A2OS/source/CryptoAES.Mod

MODULE CryptoAES;   (** AES (Rijndael) de/encryption *)

(*	2002.07.22	g.f.  *)

IMPORT  S := SYSTEM, Ciphers := CryptoCiphers, U := CryptoUtils;

CONST
	MaxR = 14;  
	ECB = Ciphers.ECB;  CBC = Ciphers.CBC;  CTR = Ciphers.CTR;
	
	b0 = S.VAL( SET, 0FFH );  b1 = S.VAL( SET, 0FF00H );  
	b2 = S.VAL( SET, 0FF0000H );  b3 = S.VAL( SET, 0FF000000H );

TYPE
	RTable = ARRAY 256 OF SET;

VAR
	e0, e1, e2, e3, e4: RTable;
	d0, d1, d2, d3, d4: RTable;
	rcon: ARRAY 10 OF SET;   (* for 128-bit blocks, Rijndael never uses more than 10 rcon values *)

TYPE
	Cipher* = OBJECT (Ciphers.Cipher)
			TYPE
				RKeys = ARRAY 4*(MaxR + 1) OF SET;
				Block = ARRAY 4 OF SET;
				Ind4 = RECORD a, b, c, d: LONGINT END;
			VAR
				rounds: SHORTINT;
				ekeys, dkeys: RKeys;
				iv: Block;

				PROCEDURE InitKey*( CONST src: ARRAY OF CHAR; keybits: LONGINT );
				BEGIN
					InitKey^( src, keybits );
					IF keybits = 128 THEN  rounds := Init128( ekeys, src )
					ELSIF keybits = 192 THEN  rounds := Init192( ekeys, src )
					ELSE  rounds := Init256( ekeys, src )
					END;
					dkeys := ekeys;  Invert( dkeys, rounds )
				END InitKey;

				PROCEDURE SetIV*( CONST src: ARRAY OF CHAR; mode: SHORTINT );
				BEGIN
					SetIV^( src, mode );   (* set mode *)
					U.BufferToBlockBE( src, 0, iv );
				END SetIV;
				
				PROCEDURE IncIV;
				VAR i, x: LONGINT;
				BEGIN
					i := 4;
					REPEAT
						DEC( i );
						x := S.VAL( LONGINT, iv[i] ) + 1;  iv[i] := S.VAL( SET, x )
					UNTIL (x # 0) OR (i = 0)
				END IncIV;

				PROCEDURE Encrypt*( VAR buf: ARRAY OF CHAR;  ofs, len: LONGINT );
				VAR i, j: LONGINT;  x, y: Block;
				BEGIN
					ASSERT( isKeyInitialized );
					ASSERT( len MOD blockSize = 0 );   (* padding must have been added *)
					i := 0;
					WHILE i < len DO
						U.BufferToBlockBE( buf, ofs + i, x );
						CASE mode OF
						| ECB:
							FOR j := 0 TO 3 DO  x[j] := x[j] / ekeys[j]  END;
							RoundE( ekeys, x, rounds );
						| CBC:
							FOR j := 0 TO 3 DO  x[j] := x[j] / ekeys[j] / iv[j]  END;
							RoundE( ekeys, x, rounds );
							iv := x;
						| CTR:
							FOR j := 0 TO 3 DO  y[j] := iv[j] / ekeys[j]  END;
							RoundE( ekeys, y, rounds );
							FOR j := 0 TO 3 DO  x[j] := x[j] / y[j]  END;
							IncIV
						END;
						U.BlockToBufferBE( x, buf, ofs + i );
						INC( i, blockSize )
					END
				END Encrypt;

