/*
 * alg2268.c - implementation of the algorithm in RFC 2268
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifdef FREEBL_NO_DEPEND
#include "stubs.h"
#endif

#include "blapi.h"
#include "secerr.h"
#ifdef XP_UNIX_XXX
#include <stddef.h>	/* for ptrdiff_t */
#endif

/*
** RC2 symmetric block cypher
*/

typedef SECStatus (rc2Func)(RC2Context *cx, unsigned char *output,
		           const unsigned char *input, unsigned int inputLen);

/* forward declarations */
static rc2Func rc2_EncryptECB;
static rc2Func rc2_DecryptECB;
static rc2Func rc2_EncryptCBC;
static rc2Func rc2_DecryptCBC;

typedef union {
    PRUint32	l[2];
    PRUint16	s[4];
    PRUint8	b[8];
} RC2Block;

struct RC2ContextStr {
    union {
    	PRUint8  Kb[128];
	PRUint16 Kw[64];
    } u;
    RC2Block     iv;
    rc2Func      *enc;
    rc2Func      *dec;
};

#define B u.Kb
#define K u.Kw
#define BYTESWAP(x) ((x) << 8 | (x) >> 8)
#define SWAPK(i)  cx->K[i] = (tmpS = cx->K[i], BYTESWAP(tmpS))
#define RC2_BLOCK_SIZE 8

#define LOAD_HARD(R) \
    R[0] = (PRUint16)input[1] << 8 | input[0]; \
    R[1] = (PRUint16)input[3] << 8 | input[2]; \
    R[2] = (PRUint16)input[5] << 8 | input[4]; \
    R[3] = (PRUint16)input[7] << 8 | input[6];
#define LOAD_EASY(R) \
    R[0] = ((PRUint16 *)input)[0]; \
    R[1] = ((PRUint16 *)input)[1]; \
    R[2] = ((PRUint16 *)input)[2]; \
    R[3] = ((PRUint16 *)input)[3];
#define STORE_HARD(R) \
    output[0] =  (PRUint8)(R[0]);   output[1] = (PRUint8)(R[0] >> 8); \
    output[2] =  (PRUint8)(R[1]);   output[3] = (PRUint8)(R[1] >> 8); \
    output[4] =  (PRUint8)(R[2]);   output[5] = (PRUint8)(R[2] >> 8); \
    output[6] =  (PRUint8)(R[3]);   output[7] = (PRUint8)(R[3] >> 8);
#define STORE_EASY(R) \
    ((PRUint16 *)output)[0] =  R[0]; \
    ((PRUint16 *)output)[1] =  R[1]; \
    ((PRUint16 *)output)[2] =  R[2]; \
    ((PRUint16 *)output)[3] =  R[3];   

#if defined (NSS_X86_OR_X64)
#define LOAD(R)  LOAD_EASY(R)
#define STORE(R) STORE_EASY(R)
#elif !defined(IS_LITTLE_ENDIAN)
#define LOAD(R)  LOAD_HARD(R)
#define STORE(R) STORE_HARD(R)
#else
#define LOAD(R) if ((ptrdiff_t)input & 1) { LOAD_HARD(R) } else { LOAD_EASY(R) }
#define STORE(R) if ((ptrdiff_t)input & 1) { STORE_HARD(R) } else { STORE_EASY(R) }
#endif

static const PRUint8 S[256] = {
0331,0170,0371,0304,0031,0335,0265,0355,0050,0351,0375,0171,0112,0240,0330,0235,
0306,0176,0067,0203,0053,0166,0123,0216,0142,0114,0144,0210,0104,0213,0373,0242,
0027,0232,0131,0365,0207,0263,0117,0023,0141,0105,0155,0215,0011,0201,0175,0062,
0275,0217,0100,0353,0206,0267,0173,0013,0360,0225,0041,0042,0134,0153,0116,0202,
0124,0326,0145,0223,0316,0140,0262,0034,0163,0126,0300,0024,0247,0214,0361,0334,
0022,0165,0312,0037,0073,0276,0344,0321,0102,0075,0324,0060,0243,0074,0266,0046,
0157,0277,0016,0332,0106,0151,0007,0127,0047,0362,0035,0233,0274,0224,0103,0003,
0370,0021,0307,0366,0220,0357,0076,0347,0006,0303,0325,0057,0310,0146,0036,0327,
0010,0350,0352,0336,0200,0122,0356,0367,0204,0252,0162,0254,0065,0115,0152,0052,
0226,0032,0322,0161,0132,0025,0111,0164,0113,0237,0320,0136,0004,0030,0244,0354,
0302,0340,0101,0156,0017,0121,0313,0314,0044,0221,0257,0120,0241,0364,0160,0071,
0231,0174,0072,0205,0043,0270,0264,0172,0374,0002,0066,0133,0045,0125,0227,0061,
0055,0135,0372,0230,0343,0212,0222,0256,0005,0337,0051,0020,0147,0154,0272,0311,
0323,0000,0346,0317,0341,0236,0250,0054,0143,0026,0001,0077,0130,0342,0211,0251,
0015,0070,0064,0033,0253,0063,0377,0260,0273,0110,0014,0137,0271,0261,0315,0056,
0305,0363,0333,0107,0345,0245,0234,0167,0012,0246,0040,0150,0376,0177,0301,0255
};

