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// Copyright 2017 The Fuchsia 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 <zircon/types.h>
#include <memory>
#include <fbl/macros.h>
// |crypto::Bytes| is a small helper class that simply wraps a buffer. It saves on some boilerplate
// when allocating a buffer. More importantly, when going out of scope, the destructor guarantees
// that the buffer will be zeroed in a way that will not be optimized away. Any buffer that holds
// cryptographically sensitive random data should be a |Bytes| and get its data via a call to
// |Bytes::Randomize|.
namespace crypto {
class __EXPORT Bytes final {
// Accessors
const uint8_t* get() const { return buf_.get(); }
uint8_t* get() { return buf_.get(); }
size_t len() const { return len_; }
// Resizes the underlying buffer to |len| bytes and fills it with random data.
zx_status_t Randomize() { return Randomize(len_); }
zx_status_t Randomize(size_t len);
// Resize the underlying buffer. If the new length is shorter, the data is truncated. If it is
// longer, it is padded with the given |fill| value.
zx_status_t Resize(size_t size, uint8_t fill = 0);
// Copies |len| bytes from |src| to |dst_off| in the underlying buffer. Resizes the buffer as
// needed, padding with zeros.
zx_status_t Copy(const void* src, size_t len, zx_off_t dst_off = 0);
zx_status_t Copy(const Bytes& src, zx_off_t dst_off = 0) {
return Copy(src.get(), src.len(), dst_off);
// Array access operators. Assert that |off| is not out of bounds.
const uint8_t& operator[](zx_off_t off) const;
uint8_t& operator[](zx_off_t off);
// Comparison operators. These are guaranteed to be constant-time.
bool operator==(const Bytes& other) const;
bool operator!=(const Bytes& other) const { return !(*this == other); }
// The underlying buffer.
std::unique_ptr<uint8_t[]> buf_;
// Length in bytes of memory currently allocated to the underlying buffer.
size_t len_;
} // namespace crypto
#endif // CRYPTO_BYTES_H_