Add UUIDv8 and v4 specifications

Correct the bit placement per RFC draft
https://datatracker.ietf.org/doc/html/draft-peabody-dispatch-new-uuid-format#name-uuid-version-8

2 files changed, 21 insertions, 11 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 5311b82..4fe6734 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,6 +13,7 @@ sqlx = "0.7.3"
 version = "1.6.1"
 features = [
     "v4",                # Lets you generate random UUIDs
+    "v8",                # Custom UUID format
     "fast-rng",          # Use a faster (but still sufficiently random) RNG
     "macro-diagnostics", # Enable better diagnostics for compile-time UUIDs
     "serde",
diff --git a/README.md b/README.md
index b7b527c..3832ec4 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ Provides at least three core systems:
 ### Token Format
 
 Tokens are 128-bit (16 byte) UUIDs which are always base64 encoded using the URL-safe alphabet without padding.
-This means that every token is a 22-character string containing the alphabet: `[a-z][A-Z][0-9]_-`
+This means that every token is a 22-character string containing the alphabet: "`[a-z][A-Z][0-9]_-`"
 
 ### Namespacing
 
@@ -26,8 +26,8 @@ If a namespace is not provided, the request is rejected.
 
 ### Prefixing
 
-A prefix is an unsigned 14-bit value (Hex: 0x000-0x3FFF) as a means of uniquely identifying token sources.
-The 14-bit value has a maximum value of 16,384 (0-16383 inclusive).
+A prefix is an unsigned 16-bit value (Hex: 0x000-0xFFFF) as a means of uniquely identifying token sources.
+The 16-bit value has a maximum value of 65,536 (0-65535 inclusive).
 
 Prefixes MAY be set via a runtime configuration or defined in the datastore within a namespace. 
 Once defined in the datastore, such prefixes MUST NOT be changed.
@@ -55,21 +55,30 @@ If operating with a remote database, FK must not try to operate in a peering / c
 
 ### Namespace limits
 
-NOTE: look at UUIDv5 methods, but *do not* use them as UUIDv5 leverages deterministic hashing to produce tokens.
+Non-prefixed UUIDs will follow the UUIDv4-Variant1 specification in [RFC-4122](https://www.rfc-editor.org/rfc/rfc4122#section-4.4):
 
-UUIDv4 (Version 4 - Variant 1) has 6 bits reserved for identification and encoding purposes - bits 6, 7, and 12-15. 
-( RFC 4122 Section 4.4 - https://datatracker.ietf.org/doc/html/rfc4122#section-4.4 )
+                0      0 0      1 1      2 2      3
+                0      7 8      5 6      3 4      1
+                -----------------------------------
+     000-031    xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx 
+     032-063    xxxxxxxx xxxxxxxx 0100xxxx xxxxxxxx
+     064-095    01xxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
+     096-127    xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
+
+
+Prefixed Tokens will use a 16-bit identifier replacing the "random" least-significant bits of the time-low (clock) sequence.
+In order to support this and prevent compatibility problems with other UUID representations, FortKnox will [generate UUIDv8-based tokens](https://datatracker.ietf.org/doc/html/draft-peabody-dispatch-new-uuid-format#name-uuid-version-8).
 
-Proposed: 14-bit identifier replacing the "random" clock value for locations which need to avoid collisions but also need to identify the source location.
 Assuming P is an identifier bit and using a zero-index count, the bit-specific structure would be as follows: 
 
                 0      0 0      1 1      2 2      3
                 0      7 8      5 6      3 4      1
                 -----------------------------------
-     000-031    XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX 
-     032-063    XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
-     064-095    XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
-     096-127    XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
+     000-031    PPPPPPPP PPPPPPPP xxxxxxxx xxxxxxxx 
+     032-063    xxxxxxxx xxxxxxxx 1000xxxx xxxxxxxx
+     064-095    01xxxxxk xxxxxxxx xxxxxxxx xxxxxxxx
+     096-127    xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
 
 
 This leaves a maximum table space of `2^106` values or 8.1129638415e31 bits. At 100 bytes per associated token, this allows for billions of exabytes per regional namespace.
+