/*

 * Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <string.h>

#include <openssl/crypto.h>

#include "crypto/modes.h"

/*

 * First you setup M and L parameters and pass the key schedule. This is

 * called once per session setup...

 */

void CRYPTO_ccm128_init(CCM128_CONTEXT *ctx,

                        unsigned int M, unsigned int L, void *key,

                        block128_f block)

{

    memset(ctx->nonce.c, 0, sizeof(ctx->nonce.c));

    ctx->nonce.c[0] = ((u8)(L - 1) & 7) | (u8)(((M - 2) / 2) & 7) << 3;

    ctx->blocks = 0;

    ctx->block = block;

    ctx->key = key;

}

/* !!! Following interfaces are to be called *once* per packet !!! */

/* Then you setup per-message nonce and pass the length of the message */

int CRYPTO_ccm128_setiv(CCM128_CONTEXT *ctx,

                        const unsigned char *nonce, size_t nlen, size_t mlen)

{

    unsigned int L = ctx->nonce.c[0] & 7; /* the L parameter */

    if (nlen < (14 - L))

        return -1;              /* nonce is too short */

    if (sizeof(mlen) == 8 && L >= 3) {

        ctx->nonce.c[8] = (u8)(mlen >> (56 % (sizeof(mlen) * 8)));

        ctx->nonce.c[9] = (u8)(mlen >> (48 % (sizeof(mlen) * 8)));

        ctx->nonce.c[10] = (u8)(mlen >> (40 % (sizeof(mlen) * 8)));

        ctx->nonce.c[11] = (u8)(mlen >> (32 % (sizeof(mlen) * 8)));

    } else

        ctx->nonce.u[1] = 0;

    ctx->nonce.c[12] = (u8)(mlen >> 24);

    ctx->nonce.c[13] = (u8)(mlen >> 16);

    ctx->nonce.c[14] = (u8)(mlen >> 8);

    ctx->nonce.c[15] = (u8)mlen;

    ctx->nonce.c[0] &= ~0x40;   /* clear Adata flag */

    memcpy(&ctx->nonce.c[1], nonce, 14 - L);

    return 0;

}

/* Then you pass additional authentication data, this is optional */

void CRYPTO_ccm128_aad(CCM128_CONTEXT *ctx,

                       const unsigned char *aad, size_t alen)

{

    unsigned int i;

    block128_f block = ctx->block;

    if (alen == 0)

        return;

    ctx->nonce.c[0] |= 0x40;    /* set Adata flag */

    (*block) (ctx->nonce.c, ctx->cmac.c, ctx->key), ctx->blocks++;

    if (alen < (0x10000 - 0x100)) {

        ctx->cmac.c[0] ^= (u8)(alen >> 8);

        ctx->cmac.c[1] ^= (u8)alen;

        i = 2;

    } else if (sizeof(alen) == 8

               && alen >= (size_t)1 << (32 % (sizeof(alen) * 8))) {

        ctx->cmac.c[0] ^= 0xFF;

        ctx->cmac.c[1] ^= 0xFF;

        ctx->cmac.c[2] ^= (u8)(alen >> (56 % (sizeof(alen) * 8)));

        ctx->cmac.c[3] ^= (u8)(alen >> (48 % (sizeof(alen) * 8)));

        ctx->cmac.c[4] ^= (u8)(alen >> (40 % (sizeof(alen) * 8)));

        ctx->cmac.c[5] ^= (u8)(alen >> (32 % (sizeof(alen) * 8)));

        ctx->cmac.c[6] ^= (u8)(alen >> 24);

        ctx->cmac.c[7] ^= (u8)(alen >> 16);

        ctx->cmac.c[8] ^= (u8)(alen >> 8);

        ctx->cmac.c[9] ^= (u8)alen;

        i = 10;

    } else {

        ctx->cmac.c[0] ^= 0xFF;

        ctx->cmac.c[1] ^= 0xFE;

        ctx->cmac.c[2] ^= (u8)(alen >> 24);

        ctx->cmac.c[3] ^= (u8)(alen >> 16);

        ctx->cmac.c[4] ^= (u8)(alen >> 8);

        ctx->cmac.c[5] ^= (u8)alen;

        i = 6;

    }

    do {

        for (; i < 16 && alen; ++i, ++aad, --alen)

            ctx->cmac.c[i] ^= *aad;

        (*block) (ctx->cmac.c, ctx->cmac.c, ctx->key), ctx->blocks++;

        i = 0;

    } while (alen);

}

/* Finally you encrypt or decrypt the message */

/*

 * counter part of nonce may not be larger than L*8 bits, L is not larger

 * than 8, therefore 64-bit counter...

