Botan 3.0.0
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#include <botan/mem_ops.h>
10#include <botan/exceptn.h>
11#include <botan/internal/charset.h>
12#include <botan/internal/ct_utils.h>
13#include <botan/internal/fmt.h>
14
15namespace Botan {
16
17namespace {
18
19char hex_encode_nibble(uint8_t n, bool uppercase)
20 {
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}
32
33void hex_encode(char output[],
34 const uint8_t input[],
35 size_t input_length,
36 bool uppercase)
37 {
38 for(size_t i = 0; i != input_length; ++i)
39 {
40 const uint8_t n0 = (input[i] >> 4) & 0xF;
41 const uint8_t n1 = (input[i] ) & 0xF;
42
43 output[2*i ] = hex_encode_nibble(n0, uppercase);
44 output[2*i+1] = hex_encode_nibble(n1, uppercase);
45 }
46 }
47
48std::string hex_encode(const uint8_t input[],
49 size_t input_length,
50 bool uppercase)
51 {
52 std::string output(2 * input_length, 0);
53
54 if(input_length)
55 hex_encode(&output.front(), input, input_length, uppercase);
56
57 return output;
58 }
59
60namespace {
61
62uint8_t hex_char_to_bin(char input)
63 {
64 const uint8_t c = static_cast<uint8_t>(input);
65
66 const auto is_alpha_upper = CT::Mask<uint8_t>::is_within_range(c, uint8_t('A'), uint8_t('F'));
67 const auto is_alpha_lower = CT::Mask<uint8_t>::is_within_range(c, uint8_t('a'), uint8_t('f'));
68 const auto is_decimal = CT::Mask<uint8_t>::is_within_range(c, uint8_t('0'), uint8_t('9'));
69
70 const auto is_whitespace = CT::Mask<uint8_t>::is_any_of(c, {
71 uint8_t(' '), uint8_t('\t'), uint8_t('\n'), uint8_t('\r')
72 });
73
74 const uint8_t c_upper = c - uint8_t('A') + 10;
75 const uint8_t c_lower = c - uint8_t('a') + 10;
76 const uint8_t c_decim = c - uint8_t('0');
77
78 uint8_t ret = 0xFF; // default value
79
80 ret = is_alpha_upper.select(c_upper, ret);
81 ret = is_alpha_lower.select(c_lower, ret);
82 ret = is_decimal.select(c_decim, ret);
83 ret = is_whitespace.select(0x80, ret);
84
85 return ret;
86 }
87
88}
89
90
91size_t hex_decode(uint8_t output[],
92 const char input[],
93 size_t input_length,
94 size_t& input_consumed,
95 bool ignore_ws)
96 {
97 uint8_t* out_ptr = output;
98 bool top_nibble = true;
99
100 clear_mem(output, input_length / 2);
101
102 for(size_t i = 0; i != input_length; ++i)
103 {
104 const uint8_t bin = hex_char_to_bin(input[i]);
105
106 if(bin >= 0x10)
107 {
108 if(bin == 0x80 && ignore_ws)
109 continue;
110
111 throw Invalid_Argument(fmt("hex_decode: invalid character '{}'",
112 format_char_for_display(input[i])));
113 }
114
115 if(top_nibble)
116 *out_ptr |= bin << 4;
117 else
118 *out_ptr |= bin;
119
120 top_nibble = !top_nibble;
121 if(top_nibble)
122 ++out_ptr;
123 }
124
125 input_consumed = input_length;
126 size_t written = (out_ptr - output);
127
128 /*
129 * We only got half of a uint8_t at the end; zap the half-written
130 * output and mark it as unread
131 */
132 if(!top_nibble)
133 {
134 *out_ptr = 0;
135 input_consumed -= 1;
136 }
137
138 return written;
139 }
140
141size_t hex_decode(uint8_t output[],
142 const char input[],
143 size_t input_length,
144 bool ignore_ws)
145 {
146 size_t consumed = 0;
147 size_t written = hex_decode(output, input, input_length,
148 consumed, ignore_ws);
149
150 if(consumed != input_length)
151 throw Invalid_Argument("hex_decode: input did not have full bytes");
152
153 return written;
154 }
155
156size_t hex_decode(uint8_t output[],
157 std::string_view input,
158 bool ignore_ws)
159 {
160 return hex_decode(output, input.data(), input.length(), ignore_ws);
161 }
162
163size_t hex_decode(std::span<uint8_t> output,
164 std::string_view input,
165 bool ignore_ws)
166 {
167 return hex_decode(output.data(), input.data(), input.length(), ignore_ws);
168 }
169
171 size_t input_length,
172 bool ignore_ws)
173 {
174 secure_vector<uint8_t> bin(1 + input_length / 2);
175
176 size_t written = hex_decode(bin.data(),
177 input,
178 input_length,
179 ignore_ws);
180
181 bin.resize(written);
182 return bin;
183 }
184
186 bool ignore_ws)
187 {
188 return hex_decode_locked(input.data(), input.size(), ignore_ws);
189 }
190
191std::vector<uint8_t> hex_decode(const char input[],
192 size_t input_length,
193 bool ignore_ws)
194 {
195 std::vector<uint8_t> bin(1 + input_length / 2);
196
197 size_t written = hex_decode(bin.data(),
198 input,
199 input_length,
200 ignore_ws);
201
202 bin.resize(written);
203 return bin;
204 }
205
206std::vector<uint8_t> hex_decode(std::string_view input,
207 bool ignore_ws)
208 {
209 return hex_decode(input.data(), input.size(), ignore_ws);
210 }
211
212}
#define BOTAN_DEBUG_ASSERT(expr)
Definition: assert.h:122
static Mask< T > is_any_of(T v, std::initializer_list< T > accepted)
Definition: ct_utils.h:194
static Mask< T > is_lt(T x, T y)
Definition: ct_utils.h:155
static Mask< T > is_within_range(T v, T l, T u)
Definition: ct_utils.h:184
Definition: alg_id.cpp:12
std::string format_char_for_display(char c)
Definition: charset.cpp:109
std::string fmt(std::string_view format, const T &... args)
Definition: fmt.h:60
secure_vector< uint8_t > hex_decode_locked(const char input[], size_t input_length, bool ignore_ws)
Definition: hex.cpp:170
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:91
std::vector< T, secure_allocator< T > > secure_vector
Definition: secmem.h:64
constexpr void clear_mem(T *ptr, size_t n)
Definition: mem_ops.h:115