cipher-twofish.c

海思KEY驱动

    0xECC94AEC, 0xFDD25EFD, 0xAB7FC1AB, 0xD8A8E0D8}
};

/* The exp_to_poly and poly_to_exp tables are used to perform efficient
 * operations in GF(2^8) represented as GF(2)[x]/w(x) where
 * w(x)=x^8+x^6+x^3+x^2+1.  We care about doing that because it's part of the
 * definition of the RS matrix in the key schedule.  Elements of that field
 * are polynomials of degree not greater than 7 and all coefficients 0 or 1,
 * which can be represented naturally by bytes (just substitute x=2).  In that
 * form, GF(2^8) addition is the same as bitwise XOR, but GF(2^8)
 * multiplication is inefficient without hardware support.  To multiply
 * faster, I make use of the fact x is a generator for the nonzero elements,
 * so that every element p of GF(2)[x]/w(x) is either 0 or equal to (x)^n for
 * some n in 0..254.  Note that that caret is exponentiation in GF(2^8),
 * *not* polynomial notation.  So if I want to compute pq where p and q are
 * in GF(2^8), I can just say:
 *    1. if p=0 or q=0 then pq=0
 *    2. otherwise, find m and n such that p=x^m and q=x^n
 *    3. pq=(x^m)(x^n)=x^(m+n), so add m and n and find pq
 * The translations in steps 2 and 3 are looked up in the tables
 * poly_to_exp (for step 2) and exp_to_poly (for step 3).  To see this
 * in action, look at the CALC_S macro.  As additional wrinkles, note that
 * one of my operands is always a constant, so the poly_to_exp lookup on it
 * is done in advance; I included the original values in the comments so
 * readers can have some chance of recognizing that this *is* the RS matrix
 * from the Twofish paper.  I've only included the table entries I actually
 * need; I never do a lookup on a variable input of zero and the biggest
 * exponents I'll ever see are 254 (variable) and 237 (constant), so they'll
 * never sum to more than 491.	I'm repeating part of the exp_to_poly table
 * so that I don't have to do mod-255 reduction in the exponent arithmetic.
 * Since I know my constant operands are never zero, I only have to worry
 * about zero values in the variable operand, and I do it with a simple
 * conditional branch.	I know conditionals are expensive, but I couldn't
 * see a non-horrible way of avoiding them, and I did manage to group the
 * statements so that each if covers four group multiplications. */

