Diff: library/pem.c

Revision:

0:cdf462088d13

Child:

1:9ebc941037d5

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/library/pem.c	Thu Jan 05 00:18:44 2017 +0000
@@ -0,0 +1,447 @@
+/*
+ *  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
+
+/* 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_PEM_PARSE_C)
+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 */