Suppose I have a public key for a particular user (perhaps extracted when using the new public key recovery format included in P2SH, and BIP32 transactions).

• Is it OK the same key for both signing and encryption?

Since I'm obtaining the public key from a message, PS2H script, or BIP32 wallet I want to make sure that all secrets (Bitcoins, private keys, and privacy relating to BIP32) is maintained.

• What are some known, safe, scenarios to use the same key for signing and encryption?