Clean up.

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

diff --git a/labo2-fsharp/CryptoFile/Crypto.fs b/labo2-fsharp/CryptoFile/Crypto.fs
index c81475b..8ea0629 100644 (file)
--- a/labo2-fsharp/CryptoFile/Crypto.fs
+++ b/labo2-fsharp/CryptoFile/Crypto.fs
@@ -11,6 +11,9 @@ module internal Crypto =
     let rsaKeySize = 2048
     let aesKeySize = 128
 
+    exception KeySizeError
+    exception IVSizeError
+
     /// Returns a cryptographically strong sequence of bytes.
     let rand size : byte[] =
         let result = Array.zeroCreate size
@@ -47,27 +50,27 @@ module internal Crypto =
 
     /// Returns an encrypted output stream.
     let encryptAES (key: byte[]) (iv: byte[]) (outputStream: Stream) : CryptoStream =
-        assert (key.Length = aesKeySize / 8 && iv.Length = 16)
-        use aes = new AesCryptoServiceProvider () // Default mode is CBC.
-        aes.KeySize <- aesKeySize
+        if key.Length <> aesKeySize / 8 then raise KeySizeError
+        if iv.Length <> 16 then raise IVSizeError
+        use aes = new AesCryptoServiceProvider (KeySize = aesKeySize) // Default mode is CBC.
         let encryptor = aes.CreateEncryptor (key, iv)
         new CryptoStream (outputStream, encryptor, CryptoStreamMode.Write)
 
     /// Returns a decrypted input stream.
     let decryptAES (key: byte[]) (iv: byte[]) (inputStream: Stream) : CryptoStream =
-        assert (key.Length = aesKeySize / 8 && iv.Length = 16)
-        use aes = new AesCryptoServiceProvider ()
-        aes.KeySize <- aesKeySize
+        if key.Length <> aesKeySize / 8 then raise KeySizeError
+        if iv.Length <> 16 then raise IVSizeError
+        use aes = new AesCryptoServiceProvider (KeySize = aesKeySize)
         let decryptor = aes.CreateDecryptor (key, iv)
         new CryptoStream (inputStream, decryptor, CryptoStreamMode.Read)
 
     // Create a stream to compute the HMAC-SHA256 against all data being written.
     let HMACStream (key: byte[]) (outputStream: Stream) : Stream * HMACSHA256 = 
-        assert (key.Length = 32)
+        if key.Length <> 32 then raise KeySizeError
         let hmac = new HMACSHA256 (key)
         new CryptoStream (outputStream, hmac, CryptoStreamMode.Write) :> Stream, hmac
 
     let ComputeHMAC (key: byte[]) (inputStream: Stream) : byte[] =
-        assert (key.Length = 32)
+        if key.Length <> 32 then raise KeySizeError
         let hmac = new HMACSHA256 (key)
         hmac.ComputeHash inputStream
\ No newline at end of file