Fossil SCM

More clarifications to cryptocurrencies vs the Fossil "blockchain".

tangent 2020-10-12 19:56 trunk

Commit 26005b81bff1b27990c13e1cb78f84631e20f7fbffb12dd68263096d4e899052

Parent 70523a718c24d92…

1 file changed +13 -7

M www/blockchain.md

+13 -7

		--- www/blockchain.md
		+++ www/blockchain.md
		@@ -54,13 +54,11 @@
54	54	Cryptocurrencies must prevent three separate types of fraud to be useful:
55	55
56	56	* Type 1 is modification of existing currency. To draw an analogy
57	57	to paper money, we wish to prevent someone from using green and
58	58	black markers to draw extra zeroes on a US $10 bill so that it
59		- claims to be a $100 bill. Cryptocurrencies apply digital signatures
60		- to each block so that a given block of currency’s face value cannot
61		- be changed after it is created.
	59	+ claims to be a $100 bill.
62	60
63	61	* Type 2 is creation of new fraudulent currency that will pass
64	62	in commerce. To extend our analogy, it is the creation of new
65	63	US $10 bills. There are two sub-types to this fraud. In terms of
66	64	our analogy, they are:
		@@ -70,23 +68,31 @@
70	68	legitimate one, yet which will still pass in commerce
71	69
72	70	* Type 3 is double-spending existing legitimate cryptocurrency.
73	71	There is no analogy in paper money due to its physical form; it is a
74	72	problem unique to digital currency due to its infinitely-copyable
75		- nature. Cryptocurrencies prevent Type 3 frauds by making the
76		- prior owner of a block sign it over to the new owner. To avoid an
77		- O(n²) auditing problem as a result, cryptocurrencies also use a
78		- chain of hashes to make checking for double-spending quick and easy.
	73	+ nature.
79	74
80	75	How does all of this compare to Fossil?
81	76
82	77	1. <a id="signatures"></a>Signatures. Cryptocurrencies use a chain
83	78	of [digital signatures][dsig] to prevent Type 1 and Type 3 frauds. This
84	79	chain forms an additional link between the blocks, separate from the
85	80	hash chain that applies an ordering and lookup scheme to the blocks.
86	81	[_Blockchain: Simple Explanation_][bse] explains this “hash chain”
87	82	vs. “block chain” distinction in more detail.
	83	+
	84	+ These signatures prevent modification of the face value of each
	85	+ transation (Type 1 fraud) by ensuring that only the one signing a
	86	+ new block has the private signing key that could change an issued
	87	+ block after the fact.
	88	+
	89	+ The fact that these signatures are also chained prevents Type
	90	+ 3 frauds by making the prior owner of a block sign it over to
	91	+ the new owner. To avoid an O(n²) auditing problem as a result,
	92	+ cryptocurrencies add a separate chain of hashes to make checking
	93	+ for double-spending quick and easy.
88	94
89	95	Fossil has [a disabled-by-default feature][cs] to call out to an
90	96	external copy of [PGP] or [GPG] to sign commit manifests before
91	97	inserting them into the repository. You may wish to couple that with
92	98	a server-side [after-receive hook][arh] to reject unsigned commits.
93	99

	--- www/blockchain.md
	+++ www/blockchain.md
	@@ -54,13 +54,11 @@
54	Cryptocurrencies must prevent three separate types of fraud to be useful:
55
56	* Type 1 is modification of existing currency. To draw an analogy
57	to paper money, we wish to prevent someone from using green and
58	black markers to draw extra zeroes on a US $10 bill so that it
59	claims to be a $100 bill. Cryptocurrencies apply digital signatures
60	to each block so that a given block of currency’s face value cannot
61	be changed after it is created.
62
63	* Type 2 is creation of new fraudulent currency that will pass
64	in commerce. To extend our analogy, it is the creation of new
65	US $10 bills. There are two sub-types to this fraud. In terms of
66	our analogy, they are:
	@@ -70,23 +68,31 @@
70	legitimate one, yet which will still pass in commerce
71
72	* Type 3 is double-spending existing legitimate cryptocurrency.
73	There is no analogy in paper money due to its physical form; it is a
74	problem unique to digital currency due to its infinitely-copyable
75	nature. Cryptocurrencies prevent Type 3 frauds by making the
76	prior owner of a block sign it over to the new owner. To avoid an
77	O(n²) auditing problem as a result, cryptocurrencies also use a
78	chain of hashes to make checking for double-spending quick and easy.
79
80	How does all of this compare to Fossil?
81
82	1. <a id="signatures"></a>Signatures. Cryptocurrencies use a chain
83	of [digital signatures][dsig] to prevent Type 1 and Type 3 frauds. This
84	chain forms an additional link between the blocks, separate from the
85	hash chain that applies an ordering and lookup scheme to the blocks.
86	[_Blockchain: Simple Explanation_][bse] explains this “hash chain”
87	vs. “block chain” distinction in more detail.











88
89	Fossil has [a disabled-by-default feature][cs] to call out to an
90	external copy of [PGP] or [GPG] to sign commit manifests before
91	inserting them into the repository. You may wish to couple that with
92	a server-side [after-receive hook][arh] to reject unsigned commits.
93

	--- www/blockchain.md
	+++ www/blockchain.md
	@@ -54,13 +54,11 @@
54	Cryptocurrencies must prevent three separate types of fraud to be useful:
55
56	* Type 1 is modification of existing currency. To draw an analogy
57	to paper money, we wish to prevent someone from using green and
58	black markers to draw extra zeroes on a US $10 bill so that it
59	claims to be a $100 bill.


60
61	* Type 2 is creation of new fraudulent currency that will pass
62	in commerce. To extend our analogy, it is the creation of new
63	US $10 bills. There are two sub-types to this fraud. In terms of
64	our analogy, they are:
	@@ -70,23 +68,31 @@
68	legitimate one, yet which will still pass in commerce
69
70	* Type 3 is double-spending existing legitimate cryptocurrency.
71	There is no analogy in paper money due to its physical form; it is a
72	problem unique to digital currency due to its infinitely-copyable
73	nature.



74
75	How does all of this compare to Fossil?
76
77	1. <a id="signatures"></a>Signatures. Cryptocurrencies use a chain
78	of [digital signatures][dsig] to prevent Type 1 and Type 3 frauds. This
79	chain forms an additional link between the blocks, separate from the
80	hash chain that applies an ordering and lookup scheme to the blocks.
81	[_Blockchain: Simple Explanation_][bse] explains this “hash chain”
82	vs. “block chain” distinction in more detail.
83
84	These signatures prevent modification of the face value of each
85	transation (Type 1 fraud) by ensuring that only the one signing a
86	new block has the private signing key that could change an issued
87	block after the fact.
88
89	The fact that these signatures are also chained prevents Type
90	3 frauds by making the prior owner of a block sign it over to
91	the new owner. To avoid an O(n²) auditing problem as a result,
92	cryptocurrencies add a separate chain of hashes to make checking
93	for double-spending quick and easy.
94
95	Fossil has [a disabled-by-default feature][cs] to call out to an
96	external copy of [PGP] or [GPG] to sign commit manifests before
97	inserting them into the repository. You may wish to couple that with
98	a server-side [after-receive hook][arh] to reject unsigned commits.
99

Fossil SCM

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