/* SEAL */

#define ALG_OK 0
#define ALG_NOTOK 1
#define WORDS_PER_SEAL_CALL 1024
         
typedef struct {
	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 */
	unsigned long counter; /* 32-bit synch value. */
	unsigned long ks_buf[WORDS_PER_SEAL_CALL];
	int ks_pos;
} seal_ctx;
         
#define ROT2(x) (((x) >>2) | ((x) << 30))
#define ROT8(x) (((x) >>8) | ((x) << 24))
#define ROT9(x) (((x) >>9) | ((x) << 23))
#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,h1,h2,h3,h4,a,b,c,d,e,temp;
unsigned char *kp;
unsigned long w[80];

	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( seal_ctx *result, unsigned char *key )
{         
int i;
unsigned long h[5];
         
	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];
	return (ALG_OK);
}

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

	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);
         
	/* This generates 64 32-bit words, or 256 bytes of keystream. */
	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);
}
         

/* Added call to refill ks_buf and reset counter and ks_pos. */
void seal_refill_buffer(seal_ctx *c){
	seal(c,c->counter,c->ks_buf);
	c->counter++;
	c->ks_pos = 0;
}

void seal_key(seal_ctx *c, unsigned char *key){
	seal_init(c,key);
	c->counter = 0; /* By default, init to zero. */
	c->ks_pos = WORDS_PER_SEAL_CALL;
	/* Refill keystream buffer on next call. */
}
         
/* This encrypts the next w words with SEAL. */
void seal_encrypt(seal_ctx *c, unsigned long *data_ptr, int w){
int i;

	for(i=0;i<w;i++){
	 if(c->ks_pos>=WORDS_PER_SEAL_CALL) seal_refill_buffer(c);
	 data_ptr[i]^=c->ks_buf[c->ks_pos];
	 c->ks_pos++;
	}
}
         
void seal_decrypt(seal_ctx *c, unsigned long *data_ptr, int w) {
	seal_encrypt(c,data_ptr,w);
}

void seal_resynch(seal_ctx *c, unsigned long synch_word){
	c->counter = synch_word;
	c->ks_pos = WORDS_PER_SEAL_CALL;
}
