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

 /*
  *  Privacy Enhanced Mail (PEM) decoding
  *
  *  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)
  */

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

 #if defined(MBEDTLS_PEM_PARSE_C) || defined(MBEDTLS_PEM_WRITE_C)

 #include "mbedtls/pem.h"
 #include "mbedtls/base64.h"
 #include "mbedtls/des.h"
 #include "mbedtls/aes.h"
 #include "mbedtls/md5.h"
 #include "mbedtls/cipher.h"

 #include <string.h>

 #if defined(MBEDTLS_PLATFORM_C)
 #include "mbedtls/platform.h"
 #else
 #include <stdlib.h>
 #define mbedtls_calloc    calloc
 #define mbedtls_free       free
 #endif

 #if defined(MBEDTLS_PEM_PARSE_C)
 /* 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;
 }

 void mbedtls_pem_init( mbedtls_pem_context *ctx )
 {
     memset( ctx, 0, sizeof( mbedtls_pem_context ) );
 }

 #if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) &&         \
     ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
 /*
  * Read a 16-byte hex string and convert it to binary
  */
 static int pem_get_iv( const unsigned char *s, unsigned char *iv,
                        size_t iv_len )
 {
     size_t i, j, k;

     memset( iv, 0, iv_len );

     for( i = 0; i < iv_len * 2; i++, s++ )
     {
         if( *s >= '0' && *s <= '9' ) j = *s - '0'; else
         if( *s >= 'A' && *s <= 'F' ) j = *s - '7'; else
         if( *s >= 'a' && *s <= 'f' ) j = *s - 'W'; else
             return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );

         k = ( ( i & 1 ) != 0 ) ? j : j << 4;

         iv[i >> 1] = (unsigned char)( iv[i >> 1] | k );
     }

     return( 0 );
 }

 static void pem_pbkdf1( unsigned char *key, size_t keylen,
                         unsigned char *iv,
                         const unsigned char *pwd, size_t pwdlen )
 {
     mbedtls_md5_context md5_ctx;
     unsigned char md5sum[16];
     size_t use_len;

     mbedtls_md5_init( &md5_ctx );

     /*
      * key[ 0..15] = MD5(pwd || IV)
      */
     mbedtls_md5_starts( &md5_ctx );
     mbedtls_md5_update( &md5_ctx, pwd, pwdlen );
     mbedtls_md5_update( &md5_ctx, iv,  8 );
     mbedtls_md5_finish( &md5_ctx, md5sum );

     if( keylen <= 16 )
     {
         memcpy( key, md5sum, keylen );

         mbedtls_md5_free( &md5_ctx );
         mbedtls_zeroize( md5sum, 16 );
         return;
     }

     memcpy( key, md5sum, 16 );

     /*
      * key[16..23] = MD5(key[ 0..15] || pwd || IV])
      */
     mbedtls_md5_starts( &md5_ctx );
     mbedtls_md5_update( &md5_ctx, md5sum,  16 );
     mbedtls_md5_update( &md5_ctx, pwd, pwdlen );
     mbedtls_md5_update( &md5_ctx, iv,  8 );
     mbedtls_md5_finish( &md5_ctx, md5sum );

     use_len = 16;
     if( keylen < 32 )
         use_len = keylen - 16;

     memcpy( key + 16, md5sum, use_len );

     mbedtls_md5_free( &md5_ctx );
     mbedtls_zeroize( md5sum, 16 );
 }

 #if defined(MBEDTLS_DES_C)
 /*
  * Decrypt with DES-CBC, using PBKDF1 for key derivation
  */
 static void pem_des_decrypt( unsigned char des_iv[8],
                                unsigned char *buf, size_t buflen,
                                const unsigned char *pwd, size_t pwdlen )
 {
     mbedtls_des_context des_ctx;
     unsigned char des_key[8];

     mbedtls_des_init( &des_ctx );

     pem_pbkdf1( des_key, 8, des_iv, pwd, pwdlen );

     mbedtls_des_setkey_dec( &des_ctx, des_key );
     mbedtls_des_crypt_cbc( &des_ctx, MBEDTLS_DES_DECRYPT, buflen,
                      des_iv, buf, buf );

