library/pkcs12.c - security/mbedtls - Rivoreo Source Code Repositories

 /*
  *  PKCS#12 Personal Information Exchange Syntax
  *
  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
  *  not use this file except in compliance with the License.
  *  You may obtain a copy of the License at
  *
  *  http://www.apache.org/licenses/LICENSE-2.0
  *
  *  Unless required by applicable law or agreed to in writing, software
  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  *
  *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 /*
  *  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
  */

 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else
 #include MBEDTLS_CONFIG_FILE
 #endif

 #if defined(MBEDTLS_PKCS12_C)

 #include "mbedtls/pkcs12.h"
 #include "mbedtls/asn1.h"
 #include "mbedtls/cipher.h"

 #include <string.h>

 #if defined(MBEDTLS_ARC4_C)
 #include "mbedtls/arc4.h"
 #endif

 #if defined(MBEDTLS_DES_C)
 #include "mbedtls/des.h"
 #endif

 /* Implementation that should never be optimized out by the compiler */
 static void mbedtls_zeroize( void *v, size_t n ) {
     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
 }

 #if defined(MBEDTLS_ASN1_PARSE_C)

 static int pkcs12_parse_pbe_params( mbedtls_asn1_buf *params,
                                     mbedtls_asn1_buf *salt, int *iterations )
 {
     int ret;
     unsigned char **p = &params->p;
     const unsigned char *end = params->p + params->len;

     /*
      *  pkcs-12PbeParams ::= SEQUENCE {
      *    salt          OCTET STRING,
      *    iterations    INTEGER
      *  }
      *
      */
     if( params->tag != ( MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) )
         return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT +
                 MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );

     if( ( ret = mbedtls_asn1_get_tag( p, end, &salt->len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
         return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT + ret );

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

     if( ( ret = mbedtls_asn1_get_int( p, end, iterations ) ) != 0 )
         return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT + ret );

     if( *p != end )
         return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT +
                 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );

     return( 0 );
 }

 #define PKCS12_MAX_PWDLEN 128

 static int pkcs12_pbe_derive_key_iv( mbedtls_asn1_buf *pbe_params, mbedtls_md_type_t md_type,
                                      const unsigned char *pwd,  size_t pwdlen,
                                      unsigned char *key, size_t keylen,
                                      unsigned char *iv,  size_t ivlen )
 {
     int ret, iterations = 0;
     mbedtls_asn1_buf salt;
     size_t i;
     unsigned char unipwd[PKCS12_MAX_PWDLEN * 2 + 2];

     if( pwdlen > PKCS12_MAX_PWDLEN )
         return( MBEDTLS_ERR_PKCS12_BAD_INPUT_DATA );

     memset( &salt, 0, sizeof(mbedtls_asn1_buf) );
     memset( &unipwd, 0, sizeof(unipwd) );

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

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

     if( ( ret = mbedtls_pkcs12_derivation( key, keylen, unipwd, pwdlen * 2 + 2,
                                    salt.p, salt.len, md_type,
                                    MBEDTLS_PKCS12_DERIVE_KEY, iterations ) ) != 0 )
     {
         return( ret );
     }

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

     if( ( ret = mbedtls_pkcs12_derivation( iv, ivlen, unipwd, pwdlen * 2 + 2,
                                    salt.p, salt.len, md_type,
                                    MBEDTLS_PKCS12_DERIVE_IV, iterations ) ) != 0 )
     {
         return( ret );
     }
     return( 0 );
 }

 #undef PKCS12_MAX_PWDLEN

 int mbedtls_pkcs12_pbe_sha1_rc4_128( mbedtls_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(MBEDTLS_ARC4_C)
     ((void) pbe_params);
     ((void) mode);
     ((void) pwd);
     ((void) pwdlen);
     ((void) data);
     ((void) len);
     ((void) output);
     return( MBEDTLS_ERR_PKCS12_FEATURE_UNAVAILABLE );
 #else
     int ret;
     unsigned char key[16];
     mbedtls_arc4_context ctx;
     ((void) mode);

     mbedtls_arc4_init( &ctx );

     if( ( ret = pkcs12_pbe_derive_key_iv( pbe_params, MBEDTLS_MD_SHA1,
                                           pwd, pwdlen,
                                           key, 16, NULL, 0 ) ) != 0 )
     {
         return( ret );
     }

     mbedtls_arc4_setup( &ctx, key, 16 );
     if( ( ret = mbedtls_arc4_crypt( &ctx, len, data, output ) ) != 0 )
         goto exit;

