Redeem script for segwit addresses How does one derive the Redeem Script for the new Pay-to-Witness Pubkey Hash addresses? With existing P2SH it's revealed after providing N number of Public Keys through a createmultisig function in the bitcoin client. Is it the same, just provide a single public key through a createwitness or similar function? 

Is it currently available for fiddling with on testnet?
Feb2018: an older request, I just answer it so that future research might reveal useful data :-)

To compose the redeem script for a P2WPKH, there is a fairly simple structure, I copied this mostly from here:

Start with OP_0, followed by the keyhash. Keyhash is calculated with  RIPEMD160(SHA256(public key)), similiar to "std" PKH. Do not use uncompressed pubkeys! 

The P2SH redeemScript will then always have 22 bytes: 

OP_0:    00
Length:  14
keyhash: (20 bytes)


The scriptPubKey is composed this way: 

OP_HASH160 hash160(redeemScript) OP_EQUAL


and the address is the corresponding P2SH address with prefix 3.

Step by step explanation here :-)