     mbedtls_des_free( &des_ctx );
     mbedtls_zeroize( des_key, 8 );
 }

 /*
  * Decrypt with 3DES-CBC, using PBKDF1 for key derivation
  */
 static void pem_des3_decrypt( unsigned char des3_iv[8],
                                unsigned char *buf, size_t buflen,
                                const unsigned char *pwd, size_t pwdlen )
 {
     mbedtls_des3_context des3_ctx;
     unsigned char des3_key[24];

     mbedtls_des3_init( &des3_ctx );

     pem_pbkdf1( des3_key, 24, des3_iv, pwd, pwdlen );

     mbedtls_des3_set3key_dec( &des3_ctx, des3_key );
     mbedtls_des3_crypt_cbc( &des3_ctx, MBEDTLS_DES_DECRYPT, buflen,
                      des3_iv, buf, buf );

     mbedtls_des3_free( &des3_ctx );
     mbedtls_zeroize( des3_key, 24 );
 }
 #endif /* MBEDTLS_DES_C */

 #if defined(MBEDTLS_AES_C)
 /*
  * Decrypt with AES-XXX-CBC, using PBKDF1 for key derivation
  */
 static void pem_aes_decrypt( unsigned char aes_iv[16], unsigned int keylen,
                                unsigned char *buf, size_t buflen,
                                const unsigned char *pwd, size_t pwdlen )
 {
     mbedtls_aes_context aes_ctx;
     unsigned char aes_key[32];

     mbedtls_aes_init( &aes_ctx );

     pem_pbkdf1( aes_key, keylen, aes_iv, pwd, pwdlen );

     mbedtls_aes_setkey_dec( &aes_ctx, aes_key, keylen * 8 );
     mbedtls_aes_crypt_cbc( &aes_ctx, MBEDTLS_AES_DECRYPT, buflen,
                      aes_iv, buf, buf );

     mbedtls_aes_free( &aes_ctx );
     mbedtls_zeroize( aes_key, keylen );
 }
 #endif /* MBEDTLS_AES_C */

 #endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
           ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */

 int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const char *footer,
                      const unsigned char *data, const unsigned char *pwd,
                      size_t pwdlen, size_t *use_len )
 {
     int ret, enc;
     size_t len;
     unsigned char *buf;
     const unsigned char *s1, *s2, *end;
 #if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) &&         \
     ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
     unsigned char pem_iv[16];
     mbedtls_cipher_type_t enc_alg = MBEDTLS_CIPHER_NONE;
 #else
     ((void) pwd);
     ((void) pwdlen);
 #endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
           ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */

     if( ctx == NULL )
         return( MBEDTLS_ERR_PEM_BAD_INPUT_DATA );

     s1 = (unsigned char *) strstr( (const char *) data, header );

     if( s1 == NULL )
         return( MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT );

     s2 = (unsigned char *) strstr( (const char *) data, footer );

     if( s2 == NULL || s2 <= s1 )
         return( MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT );

     s1 += strlen( header );
     if( *s1 == ' '  ) s1++;
     if( *s1 == '\r' ) s1++;
     if( *s1 == '\n' ) s1++;
     else return( MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT );

     end = s2;
     end += strlen( footer );
     if( *end == ' '  ) end++;
     if( *end == '\r' ) end++;
     if( *end == '\n' ) end++;
     *use_len = end - data;

     enc = 0;

     if( memcmp( s1, "Proc-Type: 4,ENCRYPTED", 22 ) == 0 )
     {
 #if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) &&         \
     ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
         enc++;

         s1 += 22;
         if( *s1 == '\r' ) s1++;
         if( *s1 == '\n' ) s1++;
         else return( MBEDTLS_ERR_PEM_INVALID_DATA );


 #if defined(MBEDTLS_DES_C)
         if( memcmp( s1, "DEK-Info: DES-EDE3-CBC,", 23 ) == 0 )
         {
             enc_alg = MBEDTLS_CIPHER_DES_EDE3_CBC;

             s1 += 23;
             if( pem_get_iv( s1, pem_iv, 8 ) != 0 )
                 return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );

             s1 += 16;
         }
         else if( memcmp( s1, "DEK-Info: DES-CBC,", 18 ) == 0 )
         {
             enc_alg = MBEDTLS_CIPHER_DES_CBC;

             s1 += 18;
             if( pem_get_iv( s1, pem_iv, 8) != 0 )
                 return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );

             s1 += 16;
         }
 #endif /* MBEDTLS_DES_C */

 #if defined(MBEDTLS_AES_C)
         if( memcmp( s1, "DEK-Info: AES-", 14 ) == 0 )
         {
             if( memcmp( s1, "DEK-Info: AES-128-CBC,", 22 ) == 0 )
                 enc_alg = MBEDTLS_CIPHER_AES_128_CBC;
             else if( memcmp( s1, "DEK-Info: AES-192-CBC,", 22 ) == 0 )
                 enc_alg = MBEDTLS_CIPHER_AES_192_CBC;
             else if( memcmp( s1, "DEK-Info: AES-256-CBC,", 22 ) == 0 )
                 enc_alg = MBEDTLS_CIPHER_AES_256_CBC;
             else
                 return( MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG );

             s1 += 22;
             if( pem_get_iv( s1, pem_iv, 16 ) != 0 )
                 return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );

             s1 += 32;
         }
 #endif /* MBEDTLS_AES_C */

         if( enc_alg == MBEDTLS_CIPHER_NONE )
             return( MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG );

         if( *s1 == '\r' ) s1++;
         if( *s1 == '\n' ) s1++;
         else return( MBEDTLS_ERR_PEM_INVALID_DATA );
 #else
         return( MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE );
 #endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
           ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
     }

     if( s1 == s2 )
         return( MBEDTLS_ERR_PEM_INVALID_DATA );

     ret = mbedtls_base64_decode( NULL, 0, &len, s1, s2 - s1 );

     if( ret == MBEDTLS_ERR_BASE64_INVALID_CHARACTER )
         return( MBEDTLS_ERR_PEM_INVALID_DATA + ret );

     if( ( buf = mbedtls_calloc( 1, len ) ) == NULL )
         return( MBEDTLS_ERR_PEM_ALLOC_FAILED );

     if( ( ret = mbedtls_base64_decode( buf, len, &len, s1, s2 - s1 ) ) != 0 )
     {
         mbedtls_free( buf );
         return( MBEDTLS_ERR_PEM_INVALID_DATA + ret );
     }

     if( enc != 0 )
     {
 #if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) &&         \
     ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
         if( pwd == NULL )
         {
             mbedtls_free( buf );
             return( MBEDTLS_ERR_PEM_PASSWORD_REQUIRED );
         }

 #if defined(MBEDTLS_DES_C)
         if( enc_alg == MBEDTLS_CIPHER_DES_EDE3_CBC )
             pem_des3_decrypt( pem_iv, buf, len, pwd, pwdlen );
         else if( enc_alg == MBEDTLS_CIPHER_DES_CBC )
             pem_des_decrypt( pem_iv, buf, len, pwd, pwdlen );
 #endif /* MBEDTLS_DES_C */

 #if defined(MBEDTLS_AES_C)
         if( enc_alg == MBEDTLS_CIPHER_AES_128_CBC )
             pem_aes_decrypt( pem_iv, 16, buf, len, pwd, pwdlen );
         else if( enc_alg == MBEDTLS_CIPHER_AES_192_CBC )
             pem_aes_decrypt( pem_iv, 24, buf, len, pwd, pwdlen );
         else if( enc_alg == MBEDTLS_CIPHER_AES_256_CBC )
             pem_aes_decrypt( pem_iv, 32, buf, len, pwd, pwdlen );
 #endif /* MBEDTLS_AES_C */

         /*
          * The result will be ASN.1 starting with a SEQUENCE tag, with 1 to 3
          * length bytes (allow 4 to be sure) in all known use cases.
          *
          * Use that as heurisitic to try detecting password mismatchs.
          */
         if( len <= 2 || buf[0] != 0x30 || buf[1] > 0x83 )
         {
             mbedtls_free( buf );
             return( MBEDTLS_ERR_PEM_PASSWORD_MISMATCH );
         }
 #else
         mbedtls_free( buf );
         return( MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE );
 #endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
           ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
     }

     ctx->buf = buf;
     ctx->buflen = len;

     return( 0 );
 }

 void mbedtls_pem_free( mbedtls_pem_context *ctx )
 {
     mbedtls_free( ctx->buf );
     mbedtls_free( ctx->info );

     mbedtls_zeroize( ctx, sizeof( mbedtls_pem_context ) );
 }
 #endif /* MBEDTLS_PEM_PARSE_C */