RC2Context * RC2_AllocateContext(void)
{
    return PORT_ZNew(RC2Context);
}
SECStatus   
RC2_InitContext(RC2Context *cx, const unsigned char *key, unsigned int len,
	        const unsigned char *input, int mode, unsigned int efLen8, 
		unsigned int unused)
{
    PRUint8    *L,*L2;
    int         i;
#if !defined(IS_LITTLE_ENDIAN)
    PRUint16    tmpS;
#endif
    PRUint8     tmpB;

    if (!key || !cx || !len || len > (sizeof cx->B) || 
	efLen8 > (sizeof cx->B)) {
	PORT_SetError(SEC_ERROR_INVALID_ARGS);
    	return SECFailure;
    }
    if (mode == NSS_RC2) {
    	/* groovy */
    } else if (mode == NSS_RC2_CBC) {
    	if (!input) {
	    PORT_SetError(SEC_ERROR_INVALID_ARGS);
	    return SECFailure;
	}
    } else {
	PORT_SetError(SEC_ERROR_INVALID_ARGS);
	return SECFailure;
    }

    if (mode == NSS_RC2_CBC) {
    	cx->enc = & rc2_EncryptCBC;
	cx->dec = & rc2_DecryptCBC;
	LOAD(cx->iv.s);
    } else {
    	cx->enc = & rc2_EncryptECB;
	cx->dec = & rc2_DecryptECB;
    }

    /* Step 0. Copy key into table. */
    memcpy(cx->B, key, len);

    /* Step 1. Compute all values to the right of the key. */
    L2 = cx->B;
    L = L2 + len;
    tmpB = L[-1];
    for (i = (sizeof cx->B) - len; i > 0; --i) {
	*L++ = tmpB = S[ (PRUint8)(tmpB + *L2++) ];
    }

    /* step 2. Adjust left most byte of effective key. */
    i = (sizeof cx->B) - efLen8;
    L = cx->B + i;
    *L = tmpB = S[*L];				/* mask is always 0xff */

    /* step 3. Recompute all values to the left of effective key. */
    L2 = --L + efLen8;
    while(L >= cx->B) {
	*L-- = tmpB = S[ tmpB ^ *L2-- ];
    }

#if !defined(IS_LITTLE_ENDIAN)
    for (i = 63; i >= 0; --i) {
        SWAPK(i);		/* candidate for unrolling */
    }
#endif
    return SECSuccess;
}

/*
** Create a new RC2 context suitable for RC2 encryption/decryption.
** 	"key" raw key data
** 	"len" the number of bytes of key data
** 	"iv" is the CBC initialization vector (if mode is NSS_RC2_CBC)
** 	"mode" one of NSS_RC2 or NSS_RC2_CBC
**	"effectiveKeyLen" in bytes, not bits.
**
** When mode is set to NSS_RC2_CBC the RC2 cipher is run in "cipher block
** chaining" mode.
*/
RC2Context *
RC2_CreateContext(const unsigned char *key, unsigned int len,
		  const unsigned char *iv, int mode, unsigned efLen8)
{
    RC2Context *cx = PORT_ZNew(RC2Context);
    if (cx) {
	SECStatus rv = RC2_InitContext(cx, key, len, iv, mode, efLen8, 0);
	if (rv != SECSuccess) {
	    RC2_DestroyContext(cx, PR_TRUE);
	    cx = NULL;
	}
    }
    return cx;
}

/*
** Destroy an RC2 encryption/decryption context.
**	"cx" the context
**	"freeit" if PR_TRUE then free the object as well as its sub-objects
*/
void 
RC2_DestroyContext(RC2Context *cx, PRBool freeit)
{
    if (cx) {
	memset(cx, 0, sizeof *cx);
	if (freeit) {
	    PORT_Free(cx);
	}
    }
}

