X-Git-Url: http://git.euphorik.ch/?a=blobdiff_plain;f=labo2-fsharp%2FCryptoFile%2FAPI.fs;h=424959da80403c3b1bb88ad0fcfcfa29f687f154;hb=2fcf3ed38874e9aa6d2ccd6b9917bd3113d76aee;hp=0014c1e280bec30e027f02c74d3bcc37fb36334f;hpb=0425c0fc231c8a5625bf7ac9b711e152de0eafaa;p=crypto_lab2.git

diff --git a/labo2-fsharp/CryptoFile/API.fs b/labo2-fsharp/CryptoFile/API.fs
index 0014c1e..424959d 100644
--- a/labo2-fsharp/CryptoFile/API.fs
+++ b/labo2-fsharp/CryptoFile/API.fs
@@ -1,49 +1,56 @@
 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 internal (@@) a1 a2 = Array.append a1 a2
 
     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)
-        use inputStream = new FileStream (inputFilePath, FileMode.Open, FileAccess.Read)
-        use outputStream = new FileStream (outputFilePath, FileMode.Create, FileAccess.Write)
+        use inputStream = fileInfo.OpenRead ()
+        use outputStream = new FileStream (outputFilePath, FileMode.Create, FileAccess.Write, FileShare.Read, 4096 * 100)
         let writer = new BinaryWriter (outputStream)
 
-        writer.Seek (32 + 256, SeekOrigin.Current) |> ignore // Skips mac and signature. They will be written later.
+        outputStream.Position <- 32L + 256L // Skips mac and signature. They will be written later.
 
-        Crypto.encryptRSA cryptPubKey (Array.append keyAES <| Array.append keyMAC iv) |> writer.Write
+        Crypto.encryptRSA cryptPubKey (keyAES @@ keyMAC @@ iv) |> writer.Write
 
-        let (hmacStream, hmac) = Crypto.HMACStream keyMAC outputStream
+        // 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.
@@ -56,14 +63,20 @@ module API =
 
         // Write the signature.
         Crypto.signRSA signaturePrivKey hmac.Hash |> writer.Write
-        ()
 
+    // May raise one of the following error:
+    //  * IntegrityError
+    //  * SignatureMismatch 
+    //  * UnableToDecryptAESKeys
     let decryptFile (sourceFilePath : string) (targetDirPath : string) (signaturePubKey: Key) (decryptPrivKey : Key) =
         use inputStream = new FileStream (sourceFilePath, FileMode.Open, FileAccess.Read)
         use reader = new BinaryReader (inputStream)
         let mac = reader.ReadBytes 32
         let signature = reader.ReadBytes 256
-        let keys = reader.ReadBytes 256 |> Crypto.decryptRSA decryptPrivKey
+        let keys = 
+            try reader.ReadBytes 256 |> Crypto.decryptRSA decryptPrivKey
+            with 
+                | :? Security.Cryptography.CryptographicException -> raise UnableToDecryptAESKeys
         let keyAES = keys.[0..31]
         let keyMAC = keys.[32..63]
         let iv = keys.[64..79]
@@ -72,7 +85,7 @@ module API =
         let mac' = Crypto.ComputeHMAC keyMAC inputStream
         if mac' <> mac then
             raise IntegrityError
-
+        
         // Authentication validation.
         if not <| Crypto.verifySignRSA signaturePubKey mac' signature then
             raise SignatureMismatch
@@ -82,8 +95,10 @@ 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