static const u8 poly_to_exp[255] = {
   0x00, 0x01, 0x17, 0x02, 0x2E, 0x18, 0x53, 0x03, 0x6A, 0x2F, 0x93, 0x19,
   0x34, 0x54, 0x45, 0x04, 0x5C, 0x6B, 0xB6, 0x30, 0xA6, 0x94, 0x4B, 0x1A,
   0x8C, 0x35, 0x81, 0x55, 0xAA, 0x46, 0x0D, 0x05, 0x24, 0x5D, 0x87, 0x6C,
   0x9B, 0xB7, 0xC1, 0x31, 0x2B, 0xA7, 0xA3, 0x95, 0x98, 0x4C, 0xCA, 0x1B,
   0xE6, 0x8D, 0x73, 0x36, 0xCD, 0x82, 0x12, 0x56, 0x62, 0xAB, 0xF0, 0x47,
   0x4F, 0x0E, 0xBD, 0x06, 0xD4, 0x25, 0xD2, 0x5E, 0x27, 0x88, 0x66, 0x6D,
   0xD6, 0x9C, 0x79, 0xB8, 0x08, 0xC2, 0xDF, 0x32, 0x68, 0x2C, 0xFD, 0xA8,
   0x8A, 0xA4, 0x5A, 0x96, 0x29, 0x99, 0x22, 0x4D, 0x60, 0xCB, 0xE4, 0x1C,
   0x7B, 0xE7, 0x3B, 0x8E, 0x9E, 0x74, 0xF4, 0x37, 0xD8, 0xCE, 0xF9, 0x83,
   0x6F, 0x13, 0xB2, 0x57, 0xE1, 0x63, 0xDC, 0xAC, 0xC4, 0xF1, 0xAF, 0x48,
   0x0A, 0x50, 0x42, 0x0F, 0xBA, 0xBE, 0xC7, 0x07, 0xDE, 0xD5, 0x78, 0x26,
   0x65, 0xD3, 0xD1, 0x5F, 0xE3, 0x28, 0x21, 0x89, 0x59, 0x67, 0xFC, 0x6E,
   0xB1, 0xD7, 0xF8, 0x9D, 0xF3, 0x7A, 0x3A, 0xB9, 0xC6, 0x09, 0x41, 0xC3,
   0xAE, 0xE0, 0xDB, 0x33, 0x44, 0x69, 0x92, 0x2D, 0x52, 0xFE, 0x16, 0xA9,
   0x0C, 0x8B, 0x80, 0xA5, 0x4A, 0x5B, 0xB5, 0x97, 0xC9, 0x2A, 0xA2, 0x9A,
   0xC0, 0x23, 0x86, 0x4E, 0xBC, 0x61, 0xEF, 0xCC, 0x11, 0xE5, 0x72, 0x1D,
   0x3D, 0x7C, 0xEB, 0xE8, 0xE9, 0x3C, 0xEA, 0x8F, 0x7D, 0x9F, 0xEC, 0x75,
   0x1E, 0xF5, 0x3E, 0x38, 0xF6, 0xD9, 0x3F, 0xCF, 0x76, 0xFA, 0x1F, 0x84,
   0xA0, 0x70, 0xED, 0x14, 0x90, 0xB3, 0x7E, 0x58, 0xFB, 0xE2, 0x20, 0x64,
   0xD0, 0xDD, 0x77, 0xAD, 0xDA, 0xC5, 0x40, 0xF2, 0x39, 0xB0, 0xF7, 0x49,
   0xB4, 0x0B, 0x7F, 0x51, 0x15, 0x43, 0x91, 0x10, 0x71, 0xBB, 0xEE, 0xBF,
   0x85, 0xC8, 0xA1
};

