ISO IEC 10118-2 pdf download – Information technology — Security techniques — Hash-functions — Part 2: Hash-functions using an n-bit block cipher
1 Scope
This part of lSO/IEC 10118 specifies hash-functions which make use of an n-bit block cipher algorithm. Theyare therefore suitable for an environment in which such an algorithm is already implemented.
Four hash-functions are specified. The first provides hash-codes of length less than or equal to n, where n isthe block-length of the underlying block cipher algorithm used.The second provides hash-codes of length lessthan or equal to 2n; the third provides hash-codes of length equal to 2n; and the fourth provides hash-codes oflength 3n.All four of the hash-functions specified in this part of ISOIEC 10118 conform to the general modelspecified in ISOnIEC 10118-1.
Normative references
The following referenced documents are indispensable for the application of this document.For datedreferences,only the edition cited applies. For undated references,the latest edition of the referenceddocument (including any amendments) applies.
ISOIEC 10118-1:2000, Information technology — Security techniques — Hash-functions — Part 1:General
3 Terms and definitions
For the purposes of this document, the terms and definitions given in lSO/IEC 10118-1 and the following apply.3.1
block
string of bits of defined length
3.2
n-bit block cipher
block cipher with the property that plaintext blocks and ciphertext blocks are n bits in length[ISO/IEC 18033-3:2005]
3.3
round function
function o (…) that transforms two binary strings of lengths L; and Lz to a binary string of length L2NOTEThe round function is used iteratively.
4symbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms given in ISO/IEC 10118-1 and thefollowing apply.
Bl
When n is even, the string composed of the n/2 leftmost bits of the block B.When n is odd, the string composed of the (n+1)/2 leftmost bits of the block B
BR
When n is even, the string composed of the n/2 rightmost bits of the block B.When n is odd, the string composed of the (n-1)/2 rightmost bits of the block B
Bx
wWhen B is a sequence of blocks and each block has m bits，Bx(x0)represents the x-th block of B.
ExP)
n-bit block cipher algorithm taking the key K and plaintext P as input. It isrecommended that the block cipher algorithms specified in ISO/IEC 18033-3are used in the hash-functions.
K
Key for the algorithm E
u or u’
Function which takes as input an n-bit block and gives as output a key for thealgorithm E.
5Use of the general model
The hash-functions specified in the next four clauses provide hash-codes H of length L.;. The hash-functionsconform to the general model specified in lSO/IEC 10118-1.For each of the four hash-functions that follow,itis therefore only necessary to specify
-the parameters L1,L2,LH,
—the padding method,
the initializing value iv,—the round function o.
-the output transformation T.
6 Hash-function 1
6.1General
The hash-function specified in this clause provides hash-codes of length L and L where Lu and Lz are equalto n.Some specific definitions that are required to specify hash-function 1 follow.
NOTEThis hash-function is described in [5].
ISO IEC 10118-2 pdf download – Information technology — Security techniques — Hash-functions — Part 2: Hash-functions using an n-bit block cipher
