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Read signature data from APK's RSA signature file

30-Dec-21 18:43

Return void instead of Task if that's what you intend.

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mynametaken30-Dec-21 4:46

Re: Read signature data from APK's RSA signature file

30-Dec-21 4:46

I have the source in java that reads signature data from RSA (erxtracted from APK (Android Package) file) and it works flawlessly but i would like to convert to C# in order to use in my c# application. The issue is i'm getting different data from GetRawCertData() no matter what I have tried.

This is the result:
C#: AQAAADCCBYkwggNxoAMCAQICFQDmX5cziG0zO22ity1a/dKI6FnZyzANBgk...
Java: AQAABY0wggWJMIIDcaADAgECAhUA5l+XM4htMzttorctWv3SiOhZ2cswDQYJKoZIhvcNA...

I'm not familar with signatures, and i'm not even sure what excat format is it but I know it is signed with Java's KeyStore file.

What should I do to get it right? it is very close though. Executing .jar file would be a workaround but I would like to avoid executing something externally

This is my C# code

X509Certificate cert = X509Certificate.CreateFromSignedFile("BNDLTOOL.RSA");

MemoryStream ms = new MemoryStream();
BinaryWriter bw = new BinaryWriter(ms);
bw.Write(1);

byte[] data = cert.GetRawCertData();
bw.Write(data);
bw.Write(data.Length);

byte[] buffer = ms.ToArray();

Debug.WriteLine(Convert.ToBase64String(buffer));

This is Java code from a project that I found online

Java

PKCS7 pkcs7 = new PKCS7(StreamUtil.readBytes(zipFile.getInputStream(ze)));
Certificate[] certs = pkcs7.getCertificates();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(baos);
dos.write(certs.length);
for (int i = 0; i < certs.length; i++) {
    byte[] data = certs[i].getEncoded();
    System.out.printf("  --SignatureHash[%d]: %08x\n", i, Arrays.hashCode(data));
    dos.writeInt(data.length);
    dos.write(data);
}
byte[] signatures = baos.toByteArray();
System.out.println(Base64.getEncoder().encodeToString(signatures));

modified 1-Jan-22 11:52am.

jschell30-Dec-21 7:35

jschell

30-Dec-21 7:35

This...

mynametaken wrote:
%08x

Is not even close to being the same as the following.

mynametaken wrote:
ToBase64String

So presumably that is not where you see a difference.

Re: Read signature data from APK's RSA signature file

mynametaken1-Jan-22 5:53

Re: Read signature data from APK's RSA signature file

1-Jan-22 5:53

%08x is not related to it. I have edited the question

Luc Pattyn30-Dec-21 7:44

Luc Pattyn

30-Dec-21 7:44

Your statement

bw.Write(1);

writes a 4-byte int with value 1, whereas your Java string "AQAABY0w..." starts with a byte of value 1. Maybe what you want is:

bw.Write((byte)1);

Luc Pattyn [My Articles]
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Re: Read signature data from APK's RSA signature file

mynametaken1-Jan-22 5:56

Re: Read signature data from APK's RSA signature file

1-Jan-22 5:56

This one in Java always returned 1

dos.write(certs.length);

So i used

bw.Write(1);

Luc Pattyn1-Jan-22 5:59

Luc Pattyn

1-Jan-22 5:59

and when you read the documentation[^] you'll notice that silly Java write method takes an int and writes a byte!!!

Luc Pattyn [My Articles]
The Windows 11 "taskbar" is disgusting. It should be at the left of the screen, with real icons, with text, progress, etc. They downgraded my developer PC to a bloody iPhone.