				PROCEDURE Decrypt*( VAR buf: ARRAY OF CHAR;  ofs, len: LONGINT );
				VAR x0, x, y: Block;  i, j: LONGINT;
				BEGIN
					ASSERT( isKeyInitialized );
					ASSERT( len MOD blockSize = 0 );   (* padding must have been added *)
					i := 0;
					WHILE i < len DO
						U.BufferToBlockBE( buf, ofs + i, x0 );
						CASE mode OF
						| ECB:
							FOR j := 0 TO 3 DO  x[j] := x0[j] / dkeys[j]  END;
							RoundD( dkeys, x, rounds );
						| CBC:
							FOR j := 0 TO 3 DO  x[j] := x0[j] / dkeys[j]  END;
							RoundD( dkeys, x, rounds );
							FOR j := 0 TO 3 DO  x[j] := x[j] / iv[j]  END;
							iv := x0;
						| CTR:
							FOR j := 0 TO 3 DO  y[j] := iv[j] / ekeys[j]  END;
							RoundE( ekeys, y, rounds );
							FOR j := 0 TO 3 DO  x[j] := x0[j] / y[j]  END;
							IncIV
						END;
						U.BlockToBufferBE( x, buf, ofs + i );
						INC( i, blockSize )
					END
				END Decrypt;


				PROCEDURE RoundE( CONST rk: RKeys;  VAR b: Block;  rounds: SHORTINT );
				VAR p, r: LONGINT;  t0, t1, t2, t3, s0, s1, s2, s3: Ind4;
				BEGIN
					split( b[0], s0 );  split( b[1], s1 );  split( b[2], s2 );  split( b[3], s3 );
					r := rounds DIV 2;  p := 0;
					LOOP
						split( e0[s0.d]/e1[s1.c]/e2[s2.b]/e3[s3.a]/rk[p + 4], t0 );
						split( e0[s1.d]/e1[s2.c]/e2[s3.b]/e3[s0.a]/rk[p + 5], t1 );
						split( e0[s2.d]/e1[s3.c]/e2[s0.b]/e3[s1.a]/rk[p + 6], t2 );
						split( e0[s3.d]/e1[s0.c]/e2[s1.b]/e3[s2.a]/rk[p + 7], t3 );
						INC( p, 8 );  DEC( r );
						IF r = 0 THEN  EXIT  END;
						split( e0[t0.d]/e1[t1.c]/e2[t2.b]/e3[t3.a]/rk[p + 0], s0 );
						split( e0[t1.d]/e1[t2.c]/e2[t3.b]/e3[t0.a]/rk[p + 1], s1 );
						split( e0[t2.d]/e1[t3.c]/e2[t0.b]/e3[t1.a]/rk[p + 2], s2 );
						split( e0[t3.d]/e1[t0.c]/e2[t1.b]/e3[t2.a]/rk[p + 3], s3 );
					END;
					b[0] := (e4[t0.d]*b3)/(e4[t1.c]*b2)/(e4[t2.b]*b1)/(e4[t3.a]*b0)/rk[p + 0];
					b[1] := (e4[t1.d]*b3)/(e4[t2.c]*b2)/(e4[t3.b]*b1)/(e4[t0.a]*b0)/rk[p + 1];
					b[2] := (e4[t2.d]*b3)/(e4[t3.c]*b2)/(e4[t0.b]*b1)/(e4[t1.a]*b0)/rk[p + 2];
					b[3] := (e4[t3.d]*b3)/(e4[t0.c]*b2)/(e4[t1.b]*b1)/(e4[t2.a]*b0)/rk[p + 3];
				END RoundE;

