1 files changed, 71 insertions, 0 deletions
diff --git a/include/crypto/curve25519.h b/include/crypto/curve25519.h
new file mode 100644
index 000000000..4e6dc840b
--- /dev/null
+++ b/include/crypto/curve25519.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#ifndef CURVE25519_H
+#define CURVE25519_H
+
+#include <crypto/algapi.h> // For crypto_memneq.
+#include <linux/types.h>
+#include <linux/random.h>
+
+enum curve25519_lengths {
+	CURVE25519_KEY_SIZE = 32
+};
+
+extern const u8 curve25519_null_point[];
+extern const u8 curve25519_base_point[];
+
+void curve25519_generic(u8 out[CURVE25519_KEY_SIZE],
+			const u8 scalar[CURVE25519_KEY_SIZE],
+			const u8 point[CURVE25519_KEY_SIZE]);
+
+void curve25519_arch(u8 out[CURVE25519_KEY_SIZE],
+		     const u8 scalar[CURVE25519_KEY_SIZE],
+		     const u8 point[CURVE25519_KEY_SIZE]);
+
+void curve25519_base_arch(u8 pub[CURVE25519_KEY_SIZE],
+			  const u8 secret[CURVE25519_KEY_SIZE]);
+
+static inline
+bool __must_check curve25519(u8 mypublic[CURVE25519_KEY_SIZE],
+			     const u8 secret[CURVE25519_KEY_SIZE],
+			     const u8 basepoint[CURVE25519_KEY_SIZE])
+{
+	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519))
+		curve25519_arch(mypublic, secret, basepoint);
+	else
+		curve25519_generic(mypublic, secret, basepoint);
+	return crypto_memneq(mypublic, curve25519_null_point,
+			     CURVE25519_KEY_SIZE);
+}
+
+static inline bool
+__must_check curve25519_generate_public(u8 pub[CURVE25519_KEY_SIZE],
+					const u8 secret[CURVE25519_KEY_SIZE])
+{
+	if (unlikely(!crypto_memneq(secret, curve25519_null_point,
+				    CURVE25519_KEY_SIZE)))
+		return false;
+
+	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519))
+		curve25519_base_arch(pub, secret);
+	else
+		curve25519_generic(pub, secret, curve25519_base_point);
+	return crypto_memneq(pub, curve25519_null_point, CURVE25519_KEY_SIZE);
+}
+
+static inline void curve25519_clamp_secret(u8 secret[CURVE25519_KEY_SIZE])
+{
+	secret[0] &= 248;
+	secret[31] = (secret[31] & 127) | 64;
+}
+
+static inline void curve25519_generate_secret(u8 secret[CURVE25519_KEY_SIZE])
+{
+	get_random_bytes_wait(secret, CURVE25519_KEY_SIZE);
+	curve25519_clamp_secret(secret);
+}
+
+#endif /* CURVE25519_H */