Module: KeeperSecretsManager::Crypto

Defined in:
lib/keeper_secrets_manager/crypto.rb

Constant Summary collapse

GCM_IV_LENGTH =

AES GCM constants

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GCM_TAG_LENGTH = 
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AES_KEY_LENGTH = 
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BLOCK_SIZE =

Block size for padding

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Class Method Summary collapse

Class Method Details

.base64_to_bytes(str) ⇒ Object

Convert base64 to bytes



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# File 'lib/keeper_secrets_manager/crypto.rb', line 44

def base64_to_bytes(str)
  Base64.strict_decode64(str)
end

.bytes_to_base64(bytes) ⇒ Object

Convert bytes to base64



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# File 'lib/keeper_secrets_manager/crypto.rb', line 39

def bytes_to_base64(bytes)
  Base64.strict_encode64(bytes)
end

.bytes_to_url_safe_str(bytes) ⇒ Object

Convert bytes to URL-safe base64 string (no padding)



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# File 'lib/keeper_secrets_manager/crypto.rb', line 27

def bytes_to_url_safe_str(bytes)
  Base64.urlsafe_encode64(bytes).delete('=')
end

.decrypt_aes_cbc(encrypted_data, key) ⇒ Object

Legacy AES-CBC decryption



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# File 'lib/keeper_secrets_manager/crypto.rb', line 167

def decrypt_aes_cbc(encrypted_data, key)
  # Extract IV
  iv = encrypted_data[0...BLOCK_SIZE]
  ciphertext = encrypted_data[BLOCK_SIZE..]

  cipher = OpenSSL::Cipher.new('AES-256-CBC')
  cipher.decrypt
  cipher.iv = iv
  cipher.key = key

  # OpenSSL handles PKCS7 padding removal automatically in cipher.final
  decrypted = cipher.update(ciphertext) + cipher.final

  decrypted
rescue OpenSSL::Cipher::CipherError => e
  raise DecryptionError, "Failed to decrypt data: #{e.message}"
end

.decrypt_aes_gcm(encrypted_data, key) ⇒ Object

Decrypt with AES-GCM or fallback to CBC



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# File 'lib/keeper_secrets_manager/crypto.rb', line 120

def decrypt_aes_gcm(encrypted_data, key)
  # Try GCM first
  # Extract components
  iv = encrypted_data[0...GCM_IV_LENGTH]
  tag = encrypted_data[-GCM_TAG_LENGTH..]
  ciphertext = encrypted_data[GCM_IV_LENGTH...-GCM_TAG_LENGTH]

  cipher = OpenSSL::Cipher.new('AES-256-GCM')
  cipher.decrypt
  cipher.iv = iv
  cipher.key = key
  cipher.auth_tag = tag

  cipher.update(ciphertext) + cipher.final
rescue RuntimeError => e
  if e.message.include?('unsupported cipher')
    # Fallback to AES-CBC
    decrypt_aes_cbc(encrypted_data, key)
  else
    raise e
  end
rescue OpenSSL::Cipher::CipherError => e
  # Maybe it's CBC encrypted?
  begin
    decrypt_aes_cbc(encrypted_data, key)
  rescue StandardError
    raise DecryptionError, "Failed to decrypt data: #{e.message}"
  end
end

.decrypt_ec(encrypted_data, private_key) ⇒ Object

Decrypt with EC private key



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# File 'lib/keeper_secrets_manager/crypto.rb', line 280

def decrypt_ec(encrypted_data, private_key)
  # Extract ephemeral public key (65 bytes for uncompressed)
  ephemeral_public_bytes = encrypted_data[0...65]
  ciphertext = encrypted_data[65..]

