Fix v1 sighash annex serialization.

Author: evoskuil

include/bitcoin/system/chain/annex.hpp

@@ -39,7 +39,7 @@ class BC_API annex
 
     inline size_t size() const NOEXCEPT;
     inline const data_chunk& data() const NOEXCEPT;
-    inline const hash_digest hash() const NOEXCEPT;
+    inline const hash_digest hash(bool prefix) const NOEXCEPT;
     inline operator bool() const NOEXCEPT;
 
     /// The stack adheres to the annex pattern [bip341].

include/bitcoin/system/impl/chain/annex.ipp

@@ -23,6 +23,7 @@
 #include <bitcoin/system/data/data.hpp>
 #include <bitcoin/system/define.hpp>
 #include <bitcoin/system/hash/hash.hpp>
+#include <bitcoin/system/stream/stream.hpp>
 
 namespace libbitcoin {
 namespace system {
@@ -72,9 +73,18 @@ inline const data_chunk& annex::data() const NOEXCEPT
     return data_ ? *data_ : empty_annex();
 }
 
-inline const hash_digest annex::hash() const NOEXCEPT
+inline const hash_digest annex::hash(bool prefix) const NOEXCEPT
 {
-    return sha256_hash(data());
+    if (!prefix)
+        return sha256_hash(data());
+
+    hash_digest out{};
+    stream::out::fast stream{ out };
+    hash::sha256::fast sink{ stream };
+    sink.write_variable(size());
+    sink.write_bytes(data());
+    sink.flush();
+    return out;
 }
 
 // static

src/chain/transaction_sighash_v1.cpp

@@ -122,8 +122,7 @@ bool transaction::version1_sighash(hash_digest& out,
 
     if (annex)
     {
-        sink.write_variable(annex.size());
-        sink.write_bytes(annex.hash());
+        sink.write_bytes(annex.hash(true));
     }
 
     if (single)