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Apr
11
comment OTP - Reusing key IS SECURE! PROVED!
By XORing the 4 formulas, it comes that independent of keys and IVs, $character_4=$ $character_1⊕character_2⊕character_3⊕cipher_1⊕cipher_2⊕cipher_3⊕cipher_4$.
Apr
11
comment OTP - Reusing key IS SECURE! PROVED!
This "proof" is not even wrong. Also, even if "IVs" are secret, character 4 is trivialy found from ciphertexts and the other three characters.
Apr
11
comment OTP - Reusing key IS SECURE! PROVED!
In standard terminology, Initialization Vectors are public (if they are not, they are keys). This makes the scheme trivially weak: character 3 (resp.4) can be found from knowns and character 1 (resp.2)
Apr
10
comment How cryptographically secure was the original WW2 Enigma machine, from a modern viewpoint?
Much of the answer will depend on what qualifies as "operator mistakes" and to what degree they are known; what "the original Enigma machine" is assumed to be (there was several variants, even the number of rotors was variable); and if the wiring of rotor (and plugboard, if any) is assumed known or not.
Apr
9
revised Encrypt entire payload or only confidential parts of payload?
typo
Apr
9
comment algebraic attacks for mixed operations (mod 2 and mod 256)
Anything wrong with the trivial: if $\oplus$ is addition modulo $2$ and $\widetilde+$ is addition modulo $2^8$, then for all integers $a$ and $b$, $a\oplus b=((a\widetilde+b)\bmod 2)$? Or perhaps you have a definition of $\oplus$ which is bitwise XOR, not "addition mod $2$" as stated in the question ?
Apr
9
revised What use is the signature without the message under RSA?
fix a formula, polish
Apr
9
revised What use is the signature without the message under RSA?
clarify both recommandations are to be followed
Apr
9
revised Encrypt entire payload or only confidential parts of payload?
Some proofreading
Apr
9
answered Encrypt entire payload or only confidential parts of payload?
Apr
8
comment Creating a random password based off of a prime number
You depend heavily on the quality of the initialization of Random(), which itself depends on the particular version of Java, and on the platform. Thus the answer is context-dependent (and largely off-topic).
Apr
8
comment How does the certificate authority generate a signature F?
Question and tentative answer are broken to the point that IMHO they are best abandoned. Some issues: 1) The question is about certificates, which require a signature scheme, which is not achievable by encryption of a hash. $\;$ 2) The two basic steps of proving identity are not distinguished/explained: a) proving tie between identity and public key; b) proving knowledge of the associated private key. $\;$ 3) Certificate authorities typically do not generate a user's public-private key pair; they issue a certificate for a public key.
Apr
8
revised Why is a Feistel network not a type of substitution-permutation network?
better justification
Apr
8
revised What use is the signature without the message under RSA?
fix formula for obtaining forgeries
Apr
7
answered Why is a Feistel network not a type of substitution-permutation network?
Apr
7
revised What use is the signature without the message under RSA?
m0 must be zero-terminated in the forgery scenario, and other polish
Apr
7
revised What use is the signature without the message under RSA?
expand
Apr
7
revised What use is the signature without the message under RSA?
polish
Apr
7
revised What use is the signature without the message under RSA?
Explain how to make forgeries, clarify
Apr
7
revised What use is the signature without the message under RSA?
added 2 characters in body