				PROCEDURE RoundD( CONST rk: RKeys;  VAR b: Block;  rounds: SHORTINT );
				VAR p, r: LONGINT;  t0, t1, t2, t3, s0, s1, s2, s3: Ind4;
				BEGIN
					split( b[0], s0 );  split( b[1], s1 );  split( b[2], s2 );  split( b[3], s3 );
					r := rounds DIV 2;  p := 0;
					LOOP
						split( d0[s0.d]/d1[s3.c]/d2[s2.b]/d3[s1.a]/rk[p + 4], t0 );
						split( d0[s1.d]/d1[s0.c]/d2[s3.b]/d3[s2.a]/rk[p + 5], t1 );
						split( d0[s2.d]/d1[s1.c]/d2[s0.b]/d3[s3.a]/rk[p + 6], t2 );
						split( d0[s3.d]/d1[s2.c]/d2[s1.b]/d3[s0.a]/rk[p + 7], t3 );
						INC( p, 8 );  DEC( r );
						IF r = 0 THEN  EXIT  END;
						split( d0[t0.d]/d1[t3.c]/d2[t2.b]/d3[t1.a]/rk[p + 0], s0 );
						split( d0[t1.d]/d1[t0.c]/d2[t3.b]/d3[t2.a]/rk[p + 1], s1 );
						split( d0[t2.d]/d1[t1.c]/d2[t0.b]/d3[t3.a]/rk[p + 2], s2 );
						split( d0[t3.d]/d1[t2.c]/d2[t1.b]/d3[t0.a]/rk[p + 3], s3 );
					END;
					b[0] := (d4[t0.d]*b3)/(d4[t3.c]*b2)/(d4[t2.b]*b1)/(d4[t1.a]*b0)/rk[p + 0];
					b[1] := (d4[t1.d]*b3)/(d4[t0.c]*b2)/(d4[t3.b]*b1)/(d4[t2.a]*b0)/rk[p + 1];
					b[2] := (d4[t2.d]*b3)/(d4[t1.c]*b2)/(d4[t0.b]*b1)/(d4[t3.a]*b0)/rk[p + 2];
					b[3] := (d4[t3.d]*b3)/(d4[t2.c]*b2)/(d4[t1.b]*b1)/(d4[t0.a]*b0)/rk[p + 3];
				END RoundD;
				
				PROCEDURE -split( s: SET;  VAR b: Ind4 );   (* split set into 4 indexes *)
				BEGIN
					b.a := S.VAL( LONGINT, s ) MOD 100H;
					b.b := S.VAL( LONGINT, s ) DIV 100H MOD 100H;
					b.c := S.VAL( LONGINT, s ) DIV 10000H MOD 100H;
					b.d := S.VAL( LONGINT, s ) DIV 1000000H MOD 100H;
				END split;


				PROCEDURE Init128( VAR rk: RKeys;  CONST src: ARRAY OF CHAR ): SHORTINT;
				VAR i, p: LONGINT;  ib: Ind4;
				BEGIN
					FOR i := 0 TO 3 DO  rk[i] := U.SetFromBufferBE( src, 4*i )  END;
					p := 0;  i := 0;
					LOOP
						split( rk[p + 3], ib );
						rk[p + 4] := rk[p] / (e4[ib.c]*b3) / (e4[ib.b]*b2) / (e4[ib.a]*b1) / (e4[ib.d]*b0) / rcon[i];
						rk[p + 5] := rk[p + 1] / rk[p + 4];
						rk[p + 6] := rk[p + 2] / rk[p + 5];
						rk[p + 7] := rk[p + 3] / rk[p + 6];
						INC( i );
						IF i = 10 THEN  EXIT   END;
						INC( p, 4 );
					END;
					RETURN 10
				END Init128;
				
				PROCEDURE Init192( VAR rk: RKeys;  CONST src: ARRAY OF CHAR ): SHORTINT;
				VAR i, p: LONGINT;  ib: Ind4;
				BEGIN
					FOR i := 0 TO 5 DO  rk[i] := U.SetFromBufferBE( src, 4*i )  END;
					p := 0;  i := 0;
					LOOP
						split( rk[p + 5], ib );
						rk[p + 6] := rk[p] / (e4[ib.c]*b3) / (e4[ib.b]*b2) / (e4[ib.a]*b1) / (e4[ib.d]*b0) / rcon[i];
						rk[p + 7] := rk[p + 1] / rk[p + 6];
						rk[p + 8] := rk[p + 2] / rk[p + 7];
						rk[p + 9] := rk[p + 3] / rk[p + 8];
						INC( i );
						IF i = 8 THEN  EXIT   END;
						rk[p + 10] := rk[p + 4] / rk[p + 9];
						rk[p + 11] := rk[p + 5] / rk[p + 10];
						INC( p, 6 );
					END;
					RETURN 12
				END Init192;
	
