/*
 *  PKCS#12 Personal Information Exchange Syntax
 *
 *  Copyright (C) 2006-2013, Brainspark B.V.
 *
 *  This file is part of PolarSSL (http://www.polarssl.org)
 *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
 *
 *  All rights reserved.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
/*
 *  The PKCS #12 Personal Information Exchange Syntax Standard v1.1
 *
 *  http://www.rsa.com/rsalabs/pkcs/files/h11301-wp-pkcs-12v1-1-personal-information-exchange-syntax.pdf
 *  ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-12/pkcs-12v1-1.asn
 */

#include "polarssl/config.h"

#if defined(POLARSSL_PKCS12_C)

#include "polarssl/pkcs12.h"
#include "polarssl/asn1.h"

#if defined(POLARSSL_ARC4_C)
#include "polarssl/arc4.h"
#endif

#if defined(POLARSSL_DES_C)
#include "polarssl/des.h"
#endif

static int pkcs12_parse_pbe_params( unsigned char **p,
                                    const unsigned char *end,
                                    asn1_buf *salt, int *iterations )
{
    int ret;
    size_t len = 0;

    /*
     *  pkcs-12PbeParams ::= SEQUENCE {
     *    salt          OCTET STRING,
     *    iterations    INTEGER
     *  }
     *
     */
    if( ( ret = asn1_get_tag( p, end, &len,
            ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
    {
        return( POLARSSL_ERR_PKCS12_PBE_INVALID_FORMAT + ret );
    }

    end = *p + len;

    if( ( ret = asn1_get_tag( p, end, &salt->len, ASN1_OCTET_STRING ) ) != 0 )
        return( POLARSSL_ERR_PKCS12_PBE_INVALID_FORMAT + ret );

    salt->p = *p;
    *p += salt->len;

    if( ( ret = asn1_get_int( p, end, iterations ) ) != 0 )
        return( POLARSSL_ERR_PKCS12_PBE_INVALID_FORMAT + ret );

    if( *p != end )
        return( POLARSSL_ERR_PKCS12_PBE_INVALID_FORMAT +
                POLARSSL_ERR_ASN1_LENGTH_MISMATCH );

    return( 0 );
}

static int pkcs12_pbe_derive_key_iv( asn1_buf *pbe_params,
                                     const unsigned char *pwd,  size_t pwdlen,
                                     unsigned char *key, size_t keylen,
                                     unsigned char *iv,  size_t ivlen )
{
    int ret, iterations;
    asn1_buf salt;
    size_t i;
    unsigned char *p, *end;
    unsigned char unipwd[258];

    memset(&salt, 0, sizeof(asn1_buf));
    memset(&unipwd, 0, sizeof(unipwd));

    p = pbe_params->p;
    end = p + pbe_params->len;

    if( ( ret = pkcs12_parse_pbe_params( &p, end, &salt, &iterations ) ) != 0 )
        return( ret );

    for(i = 0; i < pwdlen; i++)
        unipwd[i * 2 + 1] = pwd[i];

    if( ( ret = pkcs12_derivation( key, keylen, unipwd, pwdlen * 2 + 2,
                                   salt.p, salt.len, POLARSSL_MD_SHA1,
                                   PKCS12_DERIVE_KEY, iterations ) ) != 0 )
    {
        return( ret );
    }

    if( iv == NULL || ivlen == 0 )
        return( 0 );

    if( ( ret = pkcs12_derivation( iv, ivlen, unipwd, pwdlen * 2 + 2,
                                   salt.p, salt.len, POLARSSL_MD_SHA1,
                                   PKCS12_DERIVE_IV, iterations ) ) != 0 )
    {
        return( ret );
    }
    return( 0 );
}

int pkcs12_pbe_sha1_rc4_128( asn1_buf *pbe_params, int mode,
                             const unsigned char *pwd,  size_t pwdlen,
                             const unsigned char *data, size_t len,
                             unsigned char *output )
{
#if !defined(POLARSSL_ARC4_C)
    ((void) pbe_params);
    ((void) mode);
    ((void) pwd);
    ((void) pwdlen);
    ((void) data);
    ((void) len);
    ((void) output);
    return( POLARSSL_ERR_PKCS12_FEATURE_UNAVAILABLE );
#else
    int ret;
    unsigned char key[16];
    arc4_context ctx;
    ((void) mode);

    if( ( ret = pkcs12_pbe_derive_key_iv( pbe_params, pwd, pwdlen,
                                          key, 16, NULL, 0 ) ) != 0 )
    {
        return( ret );
    }

    arc4_setup( &ctx, key, 16 );
    if( ( ret = arc4_crypt( &ctx, len, data, output ) ) != 0 )
        return( ret );

    return( 0 );
}
#endif /* POLARSSL_ARC4_C */

int pkcs12_pbe_sha1_des2_ede_cbc( asn1_buf *pbe_params, int mode,
                                  const unsigned char *pwd,  size_t pwdlen,
                                  const unsigned char *data, size_t len,
                                  unsigned char *output )
{
#if !defined(POLARSSL_DES_C)
    ((void) pbe_params);
    ((void) mode);
    ((void) pwd);
    ((void) pwdlen);
    ((void) data);
    ((void) len);
    ((void) output);
    return( POLARSSL_ERR_PKCS12_FEATURE_UNAVAILABLE );
#else
    int ret;
    unsigned char key[16];
    unsigned char iv[8];
    des3_context ctx;

    if( ( ret = pkcs12_pbe_derive_key_iv( pbe_params, pwd, pwdlen,
                                          key, 16, iv, 8 ) ) != 0 )
    {
        return( ret );
    }

