| /* |
| * 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 */ |