#define ROL(x,k) (x << k | x >> (16-k))
#define MIX(j) \
    R0 = R0 + cx->K[ 4*j+0] + (R3 & R2) + (~R3 & R1);  R0 = ROL(R0,1);\
    R1 = R1 + cx->K[ 4*j+1] + (R0 & R3) + (~R0 & R2);  R1 = ROL(R1,2);\
    R2 = R2 + cx->K[ 4*j+2] + (R1 & R0) + (~R1 & R3);  R2 = ROL(R2,3);\
    R3 = R3 + cx->K[ 4*j+3] + (R2 & R1) + (~R2 & R0);  R3 = ROL(R3,5)
#define MASH \
    R0 = R0 + cx->K[R3 & 63];\
    R1 = R1 + cx->K[R0 & 63];\
    R2 = R2 + cx->K[R1 & 63];\
    R3 = R3 + cx->K[R2 & 63]

/* Encrypt one block */
static void 
rc2_Encrypt1Block(RC2Context *cx, RC2Block *output, RC2Block *input)
{
    register PRUint16 R0, R1, R2, R3;

    /* step 1. Initialize input. */
    R0 = input->s[0];
    R1 = input->s[1];
    R2 = input->s[2];
    R3 = input->s[3];

    /* step 2.  Expand Key (already done, in context) */
    /* step 3.  j = 0 */
    /* step 4.  Perform 5 mixing rounds. */

    MIX(0);
    MIX(1);
    MIX(2);
    MIX(3);
    MIX(4);

    /* step 5. Perform 1 mashing round. */
    MASH;

    /* step 6. Perform 6 mixing rounds. */

    MIX(5);
    MIX(6);
    MIX(7);
    MIX(8);
    MIX(9);
    MIX(10);

    /* step 7. Perform 1 mashing round. */
    MASH;

    /* step 8. Perform 5 mixing rounds. */

    MIX(11);
    MIX(12);
    MIX(13);
    MIX(14);
    MIX(15);

    /* output results */
    output->s[0] = R0;
    output->s[1] = R1;
    output->s[2] = R2;
    output->s[3] = R3;
}

#define ROR(x,k) (x >> k | x << (16-k))
#define R_MIX(j) \
    R3 = ROR(R3,5); R3 = R3 - cx->K[ 4*j+3] - (R2 & R1) - (~R2 & R0);  \
    R2 = ROR(R2,3); R2 = R2 - cx->K[ 4*j+2] - (R1 & R0) - (~R1 & R3);  \
    R1 = ROR(R1,2); R1 = R1 - cx->K[ 4*j+1] - (R0 & R3) - (~R0 & R2);  \
    R0 = ROR(R0,1); R0 = R0 - cx->K[ 4*j+0] - (R3 & R2) - (~R3 & R1)
#define R_MASH \
    R3 = R3 - cx->K[R2 & 63];\
    R2 = R2 - cx->K[R1 & 63];\
    R1 = R1 - cx->K[R0 & 63];\
    R0 = R0 - cx->K[R3 & 63]

/* Encrypt one block */
static void 
rc2_Decrypt1Block(RC2Context *cx, RC2Block *output, RC2Block *input)
{
    register PRUint16 R0, R1, R2, R3;

    /* step 1. Initialize input. */
    R0 = input->s[0];
    R1 = input->s[1];
    R2 = input->s[2];
    R3 = input->s[3];

    /* step 2.  Expand Key (already done, in context) */
    /* step 3.  j = 63 */
    /* step 4.  Perform 5 r_mixing rounds. */
    R_MIX(15);
    R_MIX(14);
    R_MIX(13);
    R_MIX(12);
    R_MIX(11);

    /* step 5.  Perform 1 r_mashing round. */
    R_MASH;

    /* step 6.  Perform 6 r_mixing rounds. */
    R_MIX(10);
    R_MIX(9);
    R_MIX(8);
    R_MIX(7);
    R_MIX(6);
    R_MIX(5);

    /* step 7.  Perform 1 r_mashing round. */
    R_MASH;

    /* step 8.  Perform 5 r_mixing rounds. */
    R_MIX(4);
    R_MIX(3);
    R_MIX(2);
    R_MIX(1);
    R_MIX(0);