 exit:
     mbedtls_zeroize( key, sizeof( key ) );
     mbedtls_arc4_free( &ctx );

     return( ret );
 #endif /* MBEDTLS_ARC4_C */
 }

 int mbedtls_pkcs12_pbe( mbedtls_asn1_buf *pbe_params, int mode,
                 mbedtls_cipher_type_t cipher_type, mbedtls_md_type_t md_type,
                 const unsigned char *pwd,  size_t pwdlen,
                 const unsigned char *data, size_t len,
                 unsigned char *output )
 {
     int ret, keylen = 0;
     unsigned char key[32];
     unsigned char iv[16];
     const mbedtls_cipher_info_t *cipher_info;
     mbedtls_cipher_context_t cipher_ctx;
     size_t olen = 0;

     cipher_info = mbedtls_cipher_info_from_type( cipher_type );
     if( cipher_info == NULL )
         return( MBEDTLS_ERR_PKCS12_FEATURE_UNAVAILABLE );

     keylen = cipher_info->key_bitlen / 8;

     if( ( ret = pkcs12_pbe_derive_key_iv( pbe_params, md_type, pwd, pwdlen,
                                           key, keylen,
                                           iv, cipher_info->iv_size ) ) != 0 )
     {
         return( ret );
     }

     mbedtls_cipher_init( &cipher_ctx );

     if( ( ret = mbedtls_cipher_setup( &cipher_ctx, cipher_info ) ) != 0 )
         goto exit;

     if( ( ret = mbedtls_cipher_setkey( &cipher_ctx, key, 8 * keylen, (mbedtls_operation_t) mode ) ) != 0 )
         goto exit;

     if( ( ret = mbedtls_cipher_set_iv( &cipher_ctx, iv, cipher_info->iv_size ) ) != 0 )
         goto exit;

     if( ( ret = mbedtls_cipher_reset( &cipher_ctx ) ) != 0 )
         goto exit;

     if( ( ret = mbedtls_cipher_update( &cipher_ctx, data, len,
                                 output, &olen ) ) != 0 )
     {
         goto exit;
     }

     if( ( ret = mbedtls_cipher_finish( &cipher_ctx, output + olen, &olen ) ) != 0 )
         ret = MBEDTLS_ERR_PKCS12_PASSWORD_MISMATCH;

 exit:
     mbedtls_zeroize( key, sizeof( key ) );
     mbedtls_zeroize( iv,  sizeof( iv  ) );
     mbedtls_cipher_free( &cipher_ctx );

     return( ret );
 }

 #endif /* MBEDTLS_ASN1_PARSE_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 mbedtls_pkcs12_derivation( unsigned char *data, size_t datalen,
                        const unsigned char *pwd, size_t pwdlen,
                        const unsigned char *salt, size_t saltlen,
                        mbedtls_md_type_t md_type, int id, int iterations )
 {
     int ret;
     unsigned int j;

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

     size_t hlen, use_len, v, i;

     const mbedtls_md_info_t *md_info;
     mbedtls_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( MBEDTLS_ERR_PKCS12_BAD_INPUT_DATA );

     md_info = mbedtls_md_info_from_type( md_type );
     if( md_info == NULL )
         return( MBEDTLS_ERR_PKCS12_FEATURE_UNAVAILABLE );

     mbedtls_md_init( &md_ctx );

     if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
         return( ret );
     hlen = mbedtls_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 = mbedtls_md_starts( &md_ctx ) ) != 0 )
             goto exit;

         if( ( ret = mbedtls_md_update( &md_ctx, diversifier, v ) ) != 0 )
             goto exit;

         if( ( ret = mbedtls_md_update( &md_ctx, salt_block, v ) ) != 0 )
             goto exit;

         if( ( ret = mbedtls_md_update( &md_ctx, pwd_block, v ) ) != 0 )
             goto exit;

         if( ( ret = mbedtls_md_finish( &md_ctx, hash_output ) ) != 0 )
             goto exit;

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

         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;
         }
     }

     ret = 0;

 exit:
     mbedtls_zeroize( salt_block, sizeof( salt_block ) );
     mbedtls_zeroize( pwd_block, sizeof( pwd_block ) );
     mbedtls_zeroize( hash_block, sizeof( hash_block ) );
     mbedtls_zeroize( hash_output, sizeof( hash_output ) );

     mbedtls_md_free( &md_ctx );

     return( ret );
 }

 #endif /* MBEDTLS_PKCS12_C */
	/*
	* PKCS#12 Personal Information Exchange Syntax
	*
	* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
	* SPDX-License-Identifier: Apache-2.0
	*
	* Licensed under the Apache License, Version 2.0 (the "License"); you may
	* not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*
	* This file is part of mbed TLS (https://tls.mbed.org)
	*/
	/*
	* 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
	*/

