NSTask *checksumTask = [[[NSTask alloc] init] autorelease];
				NSPipe *checksumPipe = [[[NSPipe alloc] init] autorelease];
				[checksumTask setStandardOutput:checksumPipe];
				NSFileHandle *readHandle = [checksumPipe fileHandleForReading];
				[checksumTask setLaunchPath:@"/usr/bin/openssl"];
				[checksumTask setArguments:[NSArray arrayWithObjects:
											@"dgst",
											@"-sha1",
											@"-binary",
											path,
											nil]];
				NSData *checksum = [readHandle readDataToEndOfFile];
				[checksumFile setObject:checksum forKey:[path lastPathComponent]];