6. A method of encrypting data, the method comprising: encrypting a clear text by a first encryption engine using a first instance of an encryption key to produce a first cipher text; encrypting said clear text by a second encryption engine using a second instance of said encryption key to produce a second cipher text, wherein the second instance is provided independent of the first instance of the encryption key; determining (a) whether the first instance of the encryption key and the second, different instance of the encryption key are identical and valid and (b) whether the encryption engines did not produce any errors during encryption of the clear text by comparing said first cipher text with said second cipher text; and storing one of said cipher texts if said first cipher text matches said second cipher text, which indicates that the encryption keys are identical and valid and that the encryption engines did not produce any errors during encryption.
6. A method of encrypting data, the method comprising: encrypting a clear text by a first encryption engine using a first instance of an encryption key to produce a first cipher text; encrypting said clear text by a second encryption engine using a second instance of said encryption key to produce a second cipher text, wherein the second instance is provided independent of the first instance of the encryption key; determining (a) whether the first instance of the encryption key and the second, different instance of the encryption key are identical and valid and (b) whether the encryption engines did not produce any errors during encryption of the clear text by comparing said first cipher text with said second cipher text; and storing one of said cipher texts if said first cipher text matches said second cipher text, which indicates that the encryption keys are identical and valid and that the encryption engines did not produce any errors during encryption. 7. The method as claimed in claim 6 , further comprising: reading said stored cipher text; and decrypting said read cipher text.