It is more difficult to guess the size of the
plaintext matrix [M.sub.f] from the encryption results.
Suppose [c.sub.1]([m.sub.1]) and [c.sub.2]([m.sub.2]) be ciphertexts of
plaintexts [m.sub.1] and [m.sub.2].
When the noise is close to the limit, the cloud server needs to perform bootstrapping to reduce the noise and get a fresh ciphertext having the same underlying
plaintext. After applying the bootstrapping, a fresh ciphertext allows us to continue to perform homomorphic operations if the noise is within the limitation.
case--namely, the ciphertext, the password, and the
plaintext.
Enc is an encryption algorithm, Dec is a decryption algorithm, f is an arbitrary function, [c.sub.n] is ciphertext, and [m.sub.n] is
plaintext.
This weakness is used to make effective cipher-text-only attack on this algorithm in broadcast applications, where the same
plaintext is sent to multiple receivers with different keys.
Germany's Federal Office for Information Security (BSI) said in a statement there were risks that attackers could secure access to emails in
plaintext once the recipient had decrypted them.
The advantage of the proposed adaptive encryption becomes apparent when the number of
plaintext blocks is increased.
Therefore, the corresponding keystream is different when different
plaintext is encrypted.
In this step, the target cipher and its key schedule are described by a set of Boolean equations C, which contain unknowns (master key bits, whitening key bits, subkey bits, and intermediate variables) and constants (
plaintext and ciphertext bits).
Encryption uses the process of cryptography to transform ordinary information, or
plaintext, into unintelligible ciphertext.
The AES cipher is stated as a number of repetitions of transformation rounds that convert the input
plaintext into the final output of cipher text.
