4. SEARCHING FOR INFORMATION IN THE CACHE4.DB DATABASE
4. SEARCHING FOR INFORMATION IN THE CACHE4.DB DATABASE
4.1. METHOD 1. SEARCHING FOR INFORMATION BY STRUCTURE OF DATABASE TABLES
This method is based on using standard queries for SQLite databases.
Step 1: Obtaining data from the “messages” table.
Step 2. Separating message-related information from the “data” field of the "messages" table, taking into account the structure described above.
Step 3. Obtaining the data from the “users”, “chats”, “enc_chats” tables depending on the values of the “mid”, “uid” fields from the “messages” table.
Step 4. Defining user contacts from the “user_contacts_v7”, “user_phones_v7” tables (as an option, it is possible to find the data of individual interlocutors from the “data” field of the “users” table).
4.1.1. CONVERSION OF THE "UID" FIELD VALUE
mid value
|
uid value
|
Type
|
Conversion
|
mid > 0 and not a large digit
|
uid > 0 and its length is 9 characters or less
|
chat
|
uid without conversions
|
uid < 0 and its length is 9 characters or less
|
group
|
uid without conversions
| |
mid > 0 and a large digit (16-digithexadecimal number)
|
uid < 0 and its length is10 characters
|
channel
|
uid without conversions
|
mid < 0
|
uid – 16-digit hexadecimal number
|
secret chat
|
uid with conversions
|
uid > 0 and its length is 9 characters or less
|
chat
|
uid without conversions
| |
uid < 0 and its length is10 characters
|
channel
|
uid without conversions
| |
uid < 0 and its length is 9 characters or less
|
group
|
uid without conversions
|
Possible values of the “mid” and “uid” fields:
- if “mid” and “uid” are positive – it is a regular chat; the interlocutor data can be find in the “Users” table by “uid” (usually the “uid” length is 9 characters or less)[3];
- if “mid” is a small positive digit[4] and “uid” is negative – it is a group, the data on this group can be find in the “Chats” table by “uid” (usually the “uid” length is 9 characters or less);
- if “mid” is a large positive digit[5] and “uid” is negative – it is a channel; the data on this channel can be find in the “Chats” table by “uid” (usually the “uid” length is 10 characters);
- if “mid” is negative and “uid” is 9-character length or less – the interlocutor’s data can be find in the “Users” table by “uid”;
- if “mid” is negative, “uid” is negative or positive and has a length of about 19 characters[6] – the interlocutor’s data can be find in the “Enc_chats” table by the converted “uid” value. To find the appropriate contact in the “Enc_chats” table, you need to convert the decimal “uid” number to hexadecimal, then cut off the last 8 zeros from the received number and convert the eight-digit hexadecimal number back to decimal;
- if “mid” and “uid” are negative – it is a channel or group actions with joining/adding/removing another users; the data on this channel/group can be find in the “Chats” table by “uid”.
4.1.2. TABLES RELATIONSHIPS
Relationships between “cache4.db” database tables in cases of a chat between two users, a secret chat, a group and a channel are shown in the following figures 14, 15, 16, 17.
Figure 14 Searching for information on an interlocutor in case of a chat between two users or calls
Figure 15 Searching for information on an interlocutor in case of a secret chat
Figure 16 Searching for information on an interlocutor in case of a group conversation
Figure 17 Searching for information on an interlocutor in case of a channel messages
4.2. METHOD 2. SEARCHING FOR INFORMATION BY INTERNAL STRUCTURE OF DATABASE FIELDS
The method is based on searching for values of the “data” fields of the “messages”, “users”, “chats”, and “enc_chats” tables in the “cache4.db” file[7].
Note: In addition to the SQLite database file (“cache4.db”), special interest should be given to the “cache4.db-wal” log file, which may contain data (about messages, contacts, etc.) either deleted from the main database "cache4.db " or has not yet been added to it. Due to the fact that the “cache4.db-wal” rollback file contains complete SQLite records from the main database file ("cache4.db"), this method is suitable for searching for message-related data in the "cache4.db-wal” file.
