10 minutes for the transaction to confirm
and be inscribed in the blockchain per
blockchain miners. So, for large
purchases such as a car or real estate,
you would want to wait to see the
transaction confirmed, but you wouldn’t
bother to do so for a coffee purchase.
Public/Private-Key
Cryptography 101
When the wallet is initialized or set up
for the first time, an address, public key,
and private key are automatically
generated. Bitcoin is based on public-
key encryption, meaning that you can
give out the public key freely but must
keep the private key to yourself.
Bitcoin addresses are created by the
software picking a random number and
creating a public/private key pair (per
the current standard, Elliptic Curve
Digital Signature Algorithm, or ECDSA)
that is mathematically related, and
confirmed at the time of spending the
Bitcoin. This startup operation generates
the private key, but additional steps are
required to generate the Bitcoin address.
The Bitcoin address is not simply the
public key; rather, the public key is
further transformed for more effective
use. It is cycled through additional
encryption protocols (like SHA-256 and
RIPEMD-160), a hashing operation
(transforming a string of characters into
a shorter fixed-length value or key that
represents the original string), and
administrative operations (removal of
similar-looking characters, like
lowercase
adding an identifying number to the
beginning of the address—for most
Bitcoin addresses, this is a 1, indicating
it is a public Bitcoin network address).
It is infeasible though technically
possible that two different people could
generate the same Bitcoin address. In
such a case, both would be able to spend
the coins on that particular address. The
odds of this happening are so small,
however, that it is almost
99.9999999999 percent impossible. A
Bitcoin wallet can contain multiple
addresses (one security procedure is
using or generating a new address for
each transaction), and one or more
private keys, which are saved in the
wallet file. The private keys are
mathematically related to all Bitcoin
addresses generated for the wallet.
In Bitcoin, a private key is usually a
256-bit number (although some wallets
might use between 128 and 512 bits),
which can be represented in one of
several ways. Here is one example of a
private key in hexadecimal format (256
bits in hexadecimal is 32 bytes, or 64
characters in the range 0–9 or A–F):
E9 87 3D 79 C6 D8 7D C0 FB 6A 57 78
63 33 89 F4
45 32 13 30 3D A6 1F 20 BD 67 FC 23
3A A3 32 62
Here is another example of a private key
and its corresponding public address:
Private key:
79186670301299046436858412936420417076660923359050732094116068951337164773779
Public address:
1EE8rpFCSSaBmG19sLdgQLEWuDaiYVFT9J
Doing some sort of back calculation to
derive the private key from the public
key is either impossible (per the hashing
operation, which is one-way only, or
other techniques) or prohibitively
expensive (tremendous computing power
operating over a longer time than would
be necessary to confirm the transaction).
Only the address is needed to receive
Bitcoins, whereas the public/private key
pair is required to send Bitcoins.
Appendix B. Ledra Capital
Mega Master Blockchain List
New York–based venture capital firm
Ledra Capital has an ongoing attempt to
brainstorm and enumerate the wide
range of potential uses of blockchain
technology. Some of these categories
include financial instruments; public,
private, and semipublic records;
physical asset keys; intangibles; and
other potential applications:
I. Financial instruments, records, and
models
1. Currency
2. Private equities
3. Public equities
4. Bonds
5. Derivatives (futures,
forwards, swaps, options,
and more complex
variations)
6. Voting rights associated with
any of the preceding
7. Commodities
8. Spending records
9. Trading records
10. Mortgage/loan records
11. Servicing records
12. Crowdfunding
13. Microfinance
14. Microcharity
II. Public records
15. Land titles
16. Vehicle registries
17. Business license
18. Business
incorporation/dissolution
records
19. Business ownership records
20. Regulatory records
21. Criminal records
22. Passports
23. Birth certificates
24. Death certificates
25. Voter IDs
26. Voting
27. Health/safety inspections
28. Building permits
29. Gun permits
30. Forensic evidence
31. Court records
32. Voting records
33. Nonprofit records
34. Government/nonprofit
accounting/transparency
III. Private records
35. Contracts
36. Signatures
37. Wills
38. Trusts
39. Escrows
40. GPS trails (personal)
IV. Other semipublic records
41. Degree
42. Certifications
43. Learning outcomes
44. Grades
45. HR records (salary,
performance reviews,
accomplishment)
46. Medical records
47. Accounting records
48. Business transaction records
49. Genome data
50. GPS trails (institutional)
51. Delivery records
52. Arbitration
V. Physical asset keys
53. Home/apartment keys
54. Vacation home/timeshare
keys
55. Hotel room keys
56. Car keys
57. Rental car keys
58. Leased cars keys
59. Locker keys