diff --git a/src/Simplex/Messaging/Agent.hs b/src/Simplex/Messaging/Agent.hs
index ca544a6fd..e5b214033 100644
--- a/src/Simplex/Messaging/Agent.hs
+++ b/src/Simplex/Messaging/Agent.hs
@@ -190,7 +190,7 @@ processCommand c@AgentClient {sndQ} st (corrId, connAlias, cmd) =
               msgHash = C.sha256Hash msgStr
           withStore $
             createSndMsg st sq $
-              SndMsgData {internalId, internalSndId, internalTs, msgBody, msgHash}
+              SndMsgData {internalId, internalSndId, internalTs, msgBody, internalHash = msgHash}
           sendAgentMessage c sq msgStr
           respond $ SENT (unId internalId)
 
@@ -309,7 +309,8 @@ processSMPTransmission c@AgentClient {sndQ} st (srv, rId, cmd) = do
                   senderMeta,
                   brokerMeta,
                   msgBody,
-                  msgHash,
+                  internalHash = msgHash,
+                  externalPrevSndHash = receivedPrevMsgHash,
                   msgIntegrity
                 }
           notify connAlias $
diff --git a/src/Simplex/Messaging/Agent/Store.hs b/src/Simplex/Messaging/Agent/Store.hs
index 51b9db518..778b6b6be 100644
--- a/src/Simplex/Messaging/Agent/Store.hs
+++ b/src/Simplex/Messaging/Agent/Store.hs
@@ -147,6 +147,7 @@ type PrevRcvMsgHash = MsgHash
 -- | Corresponds to `last_snd_msg_hash` in `connections` table
 type PrevSndMsgHash = MsgHash
 
+-- ? merge/replace these with RcvMsg and SndMsg
 -- * Message data containers - used on Msg creation to reduce number of parameters
 
 data RcvMsgData = RcvMsgData
@@ -156,7 +157,8 @@ data RcvMsgData = RcvMsgData
     senderMeta :: (ExternalSndId, ExternalSndTs),
     brokerMeta :: (BrokerId, BrokerTs),
     msgBody :: MsgBody,
-    msgHash :: MsgHash,
+    internalHash :: MsgHash,
+    externalPrevSndHash :: MsgHash,
     msgIntegrity :: MsgIntegrity
   }
 
@@ -165,7 +167,7 @@ data SndMsgData = SndMsgData
     internalSndId :: InternalSndId,
     internalTs :: InternalTs,
     msgBody :: MsgBody,
-    msgHash :: MsgHash
+    internalHash :: MsgHash
   }
 
 -- * Message types
@@ -194,7 +196,10 @@ data RcvMsg = RcvMsg
     -- | Timestamp of acknowledgement to sender, corresponds to `AcknowledgedToSender` status.
     -- Do not mix up with `externalSndTs` - timestamp created at sender before sending,
     -- which in its turn corresponds to `internalTs` in sending agent.
-    ackSenderTs :: AckSenderTs
+    ackSenderTs :: AckSenderTs,
+    -- | Hash of previous message as received from sender - stored for integrity forensics.
+    externalPrevSndHash :: MsgHash,
+    msgIntegrity :: MsgIntegrity
   }
   deriving (Eq, Show)
 
@@ -254,7 +259,9 @@ data MsgBase = MsgBase
     -- due to a possibility of implementation errors in different agents.
     internalId :: InternalId,
     internalTs :: InternalTs,
-    msgBody :: MsgBody
+    msgBody :: MsgBody,
+    -- | Hash of the message as computed by agent.
+    internalHash :: MsgHash
   }
   deriving (Eq, Show)
 
diff --git a/src/Simplex/Messaging/Agent/Store/SQLite.hs b/src/Simplex/Messaging/Agent/Store/SQLite.hs
index c48110065..ae9473e7d 100644
--- a/src/Simplex/Messaging/Agent/Store/SQLite.hs
+++ b/src/Simplex/Messaging/Agent/Store/SQLite.hs
@@ -40,6 +40,7 @@ import Network.Socket (ServiceName)
 import Simplex.Messaging.Agent.Store
 import Simplex.Messaging.Agent.Store.SQLite.Schema (createSchema)
 import Simplex.Messaging.Agent.Transmission
+import Simplex.Messaging.Parsers (parseAll)
 import qualified Simplex.Messaging.Protocol as SMP
 import Simplex.Messaging.Util (bshow, liftIOEither)
 import System.Exit (ExitCode (ExitFailure), exitWith)
@@ -276,6 +277,16 @@ instance ToField RcvMsgStatus where toField = toField . show
 
