diff --git a/datatrails-common-api/assets/v2/assets/assetresponse.proto b/datatrails-common-api/assets/v2/assets/assetresponse.proto
index 04d77e6..b16a908 100644
--- a/datatrails-common-api/assets/v2/assets/assetresponse.proto
+++ b/datatrails-common-api/assets/v2/assets/assetresponse.proto
@@ -33,7 +33,7 @@ message AssetResponse {
             "\"tracked\": \"TRACKED\", "
             "\"owner\": \"0x601f5A7D3e6dcB55e87bf2F17bC8A27AaCD3511\","
             "\"at_time\": \"2019-11-27T14:44:19Z\","
-            "\"proof_mechanism\": \"SIMPLE_HASH\","
+            "\"proof_mechanism\": \"MERKLE_LOG\","
             "\"public\": false,"
             "\"tenant_identity\": \"tenant/8e0b600c-8234-43e4-860c-e95bdcd695a9\" "
             "}"
@@ -117,4 +117,4 @@ message AssetResponse {
         max_length: 1024
     }];
 
-}
\ No newline at end of file
+}
diff --git a/datatrails-common-api/assets/v2/assets/createasset.proto b/datatrails-common-api/assets/v2/assets/createasset.proto
index b8bdd09..965993f 100644
--- a/datatrails-common-api/assets/v2/assets/createasset.proto
+++ b/datatrails-common-api/assets/v2/assets/createasset.proto
@@ -25,7 +25,7 @@ message CreateAssetRequest {
             "   \"arc_display_name\": \"My Garden Fence\", "
             "   \"colour\": \"Plain wood\" "
             "}, "
-            "\"proof_mechanism\": \"SIMPLE_HASH\","
+            "\"proof_mechanism\": \"MERKLE_LOG\","
             "\"public\": false"
             "}"
     };
@@ -79,4 +79,4 @@ message CreateAssetRequest {
                 "Sharing to specific organisations is not available for public assets."
         }
     ];
-}
\ No newline at end of file
+}
diff --git a/datatrails-common-api/assets/v2/assets/enums.proto b/datatrails-common-api/assets/v2/assets/enums.proto
index fe6fe5b..d440135 100644
--- a/datatrails-common-api/assets/v2/assets/enums.proto
+++ b/datatrails-common-api/assets/v2/assets/enums.proto
@@ -22,7 +22,7 @@ enum TrackedStatus {
 enum ProofMechanism {
     PROOF_MECHANISM_UNSPECIFIED = 0;
     RESERVED1 = 1;
-    SIMPLE_HASH = 2;
+    RESERVED2 = 2;
     MERKLE_LOG = 3;
 }
 
diff --git a/datatrails-common-api/assets/v2/assets/listassets.proto b/datatrails-common-api/assets/v2/assets/listassets.proto
index b6b31af..45bb0c1 100644
--- a/datatrails-common-api/assets/v2/assets/listassets.proto
+++ b/datatrails-common-api/assets/v2/assets/listassets.proto
@@ -110,7 +110,7 @@ message ListAssetsResponse {
             "           \"tracked\": \"TRACKED\", "
             "           \"owner\": \"0x601f5A7D3e6dcB55e87bf2F17bC8A27AaCD3511\","
             "           \"at_time\": \"2019-11-27T14:44:19Z\", "
-            "           \"proof_mechanism\": \"SIMPLE_HASH\","
+            "           \"proof_mechanism\": \"MERKLE_LOG\","
             "           \"public\": false,"
             "           \"tenant_identity\": \"tenant/8e0b600c-8234-43e4-860c-e95bdcd695a9\" "
             "       },"
@@ -126,7 +126,7 @@ message ListAssetsResponse {
             "           \"tracked\": \"TRACKED\", "
             "           \"owner\": \"0x601f5A7D3e6dcB55e87bf2F17bC8A27AaCD3511\","
             "           \"at_time\": \"2019-11-27T14:44:19Z\", "
-            "           \"proof_mechanism\": \"SIMPLE_HASH\","
+            "           \"proof_mechanism\": \"MERKLE_LOG\","
             "           \"public\": false,"
             "           \"tenant_identity\": \"tenant/8e0b600c-8234-43e4-860c-e95bdcd695a9\" "
             "       }"
@@ -137,4 +137,4 @@ message ListAssetsResponse {
     repeated AssetResponse assets = 1;
     // Token to retrieve the next page of results or empty if there are none.
     string next_page_token = 2;
-}
\ No newline at end of file
+}