introduction to bitcoin's scripting language
TRANSCRIPT
Overview
Function Execution
Components
Transactions Review
The Language
Examples
Computers as FunctionsGeneral purpose function execution units
von Neumann Lens
Classical Approach Towards Understanding
Text
Stack
Memory Where Execution Takes Place
LIFO ordering
Highly Structured Allocation and Deallocation Protocols
Script
Forth Like Programming Language
Reverse Polish Notation
Composed of OP_Codes
Turing incomplete
Goals of Script
The validation of a Bitcoin transaction
bitcoin will have conditions that must be met in the future to be moved - the scriptPubKey (locking script)
The script that meets these conditions - the scriptSig (unlocking script)
Bitcoin clients must run the locking and unlocking scripts to validate each transaction
Turing Incompleteness
Looping Forbidden
Transaction Scripts Must Halt
Health of the Network
scriptSig —> scriptPubKey<sig> <PubK> + DUP HASH160 <PubKHash> EQUALVERIFY CHECKSIGBoth must return not null to be valid.
Example: Alice Pays Bob
Standard Transaction used: Pay-to-Public-Key-Hash (P2PKH)
<BobSig> <BobPubK> + OP_DUP OP_HASH160 <BobPubKHash> OP_EQUAL OP_CHECKSIG
Example: Alice Pays Bob
Standard Transaction used: Pay-to-Public-Key-Hash (P2PKH)
<BobSig> <BobPubK> + OP_DUP OP_HASH160 <BobPubKHash> OP_EQUAL OP_CHECKSIG
BobSig
BobPubK
Example: Alice Pays Bob
Standard Transaction used: Pay-to-Public-Key-Hash (P2PKH)
<BobSig> <BobPubK> + OP_DUP OP_HASH160 <BobPubKHash> OP_EQUAL OP_CHECKSIG
BobSig
BobPubK
BobSig
BobPubK
BobPubK
Example: Alice Pays Bob
Standard Transaction used: Pay-to-Public-Key-Hash (P2PKH)
<BobSig> <BobPubK> + OP_DUP OP_HASH160 <BobPubKHash> OP_EQUAL OP_CHECKSIG
BobSig
BobPubK
BobSig
BobPubK
BobPubK
BobSig
BobPubK
BobPubKHash
Example: Alice Pays Bob
Standard Transaction used: Pay-to-Public-Key-Hash (P2PKH)
<BobSig> <BobPubK> + OP_DUP OP_HASH160 <BobPubKHash> OP_EQUAL OP_CHECKSIG
BobSig
BobPubK
BobSig
BobPubK
BobPubK
BobSig
BobPubK
BobPubKHash
BobSig
BobPubK
BobPubKHash
BobPubKHash
Example: Alice Pays Bob
Standard Transaction used: Pay-to-Public-Key-Hash (P2PKH)
<BobSig> <BobPubK> + OP_DUP OP_HASH160 <BobPubKHash> OP_EQUAL OP_CHECKSIG
BobSig
BobPubK
BobSig
BobPubK
BobPubK
BobSig
BobPubK
BobPubKHash
BobSig
BobPubK
BobPubKHash
BobPubKHash
BobSig
BobPubK
BobPubKHash
BobPubKHash
Example: Alice Pays Bob
Standard Transaction used: Pay-to-Public-Key-Hash (P2PKH)
<BobSig> <BobPubK> + OP_DUP OP_HASH160 <BobPubKHash> OP_EQUAL OP_CHECKSIG
BobSig
BobPubK
BobSig
BobPubK
BobPubK
BobSig
BobPubK
BobPubKHash
BobSig
BobPubK
BobPubKHash
BobPubKHash
BobSig
BobPubK
Bitcoin Script IDEhttp://www.cs.princeton.edu/~tongbinw/bitcoinIDE/build/editor.html
Resources:Bitcoin Script IDE
http://www.cs.princeton.edu/~tongbinw/bitcoinIDE/build/editor.html
Script Explorer
http://paulkernfeld.com/bse/
JS Script Interpreter
http://www.followthecoin.com/build-bitcoin-script-interpreter-javascript/
Wiki
https://en.bitcoin.it/wiki/Script
Mastering Bitcoin Chapter 5
ISBN-13: 978-1449374044