open System
open System.IO
-// To read and write metadata.
+/// To read and write metadata.
type internal Metadata (d: (string * string) list) =
- // Read metadata from a stream.
+ /// 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 ()])
+ Metadata ([for _ in 1 .. length -> reader.ReadString (), reader.ReadString ()])
- // Write metadata to a stream.
+ /// 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'.
+ /// May raise 'KeyNotFoundException'.
member this.get (key: string) : string =
List.pick (function
| (k, v) when k = key -> Some (v)
| _ -> None) d
module API =
- module internal Metadata =
- let filenameKey = "filename"
- let modificationTimeKey = "file-modification-time"
+ module internal MetadataKeys =
+ let filename = "filename"
+ let modificationTime = "file-modification-time"
- let generatKeysPair : Key * Key = Crypto.generateRSAKeysPair
+ let internal (@@) a1 a2 = Array.append a1 a2
+ let test = 256 / 8
+ let hmacSize = 256 / 8 // [byte].
+ let signatureSize = Crypto.rsaKeySize / 8 // [byte].
+ let keysSize = Crypto.rsaKeySize / 8 // [byte].
+
+ let generatKeysPair () : Key * Key = Crypto.generateRSAKeysPair ()
+
+ /// Format of the container:
+ /// <mac><signature><encrypted keys><cyphertext>
+ /// Where the sizes of the three first parts are given by 'hmacSize', 'signatureSize' and 'keysSize'.
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)
+ let keyAES, keyMAC, iv = Crypto.rand 16, Crypto.rand 32, Crypto.rand 16
+ let fileInfo = FileInfo (inputFilePath)
+ use inputStream = fileInfo.OpenRead ()
use outputStream = new FileStream (outputFilePath, FileMode.Create, FileAccess.Write)
- let writer = new BinaryWriter (outputStream)
+ use writer = new BinaryWriter (outputStream)
- writer.Seek (32 + 256, SeekOrigin.Current) |> ignore // Skips mac and signature. They will be written later.
+ outputStream.Position <- (int64 <| hmacSize + signatureSize) // 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
// Plaintext -> cryptoStream -> hmacStream -> cyphertext.
- let (hmacStream, hmac) = Crypto.HMACStream keyMAC outputStream
+ let hmacStream, hmac = Crypto.HMACStream keyMAC outputStream
use cryptoStream = Crypto.encryptAES keyAES iv hmacStream
- let cryptoWriter = new BinaryWriter (cryptoStream)
+ use cryptoWriter = new BinaryWriter (cryptoStream)
// Write the file metadata.
- let metaData = new Metadata ([Metadata.filenameKey, fileInfo.Name
- Metadata.modificationTimeKey, fileInfo.LastWriteTimeUtc.Ticks.ToString ()])
+ let metaData = Metadata ([MetadataKeys.filename, fileInfo.Name
+ MetadataKeys.modificationTime, fileInfo.LastWriteTimeUtc.Ticks.ToString ()])
metaData.WriteTo cryptoStream
// Write the content of the file.
// 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 keyAES = keys.[0..31]
- let keyMAC = keys.[32..63]
- let iv = keys.[64..79]
+ let mac = reader.ReadBytes hmacSize
+ let signature = reader.ReadBytes signatureSize
+ let keys =
+ try reader.ReadBytes keysSize |> Crypto.decryptRSA decryptPrivKey
+ with
+ | :? Security.Cryptography.CryptographicException -> raise UnableToDecryptKeys
+ let keyAES = keys.[0 .. 15]
+ let keyMAC = keys.[16 .. 47]
+ let iv = keys.[48 .. 63]
// Integrity validation.
let mac' = Crypto.ComputeHMAC keyMAC inputStream
if mac' <> mac then
raise IntegrityError
-
+
// Authentication validation.
if not <| Crypto.verifySignRSA signaturePubKey mac' signature then
raise SignatureMismatch
// Decrypt metadata.
- inputStream.Position <- 32L + 256L + 256L
+ inputStream.Position <- (int64 <| hmacSize + signatureSize + keysSize)
use cryptoStream = Crypto.decryptAES keyAES iv inputStream
- let metadata = new Metadata (cryptoStream)
+ let metadata = Metadata cryptoStream
// 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
+ let filePath = Path.Combine (targetDirPath, metadata.get MetadataKeys.filename)
+ let modificationTime = DateTime (metadata.get MetadataKeys.modificationTime |> int64)
+ let fileInfo = FileInfo filePath
+ using (fileInfo.Create ()) cryptoStream.CopyTo // We have to close the result file before updating the modification time.
fileInfo.LastWriteTimeUtc <- modificationTime
\ No newline at end of file
projects / crypto_lab2.git / blobdiff