v1.15: adds hash domain to merkle shreds (backport of #29339)

ledger/src/shred/merkle.rs

@@ -43,8 +43,10 @@ const_assert_eq!(ShredData::SIZE_OF_PAYLOAD, 1203);
 
 // Defense against second preimage attack:
 // https://en.wikipedia.org/wiki/Merkle_tree#Second_preimage_attack
-const MERKLE_HASH_PREFIX_LEAF: &[u8] = &[0x00];
-const MERKLE_HASH_PREFIX_NODE: &[u8] = &[0x01];
+// Following Certificate Transparency, 0x00 and 0x01 bytes are prepended to
+// hash data when computing leaf and internal node hashes respectively.
+const MERKLE_HASH_PREFIX_LEAF: &[u8] = b"\x00SOLANA_MERKLE_SHREDS_LEAF";
+const MERKLE_HASH_PREFIX_NODE: &[u8] = b"\x01SOLANA_MERKLE_SHREDS_NODE";
 
 pub(crate) type MerkleRoot = MerkleProofEntry;
 type MerkleProofEntry = [u8; 20];

ledger/src/shredder.rs

@@ -7,7 +7,7 @@ use {
     lru::LruCache,
     rayon::{prelude::*, ThreadPool},
     reed_solomon_erasure::{
-        galois_8::Field,
+        galois_8::ReedSolomon,
         Error::{InvalidIndex, TooFewDataShards, TooFewShardsPresent},
     },
     solana_entry::entry::Entry,
@@ -38,8 +38,6 @@ pub(crate) const ERASURE_BATCH_SIZE: [usize; 33] = [
     55, 56, 58, 59, 60, 62, 63, 64, // 32
 ];
 
-type ReedSolomon = reed_solomon_erasure::ReedSolomon<Field>;
-
 pub struct ReedSolomonCache(
     Mutex<LruCache<(/*data_shards:*/ usize, /*parity_shards:*/ usize), Arc<ReedSolomon>>>,
 );