\Encryption
seal.c
```/* seal.c - SEAL encryption algorithm */

#undef SEAL_DEBUG

#define ALG_OK 0
#define ALG_NOTOK 1

struct SealKey {
unsigned long t[520]; /* 512 rounded up to a multiple of 5 + 5*/
unsigned long s[265]; /* 256 rounded up to a multiple of 5 + 5*/
unsigned long r[20];  /* 16 rounded up to multiple of 5 */
};

#define ROT2(x) (((x) >> 2) | ((x) << 30))
#define ROT9(x) (((x) >> 9) | ((x) << 23))
#define ROT8(x) (((x) >> 8) | ((x) << 24))
#define ROT16(x) (((x) >> 16) | ((x) << 16))
#define ROT24(x) (((x) >> 24) | ((x) << 8))
#define ROT27(x) (((x) >> 27) | ((x) << 5))

#define WORD(cp)  ((cp[0] << 24)|(cp[1] << 16)|(cp[2] << 8)|(cp[3]))

#define F1(x, y, z) (((x) & (y)) | ((~(x)) & (z)))
#define F2(x, y, z) ((x)^(y)^(z))
#define F3(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
#define F4(x, y, z) ((x)^(y)^(z))

int g(in, i, h)
unsigned char *in;
int i;
unsigned long *h;
{
unsigned long h0;
unsigned long h1;
unsigned long h2;
unsigned long h3;
unsigned long h4;
unsigned long a;
unsigned long b;
unsigned long c;
unsigned long d;
unsigned long e;
unsigned char *kp;
unsigned long w[80];
unsigned long temp;

kp = in;
h0 = WORD(kp); kp += 4;
h1 = WORD(kp); kp += 4;
h2 = WORD(kp); kp += 4;
h3 = WORD(kp); kp += 4;
h4 = WORD(kp); kp += 4;

w[0] = i;
for (i=1;i<16;i++)
w[i] = 0;
for (i=16;i<80;i++)
w[i] = w[i-3]^w[i-8]^w[i-14]^w[i-16];

a = h0;
b = h1;
c = h2;
d = h3;
e = h4;

for (i=0;i<20;i++)
{
temp = ROT27(a) + F1(b, c, d) + e + w[i] + 0x5a827999;
e = d;
d = c;
c = ROT2(b);
b = a;
a = temp;
}
for (i=20;i<40;i++)
{
temp = ROT27(a) + F2(b, c, d) + e + w[i] + 0x6ed9eba1;
e = d;
d = c;
c = ROT2(b);
b = a;
a = temp;
}
for (i=40;i<60;i++)
{
temp = ROT27(a) + F3(b, c, d) + e + w[i] + 0x8f1bbcdc;
e = d;
d = c;
c = ROT2(b);
b = a;
a = temp;
}
for (i=60;i<80;i++)
{
temp = ROT27(a) + F4(b, c, d) + e + w[i] + 0xca62c1d6;
e = d;
d = c;
c = ROT2(b);
b = a;
a = temp;
}
h[0] = h0+a;
h[1] = h1+b;
h[2] = h2+c;
h[3] = h3+d;
h[4] = h4+e;

return (ALG_OK);
}

unsigned long gamma(a, i)
unsigned char *a;
int i;
{
unsigned long h[5];

(void) g(a, i/5, h);
return h[i % 5];
}

int  seal_init(key, ks)
unsigned char *key;
struct SealKey **ks;
{
struct SealKey *result;
int i;
unsigned long h[5];

result = (struct SealKey *) calloc(1, sizeof(*result));
if (result == (struct SealKey *) 0)
return (ALG_NOTOK);

for (i=0;i<510;i+=5)
g(key, i/5, &(result->t[i]));
/* horrible special case for the end */
g(key, 510/5, h);
for (i=510;i<512;i++)
result->t[i] = h[i-510];
/* 0x1000 mod 5 is +1, so have horrible special case for the start */
g(key, (-1+0x1000)/5, h);
for (i=0;i<4;i++)
result->s[i] = h[i+1];
for (i=4;i<254;i+=5)
g(key, (i+0x1000)/5, &(result->s[i]));
