crypto/constants: Change Schnorr domain prefix and add blockhash domain prefix.

src/crypto/constants.rs

@@ -4,7 +4,11 @@ pub mod util;
 
 pub use fixed_bases::{NullifierK, OrchardFixedBases, OrchardFixedBasesFull, ValueCommitV, H};
 
-pub const DRK_SCHNORR_DOMAIN: &[u8] = b"DarkFi_Schnorr";
+/// Domain prefix used for Schnorr signatures, with `hash_to_scalar`.
+pub const DRK_SCHNORR_DOMAIN: &[u8] = b"DarkFi:Schnorr";
+
+/// Domain prefix used for block hashes, with `hash_to_curve`.
+pub const BLOCK_HASH_DOMAIN: &str = "DarkFi:Block";
 
 pub const MERKLE_DEPTH_ORCHARD: usize = 32;