Figure 18 shows an example of the “cache4.db-wal” rollback file with the SQLite database's “messages” entry, which has not yet been added in the “cache4.db” file (the message body is in a rectangle, the signature of the “data” field is underlined).
Figure 18 Part of the “cache4.db-wal” file
Step 1: Searching by signatures for information on the “data” fields of the “chats”, “enc_chats”, “users” tables, as well as their initial analysis (i.e., searching for data on chats, groups, channels, and users).
Step 2. Searching by signatures for information on the “data” fields of the “messages” table (three possible options), as well as their initial analysis (i.e. searching for message bodies and interpretation of another data).
Step 3. Analysis of the “data” fields from the “messages" table – categorization of identified data (a chat between two users, a secret chat, a group, a channel, a group creation, a channel creation, a call).
Step 4. Analysis of the “data” fields from the “chats”, “enc_chats”, “users” tables – searching for matches between users id, chats id, their names and phone numbers.
Step 5. Searching for information on interlocutors by their unique identifiers among the “data” fields of the “chats”, “enc_chats”, “users” tables (depending on a category of the “data” field of the "messages" table).
DETAILED ALGORITHM:
Step 1: Searching by signatures for information on the “data” fields of the “chats”, “enc_chats”, “users” tables, as well as their initial analysis (i.e., searching for data on chats, groups, channels and users):
a) "c3 f4 13 2e" – initial 4 bytes of the "data" field with user details from the “users” table (including the “Telegram” user);
b) "36 ce 56 fa" – initial 4 bytes of the "data" field with secret chat details from the "enc_chats" table;
c) "ac 74 89 c8" – initial 4 bytes of the "data" field with channel details;
d) "54 dd 1c d9", "db 8b 32 07", "54 dd 1c d9", "1c 4b b4 0c", "15 71 0b 45"[8] - initial 4 bytes of the "data" field with group details.
Interpretation of the “data” fields of the “chats”, “enc_chats”, “users” tables is given below in tabular form. Examples of extractions of information on users, groups, channels are shown in following figures 19, 20, 21, 22.
1) User details from the “data” field of the “users” table (see the figure 19):
#
|
Offset
|
Length, bytes
|
Description
|
1
|
0
|
4
|
= «c3 f4 13 2e»
|
2
|
8
|
4
|
User id (uid)
|
3
|
20
|
1
|
Size of user name
|
4
|
21
|
variable
|
User name (it can consist of some parts. For instance, if the name is followed by the value “00”, the next non-zero byte indicates the size of the user’s phone data. If the name is followed by a non-zero character, then this byte indicates the size of a next part of username)
|
5
|
After zero bytes
|
1
|
Size of user’s phone number
|
6
|
Next bytes
|
variable
|
User’s phone number
|
Figure 19 The “data” field of the “users” table for a chat between two users
2) User details from the “data” field of the “enc_chats” table (see the figure 20):
#
|
Offset
|
Length, bytes
|
Description
|
1
|
0
|
4
|
= «36 ce 56 fa»
|
2
|
4
|
4
|
Chat id (uid)
|
3
|
24
|
4
|
User id (user)
|
Figure 20 The “data” field of the “enc_chats” table
3) User details from the “data” field of the “chats” table in case of a channel (see the figure 21):
#
|
Offset
|
Length, bytes
|
Description
|
1
|
0
|
4
|
= «ac 74 89 c8»
|
2
|
8
|
4
|
Channel id (uid)
|
3
|
20
|
1
|
Size of channel’s name
|
4
|
21
|
variable
|
Channel’s name
|
Figure 21 The “data” field of the “chats” table in case of a channel
4) User details from the “data” field of the “chats” table in case of a group (see the figure 22):
#
|
Offset
|
Length, bytes
|
Description
|
1
|
0
|
4
|
= «54 dd 1c d9», «db 8b 32 07»,
«1c 4b b4 0c», «15 71 0b 45»[9]
|
2
|
8
|
4
|
Group id (uid)
|
3
|
9
|
1
|
Size of group’s name
|
4
|
10
|
variable
|
Group’s name
|
Figure 22 The “data” field of the “chats” table in case of a group
Step 2. Searching by signatures for information on the “data” fields of the “messages” table (three possible options), as well as their initial analysis:
a) «3d b4 f9 44» [10] - initial 4 bytes of a field that contains data on a regular chat (a chat between two users, a channel or a group):
- value with offset 12 is equal to “32 e5 dd bd” - data on messages in a channel;
- value with offset 16 is equal to “bb e5 d0 ba” - data on messages in a group;
- value with offset 16 is equal to “6d bc b1 9d” - data on a chat between two users;
b) «f6 a1 19 9e» – initial 4 bytes of a field with either call or group’s/channel’s creation data;
- value with offset 12 or 16 is equal to “32 e5 dd bd” – channel’s creation data;
- value with offset 16 is equal to “bb e5 d0 ba” – group’s creation data;
- value with offset 16 is equal to “6d bc b1 9d” - calling data;
c) «fa 55 55 55» [11] - initial 4 bytes of a field with data on a secret chat (additionally – value with offset 20 is equal to “6d bc b1 9d”).