 #if defined(MBEDTLS_PEM_WRITE_C)
 int mbedtls_pem_write_buffer( const char *header, const char *footer,
                       const unsigned char *der_data, size_t der_len,
                       unsigned char *buf, size_t buf_len, size_t *olen )
 {
     int ret;
     unsigned char *encode_buf, *c, *p = buf;
     size_t len = 0, use_len, add_len = 0;

     mbedtls_base64_encode( NULL, 0, &use_len, der_data, der_len );
     add_len = strlen( header ) + strlen( footer ) + ( use_len / 64 ) + 1;

     if( use_len + add_len > buf_len )
     {
         *olen = use_len + add_len;
         return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
     }

     if( ( encode_buf = mbedtls_calloc( 1, use_len ) ) == NULL )
         return( MBEDTLS_ERR_PEM_ALLOC_FAILED );

     if( ( ret = mbedtls_base64_encode( encode_buf, use_len, &use_len, der_data,
                                der_len ) ) != 0 )
     {
         mbedtls_free( encode_buf );
         return( ret );
     }

     memcpy( p, header, strlen( header ) );
     p += strlen( header );
     c = encode_buf;

     while( use_len )
     {
         len = ( use_len > 64 ) ? 64 : use_len;
         memcpy( p, c, len );
         use_len -= len;
         p += len;
         c += len;
         *p++ = '\n';
     }

     memcpy( p, footer, strlen( footer ) );
     p += strlen( footer );

     *p++ = '\0';
     *olen = p - buf;

     mbedtls_free( encode_buf );
     return( 0 );
 }
 #endif /* MBEDTLS_PEM_WRITE_C */
 #endif /* MBEDTLS_PEM_PARSE_C || MBEDTLS_PEM_WRITE_C */
	/*
	* Privacy Enhanced Mail (PEM) decoding
	*
	* 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)
	*/

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

	#if defined(MBEDTLS_PEM_PARSE_C) \|\| defined(MBEDTLS_PEM_WRITE_C)

	#include "mbedtls/pem.h"
	#include "mbedtls/base64.h"
	#include "mbedtls/des.h"
	#include "mbedtls/aes.h"
	#include "mbedtls/md5.h"
	#include "mbedtls/cipher.h"

	#include <string.h>

	#if defined(MBEDTLS_PLATFORM_C)
	#include "mbedtls/platform.h"
	#else
	#include <stdlib.h>
	#define mbedtls_calloc calloc
	#define mbedtls_free free
	#endif

	#if defined(MBEDTLS_PEM_PARSE_C)
	/* 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;
	}

	void mbedtls_pem_init( mbedtls_pem_context *ctx )
	{
	memset( ctx, 0, sizeof( mbedtls_pem_context ) );
	}

	#if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) && \
	( defined(MBEDTLS_DES_C) \|\| defined(MBEDTLS_AES_C) )
	/*
	* Read a 16-byte hex string and convert it to binary
	*/
	static int pem_get_iv( const unsigned char s, unsigned char iv,
	size_t iv_len )
	{
	size_t i, j, k;

	memset( iv, 0, iv_len );

	for( i = 0; i < iv_len * 2; i++, s++ )
	{
	if( s >= '0' && s <= '9' ) j = *s - '0'; else
	if( s >= 'A' && s <= 'F' ) j = *s - '7'; else
	if( s >= 'a' && s <= 'f' ) j = *s - 'W'; else
	return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );

	k = ( ( i & 1 ) != 0 ) ? j : j << 4;

	iv[i >> 1] = (unsigned char)( iv[i >> 1] \| k );
	}

	return( 0 );
	}

	static void pem_pbkdf1( unsigned char *key, size_t keylen,
	unsigned char *iv,
	const unsigned char *pwd, size_t pwdlen )
	{
	mbedtls_md5_context md5_ctx;
	unsigned char md5sum[16];
	size_t use_len;

	mbedtls_md5_init( &md5_ctx );

	/*
	* key[ 0..15] = MD5(pwd \|\| IV)
	*/
	mbedtls_md5_starts( &md5_ctx );
	mbedtls_md5_update( &md5_ctx, pwd, pwdlen );
	mbedtls_md5_update( &md5_ctx, iv, 8 );
	mbedtls_md5_finish( &md5_ctx, md5sum );

	if( keylen <= 16 )
	{
	memcpy( key, md5sum, keylen );

	mbedtls_md5_free( &md5_ctx );
	mbedtls_zeroize( md5sum, 16 );
	return;
	}

	memcpy( key, md5sum, 16 );