  # Create EC key with ephemeral public key
  group = OpenSSL::PKey::EC::Group.new('prime256v1')
  ephemeral_point = OpenSSL::PKey::EC::Point.new(group, ephemeral_public_bytes)

  # Compute shared secret using ECDH
  shared_secret = private_key.dh_compute_key(ephemeral_point)

  # Derive decryption key
  decryption_key = OpenSSL::Digest::SHA256.digest(shared_secret)

  # Decrypt data
  decrypt_aes_gcm(ciphertext, decryption_key)
end

.encrypt_aes_cbc(data, key, iv = nil) ⇒ Object

Legacy AES-CBC encryption (for compatibility)



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# File 'lib/keeper_secrets_manager/crypto.rb', line 151

def encrypt_aes_cbc(data, key, iv = nil)
  cipher = OpenSSL::Cipher.new('AES-256-CBC')
  cipher.encrypt

  iv ||= generate_random_bytes(BLOCK_SIZE)
  cipher.iv = iv
  cipher.key = key

  # OpenSSL handles PKCS7 padding automatically in cipher.final
  encrypted = cipher.update(data) + cipher.final

  # Return IV + encrypted
  iv + encrypted
end

.encrypt_aes_gcm(data, key) ⇒ Object

Encrypt with AES-GCM or fallback to CBC



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# File 'lib/keeper_secrets_manager/crypto.rb', line 93

def encrypt_aes_gcm(data, key)
  cipher = OpenSSL::Cipher.new('AES-256-GCM')
  cipher.encrypt

  # Generate random IV
  iv = generate_random_bytes(GCM_IV_LENGTH)
  cipher.iv = iv
  cipher.key = key

  # Encrypt data
  encrypted = cipher.update(data) + cipher.final

  # Get authentication tag
  tag = cipher.auth_tag(GCM_TAG_LENGTH)

  # Combine IV + encrypted + tag
  iv + encrypted + tag
rescue RuntimeError => e
  if e.message.include?('unsupported cipher')
    # Fallback to AES-CBC for older Ruby/OpenSSL
    encrypt_aes_cbc(data, key)
  else
    raise e
  end
end

.encrypt_ec(data, public_key_bytes) ⇒ Object

Encrypt with EC public key (ECIES-like)



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# File 'lib/keeper_secrets_manager/crypto.rb', line 257

def encrypt_ec(data, public_key_bytes)
  # Load public key
  public_key = load_ec_public_key(public_key_bytes)

  # Generate ephemeral key pair
  ephemeral = OpenSSL::PKey::EC.generate('prime256v1')

  # Perform ECDH to get shared secret
  # The shared secret is computed using ECDH between ephemeral private key and server public key
  shared_secret = ephemeral.dh_compute_key(public_key.public_key)

  # Derive encryption key using SHA256
  encryption_key = OpenSSL::Digest::SHA256.digest(shared_secret)

  # Encrypt data with AES-GCM
  encrypted_data = encrypt_aes_gcm(data, encryption_key)

  # Return ephemeral public key + encrypted data
  ephemeral_public = ephemeral.public_key.to_octet_string(:uncompressed)
  ephemeral_public + encrypted_data
end

.export_private_key_der(ec_key) ⇒ Object

Export EC private key to DER



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# File 'lib/keeper_secrets_manager/crypto.rb', line 247

def export_private_key_der(ec_key)
  ec_key.to_der
end

.export_public_key_der(ec_key) ⇒ Object

Export EC public key to DER



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# File 'lib/keeper_secrets_manager/crypto.rb', line 252

def export_public_key_der(ec_key)
  ec_key.public_key.to_der
end

.generate_ecc_keys ⇒ Object

Generate ECC key pair



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# File 'lib/keeper_secrets_manager/crypto.rb', line 49

def generate_ecc_keys
  # Generate private key bytes
  private_key_bytes = generate_encryption_key_bytes
  private_key_str = bytes_to_url_safe_str(private_key_bytes)

  # Create EC key from private key bytes
  private_key_bn = OpenSSL::BN.new(private_key_bytes, 2)

  # OpenSSL 3.0 compatibility - use ASN1 sequence to create key
  group = OpenSSL::PKey::EC::Group.new('prime256v1')

  # Generate public key point
  public_key_point = group.generator.mul(private_key_bn)

  # Create ASN1 sequence for the key
  asn1 = OpenSSL::ASN1::Sequence([
                                   OpenSSL::ASN1::Integer(1),
                                   OpenSSL::ASN1::OctetString(private_key_bytes),
                                   OpenSSL::ASN1::ObjectId('prime256v1', 0, :EXPLICIT),
                                   OpenSSL::ASN1::BitString(public_key_point.to_octet_string(:uncompressed), 1,
                                                            :EXPLICIT)
                                 ])

