Troubleshooting WEP Problems

When having problems with WEP:

1.) Determine what your cipher length is going to be. For the purposes of troubleshooting, it is suggested that you start with a 64bit encryption.

However, the Router will usually make a contribution to the actual key length, so this will impact what your contribution is. Before proceding any further, please review your Router Documentation to see if your Router contributes to the key-length. If key-length for a 64bit key is expected to be 8 characters, then your Router is NOT contributing any overhead information to the key. The remainder of this article will presume your Router inserts it’s own 3 bytes of data.

 

a.) FOR 64-bit ENCRYPTION, the user key is typically 5 bytes long, which is to say that if you are asked to enter a key, it should be 5 ASCII characters long (or 10 HEX characters long). This is because the Router or AP will typically add another 3 bytes of it’s own data, for a total key length of 8 bytes.

Now for the math:
(user cipher)……is 5 bytes, which is 40bit, or 10 HEX Characters
(Router cipher)…is 3 bytes, which is 24bit, or 06 HEX Characters
——————————————————————————
Total Cipher length 8 bytes, which is 64bit, or 16 HEX Characters

  • Thus, when you hear someone talking about a 40-bit encryption or a 64-bit encryption, they are referring to the same cipher length. One references the user cipher length only, the other references the user cipher plus the router’s overhead contribution.

b.) FOR 128-bit ENCRYPTION, the user key is 13 bytes long, which is to say that if you are asked to enter a key, it should be 13 ASCII characters long (or 26 HEX characters long).

The math:
(user cipher)……is 13 bytes, which is 104bit, or 26 HEX Characters
(Router cipher)…is 03 bytes, which is 024bit, or 06 HEX Characters
———————————————————————————-
Total Cipher length 16 bytes, which is 128bit, or 32 HEX Characters

  • Thus, when you hear someone talking about a 104-bit encryption length, or a 128-bit encryption length, they are referring to the same cipher length. One references the user cipher length only, the other references the total cipher length (user cipher plus the router’s overhead contribution).

2.) Enter a simple 64-bit cipher key to make sure your Router/AP is going to work at a basic level with this cipher key length. Enter the cipher key in both the Router/AP and the iPAQ. If installed, use PocketWinC to enter the information into your iPAQ.

a.) For 64-bit Encryption:
ASCII cipher Key….11111
HEX cipher Key……3131313131

b.) For 128-bit Encryption:
ASCII cipher Key….1111111111111
HEX cipher Key……13131131311313113131131311313131

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