static const u8 exp_to_poly[492] = {
   0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x4D, 0x9A, 0x79, 0xF2,
   0xA9, 0x1F, 0x3E, 0x7C, 0xF8, 0xBD, 0x37, 0x6E, 0xDC, 0xF5, 0xA7, 0x03,
   0x06, 0x0C, 0x18, 0x30, 0x60, 0xC0, 0xCD, 0xD7, 0xE3, 0x8B, 0x5B, 0xB6,
   0x21, 0x42, 0x84, 0x45, 0x8A, 0x59, 0xB2, 0x29, 0x52, 0xA4, 0x05, 0x0A,
   0x14, 0x28, 0x50, 0xA0, 0x0D, 0x1A, 0x34, 0x68, 0xD0, 0xED, 0x97, 0x63,
   0xC6, 0xC1, 0xCF, 0xD3, 0xEB, 0x9B, 0x7B, 0xF6, 0xA1, 0x0F, 0x1E, 0x3C,
   0x78, 0xF0, 0xAD, 0x17, 0x2E, 0x5C, 0xB8, 0x3D, 0x7A, 0xF4, 0xA5, 0x07,
   0x0E, 0x1C, 0x38, 0x70, 0xE0, 0x8D, 0x57, 0xAE, 0x11, 0x22, 0x44, 0x88,
   0x5D, 0xBA, 0x39, 0x72, 0xE4, 0x85, 0x47, 0x8E, 0x51, 0xA2, 0x09, 0x12,
   0x24, 0x48, 0x90, 0x6D, 0xDA, 0xF9, 0xBF, 0x33, 0x66, 0xCC, 0xD5, 0xE7,
   0x83, 0x4B, 0x96, 0x61, 0xC2, 0xC9, 0xDF, 0xF3, 0xAB, 0x1B, 0x36, 0x6C,
   0xD8, 0xFD, 0xB7, 0x23, 0x46, 0x8C, 0x55, 0xAA, 0x19, 0x32, 0x64, 0xC8,
   0xDD, 0xF7, 0xA3, 0x0B, 0x16, 0x2C, 0x58, 0xB0, 0x2D, 0x5A, 0xB4, 0x25,
   0x4A, 0x94, 0x65, 0xCA, 0xD9, 0xFF, 0xB3, 0x2B, 0x56, 0xAC, 0x15, 0x2A,
   0x54, 0xA8, 0x1D, 0x3A, 0x74, 0xE8, 0x9D, 0x77, 0xEE, 0x91, 0x6F, 0xDE,
   0xF1, 0xAF, 0x13, 0x26, 0x4C, 0x98, 0x7D, 0xFA, 0xB9, 0x3F, 0x7E, 0xFC,
   0xB5, 0x27, 0x4E, 0x9C, 0x75, 0xEA, 0x99, 0x7F, 0xFE, 0xB1, 0x2F, 0x5E,
   0xBC, 0x35, 0x6A, 0xD4, 0xE5, 0x87, 0x43, 0x86, 0x41, 0x82, 0x49, 0x92,
   0x69, 0xD2, 0xE9, 0x9F, 0x73, 0xE6, 0x81, 0x4F, 0x9E, 0x71, 0xE2, 0x89,
   0x5F, 0xBE, 0x31, 0x62, 0xC4, 0xC5, 0xC7, 0xC3, 0xCB, 0xDB, 0xFB, 0xBB,
   0x3B, 0x76, 0xEC, 0x95, 0x67, 0xCE, 0xD1, 0xEF, 0x93, 0x6B, 0xD6, 0xE1,
   0x8F, 0x53, 0xA6, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x4D,
   0x9A, 0x79, 0xF2, 0xA9, 0x1F, 0x3E, 0x7C, 0xF8, 0xBD, 0x37, 0x6E, 0xDC,
   0xF5, 0xA7, 0x03, 0x06, 0x0C, 0x18, 0x30, 0x60, 0xC0, 0xCD, 0xD7, 0xE3,
   0x8B, 0x5B, 0xB6, 0x21, 0x42, 0x84, 0x45, 0x8A, 0x59, 0xB2, 0x29, 0x52,
   0xA4, 0x05, 0x0A, 0x14, 0x28, 0x50, 0xA0, 0x0D, 0x1A, 0x34, 0x68, 0xD0,
   0xED, 0x97, 0x63, 0xC6, 0xC1, 0xCF, 0xD3, 0xEB, 0x9B, 0x7B, 0xF6, 0xA1,
   0x0F, 0x1E, 0x3C, 0x78, 0xF0, 0xAD, 0x17, 0x2E, 0x5C, 0xB8, 0x3D, 0x7A,
   0xF4, 0xA5, 0x07, 0x0E, 0x1C, 0x38, 0x70, 0xE0, 0x8D, 0x57, 0xAE, 0x11,
   0x22, 0x44, 0x88, 0x5D, 0xBA, 0x39, 0x72, 0xE4, 0x85, 0x47, 0x8E, 0x51,
   0xA2, 0x09, 0x12, 0x24, 0x48, 0x90, 0x6D, 0xDA, 0xF9, 0xBF, 0x33, 0x66,
   0xCC, 0xD5, 0xE7, 0x83, 0x4B, 0x96, 0x61, 0xC2, 0xC9, 0xDF, 0xF3, 0xAB,
   0x1B, 0x36, 0x6C, 0xD8, 0xFD, 0xB7, 0x23, 0x46, 0x8C, 0x55, 0xAA, 0x19,
   0x32, 0x64, 0xC8, 0xDD, 0xF7, 0xA3, 0x0B, 0x16, 0x2C, 0x58, 0xB0, 0x2D,
   0x5A, 0xB4, 0x25, 0x4A, 0x94, 0x65, 0xCA, 0xD9, 0xFF, 0xB3, 0x2B, 0x56,
   0xAC, 0x15, 0x2A, 0x54, 0xA8, 0x1D, 0x3A, 0x74, 0xE8, 0x9D, 0x77, 0xEE,
   0x91, 0x6F, 0xDE, 0xF1, 0xAF, 0x13, 0x26, 0x4C, 0x98, 0x7D, 0xFA, 0xB9,
   0x3F, 0x7E, 0xFC, 0xB5, 0x27, 0x4E, 0x9C, 0x75, 0xEA, 0x99, 0x7F, 0xFE,
   0xB1, 0x2F, 0x5E, 0xBC, 0x35, 0x6A, 0xD4, 0xE5, 0x87, 0x43, 0x86, 0x41,
   0x82, 0x49, 0x92, 0x69, 0xD2, 0xE9, 0x9F, 0x73, 0xE6, 0x81, 0x4F, 0x9E,
   0x71, 0xE2, 0x89, 0x5F, 0xBE, 0x31, 0x62, 0xC4, 0xC5, 0xC7, 0xC3, 0xCB
};


