crypto.hpp

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#ifndef ARACHNE_CRYPTO_HPP
#define ARACHNE_CRYPTO_HPP
 
#include <array>
#include <cstddef>
#include <cstdint>
#include <filesystem>
#include <span>
#include <string>
#include <string_view>
 
namespace arachne::crypto {
 
using sha256_digest = std::array<std::byte, 32>;
 
/** Incremental SHA-256 calculator. */
class sha256_hasher final {
public:
    sha256_hasher() noexcept;
 
    void reset() noexcept;
    void update(std::span<const std::byte> bytes);
    void update(std::string_view bytes);
 
    /** Finalize the digest. Repeated calls return the same value. */
    [[nodiscard]] sha256_digest finish();
    [[nodiscard]] std::string finish_hex();
 
private:
    void transform(const std::byte* block) noexcept;
 
    std::array<std::uint32_t, 8> state_ {};
    std::array<std::byte, 64> buffer_ {};
    std::uint64_t bit_count_ = 0;
    std::size_t buffered_ = 0;
    bool finished_ = false;
    sha256_digest digest_ {};
};
 
/** Return the lowercase hexadecimal SHA-256 digest of arbitrary bytes. */
[[nodiscard]] std::string sha256(std::span<const std::byte> bytes);
 
/** Return the lowercase hexadecimal SHA-256 digest of a byte string. */
[[nodiscard]] std::string sha256(std::string_view bytes);
 
/** Stream a file in binary mode and return its lowercase SHA-256 digest. */
[[nodiscard]] std::string sha256_file(const std::filesystem::path& path);
 
/** Compatibility spelling used by early Penelope code. */
[[nodiscard]] inline std::string sha256_string(std::string_view bytes) {
    return sha256(bytes);
}
 
/**
 * Return true only for a portable, non-empty relative artifact reference.
 * Backslashes, absolute paths, empty components, and dot components are
 * rejected so a reference has the same meaning on POSIX and Windows.
 */
[[nodiscard]] bool
is_safe_relative_artifact_ref(std::string_view artifact_ref) noexcept;
 
/**
 * Join a validated artifact reference to a root. This is a lexical safety
 * primitive; callers that write files must additionally reject symlinked
 * directory components.
 */
[[nodiscard]] std::filesystem::path safe_artifact_path(
    const std::filesystem::path& root, std::string_view artifact_ref
);
 
}
 
#endif // ARACHNE_CRYPTO_HPP