/*
* RFC 1521 base64 encoding/decoding
*
* Copyright The Mbed TLS Contributors
* 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.
*/
#include "common.h"
#if defined(MBEDTLS_BASE64_C)
#include "mbedtls/base64.h"
#include "constant_time_internal.h"
#include <stdint.h>
#if defined(MBEDTLS_SELF_TEST)
#include <string.h>
#include "mbedtls/platform.h"
#endif /* MBEDTLS_SELF_TEST */
#define BASE64_SIZE_T_MAX ( (size_t) -1 ) /* SIZE_T_MAX is not standard */
/*
* Encode a buffer into base64 format
*/
int mbedtls_base64_encode( unsigned char *dst, size_t dlen, size_t *olen,
const unsigned char *src, size_t slen )
{
size_t i, n;
int C1, C2, C3;
unsigned char *p;
if( slen == 0 )
{
*olen = 0;
return( 0 );
}
n = slen / 3 + ( slen % 3 != 0 );
if( n > ( BASE64_SIZE_T_MAX - 1 ) / 4 )
{
*olen = BASE64_SIZE_T_MAX;
return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
}
n *= 4;
if( ( dlen < n + 1 ) || ( NULL == dst ) )
{
*olen = n + 1;
return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
}
n = ( slen / 3 ) * 3;
for( i = 0, p = dst; i < n; i += 3 )
{
C1 = *src++;
C2 = *src++;
C3 = *src++;
*p++ = mbedtls_ct_base64_enc_char( ( C1 >> 2 ) & 0x3F );
*p++ = mbedtls_ct_base64_enc_char( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) )
& 0x3F );
*p++ = mbedtls_ct_base64_enc_char( ( ( ( C2 & 15 ) << 2 ) + ( C3 >> 6 ) )
& 0x3F );
*p++ = mbedtls_ct_base64_enc_char( C3 & 0x3F );
}
if( i < slen )
{
C1 = *src++;
C2 = ( ( i + 1 ) < slen ) ? *src++ : 0;
*p++ = mbedtls_ct_base64_enc_char( ( C1 >> 2 ) & 0x3F );
*p++ = mbedtls_ct_base64_enc_char( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) )
& 0x3F );
if( ( i + 1 ) < slen )
*p++ = mbedtls_ct_base64_enc_char( ( ( C2 & 15 ) << 2 ) & 0x3F );
else *p++ = '=';
*p++ = '=';
}
*olen = p - dst;
*p = 0;
return( 0 );
}
/*
* Decode a base64-formatted buffer
*/
int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen,
const unsigned char *src, size_t slen )
{
size_t i; /* index in source */
size_t n; /* number of digits or trailing = in source */
uint32_t x; /* value accumulator */
unsigned accumulated_digits = 0;
unsigned equals = 0;
int spaces_present = 0;
unsigned char *p;
/* First pass: check for validity and get output length */
for( i = n = 0; i < slen; i++ )
{
/* Skip spaces before checking for EOL */
spaces_present = 0;
while( i < slen && src[i] == ' ' )
{
++i;
spaces_present = 1;
}
/* Spaces at end of buffer are OK */
if( i == slen )
break;
if( ( slen - i ) >= 2 &&
src[i] == '\r' && src[i + 1] == '\n' )
continue;
if( src[i] == '\n' )
continue;
/* Space inside a line is an error */
if( spaces_present )
return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
if( src[i] > 127 )
return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
if( src[i] == '=' )
{
if( ++equals > 2 )
return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
}
else
{
if( equals != 0 )
return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
if( mbedtls_ct_base64_dec_value( src[i] ) < 0 )
return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
}
n++;
}
if( n == 0 )
{
*olen = 0;
return( 0 );
}
/* The following expression is to calculate the following formula without
* risk of integer overflow in n:
* n = ( ( n * 6 ) + 7 ) >> 3;
*/
n = ( 6 * ( n >> 3 ) ) + ( ( 6 * ( n & 0x7 ) + 7 ) >> 3 );
n -= equals;
if( dst == NULL || dlen < n )
{
*olen = n;
return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
}
equals = 0;
for( x = 0, p = dst; i > 0; i--, src++ )
{
if( *src == '\r' || *src == '\n' || *src == ' ' )
continue;
x = x << 6;
if( *src == '=' )
++equals;
else
x |= mbedtls_ct_base64_dec_value( *src );
if( ++accumulated_digits == 4 )
{
accumulated_digits = 0;
*p++ = MBEDTLS_BYTE_2( x );
if( equals <= 1 ) *p++ = MBEDTLS_BYTE_1( x );
if( equals <= 0 ) *p++ = MBEDTLS_BYTE_0( x );
}
}
*olen = p - dst;
return( 0 );
}
#if defined(MBEDTLS_SELF_TEST)
static const unsigned char base64_test_dec[64] =
{
0x24, 0x48, 0x6E, 0x56, 0x87, 0x62, 0x5A, 0xBD,
0xBF, 0x17, 0xD9, 0xA2, 0xC4, 0x17, 0x1A, 0x01,
0x94, 0xED, 0x8F, 0x1E, 0x11, 0xB3, 0xD7, 0x09,
0x0C, 0xB6, 0xE9, 0x10, 0x6F, 0x22, 0xEE, 0x13,
0xCA, 0xB3, 0x07, 0x05, 0x76, 0xC9, 0xFA, 0x31,
0x6C, 0x08, 0x34, 0xFF, 0x8D, 0xC2, 0x6C, 0x38,
0x00, 0x43, 0xE9, 0x54, 0x97, 0xAF, 0x50, 0x4B,
0xD1, 0x41, 0xBA, 0x95, 0x31, 0x5A, 0x0B, 0x97
};
static const unsigned char base64_test_enc[] =
"JEhuVodiWr2/F9mixBcaAZTtjx4Rs9cJDLbpEG8i7hPK"
"swcFdsn6MWwINP+Nwmw4AEPpVJevUEvRQbqVMVoLlw==";
/*
* Checkup routine
*/
int mbedtls_base64_self_test( int verbose )
{
size_t len;
const unsigned char *src;
unsigned char buffer[128];
if( verbose != 0 )
mbedtls_printf( " Base64 encoding test: " );
src = base64_test_dec;
if( mbedtls_base64_encode( buffer, sizeof( buffer ), &len, src, 64 ) != 0 ||
memcmp( base64_test_enc, buffer, 88 ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
return( 1 );
}
if( verbose != 0 )
mbedtls_printf( "passed\n Base64 decoding test: " );
src = base64_test_enc;
if( mbedtls_base64_decode( buffer, sizeof( buffer ), &len, src, 88 ) != 0 ||
memcmp( base64_test_dec, buffer, 64 ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
return( 1 );
}
if( verbose != 0 )
mbedtls_printf( "passed\n\n" );
return( 0 );
}
#endif /* MBEDTLS_SELF_TEST */
#endif /* MBEDTLS_BASE64_C */