ccm128.c

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/* ====================================================================
 * Copyright (c) 2011 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
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 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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 *    [email protected].
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 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
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 */

#include <openssl/crypto.h>
#include "modes_lcl.h"
#include <string.h>

#ifndef MODES_DEBUG
# ifndef NDEBUG
#  define NDEBUG
# endif
#endif
#include <assert.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
        *(u32*)(&ctx->nonce.c[8]) = 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;
}