Add TPM supported curves (BN638 and BN256I)

[akakou]

Hello,

My name is Kosei Akama, and I am a master's student at Keio University.
I am writing to inquire about plans to adopt TPM-supported elliptic curves in the BBS draft.

The BN638 and BN256I curves are utilized for remote attestation mechanisms,
such as Direct Anonymous Attestation (DAA) and Enhanced Privacy ID (EPID), both of which are based on the BBS.

Given this context, it seems necessary to specify the BN638 and BN256I as supported curves.
Is there a plan to include these curves in the draft?