    if( mode == PKCS12_PBE_ENCRYPT )
    {
        des3_set2key_enc( &ctx, key );
        des3_crypt_cbc( &ctx, DES_ENCRYPT, len, iv, data, output );
    }
    else
    {
        des3_set2key_dec( &ctx, key );
        des3_crypt_cbc( &ctx, DES_DECRYPT, len, iv, data, output );
    }

    return( 0 );
}
#endif /* POLARSSL_DES_C */

int pkcs12_pbe_sha1_des3_ede_cbc( asn1_buf *pbe_params, int mode,
                                  const unsigned char *pwd,  size_t pwdlen,
                                  const unsigned char *data, size_t len,
                                  unsigned char *output )
{
#if !defined(POLARSSL_DES_C)
    ((void) pbe_params);
    ((void) mode);
    ((void) pwd);
    ((void) pwdlen);
    ((void) data);
    ((void) len);
    ((void) output);
    return( POLARSSL_ERR_PKCS12_FEATURE_UNAVAILABLE );
#else
    int ret;
    unsigned char key[24];
    unsigned char iv[8];
    des3_context ctx;

    if( ( ret = pkcs12_pbe_derive_key_iv( pbe_params, pwd, pwdlen,
                                          key, 24, iv, 8 ) ) != 0 )
    {
        return( ret );
    }

    if( mode == PKCS12_PBE_ENCRYPT )
    {
        des3_set3key_enc( &ctx, key );
        des3_crypt_cbc( &ctx, DES_ENCRYPT, len, iv, data, output );
    }
    else
    {
        des3_set3key_dec( &ctx, key );
        des3_crypt_cbc( &ctx, DES_DECRYPT, len, iv, data, output );
    }

    return( 0 );
}
#endif /* POLARSSL_DES_C */

static void pkcs12_fill_buffer( unsigned char *data, size_t data_len,
                                const unsigned char *filler, size_t fill_len )
{
    unsigned char *p = data;
    size_t use_len;

    while( data_len > 0 )
    {
        use_len = ( data_len > fill_len ) ? fill_len : data_len;
        memcpy( p, filler, use_len );
        p += use_len;
        data_len -= use_len;
    }
}

int pkcs12_derivation( unsigned char *data, size_t datalen,
                       const unsigned char *pwd, size_t pwdlen,
                       const unsigned char *salt, size_t saltlen,
                       md_type_t md_type, int id, int iterations )
{
    int ret, i;
    unsigned int j;

    unsigned char diversifier[128];
    unsigned char salt_block[128], pwd_block[128], hash_block[128];
    unsigned char hash_output[POLARSSL_MD_MAX_SIZE];
    unsigned char *p;
    unsigned char c;

    size_t hlen, use_len, v;

    const md_info_t *md_info;
    md_context_t md_ctx;

    // This version only allows max of 64 bytes of password or salt
    if( datalen > 128 || pwdlen > 64 || saltlen > 64 )
        return( POLARSSL_ERR_PKCS12_BAD_INPUT_DATA );

    md_info = md_info_from_type( md_type );
    if( md_info == NULL )
        return( POLARSSL_ERR_PKCS12_FEATURE_UNAVAILABLE );

    if ( ( ret = md_init_ctx( &md_ctx, md_info ) ) != 0 )
        return( ret );
    hlen = md_get_size( md_info );

    if( hlen <= 32 )
        v = 64;
    else
        v = 128;

    memset( diversifier, (unsigned char) id, v );

    pkcs12_fill_buffer( salt_block, v, salt, saltlen );
    pkcs12_fill_buffer( pwd_block,  v, pwd,  pwdlen  );

    p = data;
    while( datalen > 0 )
    {
        // Calculate hash( diversifier || salt_block || pwd_block )
        if( ( ret = md_starts( &md_ctx ) ) != 0 )
            return( ret );

        if( ( ret = md_update( &md_ctx, diversifier, v ) ) != 0 )
            return( ret );

        if( ( ret = md_update( &md_ctx, salt_block, v ) ) != 0 )
            return( ret );

        if( ( ret = md_update( &md_ctx, pwd_block, v ) ) != 0 )
            return( ret );

        if( ( ret = md_finish( &md_ctx, hash_output ) ) != 0 )
            return( ret );

        // Perform remaining ( iterations - 1 ) recursive hash calculations
        for( i = 1; i < iterations; i++ )
        {
            if( ( ret = md( md_info, hash_output, hlen, hash_output ) ) != 0 )
                return( ret );
        }

        use_len = ( datalen > hlen ) ? hlen : datalen;
        memcpy( p, hash_output, use_len );
        datalen -= use_len;
        p += use_len;

        if( datalen == 0 )
            break;

        // Concatenating copies of hash_output into hash_block (B)
        pkcs12_fill_buffer( hash_block, v, hash_output, hlen );

        // B += 1
        for( i = v; i > 0; i-- )
            if( ++hash_block[i - 1] != 0 )
                break;

        // salt_block += B
        c = 0;
        for( i = v; i > 0; i-- )
        {
            j = salt_block[i - 1] + hash_block[i - 1] + c;
            c = (unsigned char) (j >> 8);
            salt_block[i - 1] = j & 0xFF;
        }

        // pwd_block  += B
        c = 0;
        for( i = v; i > 0; i-- )
        {
            j = pwd_block[i - 1] + hash_block[i - 1] + c;
            c = (unsigned char) (j >> 8);
            pwd_block[i - 1] = j & 0xFF;
        }
    }

    return( 0 );
}

#endif /* POLARSSL_PKCS12_C */