Note on file transfer[12]:
In case of file sharing between users, the “data” field of the “messages” table contains information on file names, their sizes, etc. (after information described in the tables below).
So if you send a photo from the user's gallery, the first significant bytes is “d7 50 51 69” after message body (if any). There is data on file names, sizes of the sent file and its cached images stored in the “\storage\emulated\0\Android\data\org.telegram.messenger\cache”[13] folder. This information is after a value “76 90 d6 53”. Also the file path is incremented by one at the end of the “data” field.
In case of receiving a picture, a structure of data obtained on a received file and its cached images is similar in general. There may be several file markers (“76 90 d6 53”) which containing information about file names, sizes of the file and its cached images stored in the “\media\0\telegram\telegram images”, “\storage\emulated\0\Android\data\org.telegram.messenger\ cache”, etc.
In case of sending a file from an explorer, the first significant bytes after the message metadata are “d7 70 b0 9c”. Then you can find information on file name and its size (in case of loading the last one) in the “data” field.
Interpretation of the “data” fields of the "messages" table in cases of conversation between two users in a regular chat, a secret chat, a channel, a group, a channel’s/group’s creation, audio calls is given below in tabular form.
1) Message details in case of a chat between two users (from the “data” field of the “messages” table):
#
|
Offset
|
Length, bytes
|
Description
|
1
|
0
|
4
|
= «3d b4 f9 44»
|
2
|
8
|
4
|
Message id (mid)
|
3
|
12
|
4
|
id (uid) of user, that sent a message
|
4
|
16
|
4
|
=«6d bc b1 9d»
|
5
|
20
|
4
|
interlocutor id
|
6
|
24
|
4
|
Unix Epoch timestamp of message
|
7
|
28
|
1
|
Size of a message (if value is not equal «fe»)
|
29
|
3
|
Size of a message (this fields are used if only value at offset 28 bytes is equal «fe»)
| |
8
|
29 or 32
|
variable
|
Message body
|
2) Message details in case of a secret chat (from the “data” field of the “messages” table):
#
|
Offset
|
Length, bytes
|
Description
|
1
|
0
|
4
|
= «fa 55 55 55»
|
2
|
8
|
4
|
Message id (mid)
|
3
|
16
|
4
|
id (uid) of user, that sent a message
|
4
|
20
|
4
|
=«6d bc b1 9d»
|
5
|
24
|
4
|
interlocutor id
|
6
|
28
|
4
|
Unix Epoch timestamp of message
|
7
|
32
|
1
|
Size of a message (if a value is not equal «fe»)
|
33
|
3
|
Size of a message (this fields are used if only a value at offset 32 bytes is equal «fe»)
| |
8
|
33 or 36
|
variable
|
Message body
|
3) Message details in case of a channel (from the “data” field of the “messages” table)(items 6, 7 are taken into account in event of messages in a channel, items 8, 9 - in event of channel’s creation):
#
|
Offset
|
Length, bytes
|
Description
|
1
|
0
|
4
|
= «3d b4 f9 44» – message
