The IDL byte type is specified as follows:
byte
A byte is represented in 8 bits. The data representation format of byte data is guaranteed not to change when the data is transmitted by the RPC mechanism.
The IDL integer, character, and floating-point types (and hence any types constructed from these) are all subject to format conversion when they are transmitted between hosts that use different data representation formats. You can protect data of any type from format conversion by transmitting that type as an array of byte.