common: Add RMA reset auth challenge-response crypto

RMA auth uses X25519 to generate a relatively small challenge and
response.

Currently, nothing calls the rma_auth code.  We'll need console and
TPM vendor commands to do so.

BUG=b:37952913
BRANCH=none
TEST=make buildall

Change-Id: Iec7f2d0e3dc8243f79b009ead16bb3ba9f1bef9d
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/544184

1 files changed, 80 insertions, 0 deletions

diff --git a/include/rma_auth.h b/include/rma_auth.h
new file mode 100644
index 0000000000..db39468595
--- /dev/null
+++ b/include/rma_auth.h
@@ -0,0 +1,80 @@
+/* Copyright 2017 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.
+ */
+
+/* RMA challenge-response */
+
+#ifndef __CROS_EC_RMA_AUTH_H
+#define __CROS_EC_RMA_AUTH_H
+
+#include <stdint.h>
+
+/* Test server public and private keys */
+#define RMA_TEST_SERVER_PUBLIC_KEY {					\
+		0x03, 0xae, 0x2d, 0x2c, 0x06, 0x23, 0xe0, 0x73,		\
+		0x0d, 0xd3, 0xb7, 0x92, 0xac, 0x54, 0xc5, 0xfd,		\
+		0x7e, 0x9c, 0xf0, 0xa8, 0xeb, 0x7e, 0x2a, 0xb5,		\
+		0xdb, 0xf4, 0x79, 0x5f, 0x8a, 0x0f, 0x28, 0x3f}
+#define RMA_TEST_SERVER_PRIVATE_KEY {					\
+		0x47, 0x3b, 0xa5, 0xdb, 0xc4, 0xbb, 0xd6, 0x77,		\
+		0x20, 0xbd, 0xd8, 0xbd, 0xc8, 0x7a, 0xbb, 0x07,		\
+		0x03, 0x79, 0xba, 0x7b, 0x52, 0x8c, 0xec, 0xb3,		\
+		0x4d, 0xaa, 0x69, 0xf5, 0x65, 0xb4, 0x31, 0xad}
+#define RMA_TEST_SERVER_KEY_ID 0x10
+
+/* Current challenge protocol version */
+#define RMA_CHALLENGE_VERSION 0
+
+/* Getters and setters for version_key_id byte */
+#define RMA_CHALLENGE_VKID_BYTE(version, keyid) \
+	(((version) << 6) | ((keyid) & 0x3f))
+#define RMA_CHALLENGE_GET_VERSION(vkidbyte) ((vkidbyte) >> 6)
+#define RMA_CHALLENGE_GET_KEY_ID(vkidbyte) ((vkidbyte) & 0x3f)
+
+struct __packed rma_challenge {
+	/* Top 2 bits are protocol version; bottom 6 are server KeyID */
+	uint8_t version_key_id;
+
+	/* Ephemeral public key from device */
+	uint8_t device_pub_key[32];
+
+	/* Board ID (.type) */
+	uint8_t board_id[4];
+
+	/* Device ID */
+	uint8_t device_id[8];
+};
+
+/* Size of encoded challenge and response, and buffer sizes to hold them */
+#define RMA_CHALLENGE_CHARS 80
+#define RMA_CHALLENGE_BUF_SIZE (RMA_CHALLENGE_CHARS + 1)
+
+#define RMA_AUTHCODE_CHARS 8
+#define RMA_AUTHCODE_BUF_SIZE (RMA_AUTHCODE_CHARS + 1)
+
+/**
+ * Create a new RMA challenge/response
+ *
+ * @return EC_SUCCESS, EC_ERROR_TIMEOUT if too soon since the last challenge,
+ * or other non-zero error code.
+ */
+int rma_create_challenge(void);
+
+/**
+ * Get the current challenge string
+ *
+ * @return a pointer to the challenge string.  String will be empty if there
+ * is no active challenge.
+ */
+const char *rma_get_challenge(void);
+
+/**
+ * Try a RMA authorization code
+ *
+ * @param code		Authorization code to try
+ * @return EC_SUCCESS if the response was correct, or non-zero error code.
+ */
+int rma_try_authcode(const char *code);
+
+#endif