|
= «f6 a1 19 9e» – channel’s creation
| |||
2
|
8
|
4
|
Message id (mid)
|
3
|
12
|
4
|
= «32 e5 dd bd»
|
4
|
16
|
4
|
Channel id
|
5
|
20
|
4
|
Unix Epoch timestamp of message
|
6
|
24
|
1
|
Size of a message (if a value is not equal «fe»)
|
25
|
3
|
Size of a message (this fields are used if only a value at offset 24 bytes is equal «fe»)
| |
7
|
25 or 28
|
variable
|
Message body
|
8
|
28
|
1
|
Size of channel’s name
|
9
|
29
|
variable
|
Channel’s name
|
4) Channel’s/group’s details in case of its creation by another user and subsequent joining/adding/removing of persons (from the “data” field of the “messages” table):
#
|
Offset
|
Length, bytes
|
Description
|
1
|
0
|
4
|
= «f6 a1 19 9e» – channel/group-related action
|
2
|
8
|
4
|
Message id (mid)
|
3
|
12
|
4
|
Channel’s/group’s creator/administrator id
|
4
|
16
|
4
|
= «32 e5 dd bd»
|
5
|
20
|
4
|
Channel/group id
|
6
|
24
|
4
|
Unix Epoch timestamp of action
|
7
|
40
|
4
|
Id of joined/added/removed user
|
5) Message details in case of a group (from the “data” field of the “messages” table) (items 7, 8 are taken into account in event of messages in a group, items 9, 10 - in event of group’s creation):
#
|
Offset
|
Length, bytes
|
Description
|
1
|
0
|
4
|
= «3d b4 f9 44» – message
|
= «f6 a1 19 9e» – group’s creation
| |||
2
|
8
|
4
|
Message id (mid)
|
3
|
12
|
4
|
id (uid) of user, that sent a message
|
4
|
16
|
4
|
=«bb e5 d0 ba»
|
5
|
20
|
4
|
Group id
|
6
|
24
|
4
|
Unix Epoch timestamp of message
|
7
|
28
|
1
|
Size of a message (if a value is not equal «fe»)
|
29
|
3
|
Size of a message (this fields are used if only a value at offset 28 bytes is equal «fe»)
| |
8
|
29 or 32
|
variable
|
Message body
|
9
|
32
|
1
|
Size of group’s name
|
10
|
33
|
variable
|
Group’s name
|
6) Calling details (from the “data” field of the “messages” table):
#
|
Offset
|
Length, bytes
|
Description
|
1
|
0
|
4
|
= «f6 a1 19 9e»
|
2
|
8
|
4
|
Message id (mid)
|
3
|
12
|
4
|
id (uid) of user, that made a call
|
4
|
16
|
4
|
=«6d bc b1 9d»
|
5
|
20
|
4
|
interlocutor id
|
6
|
24
|
4
|
Unix Epoch timestamp of calling
|
7
|
32
|
1
|
If a value is equal «0x03» – a connection is successful
|
If a value is equal «0x01» – a connection is not successful
| |||
8
|
48
|
4
|
Call duration (in case of successful connection only)
|
Step 3. Analysis of the “data” fields of the “messages” table – categorization of identified data (a chat between two users, a secret chat, a group, a channel, a group’s/channel’s creation, a call).
Interpretation of information from the “data” fields of the "messages" table in cases of conversation between two users in a regular chat, a secret chat, a channel, a group, a channel’s/group’s creation, audio calls, file transfers is given below in tabular form. Examples of extractions of mentioned information are shown in following figures 23, 24, 25, 26, 27, 28, 29, 30.
