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/*
* RFC 1521 base64 encoding/decoding
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#include <limits.h>
#include "common.h"
#if defined(MBEDTLS_BASE64_C)
#include "mbedtls/base64.h"
#include "base64_internal.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 = (size_t) (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 = (size_t) (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 */
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