	/*
	* key[16..23] = MD5(key[ 0..15] \|\| pwd \|\| IV])
	*/
	mbedtls_md5_starts( &md5_ctx );
	mbedtls_md5_update( &md5_ctx, md5sum, 16 );
	mbedtls_md5_update( &md5_ctx, pwd, pwdlen );
	mbedtls_md5_update( &md5_ctx, iv, 8 );
	mbedtls_md5_finish( &md5_ctx, md5sum );

	use_len = 16;
	if( keylen < 32 )
	use_len = keylen - 16;

	memcpy( key + 16, md5sum, use_len );

	mbedtls_md5_free( &md5_ctx );
	mbedtls_zeroize( md5sum, 16 );
	}

	#if defined(MBEDTLS_DES_C)
	/*
	* Decrypt with DES-CBC, using PBKDF1 for key derivation
	*/
	static void pem_des_decrypt( unsigned char des_iv[8],
	unsigned char *buf, size_t buflen,
	const unsigned char *pwd, size_t pwdlen )
	{
	mbedtls_des_context des_ctx;
	unsigned char des_key[8];

	mbedtls_des_init( &des_ctx );

	pem_pbkdf1( des_key, 8, des_iv, pwd, pwdlen );

	mbedtls_des_setkey_dec( &des_ctx, des_key );
	mbedtls_des_crypt_cbc( &des_ctx, MBEDTLS_DES_DECRYPT, buflen,
	des_iv, buf, buf );

	mbedtls_des_free( &des_ctx );
	mbedtls_zeroize( des_key, 8 );
	}

	/*
	* Decrypt with 3DES-CBC, using PBKDF1 for key derivation
	*/
	static void pem_des3_decrypt( unsigned char des3_iv[8],
	unsigned char *buf, size_t buflen,
	const unsigned char *pwd, size_t pwdlen )
	{
	mbedtls_des3_context des3_ctx;
	unsigned char des3_key[24];

	mbedtls_des3_init( &des3_ctx );

	pem_pbkdf1( des3_key, 24, des3_iv, pwd, pwdlen );

	mbedtls_des3_set3key_dec( &des3_ctx, des3_key );
	mbedtls_des3_crypt_cbc( &des3_ctx, MBEDTLS_DES_DECRYPT, buflen,
	des3_iv, buf, buf );

	mbedtls_des3_free( &des3_ctx );
	mbedtls_zeroize( des3_key, 24 );
	}
	#endif /* MBEDTLS_DES_C */

	#if defined(MBEDTLS_AES_C)
	/*
	* Decrypt with AES-XXX-CBC, using PBKDF1 for key derivation
	*/
	static void pem_aes_decrypt( unsigned char aes_iv[16], unsigned int keylen,
	unsigned char *buf, size_t buflen,
	const unsigned char *pwd, size_t pwdlen )
	{
	mbedtls_aes_context aes_ctx;
	unsigned char aes_key[32];

	mbedtls_aes_init( &aes_ctx );

	pem_pbkdf1( aes_key, keylen, aes_iv, pwd, pwdlen );

	mbedtls_aes_setkey_dec( &aes_ctx, aes_key, keylen * 8 );
	mbedtls_aes_crypt_cbc( &aes_ctx, MBEDTLS_AES_DECRYPT, buflen,
	aes_iv, buf, buf );

	mbedtls_aes_free( &aes_ctx );
	mbedtls_zeroize( aes_key, keylen );
	}
	#endif /* MBEDTLS_AES_C */