1) Message details in case of a chat between two users (from the “data” field of the “messages” table) (see the figure 23):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «3d b4 f9 44»
|
–
|
2
|
8
|
4
|
0x00000003
|
3
|
3
|
12
|
4
|
0x26a3a99a
|
648259994
|
4
|
16
|
4
|
=«6d bc b1 9d»
|
–
|
5
|
20
|
4
|
0x26a3a99a
|
648259994
|
6
|
24
|
4
|
0x5bb1e543
|
1538385219 – 01.10.2018 12:13:39 UTC+3
|
7
|
28
|
1
|
0x21
|
33
|
8
|
29
|
33
|
–
|
I am fine. Is this a secret chat?
|
Figure 23 Message details in case of a chat between two users (from the “data” field of the “messages” table)
2) Message details in case of a secret chat (from the “data” field of the “messages” table) (see the figure 24):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «fa 55 55 55»
|
–
|
2
|
8
|
4
|
0xfffccba7
|
-210009 (0xfffffffffffccba7)
|
3
|
16
|
4
|
0x269dc727
|
647874343
|
4
|
20
|
4
|
=«6d bc b1 9d»
|
–
|
5
|
24
|
4
|
0x26a3a99a
|
648259994
|
6
|
28
|
4
|
0x5bb1e789
|
1538385801 – 01.10.2018 12:23:21 UTC+3
|
7
|
32
|
1
|
0x0c
|
12
|
8
|
33
|
12
|
–
|
Where is it?
|
Figure 24 Message details in case of a secret chat (from the “data” field of the “messages” table)
3) Message details in case of a channel (from the “data” field of the “messages” table) (see the figure 25):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «3d b4 f9 44»
|
–
|
2
|
8
|
4
|
0x00000003
|
5876046144655589379 (0x518be8d600000003)
|
3
|
12
|
4
|
= «32 e5 dd bd»
|
–
|
4
|
16
|
4
|
0x518be8d6
|
1368123606
|
5
|
20
|
4
|
0x5bb1e9ad
|
1538386349 – 01.10.2018 12:32:29 UTC+3
|
6
|
24
|
1
|
0x26
|
38
|
7
|
25
|
38
|
–
|
It is a channel about small town Sumy.
|
Figure 25 Message details in case of a channel (from the “data” field of the “messages” table)
4) Message details in case of a group (from the “data” field of the “messages” table) (see the figure 26):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «3d b4 f9 44»
|
–
|
2
|
8
|
4
|
0x00000016
|
22
|
3
|
12
|
4
|
0x09e5c49e
|
166053022
|
4
|
16
|
4
|
=«bb e5 d0 ba»
|
–
|
5
|
20
|
4
|
0x12f7659c
|
318203292
|
6
|
24
|
4
|
0x5bb1ead9
|
1538386649 – 01.10.2018 12:37:29 UTC+3
|
7
|
28
|
1
|
0x08
|
8
|
8
|
29
|
8
|
–
|
Ok. Nice
|
Figure 26 Message details in case of a group (from the “data” field of the “messages” table)
5) Message details in case of a call (from the “data” field of the “messages” table) (see the figure 27):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «f6 a1 19 9e»
|
–
|
2
|
8
|
4
|
0x0000000d
|
13
|
3
|
12
|
4
|
0x269dc727
|
647874343
|
4
|
16
|
4
|
=«6d bc b1 9d»
|
–
|
5
|
20
|
4
|
0x26a3a99a
|
648259994
|
6
|
24
|
4
|
0x5bb1e703
|
1538385667 – 01.10.2018 12:21:07 UTC+3
|
7
|
32
|
1
|
0x03
|
Successful connection
|
8
|
48
|
4
|
0x00000011
|
Call duration – 17 seconds
|
Figure 27 Message details in case of a call (from the “data” field of the “messages” table)
6) File details in case of sending a photo from the user's gallery (from the “data” field of the “messages” table) (see the figure 28):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «fa 55 55 55»
|
Signature of a secret chat
|
2
|
44
|
4
|
= «d7 50 51 69»
|
–
|
3
|
96
|
4
|
= «76 90 d6 53»
|
Beginning of data about file
|
4
|
104
|
4
|
0x80000000
|
The 1st part of file name – 2147483648
|
5
|
112
|
4
|
0xfffccbad
|
The 2nd part of file name – -210003 (=0xfffffffffffccbad)
|
6
|
132
|
4
|
0x000005bc
|
File size – 1468 bytes
|
7
|
152
|
8
|
0x49919d6e000002b1
|
The 1st part of file name – 5301191332163748529
|
8
|
