diff --git a/README.md b/README.md
index d2e453d..330b11b 100644
--- a/README.md
+++ b/README.md
@@ -36,15 +36,16 @@ namespace. Ideas:
 
 ## Shorten keys and collisions
 
-For the first version of the keys, we will use 3 bytes encoded as base64url,
-as described in [RFC4648, par. 5]. To allow for truncate-resistant upgrading
-of the URL key format, the first bit is set to `0`. That means the first base64
-character will always be in `/[A-Za-f]/`.
+First of all: A sexted is a value of 6 bits.
 
-This domain contains `8388608` values. If the service is somewhat used, we will
-get collisions early when we generate those keys at random. Instead, we will
-use format-preserving-encryption to construct a counter that visits every value
-in an unpredictable order. Daan will fix this.
+For generating keys, we will initially generate a random value of 4 sextets,
+where the first bit is set to `0`. If this collides with an existing key, we
+will generate a new one made out of 5 sextexts, and set the prefix bits to
+`0b10`. We will keep doing this until we don't have any collisions anymore.
+
+To get proper-looking keys, we format the key to characters using the
+base64url alphabet described in ([RFC4648, par. 5]). The encoded value will
+be saved in the database.
 
 [RFC4648, par. 5]: https://tools.ietf.org/html/rfc4648#section-5