header.proto

syntax = "proto3";

message Argon2Options {
  enum Argon2Type {
    Argon2d = 0;
    Argon2id = 1;
  }

  Argon2Type type = 1;
  // see https://github.com/P-H-C/phc-winner-argon2/blob/16d3df698db2486dde480b09a732bf9bf48599f9/include/argon2.h#L300
  uint32 time_iterations = 2;
  // see https://github.com/P-H-C/phc-winner-argon2/blob/16d3df698db2486dde480b09a732bf9bf48599f9/include/argon2.h#L300
  uint32 memory_kib = 3;
  // see https://github.com/P-H-C/phc-winner-argon2/blob/16d3df698db2486dde480b09a732bf9bf48599f9/include/argon2.h#L301
  uint32 parallelism = 4;
}

message Header {
  enum CryptoAlgorithm {
    AES_256_GCM = 0;
    ChaCha20_Poly1305 = 1;
  }
  enum CompressAlgorithm {
    None = 0;
    Gzip = 1;
    Brotli = 2;
  }

  CryptoAlgorithm crypto_algorithm = 1;
  bytes crypto_nonce = 2;
  bytes crypto_auth_tag = 3;
  uint32 key_length = 4;
  bytes key_salt = 5;
  oneof key_options {
    Argon2Options argon2_key_options = 15;
  }
  CompressAlgorithm compress_algorithm = 6;
}

message SimpleHeader {
  bytes crypto_auth_tag = 1;

  // The value to be added or reset to the counter included in the nonce.
  // + If the "crypto_nonce_fixed_add" field does not exist or is zero, the value will be added to the previous counter.
  //   The nonce must never be duplicated.
  //   For this reason, the encryptor cannot specify a value that means "0".
  //   Thus, the value is used as the count-up value with 1 added.
  //   "0" (this is the default value) means increment, and "1" means add 2.
  // + If the "crypto_nonce_fixed_add" field is greater than or equal to 1, the previous counter will be reset to this value.
  //   If the fixed field is incremented, the counter can be reset to zero.
  //   For this reason, the encryptor can specify a value that means "0".
  uint64 crypto_nonce_counter_add_or_reset = 2 [jstype = JS_STRING];

  // The value to be added to the fixed field included in the nonce.
  // In most cases, there is no increase in the fixed field. The only exception is when a counter overflows.
  // Therefore, unlike counters, the encryptor can specify a value that means "0" (this is the default value).
  uint64 crypto_nonce_fixed_add = 3 [jstype = JS_STRING];
}