273 lines
6.8 KiB
C
273 lines
6.8 KiB
C
/*
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* RFC 1521 base64 encoding/decoding
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "common.h"
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#if defined(MBEDTLS_BASE64_C)
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#include "mbedtls/base64.h"
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#include "constant_time_internal.h"
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#include <stdint.h>
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#if defined(MBEDTLS_SELF_TEST)
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#include <string.h>
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#include "mbedtls/platform.h"
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#endif /* MBEDTLS_SELF_TEST */
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#define BASE64_SIZE_T_MAX ( (size_t) -1 ) /* SIZE_T_MAX is not standard */
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/*
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* Encode a buffer into base64 format
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*/
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int mbedtls_base64_encode( unsigned char *dst, size_t dlen, size_t *olen,
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const unsigned char *src, size_t slen )
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{
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size_t i, n;
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int C1, C2, C3;
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unsigned char *p;
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if( slen == 0 )
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{
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*olen = 0;
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return( 0 );
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}
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n = slen / 3 + ( slen % 3 != 0 );
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if( n > ( BASE64_SIZE_T_MAX - 1 ) / 4 )
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{
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*olen = BASE64_SIZE_T_MAX;
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return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
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}
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n *= 4;
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if( ( dlen < n + 1 ) || ( NULL == dst ) )
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{
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*olen = n + 1;
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return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
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}
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n = ( slen / 3 ) * 3;
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for( i = 0, p = dst; i < n; i += 3 )
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{
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C1 = *src++;
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C2 = *src++;
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C3 = *src++;
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*p++ = mbedtls_ct_base64_enc_char( ( C1 >> 2 ) & 0x3F );
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*p++ = mbedtls_ct_base64_enc_char( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) )
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& 0x3F );
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*p++ = mbedtls_ct_base64_enc_char( ( ( ( C2 & 15 ) << 2 ) + ( C3 >> 6 ) )
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& 0x3F );
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*p++ = mbedtls_ct_base64_enc_char( C3 & 0x3F );
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}
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if( i < slen )
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{
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C1 = *src++;
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C2 = ( ( i + 1 ) < slen ) ? *src++ : 0;
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*p++ = mbedtls_ct_base64_enc_char( ( C1 >> 2 ) & 0x3F );
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*p++ = mbedtls_ct_base64_enc_char( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) )
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& 0x3F );
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if( ( i + 1 ) < slen )
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*p++ = mbedtls_ct_base64_enc_char( ( ( C2 & 15 ) << 2 ) & 0x3F );
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else *p++ = '=';
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*p++ = '=';
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}
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*olen = p - dst;
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*p = 0;
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return( 0 );
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}
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/*
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* Decode a base64-formatted buffer
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*/
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int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen,
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const unsigned char *src, size_t slen )
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{
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size_t i; /* index in source */
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size_t n; /* number of digits or trailing = in source */
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uint32_t x; /* value accumulator */
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unsigned accumulated_digits = 0;
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unsigned equals = 0;
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int spaces_present = 0;
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unsigned char *p;
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/* First pass: check for validity and get output length */
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for( i = n = 0; i < slen; i++ )
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{
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/* Skip spaces before checking for EOL */
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spaces_present = 0;
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while( i < slen && src[i] == ' ' )
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{
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++i;
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spaces_present = 1;
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}
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/* Spaces at end of buffer are OK */
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if( i == slen )
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break;
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if( ( slen - i ) >= 2 &&
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src[i] == '\r' && src[i + 1] == '\n' )
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continue;
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if( src[i] == '\n' )
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continue;
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/* Space inside a line is an error */
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if( spaces_present )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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if( src[i] > 127 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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if( src[i] == '=' )
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{
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if( ++equals > 2 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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}
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else
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{
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if( equals != 0 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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if( mbedtls_ct_base64_dec_value( src[i] ) < 0 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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}
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n++;
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}
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if( n == 0 )
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{
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*olen = 0;
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return( 0 );
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}
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/* The following expression is to calculate the following formula without
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* risk of integer overflow in n:
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* n = ( ( n * 6 ) + 7 ) >> 3;
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*/
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n = ( 6 * ( n >> 3 ) ) + ( ( 6 * ( n & 0x7 ) + 7 ) >> 3 );
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n -= equals;
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if( dst == NULL || dlen < n )
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{
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*olen = n;
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return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
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}
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equals = 0;
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for( x = 0, p = dst; i > 0; i--, src++ )
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{
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if( *src == '\r' || *src == '\n' || *src == ' ' )
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continue;
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x = x << 6;
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if( *src == '=' )
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++equals;
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else
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x |= mbedtls_ct_base64_dec_value( *src );
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if( ++accumulated_digits == 4 )
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{
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accumulated_digits = 0;
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*p++ = MBEDTLS_BYTE_2( x );
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if( equals <= 1 ) *p++ = MBEDTLS_BYTE_1( x );
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if( equals <= 0 ) *p++ = MBEDTLS_BYTE_0( x );
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}
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}
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*olen = p - dst;
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return( 0 );
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}
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#if defined(MBEDTLS_SELF_TEST)
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static const unsigned char base64_test_dec[64] =
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{
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0x24, 0x48, 0x6E, 0x56, 0x87, 0x62, 0x5A, 0xBD,
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0xBF, 0x17, 0xD9, 0xA2, 0xC4, 0x17, 0x1A, 0x01,
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0x94, 0xED, 0x8F, 0x1E, 0x11, 0xB3, 0xD7, 0x09,
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0x0C, 0xB6, 0xE9, 0x10, 0x6F, 0x22, 0xEE, 0x13,
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0xCA, 0xB3, 0x07, 0x05, 0x76, 0xC9, 0xFA, 0x31,
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0x6C, 0x08, 0x34, 0xFF, 0x8D, 0xC2, 0x6C, 0x38,
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0x00, 0x43, 0xE9, 0x54, 0x97, 0xAF, 0x50, 0x4B,
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0xD1, 0x41, 0xBA, 0x95, 0x31, 0x5A, 0x0B, 0x97
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};
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static const unsigned char base64_test_enc[] =
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"JEhuVodiWr2/F9mixBcaAZTtjx4Rs9cJDLbpEG8i7hPK"
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"swcFdsn6MWwINP+Nwmw4AEPpVJevUEvRQbqVMVoLlw==";
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/*
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* Checkup routine
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*/
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int mbedtls_base64_self_test( int verbose )
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{
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size_t len;
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const unsigned char *src;
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unsigned char buffer[128];
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if( verbose != 0 )
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mbedtls_printf( " Base64 encoding test: " );
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src = base64_test_dec;
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if( mbedtls_base64_encode( buffer, sizeof( buffer ), &len, src, 64 ) != 0 ||
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memcmp( base64_test_enc, buffer, 88 ) != 0 )
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{
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if( verbose != 0 )
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mbedtls_printf( "failed\n" );
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return( 1 );
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}
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if( verbose != 0 )
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mbedtls_printf( "passed\n Base64 decoding test: " );
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src = base64_test_enc;
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if( mbedtls_base64_decode( buffer, sizeof( buffer ), &len, src, 88 ) != 0 ||
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memcmp( base64_test_dec, buffer, 64 ) != 0 )
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{
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if( verbose != 0 )
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mbedtls_printf( "failed\n" );
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return( 1 );
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}
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if( verbose != 0 )
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mbedtls_printf( "passed\n\n" );
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return( 0 );
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}
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#endif /* MBEDTLS_SELF_TEST */
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#endif /* MBEDTLS_BASE64_C */
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