1 files changed, 30 insertions, 0 deletions
diff --git a/chip/g/dcrypto/p256.c b/chip/g/dcrypto/p256.c
new file mode 100644
index 0000000000..665144e31b
--- /dev/null
+++ b/chip/g/dcrypto/p256.c
@@ -0,0 +1,30 @@
+/* Copyright 2015 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "dcrypto.h"
+
+#include "cryptoc/p256.h"
+#include "cryptoc/util.h"
+
+static const p256_int p256_one = P256_ONE;
+
+/*
+ * Key selection based on FIPS-186-4, section B.4.2 (Key Pair
+ * Generation by Testing Candidates).
+ */
+int DCRYPTO_p256_key_from_bytes(p256_int *x, p256_int *y, p256_int *d,
+				const uint8_t key_bytes[P256_NBYTES])
+{
+	p256_int key;
+
+	p256_from_bin(key_bytes, &key);
+	if (p256_cmp(&SECP256r1_nMin2, &key) < 0)
+		return 0;
+	p256_add(&key, &p256_one, d);
+	always_memset(&key, 0, sizeof(key));
+	if (x == NULL || y == NULL)
+		return 1;
+	return dcrypto_p256_base_point_mul(d, x, y);
+}