Re: Read signature data from APK's RSA signature file

mynametaken9-Jan-22 4:37

Re: Read signature data from APK's RSA signature file

9-Jan-22 4:37

I see but when I used

bw.Write((byte)1);

, data comes out very different, not even close to Java one

jschell23-Jan-22 6:49

jschell

23-Jan-22 6:49

mynametaken wrote:
bw.Write(data);
bw.Write(data.Length);

That is not the same as the following. The order is different.

mynametaken wrote:
dos.writeInt(data.length);
dos.write(data);

Winform support in Windows service

Member 1260803929-Dec-21 23:59

Member 12608039

29-Dec-21 23:59

Hello everyone, I have a problem.
I have a project on Winform and it works great, now the customer wants to run this project as a Windows service.
The peculiarity of the project, I use a library (presumably written in C ++) that Winform uses, before calling the library I can translate the service into Windows, and I cannot translate the part where the library works. Is there a way to start a service with Winform support? I am considering all the options right up to the use of paid softs.
The system will be in Sign Out mode most of the time.

OriginalGriff30-Dec-21 0:27

OriginalGriff

30-Dec-21 0:27

Services cannot have any Winforms support: they a=cannot have any interface or methods of interaction with the user.

What you would have to do is start a user process (a Winforms project) that communicates with the service and provides it with instructions.

You can't add Winforms to a service at all!

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Member 1260803930-Dec-21 1:28

Member 12608039

30-Dec-21 1:28

I managed to start from the Winform service but it doesn't work when the user is logged out

OriginalGriff30-Dec-21 2:08

OriginalGriff

30-Dec-21 2:08

Member 12608039 wrote:
it doesn't work when the user is logged out

Of course it won't - that's what services are for, and they don't have any user interface at all! Applications aren't running while a user is logged out, but services are.
To have a user interface, you need a user - and services are designer to run with or without a logged in user. Hence, you need a separate Winforms project to communicate with your service when there is a user there, and the service runs "alone" when the user isn't logged in.

Dynamically change int from a string

#realJSOP30-Dec-21 1:20

#realJSOP

30-Dec-21 1:20

You need to break out the core functionality into its own library assembly, and then create a windows service project that references that assembly. The windows service project can be compiled as a regular console app to make debugging easier, and you can also make the winform app reference that assembly (also easier to debug).

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Matte Matik29-Dec-21 12:02

Matte Matik

29-Dec-21 12:02

Hello,
Please i would like to know how to declare an int from a dynamic given string.
Like this:

for (int i = 500; i >= 350; i--)
{
string combine = "offset_y_bar_" + i;

{
int "combine" = i;
}
}

Re: Dynamically change int from a string

Dave Kreskowiak29-Dec-21 12:36

Dave Kreskowiak

29-Dec-21 12:36

You can't. C# is a compiled language, not interpreted.

If you think you need to do something like this, you should be looking at an array instead.

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Dave Kreskowiak

Re: Dynamically change int from a string

OriginalGriff29-Dec-21 21:53

OriginalGriff

29-Dec-21 21:53

You are going to have to be a lot clearer about exactly what you want to do - you can't have "quoted strings" as variable names.

If you want to be able to associate a string "name" with a value and access it later by the name, then probably what you want to do is look at a Dictionary:

Dictionary<string, int> items = new Dictionary<string, int>();
for (int i = 500; i >= 350; i--)
    {
    string combine = $"offset_y_bar_{i}";
    items[combine] = i;
    }
Console.WriteLine(items["offset_y_bar_421"]);

C# Entity Framework : how to generate custom automatic numbers

Fidele Okito27-Dec-21 4:50

Fidele Okito

27-Dec-21 4:50

Good afternoon,

Please, I m trying to generate a customized automatic numbers using entity framework.
The number is a combination of multiple columns from a table:

table1 (next_id int, prefix_text varch(5), table_name varchar(100))

in the table2( id int, invoice_number varchar(20))

The custom automatic number is invoice_number=(prefix_text)+' '+ (next_id+1) + ' _ '+ Current_year.

I tried to google but nothing. I m trying to use the triggers and also user defined function but I m feeling it not the best way.

