310 lines
8.3 KiB
C
310 lines
8.3 KiB
C
/*
|
|
* 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 <limits.h>
|
|
|
|
#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 */
|
|
|
|
MBEDTLS_STATIC_TESTABLE
|
|
unsigned char mbedtls_ct_base64_enc_char(unsigned char value)
|
|
{
|
|
unsigned char digit = 0;
|
|
/* For each range of values, if value is in that range, mask digit with
|
|
* the corresponding value. Since value can only be in a single range,
|
|
* only at most one masking will change digit. */
|
|
digit |= mbedtls_ct_uchar_in_range_if(0, 25, value, 'A' + value);
|
|
digit |= mbedtls_ct_uchar_in_range_if(26, 51, value, 'a' + value - 26);
|
|
digit |= mbedtls_ct_uchar_in_range_if(52, 61, value, '0' + value - 52);
|
|
digit |= mbedtls_ct_uchar_in_range_if(62, 62, value, '+');
|
|
digit |= mbedtls_ct_uchar_in_range_if(63, 63, value, '/');
|
|
return digit;
|
|
}
|
|
|
|
MBEDTLS_STATIC_TESTABLE
|
|
signed char mbedtls_ct_base64_dec_value(unsigned char c)
|
|
{
|
|
unsigned char val = 0;
|
|
/* For each range of digits, if c is in that range, mask val with
|
|
* the corresponding value. Since c can only be in a single range,
|
|
* only at most one masking will change val. Set val to one plus
|
|
* the desired value so that it stays 0 if c is in none of the ranges. */
|
|
val |= mbedtls_ct_uchar_in_range_if('A', 'Z', c, c - 'A' + 0 + 1);
|
|
val |= mbedtls_ct_uchar_in_range_if('a', 'z', c, c - 'a' + 26 + 1);
|
|
val |= mbedtls_ct_uchar_in_range_if('0', '9', c, c - '0' + 52 + 1);
|
|
val |= mbedtls_ct_uchar_in_range_if('+', '+', c, c - '+' + 62 + 1);
|
|
val |= mbedtls_ct_uchar_in_range_if('/', '/', c, c - '/' + 63 + 1);
|
|
/* At this point, val is 0 if c is an invalid digit and v+1 if c is
|
|
* a digit with the value v. */
|
|
return val - 1;
|
|
}
|
|
|
|
/*
|
|
* 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 > (SIZE_MAX - 1) / 4) {
|
|
*olen = SIZE_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 */
|