ورودی این تابع یک متن و خروجی آن یک هش با طول 64 هگزادسیمال(256 بیتی) که بیشتر در فیلتر پیامهای اسپم ورمزنگاری خصوصا رمزارزها مورد استفاده قرار میگیره
کد متلب:
function out = sha256( msg )
% Initial Hash Values(8 constant 32-bit words).(§5.3.3)
default_hash = [
'6a09e667';
'bb67ae85';
'3c6ef372';
'a54ff53a';
'510e527f';
'9b05688c';
'1f83d9ab';
'5be0cd19'
];
% Constant value array (64 constant 32-bit words) to be used for the iteration t of the hash computation.(§4.2.2)
K = [
'428a2f98'; '71374491'; 'b5c0fbcf'; 'e9b5dba5';
'3956c25b'; '59f111f1'; '923f82a4'; 'ab1c5ed5';
'd807aa98'; '12835b01'; '243185be'; '550c7dc3';
'72be5d74'; '80deb1fe'; '9bdc06a7'; 'c19bf174';
'e49b69c1'; 'efbe4786'; '0fc19dc6'; '240ca1cc';
'2de92c6f'; '4a7484aa'; '5cb0a9dc'; '76f988da';
'983e5152'; 'a831c66d'; 'b00327c8'; 'bf597fc7';
'c6e00bf3'; 'd5a79147'; '06ca6351'; '14292967';
'27b70a85'; '2e1b2138'; '4d2c6dfc'; '53380d13';
'650a7354'; '766a0abb'; '81c2c92e'; '92722c85';
'a2bfe8a1'; 'a81a664b'; 'c24b8b70'; 'c76c51a3';
'd192e819'; 'd6990624'; 'f40e3585'; '106aa070';
'19a4c116'; '1e376c08'; '2748774c'; '34b0bcb5';
'391c0cb3'; '4ed8aa4a'; '5b9cca4f'; '682e6ff3';
'748f82ee'; '78a5636f'; '84c87814'; '8cc70208';
'90befffa'; 'a4506ceb'; 'bef9a3f7'; 'c67178f2'
];
% First padd the input message to be a multiple of 512(bits).(§5)
[padded_msg,padded_len] = padder( msg );
% Split padded message to N (512-bit) blocks.(§6)
[M,total_blocks] = split2block( padded_msg,padded_len );
W = zeros( 64, 32 );
H = zeros( 8, 32 );
% Main SHA-256 compuation process.(§6.2.2)
for j = 1:8 % Load initial hash values at first iteration.
H(j,:) = hexToBinaryVector( default_hash( j , : ) , 32 );
end
for i = 1:total_blocks % For every block M(i).
% Step 1 - Prepare the message schedule.
for j = 1:64
if j >= 1 && j <= 16
W( j, 1:32 ) = M( i, 32*(j-1)+1:j*32 );
else
W( j, 1:32 ) = mod32add( sigma1( W( j-2, : ) ), W( j-7, : ) , sigma0( W( j-15, : ) ), W( j-16, : ) );
end
end
% Step 2 - Initialize the eight working variables, a, b, c, d, e, f, g,
% and h, with the (i-1)st hash value.
a = H(1,:);
b = H(2,:);
c = H(3,:);
d = H(4,:);
e = H(5,:);
f = H(6,:);
g = H(7,:);
h = H(8,:);
% For t=0 to 63.
for t = 1:64
T1 = mod32add( h, capSigma1(e),ch( e, f, g ),hexToBinaryVector( K( t,: ) , 32 ), W( t,: ) );
T2 = mod32add( capSigma0(a), maj( a, b ,c ) );
h = g;
g = f;
f = e;
e = mod32add( d, T1 );
d = c;
c = b;
b = a;
a = mod32add( T1, T2 );
end
% Step 4 - Compute the ith intermediate hash value H(i).