	#if !defined(MBEDTLS_CONFIG_FILE)
	#include "mbedtls/config.h"
	#else
	#include MBEDTLS_CONFIG_FILE
	#endif

	#if defined(MBEDTLS_PKCS12_C)

	#include "mbedtls/pkcs12.h"
	#include "mbedtls/asn1.h"
	#include "mbedtls/cipher.h"

	#include <string.h>

	#if defined(MBEDTLS_ARC4_C)
	#include "mbedtls/arc4.h"
	#endif

	#if defined(MBEDTLS_DES_C)
	#include "mbedtls/des.h"
	#endif

	/* Implementation that should never be optimized out by the compiler */
	static void mbedtls_zeroize( void *v, size_t n ) {
	volatile unsigned char p = v; while( n-- ) p++ = 0;
	}

	#if defined(MBEDTLS_ASN1_PARSE_C)

	static int pkcs12_parse_pbe_params( mbedtls_asn1_buf *params,
	mbedtls_asn1_buf salt, int iterations )
	{
	int ret;
	unsigned char **p = &params->p;
	const unsigned char *end = params->p + params->len;

	/*
	* pkcs-12PbeParams ::= SEQUENCE {
	* salt OCTET STRING,
	* iterations INTEGER
	* }
	*
	*/
	if( params->tag != ( MBEDTLS_ASN1_CONSTRUCTED \| MBEDTLS_ASN1_SEQUENCE ) )
	return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT +
	MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );

	if( ( ret = mbedtls_asn1_get_tag( p, end, &salt->len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
	return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT + ret );

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

	if( ( ret = mbedtls_asn1_get_int( p, end, iterations ) ) != 0 )
	return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT + ret );

	if( *p != end )
	return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT +
	MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );

	return( 0 );
	}

	#define PKCS12_MAX_PWDLEN 128

	static int pkcs12_pbe_derive_key_iv( mbedtls_asn1_buf *pbe_params, mbedtls_md_type_t md_type,
	const unsigned char *pwd, size_t pwdlen,
	unsigned char *key, size_t keylen,
	unsigned char *iv, size_t ivlen )
	{
	int ret, iterations = 0;
	mbedtls_asn1_buf salt;
	size_t i;
	unsigned char unipwd[PKCS12_MAX_PWDLEN * 2 + 2];

	if( pwdlen > PKCS12_MAX_PWDLEN )
	return( MBEDTLS_ERR_PKCS12_BAD_INPUT_DATA );

	memset( &salt, 0, sizeof(mbedtls_asn1_buf) );
	memset( &unipwd, 0, sizeof(unipwd) );

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

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

	if( ( ret = mbedtls_pkcs12_derivation( key, keylen, unipwd, pwdlen * 2 + 2,
	salt.p, salt.len, md_type,
	MBEDTLS_PKCS12_DERIVE_KEY, iterations ) ) != 0 )
	{
	return( ret );
	}

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

	if( ( ret = mbedtls_pkcs12_derivation( iv, ivlen, unipwd, pwdlen * 2 + 2,
	salt.p, salt.len, md_type,
	MBEDTLS_PKCS12_DERIVE_IV, iterations ) ) != 0 )
	{
	return( ret );
	}
	return( 0 );
	}

	#undef PKCS12_MAX_PWDLEN

	int mbedtls_pkcs12_pbe_sha1_rc4_128( mbedtls_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(MBEDTLS_ARC4_C)
	((void) pbe_params);
	((void) mode);
	((void) pwd);
	((void) pwdlen);
	((void) data);
	((void) len);
	((void) output);
	return( MBEDTLS_ERR_PKCS12_FEATURE_UNAVAILABLE );
	#else
	int ret;
	unsigned char key[16];
	mbedtls_arc4_context ctx;
	((void) mode);

	mbedtls_arc4_init( &ctx );

	if( ( ret = pkcs12_pbe_derive_key_iv( pbe_params, MBEDTLS_MD_SHA1,
	pwd, pwdlen,
	key, 16, NULL, 0 ) ) != 0 )
	{
	return( ret );
	}

	mbedtls_arc4_setup( &ctx, key, 16 );
	if( ( ret = mbedtls_arc4_crypt( &ctx, len, data, output ) ) != 0 )
	goto exit;

