/*
salsa20-merged.c version 20051118
D. J. Bernstein
Public domain.
*/

#include "ecrypt-sync.h"
#include "qtpreprocessorsupport.h"

#define ROTATE(v,c) (ROTL32(v,c))
#define XOR(v,w) ((v) ^ (w))
#define PLUS(v,w) (U32V((v) + (w)))
#define PLUSONE(v) (PLUS((v),1))

void ECRYPT_init(void)
{
    return;
}

static const char sigma[17] = "expand 32-byte k";
static const char tau[17] = "expand 16-byte k";

void ECRYPT_keysetup(ECRYPT_ctx *x,const u8 *k,u32 kbits,u32 ivbits)
{
    Q_UNUSED(ivbits);
    const char *constants;

    x->input[1] = U8TO32_LITTLE(k + 0);
    x->input[2] = U8TO32_LITTLE(k + 4);
    x->input[3] = U8TO32_LITTLE(k + 8);
    x->input[4] = U8TO32_LITTLE(k + 12);
    if (kbits == 256) { /* recommended */
        k += 16;
        constants = sigma;
    } else { /* kbits == 128 */
        constants = tau;
    }
    x->input[11] = U8TO32_LITTLE(k + 0);
    x->input[12] = U8TO32_LITTLE(k + 4);
    x->input[13] = U8TO32_LITTLE(k + 8);
    x->input[14] = U8TO32_LITTLE(k + 12);
    x->input[0] = U8TO32_LITTLE(constants + 0);
    x->input[5] = U8TO32_LITTLE(constants + 4);
    x->input[10] = U8TO32_LITTLE(constants + 8);
    x->input[15] = U8TO32_LITTLE(constants + 12);
}

void ECRYPT_ivsetup(ECRYPT_ctx *x,const u8 *iv)
{
    x->input[6] = U8TO32_LITTLE(iv + 0);
    x->input[7] = U8TO32_LITTLE(iv + 4);
    x->input[8] = 0;
    x->input[9] = 0;
}

void ECRYPT_encrypt_bytes(ECRYPT_ctx *x,const u8 *m,u8 *c,u32 bytes)
{
    u32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
    u32 j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
    u8 *ctarget;
    u8 tmp[64];
    unsigned int i;

    if (!bytes) return;

    j0 = x->input[0];
    j1 = x->input[1];
    j2 = x->input[2];
    j3 = x->input[3];
    j4 = x->input[4];
    j5 = x->input[5];
    j6 = x->input[6];
    j7 = x->input[7];
    j8 = x->input[8];
    j9 = x->input[9];
    j10 = x->input[10];
    j11 = x->input[11];
    j12 = x->input[12];
    j13 = x->input[13];
    j14 = x->input[14];
    j15 = x->input[15];

    for (;;) {
        if (bytes < 64) {
            for (i = 0;i < bytes;++i) tmp[i] = m[i];
            m = tmp;
            ctarget = c;
            c = tmp;
        }
        x0 = j0;
        x1 = j1;
        x2 = j2;
        x3 = j3;
        x4 = j4;
        x5 = j5;
        x6 = j6;
        x7 = j7;
        x8 = j8;
        x9 = j9;
        x10 = j10;
        x11 = j11;
        x12 = j12;
        x13 = j13;
        x14 = j14;
        x15 = j15;
        for (i = 20;i > 0;i -= 2) {
            x4 = XOR( x4,ROTATE(PLUS( x0,x12), 7));
            x8 = XOR( x8,ROTATE(PLUS( x4, x0), 9));
            x12 = XOR(x12,ROTATE(PLUS( x8, x4),13));
            x0 = XOR( x0,ROTATE(PLUS(x12, x8),18));
            x9 = XOR( x9,ROTATE(PLUS( x5, x1), 7));
            x13 = XOR(x13,ROTATE(PLUS( x9, x5), 9));
            x1 = XOR( x1,ROTATE(PLUS(x13, x9),13));
            x5 = XOR( x5,ROTATE(PLUS( x1,x13),18));
            x14 = XOR(x14,ROTATE(PLUS(x10, x6), 7));
            x2 = XOR( x2,ROTATE(PLUS(x14,x10), 9));
            x6 = XOR( x6,ROTATE(PLUS( x2,x14),13));
            x10 = XOR(x10,ROTATE(PLUS( x6, x2),18));
            x3 = XOR( x3,ROTATE(PLUS(x15,x11), 7));
            x7 = XOR( x7,ROTATE(PLUS( x3,x15), 9));
            x11 = XOR(x11,ROTATE(PLUS( x7, x3),13));
            x15 = XOR(x15,ROTATE(PLUS(x11, x7),18));
            x1 = XOR( x1,ROTATE(PLUS( x0, x3), 7));
            x2 = XOR( x2,ROTATE(PLUS( x1, x0), 9));
            x3 = XOR( x3,ROTATE(PLUS( x2, x1),13));
            x0 = XOR( x0,ROTATE(PLUS( x3, x2),18));
            x6 = XOR( x6,ROTATE(PLUS( x5, x4), 7));
            x7 = XOR( x7,ROTATE(PLUS( x6, x5), 9));
            x4 = XOR( x4,ROTATE(PLUS( x7, x6),13));
            x5 = XOR( x5,ROTATE(PLUS( x4, x7),18));
            x11 = XOR(x11,ROTATE(PLUS(x10, x9), 7));
            x8 = XOR( x8,ROTATE(PLUS(x11,x10), 9));
            x9 = XOR( x9,ROTATE(PLUS( x8,x11),13));
            x10 = XOR(x10,ROTATE(PLUS( x9, x8),18));
            x12 = XOR(x12,ROTATE(PLUS(x15,x14), 7));
            x13 = XOR(x13,ROTATE(PLUS(x12,x15), 9));
            x14 = XOR(x14,ROTATE(PLUS(x13,x12),13));
            x15 = XOR(x15,ROTATE(PLUS(x14,x13),18));
        }
        x0 = PLUS(x0,j0);
        x1 = PLUS(x1,j1);
        x2 = PLUS(x2,j2);
        x3 = PLUS(x3,j3);
        x4 = PLUS(x4,j4);
        x5 = PLUS(x5,j5);
        x6 = PLUS(x6,j6);
        x7 = PLUS(x7,j7);
        x8 = PLUS(x8,j8);
        x9 = PLUS(x9,j9);
        x10 = PLUS(x10,j10);
        x11 = PLUS(x11,j11);
        x12 = PLUS(x12,j12);
        x13 = PLUS(x13,j13);
        x14 = PLUS(x14,j14);
        x15 = PLUS(x15,j15);