/* The table constants are indices of
 * S-box entries, preprocessed through q0 and q1. */
static const u8 calc_sb_tbl[512] = {
    0xA9, 0x75, 0x67, 0xF3, 0xB3, 0xC6, 0xE8, 0xF4,
    0x04, 0xDB, 0xFD, 0x7B, 0xA3, 0xFB, 0x76, 0xC8,
    0x9A, 0x4A, 0x92, 0xD3, 0x80, 0xE6, 0x78, 0x6B,
    0xE4, 0x45, 0xDD, 0x7D, 0xD1, 0xE8, 0x38, 0x4B,
    0x0D, 0xD6, 0xC6, 0x32, 0x35, 0xD8, 0x98, 0xFD,
    0x18, 0x37, 0xF7, 0x71, 0xEC, 0xF1, 0x6C, 0xE1,
    0x43, 0x30, 0x75, 0x0F, 0x37, 0xF8, 0x26, 0x1B,
    0xFA, 0x87, 0x13, 0xFA, 0x94, 0x06, 0x48, 0x3F,
    0xF2, 0x5E, 0xD0, 0xBA, 0x8B, 0xAE, 0x30, 0x5B,
    0x84, 0x8A, 0x54, 0x00, 0xDF, 0xBC, 0x23, 0x9D,
    0x19, 0x6D, 0x5B, 0xC1, 0x3D, 0xB1, 0x59, 0x0E,
    0xF3, 0x80, 0xAE, 0x5D, 0xA2, 0xD2, 0x82, 0xD5,
    0x63, 0xA0, 0x01, 0x84, 0x83, 0x07, 0x2E, 0x14,
    0xD9, 0xB5, 0x51, 0x90, 0x9B, 0x2C, 0x7C, 0xA3,
    0xA6, 0xB2, 0xEB, 0x73, 0xA5, 0x4C, 0xBE, 0x54,
    0x16, 0x92, 0x0C, 0x74, 0xE3, 0x36, 0x61, 0x51,
    0xC0, 0x38, 0x8C, 0xB0, 0x3A, 0xBD, 0xF5, 0x5A,
    0x73, 0xFC, 0x2C, 0x60, 0x25, 0x62, 0x0B, 0x96,
    0xBB, 0x6C, 0x4E, 0x42, 0x89, 0xF7, 0x6B, 0x10,
    0x53, 0x7C, 0x6A, 0x28, 0xB4, 0x27, 0xF1, 0x8C,
    0xE1, 0x13, 0xE6, 0x95, 0xBD, 0x9C, 0x45, 0xC7,
    0xE2, 0x24, 0xF4, 0x46, 0xB6, 0x3B, 0x66, 0x70,
    0xCC, 0xCA, 0x95, 0xE3, 0x03, 0x85, 0x56, 0xCB,
    0xD4, 0x11, 0x1C, 0xD0, 0x1E, 0x93, 0xD7, 0xB8,
    0xFB, 0xA6, 0xC3, 0x83, 0x8E, 0x20, 0xB5, 0xFF,
    0xE9, 0x9F, 0xCF, 0x77, 0xBF, 0xC3, 0xBA, 0xCC,
    0xEA, 0x03, 0x77, 0x6F, 0x39, 0x08, 0xAF, 0xBF,
    0x33, 0x40, 0xC9, 0xE7, 0x62, 0x2B, 0x71, 0xE2,
    0x81, 0x79, 0x79, 0x0C, 0x09, 0xAA, 0xAD, 0x82,
    0x24, 0x41, 0xCD, 0x3A, 0xF9, 0xEA, 0xD8, 0xB9,
    0xE5, 0xE4, 0xC5, 0x9A, 0xB9, 0xA4, 0x4D, 0x97,
