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[crypto_lab2.git] / labo2-fsharp / CryptoFile / API.fs

diff --git a/labo2-fsharp/CryptoFile/API.fs b/labo2-fsharp/CryptoFile/API.fs
index 0014c1e..1601c97 100644 (file)
--- a/labo2-fsharp/CryptoFile/API.fs
+++ b/labo2-fsharp/CryptoFile/API.fs
@@ -1,31 +1,35 @@
 namespace CryptoFile
+
+open System
 open System.IO
 
+// To read and write metadata.
 type internal Metadata (d: (string * string) list) =
+    // Read metadata from a stream.
     new (stream : Stream) =
         let reader = new BinaryReader (stream)
         let length = reader.ReadByte () |> int
         new Metadata ([for i in 1..length -> reader.ReadString (), reader.ReadString ()])
 
+    // Write metadata to a stream.
+    member this.WriteTo (stream : Stream) =
+        let writer = new BinaryWriter (stream)
+        writer.Write (byte d.Length)
+        List.iter (fun (key : string, value : string) -> writer.Write key; writer.Write value) d
+
     // May raise 'KeyNotFoundException'.
     member this.get (key: string) : string =
         List.pick (function
                     | (k, v) when k = key -> Some (v)
                     | _ -> None) d
 
-    member this.WriteTo (stream : Stream) =
-        let writer = new BinaryWriter (stream)
-        writer.Write (byte d.Length)
-        List.iter (fun (key : string, value : string) -> writer.Write key; writer.Write value) d
-
 module API =
     module internal Metadata =
-        let filename = "filename"
-        let creationTimeKey = "file-creation-time"
+        let filenameKey = "filename"
+        let modificationTimeKey = "file-modification-time"
 
     let generatKeysPair : Key * Key = Crypto.generateRSAKeysPair
 
-    // Encrypt a given file
     let encryptFile (inputFilePath : string) (outputFilePath : string) (signaturePrivKey: Key) (cryptPubKey : Key)  =
         let keyAES, keyMAC, iv = Crypto.rand 32, Crypto.rand 32, Crypto.rand 16
         let fileInfo = new FileInfo (inputFilePath)
@@ -37,13 +41,14 @@ module API =
 
         Crypto.encryptRSA cryptPubKey (Array.append keyAES <| Array.append keyMAC iv) |> writer.Write
 
+        // Plaintext -> cryptoStream -> hmacStream -> cyphertext.
         let (hmacStream, hmac) = Crypto.HMACStream keyMAC outputStream
         use cryptoStream = Crypto.encryptAES keyAES iv hmacStream
         let cryptoWriter = new BinaryWriter (cryptoStream)
 
         // Write the file metadata.
-        let metaData = new Metadata ([Metadata.filename, fileInfo.Name
-                                      Metadata.creationTimeKey, fileInfo.CreationTimeUtc.Ticks.ToString ()])
+        let metaData = new Metadata ([Metadata.filenameKey, fileInfo.Name
+                                      Metadata.modificationTimeKey, fileInfo.LastWriteTimeUtc.Ticks.ToString ()])
         metaData.WriteTo cryptoStream
 
         // Write the content of the file.
@@ -56,7 +61,6 @@ module API =
 
         // Write the signature.
         Crypto.signRSA signaturePrivKey hmac.Hash |> writer.Write
-        ()
 
     let decryptFile (sourceFilePath : string) (targetDirPath : string) (signaturePubKey: Key) (decryptPrivKey : Key) =
         use inputStream = new FileStream (sourceFilePath, FileMode.Open, FileAccess.Read)
@@ -82,8 +86,10 @@ module API =
         use cryptoStream = Crypto.decryptAES keyAES iv inputStream
         let metadata = new Metadata (cryptoStream)
 
-        // Create the file and write.
-        let filename = metadata.get Metadata.filename
-        use outputStream = new FileStream (Path.Combine (targetDirPath, filename), FileMode.Create, FileAccess.Write)
-        cryptoStream.CopyTo outputStream
-        ()
+        // Create the file and write its content and metadata.
+        let filePath = Path.Combine (targetDirPath, metadata.get Metadata.filenameKey)
+        let modificationTime = new DateTime (metadata.get Metadata.modificationTimeKey |> int64)
+        let fileInfo = new FileInfo (filePath)
+        using (fileInfo.Create ()) <| fun outputStream -> cryptoStream.CopyTo outputStream
+        fileInfo.LastWriteTimeUtc <- modificationTime
+    
\ No newline at end of file