Fossil SCM

Several clarity improvements to the discussion of cryptocurrencies in blockchain.md.

tangent 2020-10-12 19:45 trunk

Commit 70523a718c24d9237765a419362502d33cfcfc4d8b019d83c6d34bd3fca65f53

Parent a92365d72213c6d…

1 file changed +28 -26

M www/blockchain.md

+28 -26

		--- www/blockchain.md
		+++ www/blockchain.md
		@@ -56,18 +56,20 @@
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	59	claims to be a $100 bill. Cryptocurrencies apply digital signatures
60	60	to each block so that a given block of currency’s face value cannot
61		- be changed after it is created. The [proof-of-work][pow] aspect
62		- prevents the creator from setting its initial value fraudulently.
63		-
64		-* Type 2 is making new counterfeit $10 bills that look
65		- sufficiently like the original to pass in commerce. Cryptocurrencies
66		- chain blocks together and establish a sufficiently hard work problem
67		- to create new currency that Type 2 frauds are impractical short of
68		- doing the actual mining needed to produce legitimate cryptocurrency.
	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:
	67	+
	68	+ * Type 2a: copying of an existing legitimate $10 bill
	69	+ * Type 2b: printing a new $10 bill that is unlike an existing
	70	+ legitimate one, yet which will still pass in commerce
69	71
70	72	* Type 3 is double-spending existing legitimate cryptocurrency.
71	73	There is no analogy in paper money due to its physical form; it is a
72	74	problem unique to digital currency due to its infinitely-copyable
73	75	nature. Cryptocurrencies prevent Type 3 frauds by making the
		@@ -108,16 +110,10 @@
108	110	you don’t have any of their private signing keys, either.
109	111	Cyrptocurrencies also use the work problem to prevent Type 2
110	112	forgeries, but the application of that to Fossil is a matter we get
111	113	to [later](#work).
112	114
113		- If Fossil signatures prevent Type 1 and Type 2 frauds, why then are
114		- they not enabled by default? Because they are defense-in-depth
115		- measures, not the minimum sufficient measures needed to prevent
116		- repository fraud in Fossil. Fossil provides its primary protections
117		- through other means.
118		-
119	115	Although you have complete control over the contents of your local
120	116	Fossil repository clone, you cannot perform Type 1 forgery on its
121	117	contents short of executing a [preimage attack][prei] on the hash
122	118	algorthm. ([SHA3-256][SHA-3] by default in the current version of
123	119	Fossil.) Even if you could, Fossil’s sync protocol will prevent the
		@@ -140,21 +136,27 @@
140	136	question. (Inversely, enabling commit clearsigning is a good idea
141	137	if you have committers on your repo whom you don’t trust not to
142	138	commit Type 2 frauds. But let us be clear: your choice of setting
143	139	does not answer the question of whether Fossil is a blockchain.)
144	140
145		- If you’re wondering why Fossil’s current commit signing feature is
146		- not enabled by default and why it doesn’t verify signatures on
147		- commits, it is because Fossil is not itself a [PKI], and there is no
148		- way for regular users of Fossil to link it to a PKI, since doing so
149		- would likely result in an unwanted [PII] disclosure. There is no
150		- email address in a Fossil commit manifest that you could use to
151		- query one of the public PGP keyservers, for example. It therefore
152		- becomes a local policy matter as to whether you even want to have
153		- signatures, because they’re not without their downsides.
154		-
155		-2. <a id="work"></a>Work Contests. Cryptocurrencies prevent forgery
	141	+ If Fossil signatures prevent Type 1 and Type 2 frauds, you
	142	+ may wonder why they are not enabled by default. It is because
	143	+ they are defense-in-depth measures, not the minimum sufficient
	144	+ measures needed to prevent repository fraud, unlike the equivalent
	145	+ protections in a cryptocurrency blockcahin. Fossil provides its
	146	+ primary protections through other means, so it doesn’t need to
	147	+ mandate signatures.
	148	+
	149	+ Also, Fossil is not itself a [PKI], and there is no way for regular
	150	+ users of Fossil to link it to a PKI, since doing so would likely
	151	+ result in an unwanted [PII] disclosure. There is no email address
	152	+ in a Fossil commit manifest that you could use to query one of the
	153	+ public PGP keyservers, for example. It therefore becomes a local
	154	+ policy matter as to whether you even want to have signatures,
	155	+ because they’re not without their downsides.
	156	+
	157	+2. <a id="work"></a>Work Contests. Cryptocurrencies prevent Type 2b forgeries
156	158	by setting up some sort of contest that ensures that new coins can come
157	159	into existence only by doing some difficult work task. This “mining”
158	160	activity results in a coin that took considerable work to create,
159	161	which thus has economic value by being a) difficult to re-create,
160	162	and b) resistant to [debasement][dboc].
		@@ -178,11 +180,11 @@
178	180	not. They do this in part by identifying the linear chain with the
179	181	greatest cumulative [work time](#work) as the legitimate chain. All
180	182	blocks not on that linear chain are considered “orphans” and are
181	183	ignored by the cryptocurrency software.
182	184
183		- It inverse is sometimes called the “51% attack” because a single
	185	+ Its inverse is sometimes called the “51% attack” because a single
184	186	actor would have to do slightly more work than the entire rest of
185	187	the community using a given cryptocurrency in order for their fork
186	188	of the currency to be considered the legitimate fork. This argument
187	189	soothes concerns that a single bad actor could take over the
188	190	network.
189	191

	--- www/blockchain.md
	+++ www/blockchain.md
	@@ -56,18 +56,20 @@
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. The [proof-of-work][pow] aspect
62	prevents the creator from setting its initial value fraudulently.
63
64	* Type 2 is making new counterfeit $10 bills that look
65	sufficiently like the original to pass in commerce. Cryptocurrencies
66	chain blocks together and establish a sufficiently hard work problem
67	to create new currency that Type 2 frauds are impractical short of
68	doing the actual mining needed to produce legitimate cryptocurrency.


