Added reset.sh, cleaned up readme and CLI.

README.md

@@ -1,2 +1,45 @@
 # scrambler
 Tool for encrypting and decrypting entire directories on-the-fly.
+
+scrambler uses a block cipher and passphrase to encrypt and decrypt files in-place, as a means for quickly securing content without having to move things and/or create archives. scrambler appends a `.enc` extension to encrypted files, so it can use context clues to determine whether you want to perform encryption or decryption.
+
+As of writing, this application uses an AES-256 block cipher, with a passphrase that's hashed by SHA-256.
+
+## Usage
+```shell
+# Show help information.
+scrambler -h
+scrambler --help
+
+# Encrypt or decrypt the current directory.
+scrambler
+
+# Encrypt or decrypt a specified directory.
+scrambler my-dir
+
+# Encrypt or decrypt a single file.
+scrambler path/to/my/file.txt
+
+# Encrypt or decrypt a directory recursively.
+scrambler my-dir -r
+
+# Add -v for verbose output.
+scrambler myfile.txt -v
+
+# Explicitly choose to encrypt with -e.
+scrambler my-dir -e
+
+# Explicitly choose to decrypt with -d.
+scrambler my-encrypted-dir -d
+
+# Supply a passphrase from a file.
+scrambler my-dir -p my-passphrase.txt
+```
+
+## Download
+You can download a compatible release from the [releases](https://github.com/andrewlalis/scrambler/releases) page. If you can't find any release that's available for your system, you can build it yourself:
+```shell
+git clone git@github.com:andrewlalis/scrambler.git
+cd scrambler
+dub build --build=release
+```

reset.sh

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+
+rm -rf test-dir
+cp -R test-dir-tpl test-dir

source/app.d

@@ -14,6 +14,10 @@ import cipher_utils;
 import cli_utils;
 
 int main(string[] args) {
+	if (args.length >= 2 && (args[1] == "-h" || args[1] == "--help")) {
+		printUsage();
+		return 0;
+	}
 	Params params;
 	int result = parseParams(args, params);
 	if (result != 0) {
@@ -21,80 +25,98 @@ int main(string[] args) {
 		return result;
 	}
 
-	BlockCipher cipher = null;
-	// TODO: Use args to determine block cipher.
-	writeln("Enter a passphrase:");
-	string password = readPassphrase();
-	if (password is null) {
+	string passphrase;
+	if (params.passphraseFile !is null && exists(params.passphraseFile) && isFile(params.passphraseFile)) {
+		if (params.verbose) {
+			writefln!"Reading passphrase from \"%s\""(params.passphraseFile);
+		}
+		passphrase = readText(params.passphraseFile).strip();
+	} else {
+		write("Enter passphrase: ");
+		passphrase = readPassphrase();
+		writeln();
+	}
+	if (passphrase is null || passphrase.length == 0) {
+		stderr.writeln("Invalid or missing passphrase.");
 		return 2;
 	}
 
 	HashFunction hash = new SHA256();
-	auto secureKeyVector = hash.process(password);
-	cipher = new AES256();
+	auto secureKeyVector = hash.process(passphrase);
+	BlockCipher cipher = new AES256();
 	cipher.setKey(secureKeyVector);
 
 	ubyte[] buffer = new ubyte[cipher.blockSize];
 	if (isDir(params.target)) {
 		if (params.action == Action.ENCRYPT) {
-			encryptDir(params.target, cipher, buffer, params.recursive);
+			encryptDir(params.target, cipher, buffer, params.recursive, params.verbose);
 		} else {
-			decryptDir(params.target, cipher, buffer, params.recursive);
+			bool success = decryptDir(params.target, cipher, buffer, params.recursive, params.verbose);
+			if (!success) {
+				stderr.writeln("Decryption failed.");
+				return 3;
+			}
 		}
 	} else if (isFile(params.target)) {
 		if (params.action == Action.ENCRYPT) {
-			encryptAndRemoveFile(params.target, cipher, buffer);
+			encryptAndRemoveFile(params.target, cipher, buffer, params.verbose);
 		} else {
-			decryptAndRemoveFile(params.target, cipher, buffer);
+			bool success = decryptAndRemoveFile(params.target, cipher, buffer, params.verbose);
+			if (!success) {
+				stderr.writeln("Decryption failed.");
+				return 3;
+			}
 		}
-	} else {
-		stderr.writeln("Target is not a directory or file.");
-		return 1;
 	}
 	return 0;
 }
 
