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