Thank you in advance
F.O

Re: C# Entity Framework : how to generate custom automatic numbers

Gerry Schmitz27-Dec-21 5:16

Re: C# Entity Framework : how to generate custom automatic numbers

27-Dec-21 5:16

Creating "meaningful" primary keys is usually considered a "bad" design decision for any number of reasons. At "report time" (or for searching), you can do anything you want.

Fidele Okito27-Dec-21 5:32

Fidele Okito

27-Dec-21 5:32

Thank you for your answer, the invoice number is not the primary key. it is just to display on the report. is there another way to implement.

regards,
FO

Re: C# Entity Framework : how to generate custom automatic numbers

Gerry Schmitz27-Dec-21 6:45

Re: C# Entity Framework : how to generate custom automatic numbers

27-Dec-21 6:45

(prefix_text)+' '+ (next_id+1) + ' _ '+ Current_year.

Why can't you do that at report time?

Store the individual fields in the db record as needed; not their concatenation.

Fidele Okito27-Dec-21 7:55

Fidele Okito

27-Dec-21 7:55

Thank you so much for your time. Let me explore that option.
best regards
FO

Re: C# Entity Framework : how to generate custom automatic numbers

#realJSOP28-Dec-21 0:24

#realJSOP

28-Dec-21 0:24

You could use a datetime field's number of seconds as the "automatic number". Even in a moderately busy system, that would pretty much always be unique. When coupled with a row ID in a clustered primary key, duplicates will not be allowed, so Bob's your uncle.

EDIT ================================

If you're going to down-vote my answer, tell me why.

modified 29-Dec-21 6:01am.

Re: C# Entity Framework : how to generate custom automatic numbers

jschell29-Dec-21 7:17

jschell

29-Dec-21 7:17

I am not really in agreement with the other comments since they somehow seem to be drilling down on a 'primary' key even though I see nothing in your request that suggests that.

Your posting should focus on creating an 'invoice number'
It will need to have the following
1. Be unique
2. Be human readable
3. Be small enough that humans will not be annoyed by it.

Presumably the 'prefix_text' is unique by itself. It does not rely on the 'table_name'. If that is not the case then the uniqueness constraint for the invoice number will not be met by the form that you posted.

I would suggest that you do not use underscores. A separator is ok but use a dash since it tends to be more obvious. However you can also consider the dash as being a display character only. So for example credit card numbers often use a dash but the numbers are actually the only part of the actual id. So your UI could take it with dashes but remove it for searches. And in the database you store it without the dashes.

Without the separator the format must be fixed however. So it is a design decision.

Volume of the business and generation of the code, now and for some time into the future, impacts how you might want to do this. If you are producing say 100 of them a day then it is easier than if you are producing 100 million in a day.

There might be a security concern if you generate numbers that are easily guessed. So for example if you use the current date along with an incrementing number then it is easy to guess valid invoice numbers. This also is a matter for how the business works. It isn't much of a concern if there are other authentication factors used to limit access to the invoices.

I don't see anything conceptually wrong with your basic idea although I would format the id (pad zeros to the left.)

Fidele Okito wrote:
using entity framework.

I am guessing that this in fact is your real problem.

What you want to do is just use native SQL. Myself I would probably use a stored proc but you can do it with SQL in the application.

You need the following in a transaction. This is pseudo code but the idea is basically sound.

declare @lastId int;
update table1 set next_id = next_id + 1 where prefix_text='xxx' and table_name='fff';
select @lastId = next_id from table1 where prefix_text='xxx' and table_name='fff';
insert into table2 (invoice_number) values('xxx' + '-' + @lastId + '-' + ...);
select @lastId;

The last part of that returns the newest id to your application. Not needed if that is not something that is needed at that point.

The transaction is necessary to insure uniqueness.

Re: C# Entity Framework : how to generate custom automatic numbers

Gerry Schmitz29-Dec-21 15:22