crypto: add chacha_drbg

core/SConscript.firmware

@@ -63,6 +63,7 @@ SOURCE_MOD += [
     'vendor/trezor-crypto/chacha20poly1305/chacha_merged.c',
     'vendor/trezor-crypto/chacha20poly1305/poly1305-donna.c',
     'vendor/trezor-crypto/chacha20poly1305/rfc7539.c',
+    'vendor/trezor-crypto/chacha_drbg.c',
     'vendor/trezor-crypto/curves.c',
     'vendor/trezor-crypto/ecdsa.c',
     'vendor/trezor-crypto/ed25519-donna/curve25519-donna-32bit.c',

core/SConscript.unix

@@ -63,6 +63,7 @@ SOURCE_MOD += [
     'vendor/trezor-crypto/chacha20poly1305/chacha_merged.c',
     'vendor/trezor-crypto/chacha20poly1305/poly1305-donna.c',
     'vendor/trezor-crypto/chacha20poly1305/rfc7539.c',
+    'vendor/trezor-crypto/chacha_drbg.c',
     'vendor/trezor-crypto/ed25519-donna/curve25519-donna-32bit.c',
     'vendor/trezor-crypto/ed25519-donna/curve25519-donna-helpers.c',
     'vendor/trezor-crypto/ed25519-donna/curve25519-donna-scalarmult-base.c',

crypto/chacha_drbg.c

@@ -0,0 +1,62 @@
+/*
+ * This file is part of the Trezor project, https://trezor.io/
+ *
+ * Copyright (c) SatoshiLabs
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "chacha_drbg.h"
+
+#include <stdint.h>
+
+#define MAX(a, b) (a) > (b) ? (a) : (b)
+
+void chacha_drbg_init(CHACHA_DRBG_CTX *ctx,
+                      const uint8_t entropy[CHACHA_DRBG_SEED_LENGTH]) {
+  uint8_t buffer[MAX(CHACHA_DRBG_KEY_LENGTH, CHACHA_DRBG_IV_LENGTH)] = {0};
+  ECRYPT_keysetup(&ctx->chacha_ctx, buffer, CHACHA_DRBG_KEY_LENGTH * 8,
+                  CHACHA_DRBG_IV_LENGTH * 8);
+  ECRYPT_ivsetup(&ctx->chacha_ctx, buffer);
+
+  chacha_drbg_reseed(ctx, entropy);
+}
+
+static void chacha_drbg_update(CHACHA_DRBG_CTX *ctx,
+                               const uint8_t data[CHACHA_DRBG_SEED_LENGTH]) {
+  uint8_t buffer[CHACHA_DRBG_SEED_LENGTH] = {0};
+
+  if (data)
+    ECRYPT_encrypt_bytes(&ctx->chacha_ctx, data, buffer,
+                         CHACHA_DRBG_SEED_LENGTH);
+  else
+    ECRYPT_keystream_bytes(&ctx->chacha_ctx, buffer, CHACHA_DRBG_SEED_LENGTH);
+
+  ECRYPT_keysetup(&ctx->chacha_ctx, buffer, CHACHA_DRBG_KEY_LENGTH * 8,
+                  CHACHA_DRBG_IV_LENGTH * 8);
+  ECRYPT_ivsetup(&ctx->chacha_ctx, buffer + CHACHA_DRBG_KEY_LENGTH);
+}
+
+void chacha_drbg_generate(CHACHA_DRBG_CTX *ctx, uint8_t *output,
+                          uint8_t output_length) {
+  ECRYPT_keystream_bytes(&ctx->chacha_ctx, output, output_length);
+  chacha_drbg_update(ctx, NULL);
+  ctx->reseed_counter++;
+}
+
+void chacha_drbg_reseed(CHACHA_DRBG_CTX *ctx,
+                        const uint8_t entropy[CHACHA_DRBG_SEED_LENGTH]) {
+  chacha_drbg_update(ctx, entropy);
+  ctx->reseed_counter = 1;
+}

crypto/chacha_drbg.h

@@ -0,0 +1,43 @@
+/*
+ * This file is part of the Trezor project, https://trezor.io/
+ *
+ * Copyright (c) SatoshiLabs
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __CHACHA_DRBG__
+#define __CHACHA_DRBG__
+
+#include "chacha20poly1305/chacha20poly1305.h"
+
+// Very fast deterministic random bit generator inspired by CTR_DRBG in NIST SP
+// 800-90A
+
+#define CHACHA_DRBG_KEY_LENGTH 16
+#define CHACHA_DRBG_IV_LENGTH 8
+#define CHACHA_DRBG_SEED_LENGTH (CHACHA_DRBG_KEY_LENGTH + CHACHA_DRBG_IV_LENGTH)
+
+typedef struct _CHACHA_DRBG_CTX {
+  ECRYPT_ctx chacha_ctx;
+  uint32_t reseed_counter;
+} CHACHA_DRBG_CTX;
+
+void chacha_drbg_init(CHACHA_DRBG_CTX *ctx,
+                      const uint8_t entropy[CHACHA_DRBG_SEED_LENGTH]);
+void chacha_drbg_reseed(CHACHA_DRBG_CTX *ctx,
+                        const uint8_t entropy[CHACHA_DRBG_SEED_LENGTH]);
+void chacha_drbg_generate(CHACHA_DRBG_CTX *ctx, uint8_t *output,
+                          uint8_t output_length);
+#endif  // __CHACHA_DRBG__