20_poly1305(void) {
return &aead_chacha20_poly1305;
}
+
+static void poly1305_update_old(poly1305_state *ctx, const uint8_t *ad,
+ size_t ad_len, const uint8_t *ciphertext,
+ size_t ciphertext_len) {
+ CRYPTO_poly1305_update(ctx, ad, ad_len);
+ poly1305_update_length(ctx, ad_len);
+ CRYPTO_poly1305_update(ctx, ciphertext, ciphertext_len);
+ poly1305_update_length(ctx, ciphertext_len);
+}
+
+static int aead_chacha20_poly1305_old_seal(
+ const EVP_AEAD_CTX *ctx, uint8_t *out, size_t *out_len, size_t max_out_len,
+ const uint8_t *nonce, size_t nonce_len, const uint8_t *in, size_t in_len,
+ const uint8_t *ad, size_t ad_len) {
+ if (nonce_len != 8) {
+ OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
+ return 0;
+ }
+ uint8_t nonce_96[12];
+ memset(nonce_96, 0, 4);
+ memcpy(nonce_96 + 4, nonce, 8);
+ return seal(poly1305_update_old, ctx, out, out_len, max_out_len, nonce_96, in,
+ in_len, ad, ad_len);
+}
+
+static int aead_chacha20_poly1305_old_open(
+ const EVP_AEAD_CTX *ctx, uint8_t *out, size_t *out_len, size_t max_out_len,
+ const uint8_t *nonce, size_t nonce_len, const uint8_t *in, size_t in_len,
+ const uint8_t *ad, size_t ad_len) {
+ if (nonce_len != 8) {
+ OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
+ return 0;
+ }
+ uint8_t nonce_96[12];
+ memset(nonce_96, 0, 4);
+ memcpy(nonce_96 + 4, nonce, 8);
+ return open(poly1305_update_old, ctx, out, out_len, max_out_len, nonce_96, in,
+ in_len, ad, ad_len);
+}
+
+static const EVP_AEAD aead_chacha20_poly1305_old = {
+ 32, /* key len */
+ 8, /* nonce len */
+ POLY1305_TAG_LEN, /* overhead */
+ POLY1305_TAG_LEN, /* max tag length */
+ aead_chacha20_poly1305_init,
+ NULL, /* init_with_direction */
+ aead_chacha20_poly1305_cleanup,
+ aead_chacha20_poly1305_old_seal,
+ aead_chacha20_poly1305_old_open,
+ NULL, /* get_rc4_state */
+};
+
+const EVP_AEAD *EVP_aead_chacha20_poly1305_old(void) {
+ return &aead_chacha20_poly1305_old;
+}
