add summary

BBQr.md

@@ -1,5 +1,7 @@
 # The BBQr Protocol - Make a series of QR codes to hold lots of data
 
+Public Domain by [Coinkite](https://coinkite.com)
+
 ## Introduction
 
 This protocol is for transmitting binary data over a series of QR codes.

README.md

@@ -9,7 +9,43 @@ Project Status: **New & proposed --- looking for feedback**
 
 # Specification
 
-See [BBQr.md](BBQr.md).
+See full spec [BBQr.md](BBQr.md).
+
+# Summary
+
+This protocol enables files larger than can fit into a single QR
+to be sent as a series of QR codes (an "animated QR"). The target
+file types are PSBT (BIP-174) and signed Bitcoin transactions, but
+it also supports CBOR, JSON and Text options for general purpose use.
+
+We carefully consider the data inside QR codes, and apply a
+deep knowledge of how QR codes work, so that no pixel nor byte
+is ever wasted! Internally it supports HEX and Base2 serializations
+and a constrained ZLIB option for data compression. This is all
+done with an eye to embedded implementations on very contrained
+devices (ie. hardware wallets), which may not have enough memory
+to keep more than a single QR code around.
+
+Here are some compression numbers, using the ZLIB encoding option.
+Even though Bitcoin files have relatively high entropy (with hashes
+and UTXO's being non-compressable) we still see 30% typical size
+reduction.
+
+File (see testing/data) | Before | After | Compression Ratio
+------------------------|--------|-------|------------------
+1in1000out.psbt         |  35644 | 22095 |  38.0%
+1in100out.psbt          |   4142 | 2654  |  35.9%
+1in10out.psbt           |    992 | 670   |  32.5%
+1in20out.psbt           |   1342 | 897   |  33.2%
+1in2out.psbt            |    675 | 458   |  32.1%
+devils-txn.txn          |    666 | 356   |  46.5%
+finalized-by-ckcc.txn   |   1932 | 807   |  58.2%
+signed.txn              | 100757 | 77090 |  23.5%
+
+By using Base32 character encoding inside a QR code with the unique
+"alphanumeric" encoding (where each character takes 5.5 bits of
+space, and encodes 5 bits of binary), we can acheive the smallest
+possible QR codes.
 
 # Example Image