	#endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
	( MBEDTLS_AES_C \|\| MBEDTLS_DES_C ) */

	int mbedtls_pem_read_buffer( mbedtls_pem_context ctx, const char header, const char *footer,
	const unsigned char data, const unsigned char pwd,
	size_t pwdlen, size_t *use_len )
	{
	int ret, enc;
	size_t len;
	unsigned char *buf;
	const unsigned char s1, s2, *end;
	#if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) && \
	( defined(MBEDTLS_DES_C) \|\| defined(MBEDTLS_AES_C) )
	unsigned char pem_iv[16];
	mbedtls_cipher_type_t enc_alg = MBEDTLS_CIPHER_NONE;
	#else
	((void) pwd);
	((void) pwdlen);
	#endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
	( MBEDTLS_AES_C \|\| MBEDTLS_DES_C ) */

	if( ctx == NULL )
	return( MBEDTLS_ERR_PEM_BAD_INPUT_DATA );

	s1 = (unsigned char ) strstr( (const char ) data, header );

	if( s1 == NULL )
	return( MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT );

	s2 = (unsigned char ) strstr( (const char ) data, footer );

	if( s2 == NULL \|\| s2 <= s1 )
	return( MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT );

	s1 += strlen( header );
	if( *s1 == ' ' ) s1++;
	if( *s1 == '\r' ) s1++;
	if( *s1 == '\n' ) s1++;
	else return( MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT );

	end = s2;
	end += strlen( footer );
	if( *end == ' ' ) end++;
	if( *end == '\r' ) end++;
	if( *end == '\n' ) end++;
	*use_len = end - data;

	enc = 0;

	if( memcmp( s1, "Proc-Type: 4,ENCRYPTED", 22 ) == 0 )
	{
	#if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) && \
	( defined(MBEDTLS_DES_C) \|\| defined(MBEDTLS_AES_C) )
	enc++;

	s1 += 22;
	if( *s1 == '\r' ) s1++;
	if( *s1 == '\n' ) s1++;
	else return( MBEDTLS_ERR_PEM_INVALID_DATA );


	#if defined(MBEDTLS_DES_C)
	if( memcmp( s1, "DEK-Info: DES-EDE3-CBC,", 23 ) == 0 )
	{
	enc_alg = MBEDTLS_CIPHER_DES_EDE3_CBC;

	s1 += 23;
	if( pem_get_iv( s1, pem_iv, 8 ) != 0 )
	return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );

	s1 += 16;
	}
	else if( memcmp( s1, "DEK-Info: DES-CBC,", 18 ) == 0 )
	{
	enc_alg = MBEDTLS_CIPHER_DES_CBC;

	s1 += 18;
	if( pem_get_iv( s1, pem_iv, 8) != 0 )
	return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );

	s1 += 16;
	}
	#endif /* MBEDTLS_DES_C */

	#if defined(MBEDTLS_AES_C)
	if( memcmp( s1, "DEK-Info: AES-", 14 ) == 0 )
	{
	if( memcmp( s1, "DEK-Info: AES-128-CBC,", 22 ) == 0 )
	enc_alg = MBEDTLS_CIPHER_AES_128_CBC;
	else if( memcmp( s1, "DEK-Info: AES-192-CBC,", 22 ) == 0 )
	enc_alg = MBEDTLS_CIPHER_AES_192_CBC;
	else if( memcmp( s1, "DEK-Info: AES-256-CBC,", 22 ) == 0 )
	enc_alg = MBEDTLS_CIPHER_AES_256_CBC;
	else
	return( MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG );

	s1 += 22;
	if( pem_get_iv( s1, pem_iv, 16 ) != 0 )
	return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );

	s1 += 32;
	}
	#endif /* MBEDTLS_AES_C */

	if( enc_alg == MBEDTLS_CIPHER_NONE )
	return( MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG );

	if( *s1 == '\r' ) s1++;
	if( *s1 == '\n' ) s1++;
	else return( MBEDTLS_ERR_PEM_INVALID_DATA );
	#else
	return( MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE );
	#endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
	( MBEDTLS_AES_C \|\| MBEDTLS_DES_C ) */
	}

	if( s1 == s2 )
	return( MBEDTLS_ERR_PEM_INVALID_DATA );

	ret = mbedtls_base64_decode( NULL, 0, &len, s1, s2 - s1 );

	if( ret == MBEDTLS_ERR_BASE64_INVALID_CHARACTER )
	return( MBEDTLS_ERR_PEM_INVALID_DATA + ret );

	if( ( buf = mbedtls_calloc( 1, len ) ) == NULL )
	return( MBEDTLS_ERR_PEM_ALLOC_FAILED );

	if( ( ret = mbedtls_base64_decode( buf, len, &len, s1, s2 - s1 ) ) != 0 )
	{
	mbedtls_free( buf );
	return( MBEDTLS_ERR_PEM_INVALID_DATA + ret );
	}

	if( enc != 0 )
	{
	#if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) && \
	( defined(MBEDTLS_DES_C) \|\| defined(MBEDTLS_AES_C) )
	if( pwd == NULL )
	{
	mbedtls_free( buf );
	return( MBEDTLS_ERR_PEM_PASSWORD_REQUIRED );
	}

