Microsoft will finally kill obsolete cipher that has wreaked decades of havoc

Microsoft is killing off an obsolete and vulnerable encryption cipher that Windows has supported by default for 26 years following more than a decade of devastating hacks that exploited it and recently faced blistering criticism from a prominent US senator. When the software maker rolled out Active Directory in 2000, it made RC4 a sole means of securing the Windows component, which administrators use to configure and provision fellow administrator and user accounts inside large organizations. RC4, short for Rivest Cipher 4, is a nod to mathematician and cryptographer Ron Rivest of RSA Security, who developed the stream cipher in 1987.

Within days of the trade-secret-protected algorithm being leaked in 1994, a researcher demonstrated a cryptographic attack that significantly weakened the se