 instance ToField SndMsgStatus where toField = toField . show
 
+instance ToField MsgIntegrity where toField = toField . serializeMsgIntegrity
+
+instance FromField MsgIntegrity where
+  fromField = \case
+    f@(Field (SQLBlob b) _) ->
+      case parseAll msgIntegrityP b of
+        Right k -> Ok k
+        Left e -> returnError ConversionFailed f ("can't parse msg integrity field: " ++ e)
+    f -> returnError ConversionFailed f "expecting SQLBlob column type"
+
 fromFieldToReadable_ :: forall a. (Read a, E.Typeable a) => Field -> Ok a
 fromFieldToReadable_ = \case
   f@(Field (SQLText t) _) ->
@@ -528,10 +539,12 @@ insertRcvMsgDetails_ dbConn connAlias RcvMsgData {..} =
     [sql|
       INSERT INTO rcv_messages
         ( conn_alias, internal_rcv_id, internal_id, external_snd_id, external_snd_ts,
-          broker_id, broker_ts, rcv_status, ack_brocker_ts, ack_sender_ts)
+          broker_id, broker_ts, rcv_status, ack_brocker_ts, ack_sender_ts,
+          internal_hash, external_prev_snd_hash, integrity)
       VALUES
         (:conn_alias,:internal_rcv_id,:internal_id,:external_snd_id,:external_snd_ts,
-         :broker_id,:broker_ts,:rcv_status,           NULL,          NULL);
+         :broker_id,:broker_ts,:rcv_status,           NULL,          NULL,
+         :internal_hash,:external_prev_snd_hash,:integrity);
     |]
     [ ":conn_alias" := connAlias,
       ":internal_rcv_id" := internalRcvId,
@@ -540,7 +553,10 @@ insertRcvMsgDetails_ dbConn connAlias RcvMsgData {..} =
       ":external_snd_ts" := snd senderMeta,
       ":broker_id" := fst brokerMeta,
       ":broker_ts" := snd brokerMeta,
-      ":rcv_status" := Received
+      ":rcv_status" := Received,
+      ":internal_hash" := internalHash,
+      ":external_prev_snd_hash" := externalPrevSndHash,
+      ":integrity" := msgIntegrity
     ]
 
 updateHashRcv_ :: DB.Connection -> ConnAlias -> RcvMsgData -> IO ()
@@ -556,7 +572,7 @@ updateHashRcv_ dbConn connAlias RcvMsgData {..} =
         AND last_internal_rcv_msg_id = :last_internal_rcv_msg_id;
     |]
     [ ":last_external_snd_msg_id" := fst senderMeta,
-      ":last_rcv_msg_hash" := msgHash,
+      ":last_rcv_msg_hash" := internalHash,
       ":conn_alias" := connAlias,
       ":last_internal_rcv_msg_id" := internalRcvId
     ]
@@ -616,14 +632,15 @@ insertSndMsgDetails_ dbConn connAlias SndMsgData {..} =
     dbConn
     [sql|
       INSERT INTO snd_messages
-        ( conn_alias, internal_snd_id, internal_id, snd_status, sent_ts, delivered_ts)
+        ( conn_alias, internal_snd_id, internal_id, snd_status, sent_ts, delivered_ts, internal_hash)
       VALUES
-        (:conn_alias,:internal_snd_id,:internal_id,:snd_status,    NULL,         NULL);
+        (:conn_alias,:internal_snd_id,:internal_id,:snd_status,    NULL,         NULL,:internal_hash);
     |]
     [ ":conn_alias" := connAlias,
       ":internal_snd_id" := internalSndId,
       ":internal_id" := internalId,
-      ":snd_status" := Created
+      ":snd_status" := Created,
+      ":internal_hash" := internalHash
     ]
 
