Why is an invalid pubkey accepted in the blockchain? while trying to understand the address validation process, I fell upon this block : https://blockchain.info/tx/3d29f43a3278281192943276049c15e5f0d8c7e75d4d99a4cd6693113a948f48
In the outputs, the first two are regular pay-to-hash, but the last one is a pay-to-pubKey (the block was mentioned by the developers from blockchain.info as a bad solution to embed an ASCII message in the blockchain). My question is : as this pubKey is invalid, where does the address (1Du8MpTTV4VrQMHtgP4mG1Fq9q3ykb3L8h) come from ?
I could not manage to get it by hashing the pubKey...

thanks
Why is an invalid pubkey accepted in the blockchain?

It was intended as a message, not as a public key.
It is accepted in the blockchain because it is a valid output script, whether or not it is spendable is not relevant.

Where does the address 1Du8MpTTV4VrQMHtgP4mG1Fq9q3ykb3L8h come from?

That address is a result of the software blockchain.info uses to generate an address from an output script. Why or how that works is something you'll have to ask whoever wrote it.