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
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
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.