ECIES: add ECIES-KEM. This version supports HKDF and ECDH with NIST curves.

Change-Id: Iea5877eba0a9b13610d3d1b33d04b5657edc3550

1 files changed, 72 insertions, 0 deletions

diff --git a/nist_curve_key_exchange.h b/nist_curve_key_exchange.h
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+++ b/nist_curve_key_exchange.h
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+/*
+ * Copyright 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SYSTEM_KEYMASTER_NIST_CURVE_KEY_EXCHANGE_H_
+#define SYSTEM_KEYMASTER_NIST_CURVE_KEY_EXCHANGE_H_
+
+#include "key_exchange.h"
+
+#include <keymaster/authorization_set.h>
+#include <hardware/keymaster_defs.h>
+
+#include <UniquePtr.h>
+
+#include "openssl_utils.h"
+
+namespace keymaster {
+
+/**
+ * NistCurveKeyExchange implements a KeyExchange using elliptic-curve
+ * Diffie-Hellman on NIST curves: P-224, P-256, P-384 and P-521.
+ */
+class NistCurveKeyExchange : public KeyExchange {
+  public:
+    ~NistCurveKeyExchange() override {}
+
+    /**
+     * NistCurveKeyExchange takes ownership of \p private_key.
+     */
+    NistCurveKeyExchange(EC_KEY* private_key, keymaster_error_t* error);
+
+    /**
+     * GenerateKeyExchange generates a new public/private key pair on a NIST curve and returns
+     * a new key exchange object.
+     */
+    static NistCurveKeyExchange* GenerateKeyExchange(keymaster_ec_curve_t curve);
+
+    /**
+     * KeyExchange interface.
+     */
+    bool CalculateSharedKey(const uint8_t* peer_public_value, size_t peer_public_value_len,
+                            Buffer* shared_key) const override;
+    bool CalculateSharedKey(const Buffer& peer_public_value, Buffer* shared_key) const override;
+    bool public_value(Buffer* public_value) const override;
+
+    /* Caller takes ownership of \p private_key. */
+    EC_KEY* private_key() { return private_key_.release(); }
+
+  private:
+    keymaster_error_t ExtractPublicKey();
+
+    UniquePtr<EC_KEY, EC_KEY_Delete> private_key_;
+    UniquePtr<uint8_t[]> public_key_;
+    size_t public_key_len_;
+    size_t shared_secret_len_;
+};
+
+}  // namespace keymaster
+
+#endif  // SYSTEM_KEYMASTER_NIST_CURVE_KEY_EXCHANGE_H_
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