				PROCEDURE Init256( VAR rk: RKeys;  CONST src: ARRAY OF CHAR ): SHORTINT;
				VAR i, p: LONGINT;  ib: Ind4;
				BEGIN
					FOR i := 0 TO 7 DO  rk[i] := U.SetFromBufferBE( src, 4*i )  END;
					p := 0;  i := 0;
					LOOP
						split( rk[p + 7], ib );
						rk[p +   8] := rk[p] / (e4[ib.c]*b3) / (e4[ib.b]*b2) / (e4[ib.a]*b1) / (e4[ib.d]*b0) / rcon[i];
						rk[p +   9] := rk[p + 1] / rk[p + 8];
						rk[p + 10] := rk[p + 2] / rk[p + 9];
						rk[p + 11] := rk[p + 3] / rk[p + 10];
						INC( i );
						IF i = 7 THEN  EXIT   END;
						split( rk[p + 11], ib );
						rk[p + 12] := rk[p + 4] / (e4[ib.d]*b3) / (e4[ib.c]*b2) / (e4[ib.b]*b1) / (e4[ib.a]*b0);
						rk[p + 13] := rk[p + 5] / rk[p + 12];
						rk[p + 14] := rk[p + 6] / rk[p + 13];
						rk[p + 15] := rk[p + 7] / rk[p + 14];
						INC( p, 8 );
					END;
					RETURN 14
				END Init256;
	
				PROCEDURE Invert( VAR rk: RKeys;  rounds: SHORTINT );
				VAR i, j, k, p: LONGINT;  t: SET;  ib: Ind4;
				
					PROCEDURE ind( s: SET ): LONGINT;   (* extract index byte 0 *)
					BEGIN
						RETURN S.VAL( LONGINT, s ) MOD 100H
					END ind;
					
				BEGIN
					(* invert the order of the round keys: *)
					i := 0;  j := 4*rounds;
					WHILE i < j DO
						FOR k := 0 TO 3 DO  t := rk[i + k];  rk[i + k] := rk[j + k];  rk[j + k] := t  END;
						INC( i, 4 );  DEC( j, 4 );
					END;
					(* apply the inverse MixColumn transform to all round keys but the first and the last: *)
					FOR i := 1 TO rounds - 1 DO
						FOR j := 0 TO 3 DO
							p := 4*i + j;  
							split( rk[p], ib );
							rk[p] := d0[ind( e4[ib.d] )] / d1[ind( e4[ib.c] )] / d2[ind( e4[ib.b] )] / d3[ind( e4[ib.a] )];
						END
					END;
				END Invert;
	
	
				PROCEDURE & Init*;
				BEGIN
					SetNameAndBlocksize( "aes", 16 )
				END Init;

			END Cipher;

	PROCEDURE NewCipher*(): Ciphers.Cipher;
	VAR cipher: Cipher;
	BEGIN
		NEW( cipher );  RETURN cipher
	END NewCipher;

(*-------------------------------------------------------------------------------*)
	
	
TYPE
	ConstBuffer = OBJECT
		VAR 
			buf: ARRAY 2048 OF CHAR;  ib: LONGINT;
		
			PROCEDURE & Initialize;
			BEGIN
				ib := 0;
			END Initialize;
			
			PROCEDURE Append( CONST str: ARRAY OF CHAR );
			VAR i: LONGINT;  c: CHAR;
			BEGIN
				i := 0;
				REPEAT  c := str[i];  buf[ib] := c;  INC( i );  INC( ib )  UNTIL c = 0X;
				buf[ib - 1] := ' '
			END Append;
		
			PROCEDURE GetInt( ): LONGINT;
			VAR x: LONGINT;  c: CHAR;
			BEGIN
				WHILE buf[ib] <= ' ' DO  INC( ib )  END;
				x := 0;  c := buf[ib];  INC( ib );
				WHILE c > ' ' DO  x := 10*x + (ORD( c ) - 48);  c := buf[ib];  INC( ib )  END;
				RETURN x
			END GetInt;
			
		END ConstBuffer;


	PROCEDURE Initialize;
	VAR i, v1, i2, i4, i8, i9, ib, id, ie, v2, v3, t: LONGINT;
		buffer: ConstBuffer;

		PROCEDURE xor( a, b: LONGINT ): LONGINT;
		BEGIN
			RETURN S.VAL( LONGINT, S.VAL( SET, a ) / S.VAL( SET, b ) )
		END xor;
		