 */

static void ctr64_inc(unsigned char *counter)

{

    unsigned int n = 8;

    u8 c;

    counter += 8;

    do {

        --n;

        c = counter[n];

        ++c;

        counter[n] = c;

        if (c)

            return;

    } while (n);

}

int CRYPTO_ccm128_encrypt(CCM128_CONTEXT *ctx,

                          const unsigned char *inp, unsigned char *out,

                          size_t len)

{

    size_t n;

    unsigned int i, L;

    unsigned char flags0 = ctx->nonce.c[0];

    block128_f block = ctx->block;

    void *key = ctx->key;

    union {

        u64 u[2];

        u8 c[16];

    } scratch;

    if (!(flags0 & 0x40))

        (*block) (ctx->nonce.c, ctx->cmac.c, key), ctx->blocks++;

    ctx->nonce.c[0] = L = flags0 & 7;

    for (n = 0, i = 15 - L; i < 15; ++i) {

        n |= ctx->nonce.c[i];

        ctx->nonce.c[i] = 0;

        n <<= 8;

    }

    n |= ctx->nonce.c[15];      /* reconstructed length */

    ctx->nonce.c[15] = 1;

    if (n != len)

        return -1;              /* length mismatch */

    ctx->blocks += ((len + 15) >> 3) | 1;

    if (ctx->blocks > (U64(1) << 61))

        return -2;              /* too much data */

    while (len >= 16) {

#if defined(STRICT_ALIGNMENT)

        union {

            u64 u[2];

            u8 c[16];

        } temp;

        memcpy(temp.c, inp, 16);

        ctx->cmac.u[0] ^= temp.u[0];

        ctx->cmac.u[1] ^= temp.u[1];

#else

        ctx->cmac.u[0] ^= ((u64 *)inp)[0];

        ctx->cmac.u[1] ^= ((u64 *)inp)[1];

#endif

        (*block) (ctx->cmac.c, ctx->cmac.c, key);

        (*block) (ctx->nonce.c, scratch.c, key);

        ctr64_inc(ctx->nonce.c);

#if defined(STRICT_ALIGNMENT)

        temp.u[0] ^= scratch.u[0];

        temp.u[1] ^= scratch.u[1];

        memcpy(out, temp.c, 16);

#else

        ((u64 *)out)[0] = scratch.u[0] ^ ((u64 *)inp)[0];

        ((u64 *)out)[1] = scratch.u[1] ^ ((u64 *)inp)[1];

#endif

        inp += 16;

        out += 16;

        len -= 16;

    }

    if (len) {

        for (i = 0; i < len; ++i)

            ctx->cmac.c[i] ^= inp[i];

        (*block) (ctx->cmac.c, ctx->cmac.c, key);

        (*block) (ctx->nonce.c, scratch.c, key);

        for (i = 0; i < len; ++i)

            out[i] = scratch.c[i] ^ inp[i];

    }

    for (i = 15 - L; i < 16; ++i)

        ctx->nonce.c[i] = 0;

    (*block) (ctx->nonce.c, scratch.c, key);

    ctx->cmac.u[0] ^= scratch.u[0];

    ctx->cmac.u[1] ^= scratch.u[1];

    ctx->nonce.c[0] = flags0;

    return 0;

}

int CRYPTO_ccm128_decrypt(CCM128_CONTEXT *ctx,

                          const unsigned char *inp, unsigned char *out,

                          size_t len)

{

    size_t n;

    unsigned int i, L;

    unsigned char flags0 = ctx->nonce.c[0];

    block128_f block = ctx->block;

    void *key = ctx->key;

    union {

        u64 u[2];

        u8 c[16];

    } scratch;

    if (!(flags0 & 0x40))

        (*block) (ctx->nonce.c, ctx->cmac.c, key);

    ctx->nonce.c[0] = L = flags0 & 7;

    for (n = 0, i = 15 - L; i < 15; ++i) {

        n |= ctx->nonce.c[i];

        ctx->nonce.c[i] = 0;

        n <<= 8;

    }

    n |= ctx->nonce.c[15];      /* reconstructed length */

    ctx->nonce.c[15] = 1;

    if (n != len)

        return -1;

    while (len >= 16) {

#if defined(STRICT_ALIGNMENT)

        union {

            u64 u[2];

            u8 c[16];

        } temp;

#endif

        (*block) (ctx->nonce.c, scratch.c, key);

        ctr64_inc(ctx->nonce.c);

#if defined(STRICT_ALIGNMENT)

        memcpy(temp.c, inp, 16);

        ctx->cmac.u[0] ^= (scratch.u[0] ^= temp.u[0]);

        ctx->cmac.u[1] ^= (scratch.u[1] ^= temp.u[1]);

        memcpy(out, scratch.c, 16);

#else

        ctx->cmac.u[0] ^= (((u64 *)out)[0] = scratch.u[0] ^ ((u64 *)inp)[0]);

        ctx->cmac.u[1] ^= (((u64 *)out)[1] = scratch.u[1] ^ ((u64 *)inp)[1]);

#endif

        (*block) (ctx->cmac.c, ctx->cmac.c, key);

        inp += 16;

        out += 16;

        len -= 16;

    }

    if (len) {

        (*block) (ctx->nonce.c, scratch.c, key);

        for (i = 0; i < len; ++i)

            ctx->cmac.c[i] ^= (out[i] = scratch.c[i] ^ inp[i]);

        (*block) (ctx->cmac.c, ctx->cmac.c, key);

