Module: RubySMB::Client::Encryption

Included in:
RubySMB::Client
Defined in:
lib/ruby_smb/client/encryption.rb

Overview

Contains the methods for handling encryption / decryption

Instance Method Summary collapse

Instance Method Details

#smb3_decrypt(th) ⇒ Object 



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# File 'lib/ruby_smb/client/encryption.rb', line 40

def smb3_decrypt(th)
  unless @server_encryption_key
    raise RubySMB::Error::EncryptionError.new('The encryption algorithm has not been set') if @encryption_algorithm.nil?

    key_bit_len = OpenSSL::Cipher.new(@encryption_algorithm).key_len * 8

    case @dialect
    when '0x0300', '0x0302'
      @server_encryption_key = RubySMB::Crypto::KDF.counter_mode(
        @session_key,
        "SMB2AESCCM\x00",
        "ServerOut\x00",
        length: key_bit_len
      )
    when '0x0311'
      @server_encryption_key = RubySMB::Crypto::KDF.counter_mode(
        @session_key,
        "SMBS2CCipherKey\x00",
        @preauth_integrity_hash_value,
        length: key_bit_len
      )
    else
      raise RubySMB::Error::EncryptionError.new('Dialect is incompatible with SMBv3 decryption')
    end
    ######
    # DEBUG
    #puts "Server encryption key = #{@server_encryption_key.each_byte.map {|e| '%02x' % e}.join}"
    ######
  end

  th.decrypt(@server_encryption_key, algorithm: @encryption_algorithm)
end

#smb3_encrypt(data) ⇒ Object 



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# File 'lib/ruby_smb/client/encryption.rb', line 5

def smb3_encrypt(data)
  unless @client_encryption_key
    raise RubySMB::Error::EncryptionError.new('The encryption algorithm has not been set') if @encryption_algorithm.nil?

    key_bit_len = OpenSSL::Cipher.new(@encryption_algorithm).key_len * 8

    case @dialect
    when '0x0300', '0x0302'
      @client_encryption_key = RubySMB::Crypto::KDF.counter_mode(
        @session_key,
        "SMB2AESCCM\x00",
        "ServerIn \x00",
        length: key_bit_len
      )
    when '0x0311'
      @client_encryption_key = RubySMB::Crypto::KDF.counter_mode(
        @session_key,
        "SMBC2SCipherKey\x00",
        @preauth_integrity_hash_value,
        length: key_bit_len
      )
    else
      raise RubySMB::Error::EncryptionError.new('Dialect is incompatible with SMBv3 encryption')
    end
    ######
    # DEBUG
    #puts "Client encryption key = #{@client_encryption_key.each_byte.map {|e| '%02x' % e}.join}"
    ######
  end

  th = RubySMB::SMB2::Packet::TransformHeader.new(flags: 1, session_id: @session_id)
  th.encrypt(data, @client_encryption_key, algorithm: @encryption_algorithm)
  th
end