  # Create key from DER
  key = OpenSSL::PKey::EC.new(asn1.to_der)

  # Get public key bytes (uncompressed format)
  public_key_bytes = key.public_key.to_octet_string(:uncompressed)
  public_key_str = bytes_to_url_safe_str(public_key_bytes)

  # Also store the EC key in DER format for compatibility
  private_key_der = key.to_der

  {
    private_key_str: private_key_str,
    public_key_str: public_key_str,
    private_key_bytes: private_key_bytes,  # Use raw 32 bytes
    private_key_der: private_key_der,      # Also provide DER format
    public_key_bytes: public_key_bytes,
    private_key_obj: key
  }
end

.generate_encryption_key_bytes ⇒ Object

Generate encryption key (32 bytes)



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# File 'lib/keeper_secrets_manager/crypto.rb', line 22

def generate_encryption_key_bytes
  generate_random_bytes(AES_KEY_LENGTH)
end

.generate_hmac(key, data) ⇒ Object

Generate HMAC signature



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# File 'lib/keeper_secrets_manager/crypto.rb', line 209

def generate_hmac(key, data)
  OpenSSL::HMAC.digest('SHA512', key, data)
end

.generate_random_bytes(length) ⇒ Object

Generate random bytes



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# File 'lib/keeper_secrets_manager/crypto.rb', line 17

def generate_random_bytes(length)
  SecureRandom.random_bytes(length)
end

.load_private_key_der(der_bytes, password = nil) ⇒ Object

Load private key from DER format



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# File 'lib/keeper_secrets_manager/crypto.rb', line 233

def load_private_key_der(der_bytes, password = nil)
  OpenSSL::PKey.read(der_bytes, password)
rescue StandardError => e
  raise CryptoError, "Failed to load private key: #{e.message}"
end

.load_public_key_der(der_bytes) ⇒ Object

Load public key from DER format



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# File 'lib/keeper_secrets_manager/crypto.rb', line 240

def load_public_key_der(der_bytes)
  OpenSSL::PKey.read(der_bytes)
rescue StandardError => e
  raise CryptoError, "Failed to load public key: #{e.message}"
end

.pad_data(data) ⇒ Object

PKCS7 padding



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# File 'lib/keeper_secrets_manager/crypto.rb', line 186

def pad_data(data)
  data = data.b if data.is_a?(String)
  pad_len = BLOCK_SIZE - (data.length % BLOCK_SIZE)
  data + (pad_len.chr * pad_len).b
end

.sign_ec(data, private_key) ⇒ Object

Generate ECDSA signature



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# File 'lib/keeper_secrets_manager/crypto.rb', line 214

def sign_ec(data, private_key)
  # Use SHA256 for ECDSA signature
  digest = OpenSSL::Digest.new('SHA256')
  private_key.sign(digest, data)
end

.unpad_data(data) ⇒ Object

Remove PKCS7 padding



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# File 'lib/keeper_secrets_manager/crypto.rb', line 193

def unpad_data(data)
  return data if data.empty?

  pad_len = data[-1].ord

  # Validate padding
  if pad_len > 0 && pad_len <= BLOCK_SIZE && pad_len <= data.length
    # Check if all padding bytes are the same
    padding = data[-pad_len..]
    return data[0...-pad_len] if padding.bytes.all? { |b| b == pad_len }
  end

  data
end

.url_safe_str_to_bytes(str) ⇒ Object

Convert URL-safe base64 string to bytes



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# File 'lib/keeper_secrets_manager/crypto.rb', line 32

def url_safe_str_to_bytes(str)
  # Add padding if needed
  str += '=' * (4 - str.length % 4) if str.length % 4 != 0
  Base64.urlsafe_decode64(str)
end

.verify_hmac(key, data, signature) ⇒ Object

Verify HMAC signature



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# File 'lib/keeper_secrets_manager/crypto.rb', line 221

def verify_hmac(key, data, signature)
  expected = generate_hmac(key, data)

  # Constant time comparison
  return false unless expected.bytesize == signature.bytesize

  result = 0
  expected.bytes.zip(signature.bytes) { |a, b| result |= a ^ b }
  result == 0
end