hash_base.h

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#pragma once
 
#include <cstdint>
#include <cstddef>
#include <cstring>
#include "esphome/core/helpers.h"
 
namespace esphome {
 
class HashBase {
 public:
  virtual ~HashBase() = default;
 
  virtual void init() = 0;
 
  virtual void add(const uint8_t *data, size_t len) = 0;
  void add(const char *data, size_t len) { this->add((const uint8_t *) data, len); }
 
  virtual void calculate() = 0;
 
  void get_bytes(uint8_t *output) { memcpy(output, this->digest_, this->get_size()); }
 
  void get_hex(char *output) { format_hex_to(output, this->get_size() * 2 + 1, this->digest_, this->get_size()); }
 
  bool equals_bytes(const uint8_t *expected) { return constant_time_equals(this->digest_, expected, this->get_size()); }
 
  bool equals_hex(const char *expected) {
    uint8_t parsed[32];  // Fixed size for max hash (SHA256 = 32 bytes)
    const size_t size = this->get_size();
    if (parse_hex(expected, size * 2, parsed, size) != size * 2) {
      return false;
    }
    return this->equals_bytes(parsed);
  }
 
  virtual size_t get_size() const = 0;
 
 protected:
// ESP32 variants with DMA-based hardware SHA (all except original ESP32) require 32-byte aligned buffers.
// Original ESP32 uses a different hardware SHA implementation without DMA alignment requirements.
// Other platforms (ESP8266, RP2040, LibreTiny) use software SHA and don't need alignment.
// Storage sized for max(MD5=16, SHA256=32) bytes
#if defined(USE_ESP32) && !defined(USE_ESP32_VARIANT_ESP32)
  alignas(32) uint8_t digest_[32];
#else
  uint8_t digest_[32];
#endif
};
 
}  // namespace esphome