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Diffstat (limited to 'library/base64.c')
| -rw-r--r-- | library/base64.c | 272 |
1 files changed, 272 insertions, 0 deletions
diff --git a/library/base64.c b/library/base64.c new file mode 100644 index 000000000..9021a041b --- /dev/null +++ b/library/base64.c @@ -0,0 +1,272 @@ +/* + * 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 */ |