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. Cryptocurrencies prevent Type 3 frauds by making the
	@@ -108,16 +110,10 @@
108	you don’t have any of their private signing keys, either.
109	Cyrptocurrencies also use the work problem to prevent Type 2
110	forgeries, but the application of that to Fossil is a matter we get
111	to [later](#work).
112
113	If Fossil signatures prevent Type 1 and Type 2 frauds, why then are
114	they not enabled by default? Because they are defense-in-depth
115	measures, not the minimum sufficient measures needed to prevent
116	repository fraud in Fossil. Fossil provides its primary protections
117	through other means.
118
119	Although you have complete control over the contents of your local
120	Fossil repository clone, you cannot perform Type 1 forgery on its
121	contents short of executing a [preimage attack][prei] on the hash
122	algorthm. ([SHA3-256][SHA-3] by default in the current version of
123	Fossil.) Even if you could, Fossil’s sync protocol will prevent the
	@@ -140,21 +136,27 @@
140	question. (Inversely, enabling commit clearsigning is a good idea
141	if you have committers on your repo whom you don’t trust not to
142	commit Type 2 frauds. But let us be clear: your choice of setting
143	does not answer the question of whether Fossil is a blockchain.)
144
145	If you’re wondering why Fossil’s current commit signing feature is
146	not enabled by default and why it doesn’t verify signatures on
147	commits, it is because Fossil is not itself a [PKI], and there is no
148	way for regular users of Fossil to link it to a PKI, since doing so
149	would likely result in an unwanted [PII] disclosure. There is no
150	email address in a Fossil commit manifest that you could use to
151	query one of the public PGP keyservers, for example. It therefore
152	becomes a local policy matter as to whether you even want to have
153	signatures, because they’re not without their downsides.
154
155	2. <a id="work"></a>Work Contests. Cryptocurrencies prevent forgery






156	by setting up some sort of contest that ensures that new coins can come
157	into existence only by doing some difficult work task. This “mining”
158	activity results in a coin that took considerable work to create,
159	which thus has economic value by being a) difficult to re-create,
160	and b) resistant to [debasement][dboc].
	@@ -178,11 +180,11 @@
178	not. They do this in part by identifying the linear chain with the
179	greatest cumulative [work time](#work) as the legitimate chain. All
180	blocks not on that linear chain are considered “orphans” and are
181	ignored by the cryptocurrency software.
182
183	It inverse is sometimes called the “51% attack” because a single
184	actor would have to do slightly more work than the entire rest of
185	the community using a given cryptocurrency in order for their fork
186	of the currency to be considered the legitimate fork. This argument
187	soothes concerns that a single bad actor could take over the
188	network.
189

	--- www/blockchain.md
	+++ www/blockchain.md
	@@ -56,18 +56,20 @@
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:
67
68	* Type 2a: copying of an existing legitimate $10 bill
69	* Type 2b: printing a new $10 bill that is unlike an existing
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
	@@ -108,16 +110,10 @@
110	you don’t have any of their private signing keys, either.
111	Cyrptocurrencies also use the work problem to prevent Type 2
112	forgeries, but the application of that to Fossil is a matter we get
113	to [later](#work).
114






115	Although you have complete control over the contents of your local
116	Fossil repository clone, you cannot perform Type 1 forgery on its
117	contents short of executing a [preimage attack][prei] on the hash
118	algorthm. ([SHA3-256][SHA-3] by default in the current version of
119	Fossil.) Even if you could, Fossil’s sync protocol will prevent the
	@@ -140,21 +136,27 @@
136	question. (Inversely, enabling commit clearsigning is a good idea
137	if you have committers on your repo whom you don’t trust not to
138	commit Type 2 frauds. But let us be clear: your choice of setting
139	does not answer the question of whether Fossil is a blockchain.)
140
141	If Fossil signatures prevent Type 1 and Type 2 frauds, you
142	may wonder why they are not enabled by default. It is because
143	they are defense-in-depth measures, not the minimum sufficient
144	measures needed to prevent repository fraud, unlike the equivalent
145	protections in a cryptocurrency blockcahin. Fossil provides its
146	primary protections through other means, so it doesn’t need to
147	mandate signatures.
148
149	Also, Fossil is not itself a [PKI], and there is no way for regular
150	users of Fossil to link it to a PKI, since doing so would likely
151	result in an unwanted [PII] disclosure. There is no email address
152	in a Fossil commit manifest that you could use to query one of the
153	public PGP keyservers, for example. It therefore becomes a local
154	policy matter as to whether you even want to have signatures,
155	because they’re not without their downsides.
156
157	2. <a id="work"></a>Work Contests. Cryptocurrencies prevent Type 2b forgeries
158	by setting up some sort of contest that ensures that new coins can come
159	into existence only by doing some difficult work task. This “mining”
160	activity results in a coin that took considerable work to create,
161	which thus has economic value by being a) difficult to re-create,
162	and b) resistant to [debasement][dboc].
	@@ -178,11 +180,11 @@
180	not. They do this in part by identifying the linear chain with the
181	greatest cumulative [work time](#work) as the legitimate chain. All
182	blocks not on that linear chain are considered “orphans” and are
183	ignored by the cryptocurrency software.
184
185	Its inverse is sometimes called the “51% attack” because a single
186	actor would have to do slightly more work than the entire rest of
187	the community using a given cryptocurrency in order for their fork
188	of the currency to be considered the legitimate fork. This argument
189	soothes concerns that a single bad actor could take over the
190	network.
191

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