Fix hash HEX printing (#7496)

Author: maxtropets

src/crypto/sha256_hash.cpp

@@ -50,11 +50,7 @@ namespace ccf::crypto
 
   std::ostream& operator<<(std::ostream& os, const ccf::crypto::Sha256Hash& h)
   {
-    for (unsigned i = 0; i < ccf::crypto::Sha256Hash::SIZE; i++)
-    {
-      os << std::hex << static_cast<int>(h.h[i]);
-    }
-
+    os << h.hex_str();
     return os;
   }
 

src/crypto/test/crypto.cpp

@@ -1466,4 +1466,20 @@ TEST_CASE("Do not trust non-ca certs")
   // CA:FALSE).
   REQUIRE_FALSE(
     non_ca_cert_verifier->verify_certificate({&non_ca_cert}, {}, true));
+}
+
+TEST_CASE("Sha256 hex conversions")
+{
+  {
+    INFO("Sha256 via operator<<");
+
+    const std::string hex{
+      "f3d25d4670b742f035c1f1d9fffa2eba676ddc491c5288403fa1091e62f26dd6"};
+    auto hash = ccf::crypto::Sha256Hash::from_hex_string(hex);
+
+    std::stringstream ss;
+    ss << hash;
+
+    REQUIRE(ss.str() == hex);
+  }
 }