Recommendation ITU-T H.235.6 holds the security procedures for the encryption profile (formerly in Annex D of Recommendation ITU-T H.235) including the accompanying native H.235/H.245 key management.
This revision introduces support for key lengths larger than 2048 bits. In previous versions bit sizes of 3072 and 4096 where defined. However the field size defined in H.235.0 was limited to 2048 bits.
Before version 4 of the H.235 sub-series, this profile was contained in the main body of Recommendation ITU-T H.235 and of its Annex D. Appendices IV, V, VI to H.235.0 show the complete clause, figure, and table mapping between H.235 versions 3 and 4.