 updateHashSnd_ :: DB.Connection -> ConnAlias -> SndMsgData -> IO ()
@@ -637,7 +654,7 @@ updateHashSnd_ dbConn connAlias SndMsgData {..} =
       WHERE conn_alias = :conn_alias
         AND last_internal_snd_msg_id = :last_internal_snd_msg_id;
     |]
-    [ ":last_snd_msg_hash" := msgHash,
+    [ ":last_snd_msg_hash" := internalHash,
       ":conn_alias" := connAlias,
       ":last_internal_snd_msg_id" := internalSndId
     ]
diff --git a/src/Simplex/Messaging/Agent/Store/SQLite/Schema.hs b/src/Simplex/Messaging/Agent/Store/SQLite/Schema.hs
index 959a071e9..99ba67ccf 100644
--- a/src/Simplex/Messaging/Agent/Store/SQLite/Schema.hs
+++ b/src/Simplex/Messaging/Agent/Store/SQLite/Schema.hs
@@ -138,6 +138,9 @@ rcvMessages =
       rcv_status TEXT NOT NULL,
       ack_brocker_ts TEXT,
       ack_sender_ts TEXT,
+      internal_hash BLOB NOT NULL,
+      external_prev_snd_hash BLOB NOT NULL,
+      integrity BLOB NOT NULL,
       PRIMARY KEY (conn_alias, internal_rcv_id),
       FOREIGN KEY (conn_alias, internal_id)
         REFERENCES messages (conn_alias, internal_id)
@@ -155,6 +158,7 @@ sndMessages =
       snd_status TEXT NOT NULL,
       sent_ts TEXT,
       delivered_ts TEXT,
+      internal_hash BLOB NOT NULL,
       PRIMARY KEY (conn_alias, internal_snd_id),
       FOREIGN KEY (conn_alias, internal_id)
         REFERENCES messages (conn_alias, internal_id)
diff --git a/src/Simplex/Messaging/Agent/Transmission.hs b/src/Simplex/Messaging/Agent/Transmission.hs
index b29b919cf..fbaff38b6 100644
--- a/src/Simplex/Messaging/Agent/Transmission.hs
+++ b/src/Simplex/Messaging/Agent/Transmission.hs
@@ -315,7 +315,7 @@ commandP =
     sendCmd = ACmd SClient . SEND <$> A.takeByteString
     sentResp = ACmd SAgent . SENT <$> A.decimal
     message = do
-      msgIntegrity <- integrity <* A.space
+      msgIntegrity <- msgIntegrityP <* A.space
       recipientMeta <- "R=" *> partyMeta A.decimal
       brokerMeta <- "B=" *> partyMeta base64P
       senderMeta <- "S=" *> partyMeta A.decimal
@@ -326,13 +326,16 @@ commandP =
         <|> A.space *> (ReplyVia <$> smpServerP)
         <|> pure ReplyOn
     partyMeta idParser = (,) <$> idParser <* "," <*> tsISO8601P <* A.space
-    integrity = "OK" $> MsgOk <|> "ERR " *> (MsgError <$> msgErrorType)
+    agentError = ACmd SAgent . ERR <$> agentErrorTypeP
+
+msgIntegrityP :: Parser MsgIntegrity
+msgIntegrityP = "OK" $> MsgOk <|> "ERR " *> (MsgError <$> msgErrorType)
+  where
     msgErrorType =
       "ID " *> (MsgBadId <$> A.decimal)
         <|> "IDS " *> (MsgSkipped <$> A.decimal <* A.space <*> A.decimal)
         <|> "HASH" $> MsgBadHash
         <|> "DUPLICATE" $> MsgDuplicate
-    agentError = ACmd SAgent . ERR <$> agentErrorTypeP
 