    0x44, 0x7E, 0x08, 0xDA, 0x86, 0x7A, 0xE7, 0x17,
    0xA1, 0x66, 0x1D, 0x94, 0xAA, 0xA1, 0xED, 0x1D,
    0x06, 0x3D, 0x70, 0xF0, 0xB2, 0xDE, 0xD2, 0xB3,
    0x41, 0x0B, 0x7B, 0x72, 0xA0, 0xA7, 0x11, 0x1C,
    0x31, 0xEF, 0xC2, 0xD1, 0x27, 0x53, 0x90, 0x3E,
    0x20, 0x8F, 0xF6, 0x33, 0x60, 0x26, 0xFF, 0x5F,
    0x96, 0xEC, 0x5C, 0x76, 0xB1, 0x2A, 0xAB, 0x49,
    0x9E, 0x81, 0x9C, 0x88, 0x52, 0xEE, 0x1B, 0x21,
    0x5F, 0xC4, 0x93, 0x1A, 0x0A, 0xEB, 0xEF, 0xD9,
    0x91, 0xC5, 0x85, 0x39, 0x49, 0x99, 0xEE, 0xCD,
    0x2D, 0xAD, 0x4F, 0x31, 0x8F, 0x8B, 0x3B, 0x01,
    0x47, 0x18, 0x87, 0x23, 0x6D, 0xDD, 0x46, 0x1F,
    0xD6, 0x4E, 0x3E, 0x2D, 0x69, 0xF9, 0x64, 0x48,
    0x2A, 0x4F, 0xCE, 0xF2, 0xCB, 0x65, 0x2F, 0x8E,
    0xFC, 0x78, 0x97, 0x5C, 0x05, 0x58, 0x7A, 0x19,
    0xAC, 0x8D, 0x7F, 0xE5, 0xD5, 0x98, 0x1A, 0x57,
    0x4B, 0x67, 0x0E, 0x7F, 0xA7, 0x05, 0x5A, 0x64,
    0x28, 0xAF, 0x14, 0x63, 0x3F, 0xB6, 0x29, 0xFE,
    0x88, 0xF5, 0x3C, 0xB7, 0x4C, 0x3C, 0x02, 0xA5,
    0xB8, 0xCE, 0xDA, 0xE9, 0xB0, 0x68, 0x17, 0x44,
    0x55, 0xE0, 0x1F, 0x4D, 0x8A, 0x43, 0x7D, 0x69,
    0x57, 0x29, 0xC7, 0x2E, 0x8D, 0xAC, 0x74, 0x15,
    0xB7, 0x59, 0xC4, 0xA8, 0x9F, 0x0A, 0x72, 0x9E,
    0x7E, 0x6E, 0x15, 0x47, 0x22, 0xDF, 0x12, 0x34,
    0x58, 0x35, 0x07, 0x6A, 0x99, 0xCF, 0x34, 0xDC,
    0x6E, 0x22, 0x50, 0xC9, 0xDE, 0xC0, 0x68, 0x9B,
    0x65, 0x89, 0xBC, 0xD4, 0xDB, 0xED, 0xF8, 0xAB,
    0xC8, 0x12, 0xA8, 0xA2, 0x2B, 0x0D, 0x40, 0x52,
    0xDC, 0xBB, 0xFE, 0x02, 0x32, 0x2F, 0xA4, 0xA9,
    0xCA, 0xD7, 0x10, 0x61, 0x21, 0x1E, 0xF0, 0xB4,
    0xD3, 0x50, 0x5D, 0x04, 0x0F, 0xF6, 0x00, 0xC2,
    0x6F, 0x16, 0x9D, 0x25, 0x36, 0x86, 0x42, 0x56,
    0x4A, 0x55, 0x5E, 0x09, 0xC1, 0xBE, 0xE0, 0x91
};