	#if defined(MBEDTLS_DES_C)
	if( enc_alg == MBEDTLS_CIPHER_DES_EDE3_CBC )
	pem_des3_decrypt( pem_iv, buf, len, pwd, pwdlen );
	else if( enc_alg == MBEDTLS_CIPHER_DES_CBC )
	pem_des_decrypt( pem_iv, buf, len, pwd, pwdlen );
	#endif /* MBEDTLS_DES_C */

	#if defined(MBEDTLS_AES_C)
	if( enc_alg == MBEDTLS_CIPHER_AES_128_CBC )
	pem_aes_decrypt( pem_iv, 16, buf, len, pwd, pwdlen );
	else if( enc_alg == MBEDTLS_CIPHER_AES_192_CBC )
	pem_aes_decrypt( pem_iv, 24, buf, len, pwd, pwdlen );
	else if( enc_alg == MBEDTLS_CIPHER_AES_256_CBC )
	pem_aes_decrypt( pem_iv, 32, buf, len, pwd, pwdlen );
	#endif /* MBEDTLS_AES_C */

	/*
	* The result will be ASN.1 starting with a SEQUENCE tag, with 1 to 3
	* length bytes (allow 4 to be sure) in all known use cases.
	*
	* Use that as heurisitic to try detecting password mismatchs.
	*/
	if( len <= 2 \|\| buf[0] != 0x30 \|\| buf[1] > 0x83 )
	{
	mbedtls_free( buf );
	return( MBEDTLS_ERR_PEM_PASSWORD_MISMATCH );
	}
	#else
	mbedtls_free( buf );
	return( MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE );
	#endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
	( MBEDTLS_AES_C \|\| MBEDTLS_DES_C ) */
	}

	ctx->buf = buf;
	ctx->buflen = len;

	return( 0 );
	}

	void mbedtls_pem_free( mbedtls_pem_context *ctx )
	{
	mbedtls_free( ctx->buf );
	mbedtls_free( ctx->info );

	mbedtls_zeroize( ctx, sizeof( mbedtls_pem_context ) );
	}
	#endif /* MBEDTLS_PEM_PARSE_C */

	#if defined(MBEDTLS_PEM_WRITE_C)
	int mbedtls_pem_write_buffer( const char header, const char footer,
	const unsigned char *der_data, size_t der_len,
	unsigned char buf, size_t buf_len, size_t olen )
	{
	int ret;
	unsigned char encode_buf, c, *p = buf;
	size_t len = 0, use_len, add_len = 0;

	mbedtls_base64_encode( NULL, 0, &use_len, der_data, der_len );
	add_len = strlen( header ) + strlen( footer ) + ( use_len / 64 ) + 1;

	if( use_len + add_len > buf_len )
	{
	*olen = use_len + add_len;
	return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
	}

	if( ( encode_buf = mbedtls_calloc( 1, use_len ) ) == NULL )
	return( MBEDTLS_ERR_PEM_ALLOC_FAILED );

	if( ( ret = mbedtls_base64_encode( encode_buf, use_len, &use_len, der_data,
	der_len ) ) != 0 )
	{
	mbedtls_free( encode_buf );
	return( ret );
	}

	memcpy( p, header, strlen( header ) );
	p += strlen( header );
	c = encode_buf;

	while( use_len )
	{
	len = ( use_len > 64 ) ? 64 : use_len;
	memcpy( p, c, len );
	use_len -= len;
	p += len;
	c += len;
	*p++ = '\n';
	}

	memcpy( p, footer, strlen( footer ) );
	p += strlen( footer );

	*p++ = '\0';
	*olen = p - buf;

	mbedtls_free( encode_buf );
	return( 0 );
	}
	#endif /* MBEDTLS_PEM_WRITE_C */
	#endif /* MBEDTLS_PEM_PARSE_C \|\| MBEDTLS_PEM_WRITE_C */