        x0 = XOR(x0,U8TO32_LITTLE(m + 0));
        x1 = XOR(x1,U8TO32_LITTLE(m + 4));
        x2 = XOR(x2,U8TO32_LITTLE(m + 8));
        x3 = XOR(x3,U8TO32_LITTLE(m + 12));
        x4 = XOR(x4,U8TO32_LITTLE(m + 16));
        x5 = XOR(x5,U8TO32_LITTLE(m + 20));
        x6 = XOR(x6,U8TO32_LITTLE(m + 24));
        x7 = XOR(x7,U8TO32_LITTLE(m + 28));
        x8 = XOR(x8,U8TO32_LITTLE(m + 32));
        x9 = XOR(x9,U8TO32_LITTLE(m + 36));
        x10 = XOR(x10,U8TO32_LITTLE(m + 40));
        x11 = XOR(x11,U8TO32_LITTLE(m + 44));
        x12 = XOR(x12,U8TO32_LITTLE(m + 48));
        x13 = XOR(x13,U8TO32_LITTLE(m + 52));
        x14 = XOR(x14,U8TO32_LITTLE(m + 56));
        x15 = XOR(x15,U8TO32_LITTLE(m + 60));

        j8 = PLUSONE(j8);
        if (!j8) {
            j9 = PLUSONE(j9);
            /* stopping at 2^70 bytes per nonce is user's responsibility */
        }

        U32TO8_LITTLE(c + 0,x0);
        U32TO8_LITTLE(c + 4,x1);
        U32TO8_LITTLE(c + 8,x2);
        U32TO8_LITTLE(c + 12,x3);
        U32TO8_LITTLE(c + 16,x4);
        U32TO8_LITTLE(c + 20,x5);
        U32TO8_LITTLE(c + 24,x6);
        U32TO8_LITTLE(c + 28,x7);
        U32TO8_LITTLE(c + 32,x8);
        U32TO8_LITTLE(c + 36,x9);
        U32TO8_LITTLE(c + 40,x10);
        U32TO8_LITTLE(c + 44,x11);
        U32TO8_LITTLE(c + 48,x12);
        U32TO8_LITTLE(c + 52,x13);
        U32TO8_LITTLE(c + 56,x14);
        U32TO8_LITTLE(c + 60,x15);

        if (bytes <= 64) {
            if (bytes < 64) {
                for (i = 0;i < bytes;++i) ctarget[i] = c[i];
            }
            x->input[8] = j8;
            x->input[9] = j9;
            return;
        }
        bytes -= 64;
        c += 64;
        m += 64;
    }
}

void ECRYPT_decrypt_bytes(ECRYPT_ctx *x,const u8 *c,u8 *m,u32 bytes)
{
    ECRYPT_encrypt_bytes(x,c,m,bytes);
}

void ECRYPT_keystream_bytes(ECRYPT_ctx *x,u8 *stream,u32 bytes)
{
    u32 i;
    for (i = 0;i < bytes;++i) stream[i] = 0;
    ECRYPT_encrypt_bytes(x,stream,stream,bytes);
}