/* horrible special case for the end */
g(key, (254+0x1000)/5, h);
for (i=254;i<256;i++)
result->s[i] = h[i-254];
/* 0x2000 mod 5 is +2, so have horrible special case at the start */
g(key, (-2+0x2000)/5, h);
for (i=0;i<3;i++)
result->r[i] = h[i+2];
for (i=3;i<13;i+=5)
g(key, (i+0x2000)/5, &(result->r[i]));
/* horrible special case for the end */
g(key, (13+0x2000)/5, h);
for (i=13;i<16;i++)
result->r[i] = h[i-13];
#ifdef SEAL_DEBUG
printf("T:\n");
for (i=0;i<8;i++)
printf("%08x ", result->t[i]);
printf("\n");
for (i=0;i<8;i++)
printf("%08x ", result->t[i+8]);
printf("\n");
printf("...\n");
for (i=0;i<8;i++)
printf("%08x ", result->t[i+504]);
printf("\n");
printf("S:\n");
for (i=0;i<8;i++)
printf("%08x ", result->s[i]);
printf("\n");
for (i=0;i<8;i++)
printf("%08x ", result->s[i+8]);
printf("\n");
printf("...\n");
for (i=0;i<8;i++)
printf("%08x ", result->s[i+248]);
printf("\n");
printf("R:\n");
for (i=0;i<8;i++)
printf("%08x ", result->r[i]);
printf("\n");
for (i=0;i<8;i++)
printf("%08x ", result->r[i+8]);
printf("\n");
#endif /* SEAL_DEBUG */
*ks = result;
return (ALG_OK);
}

int seal(key, in, out)
struct SealKey *key;
unsigned long in;
unsigned long *out;
{
int i;
int j;
int l;
unsigned long a;
unsigned long b;
unsigned long c;
unsigned long d;
unsigned short p;
unsigned short q;
unsigned long n1;
unsigned long n2;
unsigned long n3;
unsigned long n4;
unsigned long *wp;

wp = out;

for (l=0;l<4;l++)
{
a = in ^ key->r[4*l];
b = ROT8(in) ^ key->r[4*l+1];
c = ROT16(in) ^ key->r[4*l+2];
d = ROT24(in) ^ key->r[4*l+3];

for (j=0;j<2;j++)
{
p = a & 0x7fc;
b += key->t[p/4];
a = ROT9(a);

p = b & 0x7fc;
c += key->t[p/4];
b = ROT9(b);

p = c & 0x7fc;
d += key->t[p/4];
c = ROT9(c);

p = d & 0x7fc;
a += key->t[p/4];
d = ROT9(d);

}
n1 = d;
n2 = b;
n3 = a;
n4 = c;

p = a & 0x7fc;
b += key->t[p/4];
a = ROT9(a);

p = b & 0x7fc;
c += key->t[p/4];
b = ROT9(b);

p = c & 0x7fc;
d += key->t[p/4];
c = ROT9(c);

p = d & 0x7fc;
a += key->t[p/4];
d = ROT9(d);

for (i=0;i<64;i++)
{
p = a & 0x7fc;
b += key->t[p/4];
a = ROT9(a);
b ^= a;

q = b & 0x7fc;
c ^= key->t[q/4];
b = ROT9(b);
c += b;

p = (p+c) & 0x7fc;
d += key->t[p/4];
c = ROT9(c);
d ^= c;

q = (q+d) & 0x7fc;
a ^= key->t[q/4];
d = ROT9(d);
a += d;

p = (p+a) & 0x7fc;
b ^= key->t[p/4];
a = ROT9(a);

q = (q+b) & 0x7fc;
c += key->t[q/4];
b = ROT9(b);

p = (p+c) & 0x7fc;
d ^= key->t[p/4];
c = ROT9(c);

q = (q+d) & 0x7fc;
a += key->t[q/4];
d = ROT9(d);

*wp = b + key->s[4*i];
wp++;
*wp = c ^ key->s[4*i+1];
wp++;
*wp = d + key->s[4*i+2];
wp++;
*wp = a ^ key->s[4*i+3];
wp++;

if (i & 1)
{
a += n3;
c += n4;
}
else
{
a += n1;
c += n2;
}

}
}
return (ALG_OK);
}

/* end of file */

```