Fixed, more or less arbitrary parameter values that appear in the definitions of cryptographic schemes, such as fixed initialization vectors for hash functions or S-box tables for block ciphers.

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Can homomorphic operations on many different ciphertexts be multiplied by a same constant?

Assume Alice encrypts messages $m_1$,...,$m_n$ using secret keys $k_1$,...,$k_n$ on a homomorphic encryption scheme (BHHO), so she would get $c_1=Enc_{k_1}(m_1)$,...,$c_n=Enc_{k_n}(m_n)$. Then Alice ...
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133 views

How have MD5 constants been determined?

For instance, the per round shift amounts, ...
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49 views

MDC-2 recommended IV values?

I'm currently reading Menezes' "Handbook of Applied Cryptography", and in it, when describing the MDC-2 cryptographic hash function, has the following line: Choose the 64-bit non-secret constants ...
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172 views

Why have round constants in hashes?

This may seem like basic crypto knowledge, but why do hash functions like SHA-2 and Whirlpool have round constants that are absorbed into their respective states? I can understand that in a cipher ...
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225 views

How many degrees of freedom up my sleeve?

Now that we know how the MD2 S-box was constructed, I find myself wondering how good a nothing up my sleeve number it really is. It is derived from $\pi$, but not in a very obvious way, even in ...
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322 views

Significance of rotation constants in SHA-512?

In a single round of SHA-512, in the operations $\Sigma_0(A)$, $\Sigma_1(E)$ why are the constants $28$, $34$, and $39$ used for the number of rotations? What significance do these numbers have? What ...
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312 views

Are the MD5 constants an S-Box?

I noticed that several hash algorithms, in this case MD5, defines some constants. MD5 defines 64 constant values (the shift count per round) which also gets expand (via sine) to a summand for a ...
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1k views

How is the MD2 hash function S-table constructed from Pi?

For fun, I'm learning more about cryptography and hashing. I'm implementing the MD2 hash function following RFC 1319 (http://tools.ietf.org/html/rfc1319). I'll preface by saying I know there are ...
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Why are the initial states of hashes functions (like SHA-1) often non-zero?

There is already a question asking "Why initialize SHA1 with specific buffer?" and my question follows on from this: Why are the initial states of hash functions often non-zero? For most, I have ...