/* Macro to perform one column of the RS matrix multiplication.  The
 * parameters a, b, c, and d are the four bytes of output; i is the index
 * of the key bytes, and w, x, y, and z, are the column of constants from
 * the RS matrix, preprocessed through the poly_to_exp table. */

#define CALC_S(a, b, c, d, i, w, x, y, z) \
   if (key[i]) { \
      tmp = poly_to_exp[key[i] - 1]; \
      (a) ^= exp_to_poly[tmp + (w)]; \
      (b) ^= exp_to_poly[tmp + (x)]; \
      (c) ^= exp_to_poly[tmp + (y)]; \
      (d) ^= exp_to_poly[tmp + (z)]; \
   }

/* Macros to calculate the key-dependent S-boxes for a 128-bit key using
 * the S vector from CALC_S.  CALC_SB_2 computes a single entry in all
 * four S-boxes, where i is the index of the entry to compute, and a and b
 * are the index numbers preprocessed through the q0 and q1 tables
 * respectively. */

#define CALC_SB_2(i, a, b) \
   ctx->s[0][i] = mds[0][q0[(a) ^ sa] ^ se]; \
   ctx->s[1][i] = mds[1][q0[(b) ^ sb] ^ sf]; \
   ctx->s[2][i] = mds[2][q1[(a) ^ sc] ^ sg]; \
   ctx->s[3][i] = mds[3][q1[(b) ^ sd] ^ sh]

/* Macro exactly like CALC_SB_2, but for 192-bit keys. */

#define CALC_SB192_2(i, a, b) \
   ctx->s[0][i] = mds[0][q0[q0[(b) ^ sa] ^ se] ^ si]; \
   ctx->s[1][i] = mds[1][q0[q1[(b) ^ sb] ^ sf] ^ sj]; \
   ctx->s[2][i] = mds[2][q1[q0[(a) ^ sc] ^ sg] ^ sk]; \
   ctx->s[3][i] = mds[3][q1[q1[(a) ^ sd] ^ sh] ^ sl];

/* Macro exactly like CALC_SB_2, but for 256-bit keys. */

#define CALC_SB256_2(i, a, b) \
   ctx->s[0][i] = mds[0][q0[q0[q1[(b) ^ sa] ^ se] ^ si] ^ sm]; \
   ctx->s[1][i] = mds[1][q0[q1[q1[(a) ^ sb] ^ sf] ^ sj] ^ sn]; \
   ctx->s[2][i] = mds[2][q1[q0[q0[(a) ^ sc] ^ sg] ^ sk] ^ so]; \
   ctx->s[3][i] = mds[3][q1[q1[q0[(b) ^ sd] ^ sh] ^ sl] ^ sp];