    /* output results */
    output->s[0] = R0;
    output->s[1] = R1;
    output->s[2] = R2;
    output->s[3] = R3;
}

static SECStatus
rc2_EncryptECB(RC2Context *cx, unsigned char *output,
	       const unsigned char *input, unsigned int inputLen)
{
    RC2Block  iBlock;

    while (inputLen > 0) {
    	LOAD(iBlock.s)
	rc2_Encrypt1Block(cx, &iBlock, &iBlock);
	STORE(iBlock.s)
	output   += RC2_BLOCK_SIZE;
	input    += RC2_BLOCK_SIZE;
	inputLen -= RC2_BLOCK_SIZE;
    }
    return SECSuccess;
}

static SECStatus
rc2_DecryptECB(RC2Context *cx, unsigned char *output,
	       const unsigned char *input, unsigned int inputLen)
{
    RC2Block  iBlock;

    while (inputLen > 0) {
    	LOAD(iBlock.s)
	rc2_Decrypt1Block(cx, &iBlock, &iBlock);
	STORE(iBlock.s)
	output   += RC2_BLOCK_SIZE;
	input    += RC2_BLOCK_SIZE;
	inputLen -= RC2_BLOCK_SIZE;
    }
    return SECSuccess;
}

static SECStatus
rc2_EncryptCBC(RC2Context *cx, unsigned char *output,
	       const unsigned char *input, unsigned int inputLen)
{
    RC2Block  iBlock;

    while (inputLen > 0) {

	LOAD(iBlock.s)
	iBlock.l[0] ^= cx->iv.l[0];
	iBlock.l[1] ^= cx->iv.l[1];
	rc2_Encrypt1Block(cx, &iBlock, &iBlock);
	cx->iv = iBlock;
	STORE(iBlock.s)
	output   += RC2_BLOCK_SIZE;
	input    += RC2_BLOCK_SIZE;
	inputLen -= RC2_BLOCK_SIZE;
    }
    return SECSuccess;
}

static SECStatus
rc2_DecryptCBC(RC2Context *cx, unsigned char *output,
	       const unsigned char *input, unsigned int inputLen)
{
    RC2Block  iBlock;
    RC2Block  oBlock;

    while (inputLen > 0) {
	LOAD(iBlock.s)
	rc2_Decrypt1Block(cx, &oBlock, &iBlock);
	oBlock.l[0] ^= cx->iv.l[0];
	oBlock.l[1] ^= cx->iv.l[1];
	cx->iv = iBlock;
	STORE(oBlock.s)
	output   += RC2_BLOCK_SIZE;
	input    += RC2_BLOCK_SIZE;
	inputLen -= RC2_BLOCK_SIZE;
    }
    return SECSuccess;
}


/*
** Perform RC2 encryption.
**	"cx" the context
**	"output" the output buffer to store the encrypted data.
**	"outputLen" how much data is stored in "output". Set by the routine
**	   after some data is stored in output.
**	"maxOutputLen" the maximum amount of data that can ever be
**	   stored in "output"
**	"input" the input data
**	"inputLen" the amount of input data
*/
SECStatus RC2_Encrypt(RC2Context *cx, unsigned char *output,
		      unsigned int *outputLen, unsigned int maxOutputLen,
		      const unsigned char *input, unsigned int inputLen)
{
    SECStatus rv = SECSuccess;
    if (inputLen) {
	if (inputLen % RC2_BLOCK_SIZE) {
	    PORT_SetError(SEC_ERROR_INPUT_LEN);
	    return SECFailure;
	}
	if (maxOutputLen < inputLen) {
	    PORT_SetError(SEC_ERROR_OUTPUT_LEN);
	    return SECFailure;
	}
	rv = (*cx->enc)(cx, output, input, inputLen);
    }
    if (rv == SECSuccess) {
    	*outputLen = inputLen;
    }
    return rv;
}

/*
** Perform RC2 decryption.
**	"cx" the context
**	"output" the output buffer to store the decrypted data.
**	"outputLen" how much data is stored in "output". Set by the routine
**	   after some data is stored in output.
**	"maxOutputLen" the maximum amount of data that can ever be
**	   stored in "output"
**	"input" the input data
**	"inputLen" the amount of input data
*/
SECStatus RC2_Decrypt(RC2Context *cx, unsigned char *output,
		      unsigned int *outputLen, unsigned int maxOutputLen,
		      const unsigned char *input, unsigned int inputLen)
{
    SECStatus rv = SECSuccess;
    if (inputLen) {
	if (inputLen % RC2_BLOCK_SIZE) {
	    PORT_SetError(SEC_ERROR_INPUT_LEN);
	    return SECFailure;
	}
	if (maxOutputLen < inputLen) {
	    PORT_SetError(SEC_ERROR_OUTPUT_LEN);
	    return SECFailure;
	}
	rv = (*cx->dec)(cx, output, input, inputLen);
    }
    if (rv == SECSuccess) {
	*outputLen = inputLen;
    }
    return rv;
}