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How to remove padding after RSA decryption??

843851Apr 13 2005 — edited Sep 17 2007

Hello,

I am testing my host apps ability to read public key that was saved in file after being exported from smart card where it was generated.
I have successfully used the private key on card to encrypt a small piece of data and the cryptogram is returned to the host.
On host side I retrieve public key from file and decrypt ciphertext
The on-card alg for Cipher is declared as follows-

RSAcipher = Cipher.getInstance(Cipher.ALG_RSA_PKCS1, true);

and in the host app

Cipher rsaCipher = Cipher.getInstance("RSA","BC");

I can see from what is returned from

byte[] decrypted = rsaCipher.doFinal(this.encryptedData);

that the correct data is being returned, but is is padded by

01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
FFFFFFFFFFFFFFFFFFFFFFFFFFFF00

How do I know where the padding ends and the plaintext begins?
Can anyone help me with this?

Thanks in advance,
Ann

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Locked on Oct 15 2007

Added on Apr 13 2005

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