		PROCEDURE f1( x: LONGINT ): LONGINT;
		VAR y: LONGINT;
		BEGIN
			y := 2*x;
			IF y < 256 THEN  RETURN y  ELSE  RETURN xor( y, 11BH )  END
		END f1;

	BEGIN
		NEW( buffer );
		buffer.Append( " 99 124 119 123 242 107 111 197  48   1 103  43 254 215 171 118 " );
		buffer.Append( "202 130 201 125 250  89  71 240 173 212 162 175 156 164 114 192 " );
		buffer.Append( "183 253 147  38  54  63 247 204  52 165 229 241 113 216  49  21 " );
		buffer.Append( "  4 199  35 195  24 150   5 154   7  18 128 226 235  39 178 117 " );
		buffer.Append( "  9 131  44  26  27 110  90 160  82  59 214 179  41 227  47 132 " );
		buffer.Append( " 83 209   0 237  32 252 177  91 106 203 190  57  74  76  88 207 " );
		buffer.Append( "208 239 170 251  67  77  51 133  69 249   2 127  80  60 159 168 " );
		buffer.Append( " 81 163  64 143 146 157  56 245 188 182 218  33  16 255 243 210 " );
		buffer.Append( "205  12  19 236  95 151  68  23 196 167 126  61 100  93  25 115 " );
		buffer.Append( " 96 129  79 220  34  42 144 136  70 238 184  20 222  94  11 219 " );
		buffer.Append( "224  50  58  10  73   6  36  92 194 211 172  98 145 149 228 121 " );
		buffer.Append( "231 200  55 109 141 213  78 169 108  86 244 234 101 122 174   8 " );
		buffer.Append( "186 120  37  46  28 166 180 198 232 221 116  31  75 189 139 138 " );
		buffer.Append( "112  62 181 102  72   3 246  14  97  53  87 185 134 193  29 158 " );
		buffer.Append( "225 248 152  17 105 217 142 148 155  30 135 233 206  85  40 223 " );
		buffer.Append( "140 161 137  13 191 230  66 104  65 153  45  15 176  84 187  22 " );
		
		buffer.Initialize;
		FOR i := 0 TO 255 DO
			v1 := buffer.GetInt();  v2 := f1( v1 );  v3 := xor( v2, v1);
			i2 := f1( i );  i4 := f1( i2 );  i8 := f1( i4 );  i9 := xor( i8, i);  
			ib := xor( i9, i2 );  id := xor( i9, i4 );  ie := xor( i8, xor( i4, i2 ) );

			e0[i] := S.VAL( SET, ASH( v2, 24 ) + ASH( v1, 16 ) + ASH( v1, 8 ) + v3 );
			e1[i] := S.VAL( SET, ASH( v3, 24 ) + ASH( v2, 16 ) + ASH( v1, 8 ) + v1 );
			e2[i] := S.VAL( SET, ASH( v1, 24 ) + ASH( v3, 16 ) + ASH( v2, 8 ) + v1 );
			e3[i] := S.VAL( SET, ASH( v1, 24 ) + ASH( v1, 16 ) + ASH( v3, 8 ) + v2 );
			e4[i] := S.VAL( SET, ASH( v1, 24 ) + ASH( v1, 16 ) + ASH( v1, 8 ) + v1 );

			d0[v1] := S.VAL( SET, ASH( ie, 24 ) + ASH( i9, 16 ) + ASH( id, 8 ) + ib );
			d1[v1] := S.VAL( SET, ASH( ib, 24 ) + ASH( ie, 16 ) + ASH( i9, 8 ) + id );
			d2[v1] := S.VAL( SET, ASH( id, 24 ) + ASH( ib, 16 ) + ASH( ie, 8 ) + i9 );
			d3[v1] := S.VAL( SET, ASH( i9, 24 ) + ASH( id, 16 ) + ASH( ib, 8 ) + ie );
			d4[v1] := S.VAL( SET, ASH(  i,  24 ) + ASH(  i, 16 ) + ASH(  i, 8 ) + i );
		END;
		t := 1;
		FOR i := 0 TO 9 DO
			rcon[i] := S.VAL( SET, ASH( t, 24 ) );
			t := f1( t );
		END;
	END Initialize;


BEGIN
	Initialize;
END CryptoAES.