New answers tagged mac
5
Standard KMAC is more than that thanks to domain separation prefixes; NIST SP 800-185
KMAC128(K, X, L, S):
Validity Conditions: $\text{len}(K) < 2^{2040}$ and $0
\le L < 2^{2040}$ and $\text{len}(S) < 2^{2040}$
newX = bytepad(encode_string(K), 168) || X || right_encode(L).
return cSHAKE128(newX, L, “KMAC”, S).
and
cSHAKE128(X, L, N, S):
...
6
Consider $H$ defined as: SHA-512, with it's output XORed with the first 512 bits of the input message (padded with zeroes for short message). With such $H$, the proposed MAC is insecure. Yet, as far as we know, this $H$ is no worse than SHA-512 from a standard standpoint.
Argument: observe that if $H(m_1\mathbin\|m_2)=\operatorname{SHA-512}(m_1\mathbin\|m_2)\...
2
Kerberos uses des-cbc-hmac (mac and encrypt) and rc4-hmac-exp based on md5 (mac and encrypt I think) in their encryptions.
Those encryptions are considered as weak and should not be used. Why are they considered as weak? What attacks can be launched against those encryptions?
Regarding the ciphers:
DES is considered to be a weak block cipher because the ...
Top 50 recent answers are included