160
|
4
|
0x22396b92
|
The 2nd part of file name – 574188434
|
9
|
252
|
4
|
0x0001f89e
|
File size – 129182 bytes
|
10
|
272
|
1
|
0x55
|
Length of file path – 85 bytes
|
11
|
273
|
85
|
–
|
File path (file name is incremented by one)
|
Figure 28 File details in case of sending a photo from the user's gallery (from the “data” field of the “messages” table)
7) File details in case of receiving a photo (from the “data” field of the “messages” table) (see the figure 29):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «3d b4 f9 44»
|
Signature of a chat
|
2
|
32
|
4
|
= «d7 50 51 69»
|
–
|
3
|
228
|
4
|
= «76 90 d6 53»
|
Beginning of data on file
|
4
|
236
|
4
|
0x0eb7c820
|
The 1st part of file name – 246925344
|
5
|
244
|
4
|
0x00043f0a
|
The 2nd part of file name – 278282
|
6
|
264
|
4
|
0x0003b2a5
|
File size – 242341 bytes
|
Figure 29 File details in case of receiving a photo (from the “data” field of the “messages” table)
8) Details on received file (in this case, a file is not loaded) (from the “data” field of the “messages” table) (see the figure 30):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «fa 55 55 55»
|
Signature of a secret chat
|
2
|
36
|
4
|
= «d7 70 b0 9c»
|
–
|
3
|
116
|
16
|
–
|
File name – «f454477n303.doc»
|
Figure 30 Details on received file (from the “data” field of the “messages” table).
Step 4: Interpretation of information from the “data” fields of the “chats”, “enc_chats” and “users” tables.
Interpretation of information from “data” fields of the “chats”, “enc_chats” and “users” tables is given below in tabular form. Examples of extractions of information on users, groups, channels are shown in following figures 31, 32, 33, 34.
1) User details from the “data” field of the “users” table (see the figure 31):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «c3 f4 13 2e»
|
–
|
2
|
8
|
4
|
0x26a3a99a
|
648259994
|
3
|
20
|
1
|
0x08
|
8
|
4
|
21
|
8
|
–
|
Grygir27
|
5
|
32
|
1
|
0x0c
|
12
|
6
|
33
|
12
|
–
|
3806********
|
Figure 31 User details from the “data” field of the “users” table.
2) User details from the “data” field of the “enc_chats” table (see the figure 32):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «36 ce 56 fa»
|
–
|
2
|
4
|
4
|
0x6b0ed8be
|
1796135102
|
3
|
24
|
4
|
0x26a3a99a
|
648259994
|
Figure 32 User details from the “data” field of the “enc_chats” table
3) User details from the “data” field of the “chats” table in case of a channel (see the figure 33):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
= «ac 74 89 c8»
|
–
|
2
|
8
|
4
|
0x518be8d6
|
1368123606
|
3
|
20
|
1
|
0x08
|
8
|
4
|
21
|
8
|
–
|
Sumy1665
|
Figure 33 User details from the “data” field of the “chats” table in case of a channel
4) User details from the “data” field of the “chats” table in case of a group (see the figure 34):
#
|
Offset
|
Length, bytes
|
Value
|
Meaning
|
1
|
0
|
4
|
«54 dd 1c d9», «db 8b 32 07»,
«1c 4b b4 0c», «15 71 0b 45»[14]
|
–
|
2
|
8
|
4
|
0x12f7659c
|
318203292
|
3
|
12
|
1
|
0x0d
|
13
|
4
|
13
|
13
|
–
|
Volleyball234
|
Figure 34 User details from the “data” field of the "chats" table in case of a group
Step 5. Searching for information on interlocutors by their unique identifiers among the “data” fields of the “chats”, “enc_chats”, “users” tables (depending on the “data” field of the “messages” table). At the same time data on names of groups/channels can be found in the “data” field of “messages” table for cases of group’s/channel’s creation.
