chacha20.h

// Copyright 2026 The Pigweed Authors
//
// 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
//
//     https://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.
 
#pragma once
 
#include <cstddef>
#include <cstdint>
 
#include "pw_bytes/span.h"
#include "pw_crypto/chacha20_backend.h"
#include "pw_status/status.h"
 
namespace pw::crypto {
 
namespace chacha20 {
 
inline constexpr size_t kKeySizeBytes = 32;    // 256 bits
inline constexpr size_t kNonceSizeBytes = 12;  // 96 bits
 
inline Status Crypt(span<const std::byte> key,
                    span<const std::byte> nonce,
                    span<const std::byte> input,
                    span<std::byte> output) {
  if (key.size() != kKeySizeBytes) {
    return Status::InvalidArgument();
  }
  if (nonce.size() != kNonceSizeBytes) {
    return Status::InvalidArgument();
  }
  if (output.size() < input.size()) {
    return Status::InvalidArgument();
  }
 
  return backend::DoChaCha20Crypt(key, nonce, input, output);
}
 
}  // namespace chacha20
}  // namespace pw::crypto