# Tag Info

9

There are some serious problems with this design that would preclude it from being standardized, so it probably does not have a name. The 2 visibly main flaws are as follows: If the plaintext follows a pattern similar to the block counter, the block cipher inputs may repeat, exposing information about the plaintext (exact same issue as reuse of nonce, but ...

2

It probably doesn't. Yes. For strings $x,m0,m1$ such that $\text {length}(x) = \text{length}(nonce)$ and $\text{length}(m0) = \text{length}(i) = \text{length}(m1)$ $( nonce || i ) \oplus ( x || m0 ) = ( nonce || j ) \oplus ( x || m1 ) \iff m0 \oplus m1 = i \oplus j$ . I'm not aware of any.

2

AES-GCM uses single block cipher operation and can be processed in parallel, therefore it should be faster. CTR+HMAC requires block cipher and hash function, which usually can't be processed in parallel. Also it requires 2 keys. It is often miss-implemented (MAC-than-encrypt or MAC-and-encrypt, using single key). Cipher-text length is the same for same ...

0

I don't see any reason to expect this to provide integrity (INT-PTXT or INT-CTXT). In fact, if $R1,R2$ were known to the attacker, I can show that in general it does not provide integrity: there exist some encryption algorithms that are IND-CPA secure but where your scheme does not provide integrity. (e.g., any stream cipher.) This sounds like a ...

0

Yes, as long as you obey all the total usage limits and choose the IV appropriately (see below). Whilst IV is a general term for any initialisation vector the recent trend has been to use the term 'IV' to refer to a random vector, and "nonce" (a contraction of "n-umber used once") to refer to an input vector that need not be random, but cannot be repeated. ...

1

IV (initial value or initialization vector) is a vague term that describes some kind of starting value for a mode of operation that is known to both parties, and generally sent in the clear with the encrypted data (and known to the attacker) IVs in many modes of operation have specific requirements to that mode. In some modes the requirement is that is ...

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