This landscape covers published records that combine a key-establishment concept — key encapsulation mechanisms, key agreement protocols or cipher suite negotiation — with a deployment-level constraint such as handshake message size, packet fragmentation, downgrade protection, handshake latency, session resumption or shared secret derivation. The search deliberately pairs the cryptographic primitive with the practical mechanics of shipping it in a protocol, since many filings claim the primitive alone without addressing deployment. There are 140 such records in scope, published between 2015 and mid-2026.

The assignee ranking covers 44 companies, with the leader holding 19 records against a fifth-place figure of 14 and a tenth-place figure of 7. The top 5 assignees together account for 60.7% of all 140 records, and the top 10 account for 98.6%, meaning nearly all activity sits within a small group of network equipment vendors, device makers and specialist cryptography firms. This is a concentrated field rather than a fragmented one, so a competitive review should prioritise the leading names before scanning the long tail.

Filing volume peaked at 20 records in 2019 and has since eased, with the most recent complete comparison — 2021 at 8 records versus 2024 at 7 — showing a -13% change. Figures for 2025 and 2026 are still incomplete because publication typically lags filing by around 18 months, so they should not be read as evidence of continued decline. The honest read is that the field has settled into a steadier, lower-volume pace after its 2019 peak rather than that it is shrinking.