61 lines
1.8 KiB
C++
61 lines
1.8 KiB
C++
// Copyright 2012 The Chromium OS Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef LIBWEAVE_THIRD_PARTY_CHROMIUM_P224_H_
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#define LIBWEAVE_THIRD_PARTY_CHROMIUM_P224_H_
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#include <stddef.h>
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#include <stdint.h>
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#include <string>
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#include "base/strings/string_piece.h"
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namespace crypto {
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// P224 implements an elliptic curve group, commonly known as P224 and defined
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// in FIPS 186-3, section D.2.2.
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namespace p224 {
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// An element of the field (ℤ/pℤ) is represented with 8, 28-bit limbs in
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// little endian order.
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typedef uint32_t FieldElement[8];
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struct Point {
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// SetFromString the value of the point from the 56 byte, external
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// representation. The external point representation is an (x, y) pair of a
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// point on the curve. Each field element is represented as a big-endian
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// number < p.
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bool SetFromString(const base::StringPiece& in);
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// ToString returns an external representation of the Point.
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std::string ToString() const;
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// An Point is represented in Jacobian form (x/z², y/z³).
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FieldElement x, y, z;
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};
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// kScalarBytes is the number of bytes needed to represent an element of the
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// P224 field.
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static const size_t kScalarBytes = 28;
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// ScalarMult computes *out = in*scalar where scalar is a 28-byte, big-endian
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// number.
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void ScalarMult(const Point& in, const uint8_t* scalar, Point* out);
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// ScalarBaseMult computes *out = g*scalar where g is the base point of the
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// curve and scalar is a 28-byte, big-endian number.
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void ScalarBaseMult(const uint8_t* scalar, Point* out);
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// Add computes *out = a+b.
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void Add(const Point& a, const Point& b, Point* out);
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// Negate calculates out = -a;
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void Negate(const Point& a, Point* out);
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} // namespace p224
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} // namespace crypto
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#endif // LIBWEAVE_THIRD_PARTY_CHROMIUM_P224_H_
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