 
-void encryptAndRemoveFile(string filename, BlockCipher cipher, ref ubyte[] buffer) {
-	string encryptedFilename = filename ~ ".enc";
-	encryptFile(filename, encryptedFilename, cipher, buffer);
+void encryptAndRemoveFile(string filename, BlockCipher cipher, ref ubyte[] buffer, bool verbose) {
+	string encryptedFilename = filename ~ ENCRYPTED_SUFFIX;
+	encryptFile(filename, encryptedFilename, cipher, buffer, verbose);
 	std.file.remove(filename);
 }
 
-void decryptAndRemoveFile(string filename, BlockCipher cipher, ref ubyte[] buffer) {
-	string decryptedFilename = filename[0 .. $-4];
-	decryptFile(filename, decryptedFilename, cipher, buffer);
+bool decryptAndRemoveFile(string filename, BlockCipher cipher, ref ubyte[] buffer, bool verbose) {
+	string decryptedFilename = filename[0 .. $-ENCRYPTED_SUFFIX.length];
+	bool success = decryptFile(filename, decryptedFilename, cipher, buffer, verbose);
+	if (!success) return false;
 	std.file.remove(filename);
+	return true;
 }
 
-void encryptDir(string dirname, BlockCipher cipher, ref ubyte[] buffer, bool recursive) {
+void encryptDir(string dirname, BlockCipher cipher, ref ubyte[] buffer, bool recursive, bool verbose) {
 	string[] dirsToTraverse;
 	foreach (DirEntry entry; dirEntries(dirname, SpanMode.shallow, false)) {
-		if (entry.isFile && !endsWith(entry.name, ".enc")) {
-			encryptAndRemoveFile(entry.name, cipher, buffer);
+		if (entry.isFile && !endsWith(entry.name, ENCRYPTED_SUFFIX)) {
+			encryptAndRemoveFile(entry.name, cipher, buffer, verbose);
 		} else if (entry.isDir && recursive) {
 			dirsToTraverse ~= entry.name;
 		}
 	}
 	if (recursive) {
 		foreach (string childDirname; dirsToTraverse) {
-			encryptDir(childDirname, cipher, buffer, recursive);
+			encryptDir(childDirname, cipher, buffer, recursive, verbose);
 		}
 	}
 }
 
-void decryptDir(string dirname, BlockCipher cipher, ref ubyte[] buffer, bool recursive) {
+bool decryptDir(string dirname, BlockCipher cipher, ref ubyte[] buffer, bool recursive, bool verbose) {
 	string[] dirsToTraverse;
 	foreach (DirEntry entry; dirEntries(dirname, SpanMode.shallow, false)) {
-		if (entry.isFile && endsWith(entry.name, ".enc")) {
-			decryptAndRemoveFile(entry.name, cipher, buffer);
+		if (entry.isFile && endsWith(entry.name, ENCRYPTED_SUFFIX)) {
+			bool success = decryptAndRemoveFile(entry.name, cipher, buffer, verbose);
+			if (!success) return false;
 		} else if (entry.isDir && recursive) {
 			dirsToTraverse ~= entry.name;
 		}
 	}
 	if (recursive) {
 		foreach (string childDirname; dirsToTraverse) {
-			decryptDir(childDirname, cipher, buffer, recursive);
+			bool success = decryptDir(childDirname, cipher, buffer, recursive, verbose);
+			if (!success) return false;
 		}
 	}
+	return true;
 }

source/cipher_utils.d

@@ -2,13 +2,31 @@ module cipher_utils;
 
 import botan.block.block_cipher : BlockCipher;
 import std.stdio;
+import std.file;
 
