algorithm

More and more, we hear talks about hackers entering personal accounts on systems such as Facebook, Twitter, Instagram and many others. There are many reasons why someone's account will be hacked. One of them is the lack of imagination for their password. Plus, some people use the same password for all of their accounts.

So, if you do it right, you will end up with many passwords. On my end, I have one password per account and that means about 400 passwords... That's totally unmanageable in a fairly standard human brain. For this reason, you end up writing down all your passwords on ...

Alan Turing Centenary

Starting tomorrow, Jun 23, 2012, many countries are to celebrate the centeray birth year of Alan Turing. Alan created the Turing machine concepts and formalized algorithm and computation that are now in use in all our computers (including your portable phone and your electronic watch.)

He actually participated to the creation of the first electronic computer during second world war in England. His algorithms and knowledge of cryptography gave him the necessary skills to crack the encoding of the German Enigma Machine (a form of printer that would encode messages with a level of complexity too ...

SWF Any Filter (swf_any_filter)

SWF Structure Info
Tag Flash Version:
8
SWF Structure:
```/* the filter type */
struct swf_filter_type {
unsigned char	f_type;
};

struct swf_filter_glow {
swf_filter_type	f_type;		/* 0, 2, 3, 4 or 7 */
unsigned char		f_count;
}
else {
f_count = 1;
}
swf_rgba		f_rgba[f_count];
if(f_type == Bevel) {
swf_rgba		f_highlight_rgba[f_count];
}
unsigned char		f_position[f_count];
}
signed long fixed	f_blur_horizontal;
signed long fixed	f_blur_vertical;
if(f_type != Glow) {
signed long fixed	f_distance;
}
signed short fixed	f_strength;
unsigned		f_knock_out : 1;
unsigned		f_composite_source : 1;
if(f_type == Bevel) {
unsigned		f_on_top : 1;
}
else {
unsigned		f_reserved : 1;
}
unsigned		f_passes : 4;
}
else {
unsigned		f_reserved : 4;
}
};

struct swf_filter_blur {
swf_filter_type		f_type;	/* 1 */
unsigned long fixed	f_blur_horizontal;
unsigned long fixed	f_blur_vertical;
unsigned		f_passes : 5;
unsigned		f_reserved : 3;
};

struct swf_filter_convolution {
swf_filter_type	f_type;		/* 5 */
unsigned char	f_columns;
unsigned char	f_rows;
long float	f_divisor;
long float	f_bias;
long float	f_weights[f_columns × f_rows];
swf_rgba	f_default_color;
unsigned	f_reserved : 6;
unsigned	f_clamp : 1;
unsigned	f_preserve_alpha : 1;
};

struct swf_filter_colormatrix {
swf_filter_type	f_type;		/* 6 */
long float	f_matrix[20];
};

struct swf_any_filter {
swf_filter_type			f_fitler_type;
swf_filter_blur			f_filter_blur;
swf_filter_colormatrix		f_filter_colormatrix;
swf_filter_convolution		f_filter_convolution;
swf_filter_glow			f_filter_glow;
};
```

A filter defines how to transform the objects it is attached to. The first byte is the filter type. The data following depend on the type. Because each filter is much different, they are defined in separate structures. You can attach a filter to an object using an ActionScript or the PlaceObject3 tag.

The following describes the different filters available since version 8.

...
Value Name Version

Protect

Tag Info
Tag Number:
24
Tag Type:
Define
Tag Flash Version:
2
Brief Description:

Disable edition capabilities of the given SWF file. Though this doesn't need to be enforced by an SWF editor, it marks the file as being copyrighted in a way.

WARNING: this tag is only valid in Flash V2.x, V3.x, and V4.x, use the EnableDebugger instead in V5.x and EnableDebugger2 in V6.x and newer movies.

Tag Structure:
```struct swf_protect {
swf_tag			f_tag;		/* 24, 58 or 64  */
if(version >= 5) {
if(tag == ProtectDebug2) {
unsigned short	f_reserved;1
}
/* the password is optional when tag == Protect */
}
};
```
• 1. f_reserved must be set to zero.

The protection tag is totally useless. The SWF format is an open format, otherwise how would you have so many players and tools to work with SWF movies? Thus, you can pretend to protect your movies, but anyone with a simple binary editor can transform the tag and make it another which has no such effect. Also, swf_dump and some other tools (such as flasm) can read your movie anyway.

For the sake of defining what you have in each tag, there are the protection tags fully described.

According to Macromedia, you can find some free implementation of the MD5 algorithm by Poul-Henning Kamp in ...

[un]signed

Tag Flash Version:
1
Used by PushData Action:
Not available in PushData Action

A signed or unsigned bit field which width does not directly correspond to an existing C type.

In structures, the width of the field is specified after the field name like in C bit fields. In case of Flash, it can be dynamic in which case a variable name is specified.

Signed bit fields have an implied sign extend of the most significant bit of the bit field. So a signed bit field of 2 bits support the following values: