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mbedtls/library/pem.c
Paul Bakker 00b2860e8d pem_read_buffer() already update use_len after header and footer are read 
After header and footer are read, pem_read_buffer() is able to determine
the length of input data used. This allows calling functions to skip
this PEM bit if an error occurs during its parsing.
(cherry picked from commit 9255e8300e)
2013-06-24 19:09:25 +02:00

354 lines
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C
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/*
* Privacy Enhanced Mail (PEM) decoding
*
* 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.
*/
#include "polarssl/config.h"
#if defined(POLARSSL_PEM_C)
#include "polarssl/pem.h"
#include "polarssl/base64.h"
#include "polarssl/des.h"
#include "polarssl/aes.h"
#include "polarssl/md5.h"
#include "polarssl/cipher.h"
#include <stdlib.h>
void pem_init( pem_context *ctx )
{
memset( ctx, 0, sizeof( pem_context ) );
}
#if defined(POLARSSL_MD5_C) && (defined(POLARSSL_DES_C) || defined(POLARSSL_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( POLARSSL_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 )
{
md5_context md5_ctx;
unsigned char md5sum[16];
size_t use_len;
/*
* key[ 0..15] = MD5(pwd || IV)
*/
md5_starts( &md5_ctx );
md5_update( &md5_ctx, pwd, pwdlen );
md5_update( &md5_ctx, iv, 8 );
md5_finish( &md5_ctx, md5sum );
if( keylen <= 16 )
{
memcpy( key, md5sum, keylen );
memset( &md5_ctx, 0, sizeof( md5_ctx ) );
memset( md5sum, 0, 16 );
return;
}
memcpy( key, md5sum, 16 );
/*
* key[16..23] = MD5(key[ 0..15] || pwd || IV])
*/
md5_starts( &md5_ctx );
md5_update( &md5_ctx, md5sum, 16 );
md5_update( &md5_ctx, pwd, pwdlen );
md5_update( &md5_ctx, iv, 8 );
md5_finish( &md5_ctx, md5sum );
use_len = 16;
if( keylen < 32 )
use_len = keylen - 16;
memcpy( key + 16, md5sum, use_len );
memset( &md5_ctx, 0, sizeof( md5_ctx ) );
memset( md5sum, 0, 16 );
}
#if defined(POLARSSL_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 )
{
des_context des_ctx;
unsigned char des_key[8];
pem_pbkdf1( des_key, 8, des_iv, pwd, pwdlen );
des_setkey_dec( &des_ctx, des_key );
des_crypt_cbc( &des_ctx, DES_DECRYPT, buflen,
des_iv, buf, buf );
memset( &des_ctx, 0, sizeof( des_ctx ) );
memset( des_key, 0, 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 )
{
des3_context des3_ctx;
unsigned char des3_key[24];
pem_pbkdf1( des3_key, 24, des3_iv, pwd, pwdlen );
des3_set3key_dec( &des3_ctx, des3_key );
des3_crypt_cbc( &des3_ctx, DES_DECRYPT, buflen,
des3_iv, buf, buf );
memset( &des3_ctx, 0, sizeof( des3_ctx ) );
memset( des3_key, 0, 24 );
}
#endif /* POLARSSL_DES_C */
#if defined(POLARSSL_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 )
{
aes_context aes_ctx;
unsigned char aes_key[32];
pem_pbkdf1( aes_key, keylen, aes_iv, pwd, pwdlen );
aes_setkey_dec( &aes_ctx, aes_key, keylen * 8 );
aes_crypt_cbc( &aes_ctx, AES_DECRYPT, buflen,
aes_iv, buf, buf );
memset( &aes_ctx, 0, sizeof( aes_ctx ) );
memset( aes_key, 0, keylen );
}
#endif /* POLARSSL_AES_C */
#endif /* POLARSSL_MD5_C && (POLARSSL_AES_C || POLARSSL_DES_C) */
int pem_read_buffer( pem_context *ctx, char *header, 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(POLARSSL_MD5_C) && (defined(POLARSSL_DES_C) || defined(POLARSSL_AES_C))
unsigned char pem_iv[16];
cipher_type_t enc_alg = POLARSSL_CIPHER_NONE;
#else
((void) pwd);
((void) pwdlen);
#endif /* POLARSSL_MD5_C && (POLARSSL_AES_C || POLARSSL_DES_C) */
if( ctx == NULL )
return( POLARSSL_ERR_PEM_BAD_INPUT_DATA );
s1 = (unsigned char *) strstr( (const char *) data, header );
