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Diffstat (limited to 'polarssl/src/library/pem.c')
| -rw-r--r-- | polarssl/src/library/pem.c | 352 |
1 files changed, 352 insertions, 0 deletions
diff --git a/polarssl/src/library/pem.c b/polarssl/src/library/pem.c new file mode 100644 index 0000000..33e74ab --- /dev/null +++ b/polarssl/src/library/pem.c @@ -0,0 +1,352 @@ +/* + * Privacy Enhanced Mail (PEM) decoding + * + * Copyright (C) 2006-2010, 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; + unsigned char *s1, *s2; +#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_INVALID_DATA ); + + s1 = (unsigned char *) strstr( (char *) data, header ); + + if( s1 == NULL ) + return( POLARSSL_ERR_PEM_NO_HEADER_PRESENT ); + + s2 = (unsigned char *) strstr( (char *) data, footer ); + + if( s2 == NULL || s2 <= s1 ) + return( POLARSSL_ERR_PEM_INVALID_DATA ); + + s1 += strlen( header ); + if( *s1 == '\r' ) s1++; + if( *s1 == '\n' ) s1++; + else return( POLARSSL_ERR_PEM_INVALID_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; + s2 += strlen( footer ); + if( *s2 == '\r' ) s2++; + if( *s2 == '\n' ) s2++; + *use_len = s2 - data; + + 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 |