Due to restrictions on the export of cryptography from the United States, most software for use outside of the US and Canada were restricted to 40-bit RC2 and RC4 encryption from 1992 to 1999, and 56-bit encryption in 1999. In January 2000, the restriction was lifted entirely, allowing full-size encryption to be used.

Non-English versions of Windows and Internet Explorer (including service packs) released before January 2000 had "low encryption", restricted either to 40-bit or 56-bit. English versions had both "high encryption" (128-bit) (for US and Canada use only) and "low encryption" (for use in other countries). However, service packs and updates released after that date would upgrade the system to high encryption:

• SPNotes.htm in Windows 2000 SP4 installation media states that SP2 (released on 2001/05/16) or later would upgrade the system to high encryption, and only formatting and re-installing RTM or SP1 can restore the system back to 56-bit encryption.
• Installing IE 5.5 (released on 2000/06/19) or later would upgrade 9x and NT4 to high encryption, regardless of language.

IE 5.5 on NT 4.0 is particularly problematic: it only requires SP3 on NT 4.0, so a user might want to install a later service pack version after installing IE 5.5, which would not be possible, because the service packs, even SP6a, are only available in low encryption for non-English versions of Windows; high encryption versions are only available in English, and are thus incompatible. The workaround is to rename or remove schannel.dll before installing the service pack, as that file is what the service pack installer checks when determining whether the system has high encryption. (source) (KB261328 states that rsabase.dll and rsaenh.dll are also used in encryption.) For new installations, it's easier to just install SP6a before installing IE.

High encryption market bulletin

High encryption packs:

• IE
• Windows 2000