pub fn aggregate_partials(
partials: &[PartialDecryption],
threshold: u32,
_ciphertext: &Ciphertext,
) -> Result<Vec<u8>, ElGamalError>Expand description
Aggregate T partial decryptions into the shared secret point.
For KEM-style encapsulate (shared_secret = X(r * recipient_pubkey)):
the shared secret point is combined = sum_i λ_i * partial_i = x * c1.
Returns the X-coordinate of combined (32 bytes).