RC4 encryption/decryption problem in asp.net

Question

I have implemented RC4 encryption/decryption in my application as given below. at the end of the line exception coming.

string sFNToBase64String = Convert.ToBase64String(Encoding.ASCII.GetBytes("Malhotra")); string sEnFirstName = CommonFunction.RC4EncryptDecrypt(sKey, sFNToBase64String); //calling webservice localhost.LoginRequest objRQ = new localhost.LoginRequest(); string sIsValidate = objRQ.ValidateRequest(sEnFirstName); //Exception coming on this line

Exception comes

 //Exception coming The request failed with HTTP status 400: Bad Request. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Net.WebException: The request failed with HTTP status 400: Bad Request.

How can we resolve it.

-----------UPDATE-------------------

Actually the problem is only with encrypted text of "Malhotra"[ encrypted text: CX±£þÕlêÁ$]. i think there are some special characters that web service call doesn't allow.

How can we handle this one?

-----------------------Encrypted/Decrypted Process---------------------

//Encrypte string sEnLastName = CommonFunction.RC4EncryptDecrypt(sKey, "Malhotra"); //Encode string sLNToBase64String = Convert.ToBase64String(Encoding.ASCII.GetBytes(sEnLastName)); //Decode string sDecodeLastName = Encoding.ASCII.GetString(Convert.FromBase64String(sLNToBase64String)); //Decrypte string sDeLastName = CommonFunction.RC4EncryptDecrypt(sKey, sDecodeLastName);

Which line is the exception happening on?

Jaymz
– Jaymz

2011-04-04 08:22:06 +00:00
Commented Apr 4, 2011 at 8:22 — Jaymz
– Jaymz, Commented Apr 4, 2011 at 8:22
string sIsValidate = objRQ.ValidateRequest(sEnFirstName);

Sukhjeevan
– Sukhjeevan

2011-04-04 09:12:47 +00:00
Commented Apr 4, 2011 at 9:12 — Sukhjeevan
– Sukhjeevan, Commented Apr 4, 2011 at 9:12

Jaymz · Accepted Answer · 2011-04-04 10:29:00Z

1

First point - base64 is an encoding standard, NOT encryption.

It looks as though you are passing the encrypted string without base 64 encoding to the webservice, is this your intention?

I would suggest trying to change this, if possible, to require the base 64 encoded string to be passed to the webservice, and for the web service to decode back from base 64 before it does its work.

Base 64 can only contain A-Z, a-z, 0-9, +, -, and = for padding. These characters will not cause issues with your webservice.

edited Apr 4, 2011 at 10:29

answered Apr 4, 2011 at 9:52

Jaymz

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11 Comments

Sukhjeevan Over a year ago

actually i want to pass Step 1)base64 encoded. Step 2)RC4 encrypted string to webservice.

Sukhjeevan Over a year ago

if i pass "Raj" text code working fine. but problem is with the "Malhotra" text.i think after encoding and encryption it generate a text which web services call doesn't allow due to some characters.can we resolve this as described in the question.

Jaymz Over a year ago

As I said, base 64 encode the encrypted string before sending, and get the web service to decode from base 64 once it receives it. Base 64 encoded text is "safe" to pass across web services, as it only contains ASCII characters. So: encrypt your string, then encode the encrypted string, pass that to web service; web service then decodes that and works with the encrypted string.

Sukhjeevan Over a year ago

I tried in yr way as step1)encrypt string step2)encode string and call web service with this value. now this time web service call is complete but when i decrypted the value in web service method i got as excepted with "Raj" but not with "Malhotra".i.e. when i pass "Raj" i got after decryption "Raj" but same not worked with "Malhotra"

Jaymz Over a year ago

OK, my best guess is that you're using different encodings in your encryption routine than you are in your base64 encoding. Encoding.ASCII.GetBytes - try changing to Encoding.UTF32.GetBytes for example. Double check what character encoding you're using in the encryption routine, and ensure you're using the same everywhere you need it.

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