Pictures and non-transaction data in block chain It is well known that non transaction related information has found its way into the block chain. This raises multiple questions: (1) How was it done, and is it still possible (2) If someone where to introduce contraband into the block chain, this would be propagated to all copies of the ledger. Could make it illegal real quick. I know my questions are from a devils advocate - not because I don't like BitCoin, to the contrary, but I want to fully understand its risks as well. Thanks
It is still possible to embed data into the blockchain, and it is actually fairly trivial. But don't do it. It is rude and detrimental to the network as it takes up resources to host your random data on all full nodes in the network. The polite way to do it is to create an OP_RETURN output, but that only allows up to 80 bytes of data. The impolite way is to just put your data into the output script since output scripts are not validated until they are spent. But that is impolite as the output is not provably unspendable (and thus can be pruned from the UTXO set) so it will take up full nodes' disk space and memory.