-public void encryptFile(string filename, string outputFilename, BlockCipher cipher, ref ubyte[] buffer) {
+public const string ENCRYPTED_SUFFIX = ".enc";
+
+public void encryptFile(string filename, string outputFilename, BlockCipher cipher, ref ubyte[] buffer, bool verbose) {
     assert(buffer.length == cipher.blockSize, "Buffer length must match cipher block size.");
+    if (verbose) {
+        writefln!"Encrypting file \"%s\" of %d bytes to \"%s\" using cipher %s."(
+            filename,
+            getSize(filename),
+            outputFilename,
+            cipher.name
+        );
+    }
     File fIn = File(filename, "rb");
     File fOut = File(outputFilename, "wb");
     // First, write one block containing the file's size.
     writeSizeBytes(buffer, fIn.size);
+    // Fill the rest of the block with an incrementing series of bytes, so we can easily validate decryption.
+    if (buffer.length > 8) {
+        ubyte marker = 1;
+        for (size_t i = 8; i < buffer.length; i++) {
+            buffer[i] = marker++;
+        }
+    }
     cipher.encrypt(buffer);
     fOut.rawWrite(buffer);
     // Then write the rest of the file.
@@ -18,17 +36,49 @@ public void encryptFile(string filename, string outputFilename, BlockCipher ciph
     }
     fIn.close();
     fOut.close();
+    if (verbose) {
+        writefln!"  Encrypted file has a size of %d bytes."(getSize(outputFilename));
+    }
 }
 
-public void decryptFile(string filename, string outputFilename, BlockCipher cipher, ref ubyte[] buffer) {
+public bool decryptFile(string filename, string outputFilename, BlockCipher cipher, ref ubyte[] buffer, bool verbose) {
     assert(buffer.length == cipher.blockSize, "Buffer length must match cipher block size.");
+    if (verbose) {
+        writefln!"Decrypting file \"%s\" of %d bytes to \"%s\" using cipher %s."(
+            filename,
+            getSize(filename),
+            outputFilename,
+            cipher.name
+        );
+    }
     File fIn = File(filename, "rb");
-    File fOut = File(outputFilename, "wb");
     // First, read one block containing the file's size.
     fIn.rawRead(buffer);
     cipher.decrypt(buffer);
+    // Verify the sequence of values to ensure decryption was successful.
+    if (buffer.length > 8) {
+        ubyte expectedMarker = 1;
+        for (size_t i = 8; i < buffer.length; i++) {
+            if (buffer[i] != expectedMarker) {
+                if (verbose) {
+                    writefln!"  Decryption validation failed. Expected byte at index %d to be %d, but got %d."(
+                        i,
+                        expectedMarker,
+                        buffer[i]
+                    );
+                }
+                fIn.close();
+                return false;
+            }
+            expectedMarker++;
+        }
+    }
     ulong size = readSizeBytes(buffer);
+    if (verbose) {
+        writefln!"  Original file had size of %d bytes."(size);
+    }
     ulong bytesWritten = 0;
+    File fOut = File(outputFilename, "wb");
     // Then read the rest of the file.
     foreach (ubyte[] chunk; fIn.byChunk(buffer)) {
         cipher.decrypt(buffer);
@@ -41,27 +91,48 @@ public void decryptFile(string filename, string outputFilename, BlockCipher ciph
     }
     fIn.close();
     fOut.close();
+    if (verbose) {
+        writefln!"  Decrypted file has a size of %d bytes."(getSize(outputFilename));
+    }
+    return true;
+}
+
+union LongByteArrayUnion {
+    ulong longValue;
+    ubyte[8] bytes;
 }
 
 private void writeSizeBytes(ref ubyte[] bytes, ulong size) {
-    assert(bytes.length >= 4, "Array length must be at least 4.");
-    bytes[0] = size & 0xFF;
-    bytes[1] = (size << 8) & 0xFF;
-    bytes[2] = (size << 16) & 0xFF;
-    bytes[3] = (size << 24) & 0xFF;
-    if (bytes.length > 4) {
-        for (size_t i = 4; i < bytes.length; i++) {
+    assert(bytes.length >= 8, "Array length must be at least 8.");
+    LongByteArrayUnion u;
+    u.longValue = size;
+    for (size_t i = 0; i < 8; i++) bytes[i] = u.bytes[i];
+    if (bytes.length > 8) {
+        for (size_t i = 8; i < bytes.length; i++) {
             bytes[i] = 0;
         }
     }
 }
 