H(1,:) = mod32add( a, H(1,:) );
H(2,:) = mod32add( b, H(2,:) );
H(3,:) = mod32add( c, H(3,:) );
H(4,:) = mod32add( d, H(4,:) );
H(5,:) = mod32add( e, H(5,:) );
H(6,:) = mod32add( f, H(6,:) );
H(7,:) = mod32add( g, H(7,:) );
H(8,:) = mod32add( h, H(8,:) );
end
% Final Step - After hash process the resulting 256-bit message digest
% of the message, M, is:
out = binaryVectorToHex( horzcat( H(1,:), H(2,:), H(3,:), H(4,:), H(5,:), H(6,:) ,H(7,:), H(8,:) ) );
end
function [out,len] = padder( msg )
% Function padder : Padds the input message.(§5.1.1)
padded = []; % Initialize output.
l = length(msg)*8; % Length of the input message in dec.
for i = 1:length(msg) % First append message body.
padded = strcat(padded,dec2bin(msg(i),8));
end
padded( end + 1 ) = '1'; % Append bit '1' at the end of message body.
% Calculate number of zeros to be added at the padded message.
k = mod( 447 - l , 512 );
padded( end + 1 : end + k ) = '0'; % Append k bits '0' at the end of message body.
% Append the length of the input message (in 64-bits).
padded( end + 1: end + 64 ) = reshape( dec2bin( l, 64 ), 1, [] );
out = logical(padded(:)'-'0'); % Convery to logical array.
len = length( padded ); % Return also length of the padded message.
end
function [out,total_blocks] = split2block( padded_msg,padded_len )
% Function split2block : Splits the padded message to N 512-bit blocks M(N).(§5.2.1)
total_blocks = padded_len/512; % Calculate total number of blocks.
out = zeros( total_blocks, 512 );
for i = 1:total_blocks % Split per 512 bits (Big-Endianess).
out( i, 1:512 ) = padded_msg( (i-1)*512 + 1:i*512 );
end
end
function out = fix2mod( x )
% Function fix2mod : Converts the input logical word to binary.
out = num2str( x );
out(isspace(out)) = '';
out = bin2dec(out);
end
function out = mod32add( varargin )
% Function mod32add : Performs addition modulo 32.(§3.2.1)
out = 0; % initialise return arguments
for i = 1:length( varargin ) % Calculate addition
out = out + fix2mod(varargin{i});
end
% Perform modulo 32 operation.
out = dec2bin( mod( ( out ), 2^32 ),32 ) ;
out = logical( out(:)'-'0' ); % Cast output to logical array.
end
function out = rotr( word, pos )
% Function rotr : Performs ROTR (Cirular right shift) operation.(§3.2.1)
out = zeros( 1, length( word ) );
out( pos + 1:end ) = word( 1:end - pos + 0 );
out( 1:pos ) = word( end - pos + 1 : end );
end
function out = shr( word, pos )
% Function rotr : Performs SHR (Right shift) operation.(§3.2.1)
out = zeros( 1, length( word ) );
out( 1 + pos:end ) = word( 1:end - pos );
end
function out = maj( x, y, z )
% Function maj : Performs MAJ operation.(§4.1.2)
out = bitxor( bitxor( x & y, x & z ) , y & z );
end
function out = ch( x, y, z )
% Function maj : Performs CH operation.(§4.1.2)
out = bitxor( x & y ,~x & z );
end
function out = capSigma0( x )
% Function Ó0 : Performs Ó0 operation.(§4.1.2)
out = bitxor( bitxor( rotr( x, 2 ), rotr( x, 13 ) ) , rotr( x, 22 ) );
end
function out = capSigma1( word )
% Function Ó1 : Performs Ó0 operation.(§4.1.2)
out = bitxor( bitxor( rotr( word, 6 ), rotr( word, 11 ) ) , rotr( word, 25 ) );
end
function out = sigma0( word )
% Function ó0 : Performs Ó0 operation.(§4.1.2)
out = bitxor( bitxor( rotr( word, 7 ), rotr( word, 18 ) ) , shr( word, 3 ) );
end
function out = sigma1( word )
% Function ó1 : Performs Ó0 operation.(§4.1.2)
out = bitxor( bitxor( rotr( word, 17 ), rotr( word, 19 ) ), shr( word, 10 ) );
end
نحوه فراخوانی نمونه:
msg =num2str(randi(40000,1))';
sh=sha256( msg )
نمونه خروجی:
