Botan 3.3.0
Crypto and TLS for C&
hex.cpp
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1/*
2* Hex Encoding and Decoding
3* (C) 2010,2020 Jack Lloyd
4*
5* Botan is released under the Simplified BSD License (see license.txt)
6*/
7
8#include <botan/hex.h>
9
10#include <botan/exceptn.h>
11#include <botan/mem_ops.h>
12#include <botan/internal/charset.h>
13#include <botan/internal/ct_utils.h>
14#include <botan/internal/fmt.h>
15
16namespace Botan {
17
18namespace {
19
20char hex_encode_nibble(uint8_t n, bool uppercase) {
21 BOTAN_DEBUG_ASSERT(n <= 15);
22
23 const auto in_09 = CT::Mask<uint8_t>::is_lt(n, 10);
24
25 const char c_09 = n + '0';
26 const char c_af = n + (uppercase ? 'A' : 'a') - 10;
27
28 return in_09.select(c_09, c_af);
29}
30
31} // namespace
32
33void hex_encode(char output[], const uint8_t input[], size_t input_length, bool uppercase) {
34 for(size_t i = 0; i != input_length; ++i) {
35 const uint8_t n0 = (input[i] >> 4) & 0xF;
36 const uint8_t n1 = (input[i]) & 0xF;
37
38 output[2 * i] = hex_encode_nibble(n0, uppercase);
39 output[2 * i + 1] = hex_encode_nibble(n1, uppercase);
40 }
41}
42
43std::string hex_encode(const uint8_t input[], size_t input_length, bool uppercase) {
44 std::string output(2 * input_length, 0);
45
46 if(input_length) {
47 hex_encode(&output.front(), input, input_length, uppercase);
48 }
49
50 return output;
51}
52
53namespace {
54
55uint8_t hex_char_to_bin(char input) {
56 const uint8_t c = static_cast<uint8_t>(input);
57
58 const auto is_alpha_upper = CT::Mask<uint8_t>::is_within_range(c, uint8_t('A'), uint8_t('F'));
59 const auto is_alpha_lower = CT::Mask<uint8_t>::is_within_range(c, uint8_t('a'), uint8_t('f'));
60 const auto is_decimal = CT::Mask<uint8_t>::is_within_range(c, uint8_t('0'), uint8_t('9'));
61
62 const auto is_whitespace =
63 CT::Mask<uint8_t>::is_any_of(c, {uint8_t(' '), uint8_t('\t'), uint8_t('\n'), uint8_t('\r')});
64
65 const uint8_t c_upper = c - uint8_t('A') + 10;
66 const uint8_t c_lower = c - uint8_t('a') + 10;
67 const uint8_t c_decim = c - uint8_t('0');
68
69 uint8_t ret = 0xFF; // default value
70
71 ret = is_alpha_upper.select(c_upper, ret);
72 ret = is_alpha_lower.select(c_lower, ret);
73 ret = is_decimal.select(c_decim, ret);
74 ret = is_whitespace.select(0x80, ret);
75
76 return ret;
77}
78
79} // namespace
80
81size_t hex_decode(uint8_t output[], const char input[], size_t input_length, size_t& input_consumed, bool ignore_ws) {
82 uint8_t* out_ptr = output;
83 bool top_nibble = true;
84
85 clear_mem(output, input_length / 2);
86
87 for(size_t i = 0; i != input_length; ++i) {
88 const uint8_t bin = hex_char_to_bin(input[i]);
89
90 if(bin >= 0x10) {
91 if(bin == 0x80 && ignore_ws) {
92 continue;
93 }
94
95 throw Invalid_Argument(fmt("hex_decode: invalid character '{}'", format_char_for_display(input[i])));
96 }
97
98 if(top_nibble) {
99 *out_ptr |= bin << 4;
100 } else {
101 *out_ptr |= bin;
102 }
103
104 top_nibble = !top_nibble;
105 if(top_nibble) {
106 ++out_ptr;
107 }
108 }
109
110 input_consumed = input_length;
111 size_t written = (out_ptr - output);
112
113 /*
114 * We only got half of a uint8_t at the end; zap the half-written
115 * output and mark it as unread
116 */
117 if(!top_nibble) {
118 *out_ptr = 0;
119 input_consumed -= 1;
120 }
121
122 return written;
123}
124
125size_t hex_decode(uint8_t output[], const char input[], size_t input_length, bool ignore_ws) {
126 size_t consumed = 0;
127 size_t written = hex_decode(output, input, input_length, consumed, ignore_ws);
128
129 if(consumed != input_length) {
130 throw Invalid_Argument("hex_decode: input did not have full bytes");
131 }
132
133 return written;
134}
135
136size_t hex_decode(uint8_t output[], std::string_view input, bool ignore_ws) {
137 return hex_decode(output, input.data(), input.length(), ignore_ws);
138}
139
140size_t hex_decode(std::span<uint8_t> output, std::string_view input, bool ignore_ws) {
141 return hex_decode(output.data(), input.data(), input.length(), ignore_ws);
142}
143
144secure_vector<uint8_t> hex_decode_locked(const char input[], size_t input_length, bool ignore_ws) {
145 secure_vector<uint8_t> bin(1 + input_length / 2);
146
147 size_t written = hex_decode(bin.data(), input, input_length, ignore_ws);
148
149 bin.resize(written);
150 return bin;
151}
152
153secure_vector<uint8_t> hex_decode_locked(std::string_view input, bool ignore_ws) {
154 return hex_decode_locked(input.data(), input.size(), ignore_ws);
155}
156
157std::vector<uint8_t> hex_decode(const char input[], size_t input_length, bool ignore_ws) {
158 std::vector<uint8_t> bin(1 + input_length / 2);
159
160 size_t written = hex_decode(bin.data(), input, input_length, ignore_ws);
161
162 bin.resize(written);
163 return bin;
164}
165
166std::vector<uint8_t> hex_decode(std::string_view input, bool ignore_ws) {
167 return hex_decode(input.data(), input.size(), ignore_ws);
168}
169
170} // namespace Botan
#define BOTAN_DEBUG_ASSERT(expr)
Definition assert.h:98
static Mask< T > is_any_of(T v, std::initializer_list< T > accepted)
Definition ct_utils.h:159
static Mask< T > is_lt(T x, T y)
Definition ct_utils.h:133
static Mask< T > is_within_range(T v, T l, T u)
Definition ct_utils.h:150
std::string format_char_for_display(char c)
Definition charset.cpp:98
std::string fmt(std::string_view format, const T &... args)
Definition fmt.h:53
secure_vector< uint8_t > hex_decode_locked(const char input[], size_t input_length, bool ignore_ws)
Definition hex.cpp:144
void hex_encode(char output[], const uint8_t input[], size_t input_length, bool uppercase)
Definition hex.cpp:33
size_t hex_decode(uint8_t output[], const char input[], size_t input_length, size_t &input_consumed, bool ignore_ws)
Definition hex.cpp:81
std::vector< T, secure_allocator< T > > secure_vector
Definition secmem.h:61
constexpr void clear_mem(T *ptr, size_t n)
Definition mem_ops.h:120