Alexander Bernauer

What is Bitcoin?

Bitcoin Client

Motivation

What is a Currency? ● unforgeable ● exchangable ● quantifiable ● storable TRUS T

How can I obtain Bitcoins?

What can I spend Bitcoins on?

The Distributed Database Block n Block n + 1 Transaction

Controlled Currency Supply ● 6 blocks per hour ● 50 BTC per block award ● 50% award reduction per 4 years ● max. 21e6 BTC in 136 years

Bitcoin Address ABCDEFGHJKLMNPQRSTUVWX YZ abcdefghijkmnopqrstuvwxyz version [1]: 0x00 (main) | 0x6f (test) | 0x34 (namecoin) key_hash [21]: version + ripemd_160(sha_256(public_key)) point on elliptic curve (ECDSA) x [32]:... y [32]:... public_key [65]: 0x04 + x + y checksum [4]: head(sha_256(sha_256(key_hash))) address [25-34]: base58(key_hash + checksum)

Block

Merkle Tree

Target ● Keep 10 minutes per block on average ● Re-target every 2016 blocks ● Change is always less than factor 4 Maximum Target: 0x ffff Packed representation: a [3]: significant b [1]: exponent target [32]: a * 2^(8*(b-3)) bits [4]: b + a Maximum Target (packed): 0x1d00ffff

Difficulty Definition: difficulty := maximum_target / current_target

Transaction

Block n+1 Block n The Distributed Database Revised

Output Point

Input Point

Bitcoin Script Transfer to Bitcoin address: sig_script: pk_script:OP_DUP OP_HASH160 OP_EQUALVERIFY OP_CHECKSIG Transfer to IP address: sig_script: pk_script: OP_CHECKSIG Authorization: exec(sig_script + pk_script) = True

Signatures SIGHASH_ALL

Signatures SIGHASH_NONE my input foreign input

Signatures SIGHASH_SINGLE my in point out point with same index foreign input

Signatures SIGHASH_ALL + ANYONECANPAY my input foreign input

Contracts Escrow: sig_script: pk_script:2 3 OP_CHECKMULTISIG ● Providing a deposit ● Assurance contracts ● Digital heritage

Fees and Generated Coins Transaction fee: sum(output values) - sum(input values) Miner award: mined_coins + sum(fees) Block body: generation transaction transaction 2... transaction n

Generation Transaction Generation Input Point Transfer to IP address Transfer to Bitcoin address......

Generation Input Point

Numbers ● Number of Bitcoins ● ● Size of the block chain ● ● ● Odds ● ● ● Total power consumption ● ● arison

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Properties 0xdeadbeef

Problems

Links ● ● ● ● ● ● ● ●

Sources bill%2C_obverse.jpg png/ bank-icon-png/ icon-png/ icon-png/ Coffee.jpg