diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2d856b6..09b4ead 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -119,6 +119,12 @@ capsules. `SpecVersion` is 0.11.
   which `EncryptOptions.LargeArea` lets the writer use, after the signatures
   are made, only when what they produced does not fit in 32 KiB. The fixtures of v0.10 keep their 512 bytes
   (`AreaUnit`), which a reader accepts.
+- **Key of words.** Package `wordkey` derives a credential of `time_and_key`
+  from six or more words that the person chooses, with PBKDF2-HMAC-SHA256 of
+  600 000 iterations salted with the chain, the round and `capsule_id`
+  (§38.1); the words are normalised with the tables of Unicode 18.0.0.
+  `EncryptOptions.Words` adds it as one more credential, and the CLI takes
+  `-words` and `-words-file` in `encrypt` and `decrypt`.
 - **Author signature, `alg` 1.** `internal/ed25519strict` verifies with the
   strict profile of §29.9 and `authorkey` keeps the keys `dkauthor1…`.
   `EncryptOptions.AuthorKey` signs, inside the writer and after its checks;