The document discusses wallet technologies, particularly focusing on private keys, hierarchical deterministic (HD) wallets, and multisig features. It highlights the benefits of HD wallets in managing multiple addresses while addressing privacy issues and the challenges of backup. Additionally, it explains the concept of generating private keys from a master key and the use of mnemonics for easier human interaction.

2. Wallet Technologies
- a semi-technical look at -
Private Keys, HD Wallets & MultiSig
Ruben de Vries - CTO, BlockTrail
@rubensayshi
2015 – the real year of MultiSig and HD wallets

3. - A really big number
- between 1 and 2^256
115792089237316195423570985008687907852837564279074904382605163141
518161494400
^---- ~ 11 with 77 0's
1000000000000
1000000000
One million -> 1000000
What is a Private Key?

4. - Hierarchical Deterministic Wallet
- BIP32
HD Wallet

5. - Problem: all transactions are public
- Problem: reuse addresses = bad for privacy
- Solution: MANY private keys
HD Wallet

6. - Problem: we need to backup every new private keys
- Solution: generate 100 private keys in advance
- Problem: safe backups are a lot of work
- Problem: we're lazy
HD Wallet

7. - More Problems (that HD wallets solve):
- we want to have fine grained control over who has
access to wallets
- we want to let a 3rd party generate addresses for
us
HD Wallet

8. - Private Key is a number
- So if we +1 that number, we have a new Private Key
- with a new address
- Start from a 'Master Key'
- easy to reproduce all keys from there
- to get key 14474 you just 'Master Key' + 14474
- In reality it's more like multiplying than adding
HD Wallet to the rescue

11. Between

12. - Give your mining pool M/500 and they can generate new
addresses to do payouts;
- M/500/1, M/500/2, M/500/3
This works for public keys too!!

13. Hierarchical Deterministic Keys

14. - BIP39 – mnemonics
“region clock summer pig account pistol under maple trash organ
idea laugh”
words bits
12 128
16 192
24 256
HD Wallet; the Master Seed

15. Mnemonic:
“region clock summer pig account pistol under maple trash organ
idea laugh”
Hex:
bba8844939bb875c81d956ddb723180fee1217596c5bb8be2826c743e3922fb9bd
fad8b6d8afb09b23ac4fe1e209c4c5c93539165804309c388f9c381903ebfd
Int:
982846101892683200542478295468301190003993215044065721400615115897
630304237843873081670725340206594483057811523827869114800091709139
8156914557840747916285
Bin:
101110111010100010000100010010010011100110111011100001110101110010
000001110110010101011011011101101101110010001100011000000011111110
111000010010000101110101100101101100010110111011100010111110001010
000010011011000111010000111110001110010010001011111011100110111101
Mnemonic = human readable representation