X-Git-Url: http://git.euphorik.ch/?a=blobdiff_plain;f=labo2-fsharp%2FCryptoFile%2FAPI.fs;h=925f933b7b6f48ee165e69358927abd52dce7842;hb=57d7ae8d75a854296718cb1056efbeb476309908;hp=0014c1e280bec30e027f02c74d3bcc37fb36334f;hpb=0425c0fc231c8a5625bf7ac9b711e152de0eafaa;p=crypto_lab2.git diff --git a/labo2-fsharp/CryptoFile/API.fs b/labo2-fsharp/CryptoFile/API.fs index 0014c1e..925f933 100644 --- a/labo2-fsharp/CryptoFile/API.fs +++ b/labo2-fsharp/CryptoFile/API.fs @@ -1,49 +1,64 @@ 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 ()]) - - // May raise 'KeyNotFoundException'. - member this.get (key: string) : string = - List.pick (function - | (k, v) when k = key -> Some (v) - | _ -> None) d + Metadata ([for _ 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 + module API = - module internal Metadata = + module internal MetadataKeys = let filename = "filename" - let creationTimeKey = "file-creation-time" + let modificationTime = "file-modification-time" + + let internal (@@) a1 a2 = Array.append a1 a2 - let generatKeysPair : Key * Key = Crypto.generateRSAKeysPair + let test = 256 / 8 + let hmacSize = 256 / 8 // [byte]. + let signatureSize = Crypto.rsaKeySize / 8 // [byte]. + let keysSize = Crypto.rsaKeySize / 8 // [byte]. - // Encrypt a given file + let generatKeysPair () : Key * Key = Crypto.generateRSAKeysPair () + + /// Format of the container: + /// + /// 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 - 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) + use cryptoWriter = new BinaryWriter (cryptoStream) // Write the file metadata. - let metaData = new Metadata ([Metadata.filename, fileInfo.Name - Metadata.creationTimeKey, fileInfo.CreationTimeUtc.Ticks.ToString ()]) + let metaData = Metadata ([MetadataKeys.filename, fileInfo.Name + MetadataKeys.modificationTime, fileInfo.LastWriteTimeUtc.Ticks.ToString ()]) metaData.WriteTo cryptoStream // Write the content of the file. @@ -56,34 +71,42 @@ 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 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) - - // 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 - () + let metadata = Metadata cryptoStream + + // Create the file and write its content and metadata. + 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