/* Macros to calculate the whitening and round subkeys.  CALC_K_2 computes the
 * last two stages of the h() function for a given index (either 2i or 2i+1).
 * a, b, c, and d are the four bytes going into the last two stages.  For
 * 128-bit keys, this is the entire h() function and a and c are the index
 * preprocessed through q0 and q1 respectively; for longer keys they are the
 * output of previous stages.  j is the index of the first key byte to use.
 * CALC_K computes a pair of subkeys for 128-bit Twofish, by calling CALC_K_2
 * twice, doing the Psuedo-Hadamard Transform, and doing the necessary
 * rotations.  Its parameters are: a, the array to write the results into,
 * j, the index of the first output entry, k and l, the preprocessed indices
 * for index 2i, and m and n, the preprocessed indices for index 2i+1.
 * CALC_K192_2 expands CALC_K_2 to handle 192-bit keys, by doing an
 * additional lookup-and-XOR stage.  The parameters a, b, c and d are the
 * four bytes going into the last three stages.  For 192-bit keys, c = d
 * are the index preprocessed through q0, and a = b are the index
 * preprocessed through q1; j is the index of the first key byte to use.
 * CALC_K192 is identical to CALC_K but for using the CALC_K192_2 macro
 * instead of CALC_K_2.
 * CALC_K256_2 expands CALC_K192_2 to handle 256-bit keys, by doing an
 * additional lookup-and-XOR stage.  The parameters a and b are the index
 * preprocessed through q0 and q1 respectively; j is the index of the first
 * key byte to use.  CALC_K256 is identical to CALC_K but for using the
 * CALC_K256_2 macro instead of CALC_K_2. */

#define CALC_K_2(a, b, c, d, j) \
     mds[0][q0[a ^ key[(j) + 8]] ^ key[j]] \
   ^ mds[1][q0[b ^ key[(j) + 9]] ^ key[(j) + 1]] \
   ^ mds[2][q1[c ^ key[(j) + 10]] ^ key[(j) + 2]] \
   ^ mds[3][q1[d ^ key[(j) + 11]] ^ key[(j) + 3]]

#define CALC_K(a, j, k, l, m, n) \
   x = CALC_K_2 (k, l, k, l, 0); \
   y = CALC_K_2 (m, n, m, n, 4); \
   y = (y << 8) + (y >> 24); \
   x += y; y += x; ctx->a[j] = x; \
   ctx->a[(j) + 1] = (y << 9) + (y >> 23)

#define CALC_K192_2(a, b, c, d, j) \
   CALC_K_2 (q0[a ^ key[(j) + 16]], \
	     q1[b ^ key[(j) + 17]], \
	     q0[c ^ key[(j) + 18]], \
	     q1[d ^ key[(j) + 19]], j)

#define CALC_K192(a, j, k, l, m, n) \
   x = CALC_K192_2 (l, l, k, k, 0); \
   y = CALC_K192_2 (n, n, m, m, 4); \
   y = (y << 8) + (y >> 24); \
   x += y; y += x; ctx->a[j] = x; \
   ctx->a[(j) + 1] = (y << 9) + (y >> 23)

#define CALC_K256_2(a, b, j) \
   CALC_K192_2 (q1[b ^ key[(j) + 24]], \
	        q1[a ^ key[(j) + 25]], \
	        q0[a ^ key[(j) + 26]], \
	        q0[b ^ key[(j) + 27]], j)

#define CALC_K256(a, j, k, l, m, n) \
   x = CALC_K256_2 (k, l, 0); \
   y = CALC_K256_2 (m, n, 4); \
   y = (y << 8) + (y >> 24); \
   x += y; y += x; ctx->a[j] = x; \
   ctx->a[(j) + 1] = (y << 9) + (y >> 23)

/* Perform the key setup. */

static int twofish_set_key (struct cipher_context *cx, 
			    const u8 *key, int key_len, int atomic)
{
        twofish_key_t *ctx = (twofish_key_t *) cx->keyinfo;

	int i, j, k;

	/* Temporaries for CALC_K. */
	u32 x, y;

	/* The S vector used to key the S-boxes, split up into individual bytes.
	 * 128-bit keys use only sa through sh; 256-bit use all of them. */