I am trying to parse the block chain and have come across some unusual transaction outputs. Maybe someone could enlighten me.
The first one is output 1 of tx b728387a3cf1dfcff1eef13706816327907f79f9366a7098ee48fc0c00ad2726.
https://blockchain.info/tx/b728387a3cf1dfcff1eef13706816327907f79f9366a7098ee48fc0c00ad2726?show_adv=trueThe script is 64 <64 bytes> 172. It looks like the <64 bytes> should be the public key with the prefix missing. This seems like "Format 2" described by John Ratcliff, but it's the prefix that's missing, not the length.
http://codesuppository.blogspot.com/2014/01/how-to-parse-bitcoin-blockchain.html The important thing is the (x,y) value I get from these 64 bytes is not on the curve, so it can't be a public key.
A bit later there is output 1 of tx 7729045ec9b7cfe62811c7fee5b9b2839a1e45f3827867776b6671cabae84462.
https://blockchain.info/tx/7729045ec9b7cfe62811c7fee5b9b2839a1e45f3827867776b6671cabae84462Here the format is like a standard pubkey output script: 65 04 <64 bytes> 172, but the 64 bytes are actually the same as the previous example, which does not give a point on the curve.
In spite of the (x,y) not being on the curve, I can form a bitcoin address starting from 04 x y in the usual way and get the address 1HSrPfMA5joCS5vTnRWQF7GyeodLQZHu6e. This is the address shown by both blockchain.info and the Satoshi client for the second example. However, for the first example, blockchain.info reports the address 18EC4j7GGUenVxtxQ8xtgLm1oefxbki8ne while the Satoshi client reports the address 1HT7xU2Ngenf7D4yocz2SAcnNLW7rK8d4E. How are these other addresses calculated?
Are both of these outputs are provably unspendable?
Searching the forum for these txids and addresses, the only one I found was 1HT7xU2Ngenf7D4yocz2SAcnNLW7rK8d4E (the one reported by the Satoshi client in the first example). It seems to be an address people have erroneously spent coins to before.
Explanations or links to explanations would be appreciated.