BlockTrail's CTO Ruben De Vries presentation on HD wallets at Bitcoin Wednesday meetup Amsterdam. *Disclaimer: This presentation is meant to be a general overview of the cryptography concepts mainly aimed at the non-tech user. Visit www.blocktrail.com for more information.

1. @BLOCKTRAIL

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

3. WIF:
5KW3g12hpQttWZxzKNkPmJUf54DaeUxXFsp7geC17ucZWHBnEZM
Private Key:
10040282235063873007714010036463238031100864115204934060177595144448851
5499779
What is a Private Key?

4. - 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?

5. - Private Key 1
- 1EHNa6Q4Jz2uvNExL497mE43ikXhwF6kZm
- Private Key int(sha256('to be or not to be'))
- 1J3m4nneGFppRjx6qv92qyz7EsMVdLfr8R
What is a Private Key?

6. - Randomly generated
- Considered safe / unique
How do we create a Private Key?

7. - To iterate over all of them:
- at 1 trillion (1000.000.000) keys / sec
- more than the age of the universe needed
- cost: ~ 32 years of the sun total energy output
Why is a Private Key safe / unique?

9. Private Key → Public Key → ScriptHash → Address
How do we get the address?

10. - “asymmetric cryptography”
- “elliptic curve”
- Private Key → Public Key is 'easy'
- Public Key → Private Key is 'impossible'
Private Key → Public Key

11. EC secp256k1

12. “Easy to compute, hard to reverse”

13. “Easy to compute, hard to reverse”

14. Magic Byte: 00
ScriptHash:
38831f7d12670c137bf2c6ec0956376e5e141683
Checksum: e88e9d67
base58(00 ~ 38831f7d12670c137bf2c6ec0956376e5e141683 ~
e88e9d67)
Address: 169ovL3nmvTbuNQTc2hipHi8wQiq3EvUk6
Public Key → ScriptHash → Address

15. Ruben de Vries - CTO, BlockTrail
@rubensayshi
2015 – the year of MultiSig and HD wallets