Methods and devices for a chained encryption mode

A device for generating an encryption key for encrypting a present plaintext block of digital data, the present plaintext block belonging to an ordered series of at least two plaintext blocks, the device comprising:

• a communication unit adapted to retrieve the present plaintext block;
• and
• a processor adapted to:
• generate a second encryption key for the present plaintext block by combining a previous plaintext block with a first encryption key, wherein the first encryption key is an encryption key that was used for encryption of a previous plaintext block, the previous plaintext block being a plaintext block that immediately precedes the present plaintext block in the ordered series.

A device for generating a decryption key for decrypting a present ciphertext block of digital data, the present ciphertext block belonging to an ordered series of at least two ciphertext blocks, the device comprising:

• a communication unit adapted to retrieve the present ciphertext block;
• and
• a processor adapted to:
• generate a second decryption key for the present ciphertext block by combining a previously obtained plaintext block with a first decryption key, wherein the first decryption key is a decryption key that was used to obtain the previous plaintext block, the previous plaintext block corresponding to the ciphertext block that immediately precedes the present ciphertext block in the ordered series.