Split to multiple files and add Makefile.

Buffer.c

@@ -0,0 +1,51 @@
+#include "Buffer.h"
+
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <CoreFoundation/CoreFoundation.h>
+
+void Read( struct buffer *buf, size_t length, void *destination )
+{
+	assert( buf->next + length < buf->start + buf->length );
+	memcpy( destination, buf->next, length );
+	buf->next += length;
+}
+
+uint32_t Read32( struct buffer *buf )
+{
+	uint32_t result;
+	Read( buf, sizeof result, &result );
+	return CFSwapInt32BigToHost( result );
+}
+
+uint16_t Read16( struct buffer *buf )
+{
+	uint16_t result;
+	Read( buf, sizeof result, &result );
+	return CFSwapInt16BigToHost( result );
+}
+
+bool OpenFile( struct buffer *buf, const char *fn )
+{
+	buf->fd = open( fn, O_RDONLY );
+	if (buf->fd < 0) return false;
+	
+	struct stat stat;
+	if (fstat( buf->fd, &stat ) < 0) {
+		close( buf->fd );
+		return false;
+	}
+	
+	buf->length = stat.st_size;
+	
+	buf->start = mmap( NULL, buf->length, PROT_READ, MAP_FILE | MAP_PRIVATE, buf->fd, 0 );
+	if (!buf->start) {
+		close( buf->fd );
+		return false;
+	}
+	
+	buf->next = buf->start;
+	
+	return true;
+}

Buffer.h

@@ -0,0 +1,21 @@
+#ifndef _Buffer_h_included_
+#define _Buffer_h_included_
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+
+struct buffer {
+	uint8_t *start;
+	size_t length;
+	uint8_t *next;
+	int fd;
+};
+
+void Read( struct buffer *buf, size_t length, void *destination );
+uint32_t Read32( struct buffer *buf );
+uint16_t Read16( struct buffer *buf );
+
+bool OpenFile( struct buffer *buf, const char *fn );
+
+#endif

Common.h

@@ -0,0 +1,26 @@
+#ifndef _Common_h_included_
+#define _Common_h_included_
+
+#include <stdint.h>
+
+struct header
+{
+	char magic[4]; 			// magic bytes \x43 \x46 \x47 \x31 (CFG1)
+	uint32_t payload_size; 	// length of ciphertext = length of padded plaintext (big endian)
+	char header_md5[8];		// first 8 bytes of MD5 computed over header (assuming the 8 bytes of "header_md5" are \x00)
+	char etl[7]; 			// blank electronic label (etl), always "000000" (null-terminated char array)
+	char unused1; 			// not used at the moment
+	uint16_t password_len; 	// length of the password used in AES encryption (big endian)
+	uint16_t padding_len; 	// number of padding bytes added to plaintext (big endian)
+	char unused2[4];		// not used at the moment
+	char plaintext_md5[16]; // MD5 hash of the plaintext
+};
+
+static const char aes_key[32] = {
+  0x64, 0x75, 0x6d, 0x6d, 0x79, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+#endif

Decrypt.c

@@ -2,59 +2,12 @@
  * Code is under the MIT license, see the LICENSE file.
  */
 
+#include "Common.h"
+#include "Buffer.h"
+
 #include <CoreFoundation/CoreFoundation.h>
 #include <CommonCrypto/CommonCrypto.h>
-#include <sys/stat.h>
-#include <sys/mman.h>
 
-struct header
-{
-	char magic[4]; 			// magic bytes \x43 \x46 \x47 \x31 (CFG1)
-	uint32_t payload_size; 	// length of ciphertext = length of padded plaintext (big endian)
-	char header_md5[8];		// first 8 bytes of MD5 computed over header (assuming the 8 bytes of "header_md5" are \x00)
-	char etl[7]; 			// blank electronic label (etl), always "000000" (null-terminated char array)
-	char unused1; 			// not used at the moment
-	uint16_t password_len; 	// length of the password used in AES encryption (big endian)
-	uint16_t padding_len; 	// number of padding bytes added to plaintext (big endian)
-	char unused2[4];		// not used at the moment
-	char plaintext_md5[16]; // MD5 hash of the plaintext
-};
-
-static const char aes_key[32] = {
-	0x64, 0x75, 0x6d, 0x6d, 0x79, 0x00, 0x00, 0x00,
-  	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
-};
-
-
-struct buffer {
-	uint8_t *start;
-	size_t length;
-	uint8_t *next;
-	int fd;
-};
-
-void Read( struct buffer *buf, size_t length, void *destination )
-{
-	assert( buf->next + length < buf->start + buf->length );
-	memcpy( destination, buf->next, length );
-	buf->next += length;
-}
-
-uint32_t Read32( struct buffer *buf )
-{
-	uint32_t result;
-	Read( buf, sizeof result, &result );
-	return CFSwapInt32BigToHost( result );
-}
-
-uint16_t Read16( struct buffer *buf )
-{
-	uint16_t result;
-	Read( buf, sizeof result, &result );
-	return CFSwapInt16BigToHost( result );
-}
 
 void ReadHeader( struct buffer *buf, struct header *header )
 {
@@ -69,30 +22,6 @@ void ReadHeader( struct buffer *buf, struct header *header )
 	Read( buf, 16, header->plaintext_md5 );
 }
 
-bool OpenFile( struct buffer *buf, const char *fn )
-{
-	buf->fd = open( fn, O_RDONLY );
-	if (buf->fd < 0) return false;
-	
-	struct stat stat;
-	if (fstat( buf->fd, &stat ) < 0) {
-		close( buf->fd );
-		return false;
-	}
-	
-	buf->length = stat.st_size;
-	
-	buf->start = mmap( NULL, buf->length, PROT_READ, MAP_FILE | MAP_PRIVATE, buf->fd, 0 );
-	if (!buf->start) {
-		close( buf->fd );
-		return false;
-	}
-	
-	buf->next = buf->start;
-	
-	return true;
-}
-
 int main( int argc, const char *argv[] ) 
 {
 	if (argc != 3) {

Makefile

@@ -0,0 +1,11 @@
+all: Decrypt
+
+Decrypt: Decrypt.o Buffer.o
+	clang -o $@ Decrypt.o Buffer.o
+
+Decrypt.o: Decrypt.c Buffer.h Common.h
+Buffer.o: Buffer.c Buffer.h
+
+.c.o:
+	clang -c -o $@ $<
+

README.md

@@ -6,7 +6,7 @@ Thanks to [hph][1] for reverse engineering the details of that config format.
 
 ## Compile:
 
-	clang Decrypt.c -o Decrypt
+	make
 
 ## Run: