How to use of blinding nonces in `sign_psbt`

[altafan]

I'm trying to sign with sign_psbt a pset created with this version of libwally that contains inputs owned by a 2of2_no_recovery account.
As per documentation, I have to pass a list of blinding_nonces within the JSON object, but it's not clear to me how to calculate or retrieve these values.

[jgriffiths]

Hi @altafan

The blinding nonces are constructed as sha256(ecdh(pub_key, priv_key)) where:

• pub_key is the blinding pubkey of the output (retrievable from the receiving confidential address by e.g. wally_confidential_addr_to_ec_public_key from wally, present in a PSET as PSET_OUT_BLINDING_PUBKEY)
• priv_key is an ephemeral randomly generated private key (32 bits of entropy).

The PR you've linked now has wally_ecdh_nonce_hash exposed to perform this computation for you.