- Parsing of PEM files moved to separate module (Fixes ticket #13). Also possible to remove PEM support for systems only using DER encoding
- Parsing PEM private keys encrypted with DES and AES are now supported (Fixes ticket #5)
- Added tests for encrypted keyfiles
diff --git a/library/pem.c b/library/pem.c
new file mode 100644
index 0000000..6117f04
--- /dev/null
+++ b/library/pem.c
@@ -0,0 +1,350 @@
+/*
+ * 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>
+#include <string.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, int iv_len )
+{
+ int 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, int keylen,
+ unsigned char *iv,
+ const unsigned char *pwd, int pwdlen )
+{
+ md5_context md5_ctx;
+ unsigned char md5sum[16];
+ int 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, int buflen,
+ const unsigned char *pwd, int 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, int buflen,
+ const unsigned char *pwd, int 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], int keylen,
+ unsigned char *buf, int buflen,
+ const unsigned char *pwd, int 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, int pwdlen, int *use_len )
+{
+ int ret, len, enc;
+ 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( ret | POLARSSL_ERR_PEM_INVALID_DATA );
+
+ 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( ret | POLARSSL_ERR_PEM_INVALID_DATA );
+ }
+
+ 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 );
+}
+
+#endif