(AEAD; that is, data that are not encrypted but should be authenticated) and a new method for generating a sequence of offsets. OCB2 was first published in 2003, originally named authenticated-encryption mode, or advanced encryption mode (AEM) and was shown to be completely insecure in 2019. OCB3, published in 2011, changes again the way offsets are computed and introduces minor performance improvements.

OCB2 was standardized in ISO/IEC19772:2009 (although it was removed from the standard following the publication of the attack) and a