/* * 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 #if defined(MBEDTLS_SELF_TEST) #include #if defined(MBEDTLS_PLATFORM_C) #include "mbedtls/platform.h" #else #include #define mbedtls_printf printf #endif /* MBEDTLS_PLATFORM_C */ #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 */