 parseCommand :: ByteString -> Either AgentErrorType ACmd
 parseCommand = parse commandP $ CMD SYNTAX
@@ -369,16 +372,17 @@ serializeCommand = \case
       ReplyOn -> ""
     showTs :: UTCTime -> ByteString
     showTs = B.pack . formatISO8601Millis
-    serializeMsgIntegrity :: MsgIntegrity -> ByteString
-    serializeMsgIntegrity = \case
-      MsgOk -> "OK"
-      MsgError e ->
-        "ERR " <> case e of
-          MsgSkipped fromMsgId toMsgId ->
-            B.unwords ["NO_ID", bshow fromMsgId, bshow toMsgId]
-          MsgBadId aMsgId -> "ID " <> bshow aMsgId
-          MsgBadHash -> "HASH"
-          MsgDuplicate -> "DUPLICATE"
+
+serializeMsgIntegrity :: MsgIntegrity -> ByteString
+serializeMsgIntegrity = \case
+  MsgOk -> "OK"
+  MsgError e ->
+    "ERR " <> case e of
+      MsgSkipped fromMsgId toMsgId ->
+        B.unwords ["NO_ID", bshow fromMsgId, bshow toMsgId]
+      MsgBadId aMsgId -> "ID " <> bshow aMsgId
+      MsgBadHash -> "HASH"
+      MsgDuplicate -> "DUPLICATE"
 
 agentErrorTypeP :: Parser AgentErrorType
 agentErrorTypeP =
diff --git a/src/Simplex/Messaging/Crypto.hs b/src/Simplex/Messaging/Crypto.hs
index 19f37d78f..808699fe7 100644
--- a/src/Simplex/Messaging/Crypto.hs
+++ b/src/Simplex/Messaging/Crypto.hs
@@ -79,8 +79,8 @@ import Data.ByteString.Lazy (fromStrict, toStrict)
 import Data.String
 import Data.Typeable (Typeable)
 import Data.X509
-import Database.SQLite.Simple as DB
-import Database.SQLite.Simple.FromField
+import Database.SQLite.Simple (ResultError (..), SQLData (..))
+import Database.SQLite.Simple.FromField (FieldParser, FromField (..), returnError)
 import Database.SQLite.Simple.Internal (Field (..))
 import Database.SQLite.Simple.Ok (Ok (Ok))
 import Database.SQLite.Simple.ToField (ToField (..))
diff --git a/tests/AgentTests/SQLiteTests.hs b/tests/AgentTests/SQLiteTests.hs
index 450e568f3..5442705f0 100644
--- a/tests/AgentTests/SQLiteTests.hs
+++ b/tests/AgentTests/SQLiteTests.hs
@@ -323,7 +323,7 @@ ts :: UTCTime
 ts = UTCTime (fromGregorian 2021 02 24) (secondsToDiffTime 0)
 
 mkRcvMsgData :: InternalId -> InternalRcvId -> ExternalSndId -> BrokerId -> MsgHash -> RcvMsgData
-mkRcvMsgData internalId internalRcvId externalSndId brokerId msgHash =
+mkRcvMsgData internalId internalRcvId externalSndId brokerId internalHash =
   RcvMsgData
     { internalId,
       internalRcvId,
@@ -331,7 +331,8 @@ mkRcvMsgData internalId internalRcvId externalSndId brokerId msgHash =
       senderMeta = (externalSndId, ts),
       brokerMeta = (brokerId, ts),
       msgBody = hw,
-      msgHash = msgHash,
+      internalHash,
+      externalPrevSndHash = "hash_from_sender",
       msgIntegrity = MsgOk
     }
 
@@ -351,13 +352,13 @@ testCreateRcvMsg = do
     testCreateRcvMsg' store 1 "hash_dummy" rcvQueue1 $ mkRcvMsgData (InternalId 2) (InternalRcvId 2) 2 "2" "new_hash_dummy"
 
 mkSndMsgData :: InternalId -> InternalSndId -> MsgHash -> SndMsgData
-mkSndMsgData internalId internalSndId msgHash =
+mkSndMsgData internalId internalSndId internalHash =
   SndMsgData
     { internalId,
       internalSndId,
       internalTs = ts,
       msgBody = hw,
-      msgHash = msgHash
+      internalHash
     }
 
 testCreateSndMsg' :: SQLiteStore -> PrevSndMsgHash -> SndQueue -> SndMsgData -> Expectation