What do you think the chances of larger agencies corrupting crytocurrencies

[MediChain]

I'm specifically thinking that if you can afford the resources to be doing 51% of all the mining, you can subvert a blockchain. You might want to do this if you had currency exchange barriers and individuals where moving funds using cryptocurrencies. For example which governments or organizations could afford to do this? What might be the consequences?

[WyattS]

Best fear based attack on BTC that I've heard about is if the great firewall of China decided to block miners connecting to each other.  If they did this, then BTC would run two chains, one in China and one in the rest of the world.  It'd cause a split and really confuse the value.  Then, they could cause even more harm by reopening the firewall and watching the chains attempt to reconcile.

That said, it's all fear based talk.  Lots of work has gone into these and creating a 51% attack is not cheap or easy.  Which is the point.

[MediChain]

"fear based talk" - I guess I'm not a particularly panic based person so that doesn't worry me. I'm looking for a coolheaded assessment of the level of resources needed to undermine specific systems through a 51% attack. This calm approach allows us to think of solutions. So it's not "fear based" any more than any other cryptographic threat assessment is.

[Branko]

Many coins are cheap  enough to make it possible...you'd need something like 7-8000 GPUs to take
more than 50% hashing power of some ethash blockchains