Class: Saro::Dat::DatCrypto

Inherits:
Object
  • Object
show all
Defined in:
lib/saro/dat/crypto.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(algorithm, key_bytes, config = nil) ⇒ DatCrypto

Returns a new instance of DatCrypto.



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# File 'lib/saro/dat/crypto.rb', line 33

def initialize(algorithm, key_bytes, config = nil)
  @config = config || Saro::Dat.get_crypto_config(algorithm)
  # OpenSSL accepts any valid AES length, so a 16-byte key would silently
  # become AES-128 under an IV-AES256-GCM label without this check.
  if key_bytes.bytesize != @config[:length]
    raise Saro::Dat::Error.new(
      Saro::Dat::ErrorCode::KEY_INVALID,
      "#{algorithm} key must be #{@config[:length]} bytes, got #{key_bytes.bytesize}"
    )
  end
  @algorithm = algorithm
  @key_bytes = key_bytes
end

Instance Attribute Details

#algorithm ⇒ Object (readonly)

Returns the value of attribute algorithm.



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# File 'lib/saro/dat/crypto.rb', line 31

def algorithm
  @algorithm
end

Class Method Details

.generate(algorithm) ⇒ Object 



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# File 'lib/saro/dat/crypto.rb', line 47

def self.generate(algorithm)
  config = Saro::Dat.get_crypto_config(algorithm)
  key_bytes = OpenSSL::Random.random_bytes(config[:length])
  new(algorithm, key_bytes, config)
end

.imports(algorithm, base64_str) ⇒ Object 



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# File 'lib/saro/dat/crypto.rb', line 53

def self.imports(algorithm, base64_str)
  key_bytes = Saro::Dat::Util.decode_base64_url(base64_str)
  new(algorithm, key_bytes)
end

Instance Method Details

#decrypt(data) ⇒ Object

Decrypts raw (already decoded) ciphertext: nonce(12) + ciphertext + tag(16). Use #decrypt_base64 for encoded input. The branch used to be picked from the string's encoding tag, so raw ciphertext that merely carried a UTF-8 tag was silently mangled by the base64 decoder.



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# File 'lib/saro/dat/crypto.rb', line 94

def decrypt(data)
  return "".b if data.nil? || data.empty?

  # Slice by bytes, never by characters: String#[] is character-indexed on
  # a non-binary string, so raw ciphertext carrying a UTF-8 tag would be
  # split at the wrong offsets.
  data = data.b if data.is_a?(String) && data.encoding != Encoding::BINARY

  if data.bytesize <= 12 + 16 # nonce(12) + tag(16)
    raise Saro::Dat::Error.new(Saro::Dat::ErrorCode::CRYPTO_DATA_INVALID, "ciphertext is shorter than iv(12) + tag(16)")
  end

  nonce = data[0, 12]
  tag = data[-16, 16]
  ciphertext = data[12...-16]

  cipher = OpenSSL::Cipher.new(@config[:name])
  cipher.decrypt
  cipher.key = @key_bytes
  cipher.iv_len = 12
  cipher.iv = nonce
  cipher.auth_tag = tag

  # cipher.final 에서 나는 실패는 GCM 인증 태그 불일치다 — 변조된 secure 이거나
  # 잘못된 인증서 키다. 예전에는 OpenSSL::Cipher::CipherError 가 그대로 공개
  # API 밖으로 새어 나갔다. 서명 검증을 건너뛰는 경로에서는 이것이 유일한
  # 무결성 검사이므로 백엔드 오류(CRYPTO_BACKEND)와 반드시 구분한다.
  begin
    res = cipher.update(ciphertext) + cipher.final
  rescue OpenSSL::Cipher::CipherError => e
    raise Saro::Dat::Error.new(Saro::Dat::ErrorCode::CRYPTO_TAG_MISMATCH, "gcm authentication tag mismatch", cause: e)
  end
  res.force_encoding('BINARY')
  res
end

#decrypt_base64(base64_str) ⇒ Object

Decrypts base64url-encoded ciphertext.



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# File 'lib/saro/dat/crypto.rb', line 86

def decrypt_base64(base64_str)
  decrypt(Saro::Dat::Util.decode_base64_url(base64_str))
end

#encrypt(data) ⇒ Object 



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# File 'lib/saro/dat/crypto.rb', line 62

def encrypt(data)
  if data.is_a?(String) && data.encoding != Encoding::BINARY && data.encoding != Encoding::UTF_8
    data = data.encode('utf-8')
  end
  return "".b if data.nil? || data.empty?

  cipher = OpenSSL::Cipher.new(@config[:name])
  cipher.encrypt
  cipher.key = @key_bytes
  nonce = OpenSSL::Random.random_bytes(12)
  cipher.iv_len = 12
  cipher.iv = nonce
  
  begin
    ciphertext = cipher.update(data) + cipher.final
    tag = cipher.auth_tag
  rescue OpenSSL::Cipher::CipherError => e
    raise Saro::Dat::Error.new(Saro::Dat::ErrorCode::CRYPTO_BACKEND, "aes-gcm encrypt failed", cause: e)
  end

  nonce + ciphertext + tag
end

#exports ⇒ Object 



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# File 'lib/saro/dat/crypto.rb', line 58

def exports
  Saro::Dat::Util.encode_base64_url_str(@key_bytes)
end