<s>
An	O
.ipa	B-General_Concept
file	O
is	O
an	O
iOS	B-Application
and	O
iPadOS	B-Operating_System
application	O
archive	O
file	O
which	O
stores	O
an	O
iOS/iPadOS	O
app	B-Application
.	O
</s>
<s>
Each	O
.ipa	B-General_Concept
file	O
includes	O
a	O
binary	O
and	O
can	O
only	O
be	O
installed	O
on	O
an	O
iOS	B-Application
,	O
iPadOS	B-Operating_System
,	O
or	O
ARM-based	O
macOS	B-Application
device	O
.	O
</s>
<s>
Files	O
with	O
the	O
.ipa	B-General_Concept
extension	O
can	O
be	O
uncompressed	O
by	O
changing	O
the	O
extension	O
to	O
.zip	B-General_Concept
and	O
unzipping	O
.	O
</s>
<s>
Most	O
.ipa	B-General_Concept
files	O
cannot	O
be	O
installed	O
on	O
the	O
iPhone	B-Operating_System
Simulator	I-Operating_System
because	O
they	O
do	O
not	O
contain	O
a	O
binary	O
for	O
the	O
x86	B-Operating_System
architecture	I-Operating_System
,	O
only	O
one	O
for	O
the	O
ARM	B-Architecture
architecture	I-Architecture
of	O
mobile	O
phones	O
and	O
tablets	O
.	O
</s>
<s>
To	O
run	O
applications	O
on	O
the	O
simulator	O
,	O
original	O
project	O
files	O
which	O
can	O
be	O
opened	O
using	O
the	O
Xcode	B-Operating_System
SDK	B-Application
are	O
required	O
.	O
</s>
<s>
However	O
,	O
some	O
.ipa	B-General_Concept
files	O
can	O
be	O
opened	O
on	O
the	O
simulator	O
by	O
extracting	O
and	O
copying	O
over	O
the	O
.app	B-Application
file	O
found	O
in	O
the	O
Payload	O
folder	O
.	O
</s>
<s>
Prior	O
to	O
iTunes	B-Operating_System
12.7	O
(	O
September	O
2017	O
)	O
,	O
users	O
had	O
direct	O
access	O
to	O
ipa	O
files	O
in	O
the	O
form	O
of	O
App	B-Application
Store	I-Application
downloads	O
.	O
</s>
<s>
An	O
IPA	O
has	O
a	O
built-in	O
structure	O
for	O
iTunes	B-Operating_System
and	O
App	B-Application
Store	I-Application
to	O
recognize	O
.	O
</s>
<s>
As	O
shown	O
above	O
,	O
the	O
Payload	O
folder	O
is	O
what	O
contains	O
all	O
the	O
app	B-Application
data	O
.	O
</s>
<s>
The	O
iTunes	B-Operating_System
Artwork	O
file	O
is	O
a	O
512×512	O
pixel	O
PNG	O
image	O
,	O
containing	O
the	O
app	B-Application
's	O
icon	O
for	O
showing	O
in	O
iTunes	B-Operating_System
and	O
the	O
App	B-Application
Store	I-Application
app	B-Application
on	O
the	O
iPad	B-Device
.	O
</s>
<s>
The	O
iTunesMetadata.plist	O
contains	O
various	O
bits	O
of	O
information	O
,	O
ranging	O
from	O
the	O
developer	O
's	O
name	O
and	O
ID	O
,	O
the	O
bundle	B-Application
identifier	O
,	O
copyright	O
information	O
,	O
genre	O
,	O
the	O
name	O
of	O
the	O
app	B-Application
,	O
release	O
date	O
,	O
purchase	O
date	O
,	O
etc	O
.	O
</s>
<s>
Since	O
2017	O
,	O
Apple	O
has	O
used	O
LZFSE	B-Application
instead	O
of	O
registered	O
Zip	B-General_Concept
algorithms	O
in	O
IPAs	O
.	O
</s>
<s>
Code	O
signing	O
is	O
handled	O
in	O
the	O
.app	B-Application
bundle	B-Application
directory	O
.	O
</s>
<s>
The	O
META-INF	B-Language
folder	O
only	O
contains	O
metadata	O
about	O
what	O
program	O
was	O
used	O
to	O
create	O
the	O
IPA	O
.	O
</s>
<s>
An	O
unsigned	O
.ipa	B-General_Concept
can	O
be	O
created	O
by	O
copying	O
the	O
folder	O
with	O
the	O
extension	O
.app	B-Application
from	O
the	O
Products	O
folder	O
of	O
the	O
application	O
in	O
Xcode	B-Operating_System
to	O
a	O
folder	O
called	O
Payload	O
and	O
compressing	O
the	O
latter	O
using	O
the	O
command	O
zip	B-General_Concept
-0	O
-y	O
-r	O
myAppName.ipa	O
Payload/	O
.	O
</s>
<s>
It	O
is	O
then	O
possible	O
to	O
install	O
unsigned	O
.ipa	B-General_Concept
files	O
on	O
iOS	B-Application
jailbroken	I-Application
devices	O
using	O
third	O
party	O
software	O
.	O
</s>
<s>
Similar	O
to	O
the	O
case	O
of	O
game	O
console	O
hacking	O
,	O
people	O
are	O
known	O
to	O
use	O
this	O
installation	O
for	O
piracy	O
,	O
against	O
the	O
tool	O
developer	O
's	O
wishes	O
:	O
some	O
underground	O
communities	O
form	O
around	O
buying	O
an	O
app	B-Application
and	O
then	O
sharing	O
its	O
DRM-free	O
unsigned	O
version	O
.	O
</s>