    }

    for (i = 15 - L; i < 16; ++i)

        ctx->nonce.c[i] = 0;

    (*block) (ctx->nonce.c, scratch.c, key);

    ctx->cmac.u[0] ^= scratch.u[0];

    ctx->cmac.u[1] ^= scratch.u[1];

    ctx->nonce.c[0] = flags0;

    return 0;

}

static void ctr64_add(unsigned char *counter, size_t inc)

{

    size_t n = 8, val = 0;

    counter += 8;

    do {

        --n;

        val += counter[n] + (inc & 0xff);

        counter[n] = (unsigned char)val;

        val >>= 8;              /* carry bit */

        inc >>= 8;

    } while (n && (inc || val));

}

int CRYPTO_ccm128_encrypt_ccm64(CCM128_CONTEXT *ctx,

                                const unsigned char *inp, unsigned char *out,

                                size_t len, ccm128_f stream)

{

    size_t n;

    unsigned int i, L;

    unsigned char flags0 = ctx->nonce.c[0];

    block128_f block = ctx->block;

    void *key = ctx->key;

    union {

        u64 u[2];

        u8 c[16];

    } scratch;

    if (!(flags0 & 0x40))

        (*block) (ctx->nonce.c, ctx->cmac.c, key), ctx->blocks++;

    ctx->nonce.c[0] = L = flags0 & 7;

    for (n = 0, i = 15 - L; i < 15; ++i) {

        n |= ctx->nonce.c[i];

        ctx->nonce.c[i] = 0;

        n <<= 8;

    }

    n |= ctx->nonce.c[15];      /* reconstructed length */

    ctx->nonce.c[15] = 1;

    if (n != len)

        return -1;              /* length mismatch */

    ctx->blocks += ((len + 15) >> 3) | 1;

    if (ctx->blocks > (U64(1) << 61))

        return -2;              /* too much data */

    if ((n = len / 16)) {

        (*stream) (inp, out, n, key, ctx->nonce.c, ctx->cmac.c);

        n *= 16;

        inp += n;

        out += n;

        len -= n;

        if (len)

            ctr64_add(ctx->nonce.c, n / 16);

    }

    if (len) {

        for (i = 0; i < len; ++i)

            ctx->cmac.c[i] ^= inp[i];

        (*block) (ctx->cmac.c, ctx->cmac.c, key);

        (*block) (ctx->nonce.c, scratch.c, key);

        for (i = 0; i < len; ++i)

            out[i] = scratch.c[i] ^ inp[i];

    }

    for (i = 15 - L; i < 16; ++i)

        ctx->nonce.c[i] = 0;

    (*block) (ctx->nonce.c, scratch.c, key);

    ctx->cmac.u[0] ^= scratch.u[0];

    ctx->cmac.u[1] ^= scratch.u[1];

    ctx->nonce.c[0] = flags0;

    return 0;

}

int CRYPTO_ccm128_decrypt_ccm64(CCM128_CONTEXT *ctx,

                                const unsigned char *inp, unsigned char *out,

                                size_t len, ccm128_f stream)

{

    size_t n;

    unsigned int i, L;

    unsigned char flags0 = ctx->nonce.c[0];

    block128_f block = ctx->block;

    void *key = ctx->key;

    union {

        u64 u[2];

        u8 c[16];

    } scratch;

    if (!(flags0 & 0x40))

        (*block) (ctx->nonce.c, ctx->cmac.c, key);

    ctx->nonce.c[0] = L = flags0 & 7;

    for (n = 0, i = 15 - L; i < 15; ++i) {

        n |= ctx->nonce.c[i];

        ctx->nonce.c[i] = 0;

        n <<= 8;

    }

    n |= ctx->nonce.c[15];      /* reconstructed length */

    ctx->nonce.c[15] = 1;

    if (n != len)

        return -1;

    if ((n = len / 16)) {

        (*stream) (inp, out, n, key, ctx->nonce.c, ctx->cmac.c);

        n *= 16;

        inp += n;

        out += n;

        len -= n;

        if (len)

            ctr64_add(ctx->nonce.c, n / 16);

    }

    if (len) {

        (*block) (ctx->nonce.c, scratch.c, key);

        for (i = 0; i < len; ++i)

            ctx->cmac.c[i] ^= (out[i] = scratch.c[i] ^ inp[i]);

        (*block) (ctx->cmac.c, ctx->cmac.c, key);

    }

    for (i = 15 - L; i < 16; ++i)

        ctx->nonce.c[i] = 0;

    (*block) (ctx->nonce.c, scratch.c, key);

    ctx->cmac.u[0] ^= scratch.u[0];

    ctx->cmac.u[1] ^= scratch.u[1];

    ctx->nonce.c[0] = flags0;

    return 0;

}

size_t CRYPTO_ccm128_tag(CCM128_CONTEXT *ctx, unsigned char *tag, size_t len)

{

    unsigned int M = (ctx->nonce.c[0] >> 3) & 7; /* the M parameter */

    M *= 2;

    M += 2;

    if (len != M)

        return 0;

    memcpy(tag, ctx->cmac.c, M);

    return M;

}