	exit:
	mbedtls_zeroize( key, sizeof( key ) );
	mbedtls_arc4_free( &ctx );

	return( ret );
	#endif /* MBEDTLS_ARC4_C */
	}

	int mbedtls_pkcs12_pbe( mbedtls_asn1_buf *pbe_params, int mode,
	mbedtls_cipher_type_t cipher_type, mbedtls_md_type_t md_type,
	const unsigned char *pwd, size_t pwdlen,
	const unsigned char *data, size_t len,
	unsigned char *output )
	{
	int ret, keylen = 0;
	unsigned char key[32];
	unsigned char iv[16];
	const mbedtls_cipher_info_t *cipher_info;
	mbedtls_cipher_context_t cipher_ctx;
	size_t olen = 0;

	cipher_info = mbedtls_cipher_info_from_type( cipher_type );
	if( cipher_info == NULL )
	return( MBEDTLS_ERR_PKCS12_FEATURE_UNAVAILABLE );

	keylen = cipher_info->key_bitlen / 8;

	if( ( ret = pkcs12_pbe_derive_key_iv( pbe_params, md_type, pwd, pwdlen,
	key, keylen,
	iv, cipher_info->iv_size ) ) != 0 )
	{
	return( ret );
	}

	mbedtls_cipher_init( &cipher_ctx );

	if( ( ret = mbedtls_cipher_setup( &cipher_ctx, cipher_info ) ) != 0 )
	goto exit;

	if( ( ret = mbedtls_cipher_setkey( &cipher_ctx, key, 8 * keylen, (mbedtls_operation_t) mode ) ) != 0 )
	goto exit;

	if( ( ret = mbedtls_cipher_set_iv( &cipher_ctx, iv, cipher_info->iv_size ) ) != 0 )
	goto exit;

	if( ( ret = mbedtls_cipher_reset( &cipher_ctx ) ) != 0 )
	goto exit;

	if( ( ret = mbedtls_cipher_update( &cipher_ctx, data, len,
	output, &olen ) ) != 0 )
	{
	goto exit;
	}

	if( ( ret = mbedtls_cipher_finish( &cipher_ctx, output + olen, &olen ) ) != 0 )
	ret = MBEDTLS_ERR_PKCS12_PASSWORD_MISMATCH;

	exit:
	mbedtls_zeroize( key, sizeof( key ) );
	mbedtls_zeroize( iv, sizeof( iv ) );
	mbedtls_cipher_free( &cipher_ctx );

	return( ret );
	}

	#endif /* MBEDTLS_ASN1_PARSE_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 mbedtls_pkcs12_derivation( unsigned char *data, size_t datalen,
	const unsigned char *pwd, size_t pwdlen,
	const unsigned char *salt, size_t saltlen,
	mbedtls_md_type_t md_type, int id, int iterations )
	{
	int ret;
	unsigned int j;

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

	size_t hlen, use_len, v, i;

	const mbedtls_md_info_t *md_info;
	mbedtls_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( MBEDTLS_ERR_PKCS12_BAD_INPUT_DATA );

	md_info = mbedtls_md_info_from_type( md_type );
	if( md_info == NULL )
	return( MBEDTLS_ERR_PKCS12_FEATURE_UNAVAILABLE );

	mbedtls_md_init( &md_ctx );

	if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
	return( ret );
	hlen = mbedtls_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 = mbedtls_md_starts( &md_ctx ) ) != 0 )
	goto exit;

	if( ( ret = mbedtls_md_update( &md_ctx, diversifier, v ) ) != 0 )
	goto exit;

	if( ( ret = mbedtls_md_update( &md_ctx, salt_block, v ) ) != 0 )
	goto exit;

	if( ( ret = mbedtls_md_update( &md_ctx, pwd_block, v ) ) != 0 )
	goto exit;

	if( ( ret = mbedtls_md_finish( &md_ctx, hash_output ) ) != 0 )
	goto exit;

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

	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;
	}
	}

	ret = 0;

	exit:
	mbedtls_zeroize( salt_block, sizeof( salt_block ) );
	mbedtls_zeroize( pwd_block, sizeof( pwd_block ) );
	mbedtls_zeroize( hash_block, sizeof( hash_block ) );
	mbedtls_zeroize( hash_output, sizeof( hash_output ) );

	mbedtls_md_free( &md_ctx );

	return( ret );
	}

	#endif /* MBEDTLS_PKCS12_C */