The RAR 5 format improves multi-core processor utilization, and adds a larger dictionary size of up to 1 GiB with 64-bit WinRAR. Special optional compression algorithms optimized for RGB bitmaps, raw audio files, Itanium executables, and plain text, which were supported by earlier versions, are supported only in the older RAR format, not RAR5.[14] Optional optimized compression of x86 executables and delta compression (for structured table data) are supported in both file formats. 5.50 (2017-08): adds support for a master password which can be used to encrypt passwords stored in WinRAR.