JCE and CryptoAPI

[schw]

Hi

In my server app written in c++ I use Microsoft Crypto API with 3DES
algorithms to encrypt/decode data. The API uses effective key length
of 21 bytes - 168 bits.

Now I am writting a client app in java that has to encrypt some data
before sending them over but I've noticed that the JCE uses 24 bytes
length keys - 192bits. This is as 3DES ignores every seventh bit so the
effective key length is 21 bytes long.

is there any other provider that uses same key length as Crypto API or
how could I write a procedure that converts 21 bytes into 24 bytes
adding 1 bit after every seven bits in the source? I am new to Java so
help would be much apreciated.

best regards,
schw

 

[JPractitioner]

Hi schw,
yes u could use padding..
say for example, in your case, u can pad extra 18 bytes to ur data
(with 0s maybe)
so it will be 42 bytes.

when the data is decrypted, u will have to clean-up the trailing pads.

U also might want to check the API for DES encryption with pading
mechanism.
http://java.sun.com/j2se/1.5.0/docs/guide/security/jce/JCERefGuide.html

u can see how the padding is done with
Cipher.getInstance("DES/ECB/PKCS5Padding");


HTH

 

[Thomas Weidenfeller]

Hi schw,
yes u could use padding..
say for example, in your case, u can pad extra 18 bytes to ur data
(with 0s maybe)

And you could use real words like "you".