if( s1 == NULL )
return( POLARSSL_ERR_PEM_NO_HEADER_FOOTER_PRESENT );
s2 = (unsigned char *) strstr( (const char *) data, footer );
if( s2 == NULL || s2 <= s1 )
return( POLARSSL_ERR_PEM_NO_HEADER_FOOTER_PRESENT );
s1 += strlen( header );
if( *s1 == '\r' ) s1++;
if( *s1 == '\n' ) s1++;
else return( POLARSSL_ERR_PEM_NO_HEADER_FOOTER_PRESENT );
end = s2;
end += strlen( footer );
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(POLARSSL_MD5_C) && (defined(POLARSSL_DES_C) || defined(POLARSSL_AES_C))
enc++;
s1 += 22;
if( *s1 == '\r' ) s1++;
if( *s1 == '\n' ) s1++;
else return( POLARSSL_ERR_PEM_INVALID_DATA );
#if defined(POLARSSL_DES_C)
if( memcmp( s1, "DEK-Info: DES-EDE3-CBC,", 23 ) == 0 )
{
enc_alg = POLARSSL_CIPHER_DES_EDE3_CBC;
s1 += 23;
if( pem_get_iv( s1, pem_iv, 8 ) != 0 )
return( POLARSSL_ERR_PEM_INVALID_ENC_IV );
s1 += 16;
}
else if( memcmp( s1, "DEK-Info: DES-CBC,", 18 ) == 0 )
{
enc_alg = POLARSSL_CIPHER_DES_CBC;
s1 += 18;
if( pem_get_iv( s1, pem_iv, 8) != 0 )
return( POLARSSL_ERR_PEM_INVALID_ENC_IV );
s1 += 16;
}
#endif /* POLARSSL_DES_C */
#if defined(POLARSSL_AES_C)
if( memcmp( s1, "DEK-Info: AES-", 14 ) == 0 )
{
if( memcmp( s1, "DEK-Info: AES-128-CBC,", 22 ) == 0 )
enc_alg = POLARSSL_CIPHER_AES_128_CBC;
else if( memcmp( s1, "DEK-Info: AES-192-CBC,", 22 ) == 0 )
enc_alg = POLARSSL_CIPHER_AES_192_CBC;
else if( memcmp( s1, "DEK-Info: AES-256-CBC,", 22 ) == 0 )
enc_alg = POLARSSL_CIPHER_AES_256_CBC;
else
return( POLARSSL_ERR_PEM_UNKNOWN_ENC_ALG );
s1 += 22;
if( pem_get_iv( s1, pem_iv, 16 ) != 0 )
return( POLARSSL_ERR_PEM_INVALID_ENC_IV );
s1 += 32;
}
#endif /* POLARSSL_AES_C */
if( enc_alg == POLARSSL_CIPHER_NONE )
return( POLARSSL_ERR_PEM_UNKNOWN_ENC_ALG );
if( *s1 == '\r' ) s1++;
if( *s1 == '\n' ) s1++;
else return( POLARSSL_ERR_PEM_INVALID_DATA );
#else
return( POLARSSL_ERR_PEM_FEATURE_UNAVAILABLE );
#endif /* POLARSSL_MD5_C && (POLARSSL_AES_C || POLARSSL_DES_C) */
}
len = 0;
ret = base64_decode( NULL, &len, s1, s2 - s1 );
if( ret == POLARSSL_ERR_BASE64_INVALID_CHARACTER )
return( POLARSSL_ERR_PEM_INVALID_DATA + ret );
if( ( buf = (unsigned char *) malloc( len ) ) == NULL )
return( POLARSSL_ERR_PEM_MALLOC_FAILED );
if( ( ret = base64_decode( buf, &len, s1, s2 - s1 ) ) != 0 )
{
free( buf );
return( POLARSSL_ERR_PEM_INVALID_DATA + ret );
}
if( enc != 0 )
{
#if defined(POLARSSL_MD5_C) && (defined(POLARSSL_DES_C) || defined(POLARSSL_AES_C))
if( pwd == NULL )
{
free( buf );
return( POLARSSL_ERR_PEM_PASSWORD_REQUIRED );
}
#if defined(POLARSSL_DES_C)
if( enc_alg == POLARSSL_CIPHER_DES_EDE3_CBC )
pem_des3_decrypt( pem_iv, buf, len, pwd, pwdlen );
else if( enc_alg == POLARSSL_CIPHER_DES_CBC )
pem_des_decrypt( pem_iv, buf, len, pwd, pwdlen );
#endif /* POLARSSL_DES_C */
#if defined(POLARSSL_AES_C)
if( enc_alg == POLARSSL_CIPHER_AES_128_CBC )
pem_aes_decrypt( pem_iv, 16, buf, len, pwd, pwdlen );
else if( enc_alg == POLARSSL_CIPHER_AES_192_CBC )
pem_aes_decrypt( pem_iv, 24, buf, len, pwd, pwdlen );
else if( enc_alg == POLARSSL_CIPHER_AES_256_CBC )
pem_aes_decrypt( pem_iv, 32, buf, len, pwd, pwdlen );
#endif /* POLARSSL_AES_C */
if( buf[0] != 0x30 || buf[1] != 0x82 ||
buf[4] != 0x02 || buf[5] != 0x01 )
{
free( buf );
return( POLARSSL_ERR_PEM_PASSWORD_MISMATCH );
}
#else
return( POLARSSL_ERR_PEM_FEATURE_UNAVAILABLE );
#endif
}
ctx->buf = buf;
ctx->buflen = len;
return( 0 );
}
void pem_free( pem_context *ctx )
{
if( ctx->buf )
free( ctx->buf );
if( ctx->info )
free( ctx->info );
memset( ctx, 0, sizeof( pem_context ) );
}
#endif
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