Addressing errata 151328

ch08.asciidoc

@@ -866,6 +866,8 @@ P2Pool mining is more complex than pool mining because it requires that the pool
 
 Recently, participation in P2Pool has increased significantly as mining concentration in mining pools has approached levels that create concerns of a((("51% attacks"))) 51% attack (see <<consensus_attacks>>). Further development of the P2Pool protocol continues with the expectation of removing the need for running a full node and therefore making decentralized mining even easier to use.(((range="endofrange", startref="ix_ch08-asciidoc25")))(((range="endofrange", startref="ix_ch08-asciidoc24")))(((range="endofrange", startref="ix_ch08-asciidoc23"))) 
 
+Even though P2Pool reduces the concentration of power by mining pool operators, it is conceivably vulnerable to 51% attacks against the share chain itself. A much broader adoption of P2Pool does not solve the 51% attack problem for bitcoin itself. Rather, P2Pool makes bitcoin more robust overall, as part of a diversified mining ecosystem. 
+
 [[consensus_attacks]]
 === Consensus Attacks
 
@@ -887,7 +889,7 @@ Despite its name, the 51% attack scenario doesn't actually require 51% of the ha
 
 The massive increase of total hashing power has arguably made bitcoin impervious to attacks by a single miner. There is no possible way for a solo miner to control more than a small percentage of the total mining power. However, the centralization of control caused by mining pools has introduced the risk of for-profit attacks by a mining pool operator. The pool operator in a managed pool controls the construction of candidate blocks and also controls which transactions are included. This gives the pool operator the power to exclude transactions or introduce double-spend transactions. If such abuse of power is done in a limited and subtle way, a pool operator could conceivably profit from a consensus attack without being noticed.
 
-Not all attackers will be motivated by profit, however. One potential attack scenario is where an attacker intends to disrupt the bitcoin network without the possibility of profiting from such disruption. A malicious attack aimed at crippling bitcoin would require enormous investment and covert planning, but could conceivably be launched by a well-funded, most likely state-sponsored, attacker. Alternatively, a well-funded attacker could attack bitcoin's consensus by simultaneously amassing mining hardware, compromising pool operators and attacking other pools with denial-of-service. All of these scenarios are theoretically possible, but increasingly impractical as the bitcoin network's overall hashing power continues to grow exponentially. Recent advancements in bitcoin, such as P2Pool mining, aim to further decentralize mining control, making bitcoin consensus even harder to attack.  
+Not all attackers will be motivated by profit, however. One potential attack scenario is where an attacker intends to disrupt the bitcoin network without the possibility of profiting from such disruption. A malicious attack aimed at crippling bitcoin would require enormous investment and covert planning, but could conceivably be launched by a well-funded, most likely state-sponsored, attacker. Alternatively, a well-funded attacker could attack bitcoin's consensus by simultaneously amassing mining hardware, compromising pool operators and attacking other pools with denial-of-service. All of these scenarios are theoretically possible, but increasingly impractical as the bitcoin network's overall hashing power continues to grow exponentially. 
 
 Undoubtedly, a serious consensus attack would erode confidence in bitcoin in the short term, possibly causing a significant price decline. However, the bitcoin network and software are constantly evolving, so consensus attacks would be met with immediate countermeasures by the bitcoin community, making bitcoin hardier, stealthier, and more robust than ever.(((range="endofrange", startref="ix_ch08-asciidoc29")))(((range="endofrange", startref="ix_ch08-asciidoc28")))(((range="endofrange", startref="ix_ch08-asciidoc1")))(((range="endofrange", startref="ix_ch08-asciidoc0")))