Main step of GOST 28147-89: Difference between revisions

<lang rexx>/*REXX program implements main step GOST 28147-89 based on a Feistel network. */

numeric digits 12 /* ┌── a list of 4─bit S─box values used by */

/* ↓ the Central Bank of Russian Federation.*/

@.0 = 4 10 9 2 13 8 0 14 6 11 1 12 7 15 5 3

@.1 = 14 11 4 12 6 13 15 10 2 3 8 1 0 7 5 9

@.2 = 5 8 1 13 10 3 4 2 14 15 12 7 6 0 9 11

@.3 = 7 13 10 1 0 8 9 15 14 4 6 12 11 2 5 3

@.4 = 6 12 7 1 5 15 13 8 4 10 9 14 0 3 11 2

@.5 = 4 11 10 0 7 2 1 13 3 6 8 5 9 12 15 14

@.6 = 13 11 4 1 3 15 5 9 0 10 14 7 6 8 2 12

@.7 = 1 15 13 0 5 7 10 4 9 2 3 14 6 11 8 12

/* [↓] build the sub-keys array from above. */

do r=0 for 8; do c=0 for 16; !.r.c=word(@.r, c + 1); end; end

z=0

#1=x2d( 43b0421 ); #2=x2d( 4320430 ); k=#1 + x2d( 0e2c104f9 )

do while k > x2d( 7ffFFffF ); k=k - 2**32; end

do while k < x2d( 80000000 ); k=k + 2**32; end

do j=0 for 4; jj=j + j; jjp=jj + 1 /*calculate the array'a "subscripts". */

$=x2d( right( d2x( k % 2 ** (j * 8) ), 2) )

cm=$ // 16; cd=$ % 16 /*perform modulus and integer division.*/

z=z + (!.jj.cm + 16 * !.jjp.cd) * 2**(j*8)

end /*i*/ /* [↑] encryption algorithm for S-box.*/

/* [↓] encryption algorithm round. */

k = c2d( bitxor( bitor( d2c(z * 2**11, 4), d2c(z % 2**21, 4) ), d2c(#2, 4) ) )

say center(d2x(k) ' ' d2x(#1), 79) /*stick a fork in it, we're all done. */</lang>

{{out|output|:}}

7CF881F 43B0421