 private ulong readSizeBytes(ref ubyte[] bytes) {
-    assert(bytes.length >= 4, "Array length must be at least 4.");
-    ulong size = 0;
-    size += bytes[0];
-    size += bytes[1] << 8;
-    size += bytes[2] << 16;
-    size += bytes[3] << 24;
-    return size;
+    assert(bytes.length >= 8, "Array length must be at least 8.");
+    LongByteArrayUnion u;
+    for (size_t i = 0; i < 8; i++) u.bytes[i] = bytes[i];
+    return u.longValue;
+}
+
+unittest {
+    ubyte[] buffer = new ubyte[16];
+
+    void doAssert(ulong size) {
+        import std.format;
+        writeSizeBytes(buffer, size);
+        ulong r = readSizeBytes(buffer);
+        assert(r == size, format!"Value read: %d does not match expected: %d."(r, size));
+    }
+    
+    doAssert(0);
+    doAssert(1);
+    doAssert(42);
+    doAssert(74_092_382_742_030);
 }

source/cli_utils.d

@@ -1,5 +1,7 @@
 module cli_utils;
 
+import cipher_utils : ENCRYPTED_SUFFIX;
+
 enum Action {
 	ENCRYPT,
 	DECRYPT
@@ -10,6 +12,7 @@ struct Params {
 	string target = ".";
 	bool recursive = false;
 	bool verbose = false;
+	string passphraseFile = null;
 }
 
 int parseParams(string[] args, ref Params params) {
@@ -24,19 +27,12 @@ int parseParams(string[] args, ref Params params) {
 		"recursive|r", &params.recursive,
 		"verbose|v", &params.verbose,
 		"encrypt|e", &isEncrypting,
-		"decrypt|d", &isDecrypting
+		"decrypt|d", &isDecrypting,
+		"passphrase-file|p", &params.passphraseFile
 	);
 	if (isEncrypting && isDecrypting) {
 		stderr.writeln("Invalid arguments: Cannot specify both the --encrypt and --decrypt flags.");
 	}
-	if (isEncrypting) {
-		params.action = Action.ENCRYPT;
-	} else if (isDecrypting) {
-		params.action = Action.DECRYPT;
-	} else {
-		writeln("Determining if we should encrypt or decrypt");
-		params.action = Action.ENCRYPT;
-	}
 
 	if (args.length > 1) {
 		params.target = args[1];
@@ -45,9 +41,33 @@ int parseParams(string[] args, ref Params params) {
 			return 1;
 		}
 	}
+
+	if (isEncrypting) {
+		params.action = Action.ENCRYPT;
+	} else if (isDecrypting) {
+		params.action = Action.DECRYPT;
+	} else {
+		params.action = determineBestAction(params.target);
+	}
 	return 0;
 }
 
+Action determineBestAction(string target) {
+	import std.file;
+	import std.algorithm : endsWith;
+
+	if (isFile(target)) {
+		return endsWith(target, ENCRYPTED_SUFFIX) ? Action.DECRYPT : Action.ENCRYPT;
+	} else if (isDir(target)) {
+		foreach (DirEntry entry; dirEntries(target, SpanMode.breadth, false)) {
+			if (entry.isFile && endsWith(entry.name, ENCRYPTED_SUFFIX)) return Action.DECRYPT;
+		}
+		return Action.ENCRYPT;
+	} else {
+		return Action.ENCRYPT;
+	}
+}
+
 void printUsage() {
     import std.stdio : writeln;
 	writeln(q"HELP
@@ -60,6 +80,9 @@ The following options are available:
                            directory.
   -d | --decrypt         Do a decryption operation on the target file or
                            directory.
+  -p | --passphrase-file A file to read the passphrase from, instead of
+                           prompting the user for a passphrase in the command
+						   line.
   -r | --recursive       Recursively encrypt/decrypt nested directories.
   -v | --verbose         Show verbose output during runtime.
   -s | --no-suffix       Do not add the ".enc" suffix to files.
@@ -67,8 +90,7 @@ The following options are available:
 Encrypted files are suffixed with ".enc" to indicate that they're encrypted and
 cannot be read as usual. If neither --encrypt nor --decrypt flags are provided,
 Scrambler will try to determine which operation to do based on the presence of
-".enc" file(s) at the target location. It's recommended that you always do
-provide an explicit --encrypt or --decrypt flag.
+".enc" file(s) at the target location.
 HELP");
 }