Botan 2.19.2
Crypto and TLS for C&
mdx_hash.cpp
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1/*
2* Merkle-Damgard Hash Function
3* (C) 1999-2008,2018 Jack Lloyd
4*
5* Botan is released under the Simplified BSD License (see license.txt)
6*/
7
8#include <botan/mdx_hash.h>
9#include <botan/exceptn.h>
10#include <botan/loadstor.h>
11#include <botan/internal/bit_ops.h>
12
13namespace Botan {
14
15/*
16* MDx_HashFunction Constructor
17*/
19 bool byte_big_endian,
20 bool bit_big_endian,
21 uint8_t cnt_size) :
22 m_pad_char(bit_big_endian == true ? 0x80 : 0x01),
23 m_counter_size(cnt_size),
24 m_block_bits(ceil_log2(block_len)),
25 m_count_big_endian(byte_big_endian),
26 m_count(0),
27 m_buffer(block_len),
28 m_position(0)
29 {
30 if(!is_power_of_2(block_len))
31 throw Invalid_Argument("MDx_HashFunction block length must be a power of 2");
32 if(m_block_bits < 3 || m_block_bits > 16)
33 throw Invalid_Argument("MDx_HashFunction block size too large or too small");
34 if(m_counter_size < 8 || m_counter_size > block_len)
35 throw Invalid_State("MDx_HashFunction invalid counter length");
36 }
37
38/*
39* Clear memory of sensitive data
40*/
42 {
43 zeroise(m_buffer);
44 m_count = m_position = 0;
45 }
46
47/*
48* Update the hash
49*/
50void MDx_HashFunction::add_data(const uint8_t input[], size_t length)
51 {
52 const size_t block_len = static_cast<size_t>(1) << m_block_bits;
53
54 m_count += length;
55
56 if(m_position)
57 {
58 buffer_insert(m_buffer, m_position, input, length);
59
60 if(m_position + length >= block_len)
61 {
62 compress_n(m_buffer.data(), 1);
63 input += (block_len - m_position);
64 length -= (block_len - m_position);
65 m_position = 0;
66 }
67 }
68
69 // Just in case the compiler can't figure out block_len is a power of 2
70 const size_t full_blocks = length >> m_block_bits;
71 const size_t remaining = length & (block_len - 1);
72
73 if(full_blocks > 0)
74 {
75 compress_n(input, full_blocks);
76 }
77
78 buffer_insert(m_buffer, m_position, input + full_blocks * block_len, remaining);
79 m_position += remaining;
80 }
81
82/*
83* Finalize a hash
84*/
85void MDx_HashFunction::final_result(uint8_t output[])
86 {
87 const size_t block_len = static_cast<size_t>(1) << m_block_bits;
88
89 clear_mem(&m_buffer[m_position], block_len - m_position);
90 m_buffer[m_position] = m_pad_char;
91
92 if(m_position >= block_len - m_counter_size)
93 {
94 compress_n(m_buffer.data(), 1);
95 zeroise(m_buffer);
96 }
97
98 write_count(&m_buffer[block_len - m_counter_size]);
99
100 compress_n(m_buffer.data(), 1);
101 copy_out(output);
102 clear();
103 }
104
105/*
106* Write the count bits to the buffer
107*/
109 {
110 BOTAN_ASSERT_NOMSG(m_counter_size <= output_length());
111 BOTAN_ASSERT_NOMSG(m_counter_size >= 8);
112
113 const uint64_t bit_count = m_count * 8;
114
115 if(m_count_big_endian)
116 store_be(bit_count, out + m_counter_size - 8);
117 else
118 store_le(bit_count, out + m_counter_size - 8);
119 }
120
121}
#define BOTAN_ASSERT_NOMSG(expr)
Definition: assert.h:68
virtual size_t output_length() const =0
void final_result(uint8_t output[]) override final
Definition: mdx_hash.cpp:85
void clear() override
Definition: mdx_hash.cpp:41
virtual void compress_n(const uint8_t blocks[], size_t block_n)=0
MDx_HashFunction(size_t block_length, bool big_byte_endian, bool big_bit_endian, uint8_t counter_size=8)
Definition: mdx_hash.cpp:18
virtual void write_count(uint8_t out[])
Definition: mdx_hash.cpp:108
void add_data(const uint8_t input[], size_t length) override final
Definition: mdx_hash.cpp:50
virtual void copy_out(uint8_t buffer[])=0
Definition: alg_id.cpp:13
void zeroise(std::vector< T, Alloc > &vec)
Definition: secmem.h:114
size_t buffer_insert(std::vector< T, Alloc > &buf, size_t buf_offset, const T input[], size_t input_length)
Definition: mem_ops.h:228
uint8_t ceil_log2(T x)
Definition: bit_ops.h:119
void store_be(uint16_t in, uint8_t out[2])
Definition: loadstor.h:438
void store_le(uint16_t in, uint8_t out[2])
Definition: loadstor.h:454
constexpr bool is_power_of_2(T arg)
Definition: bit_ops.h:43
void clear_mem(T *ptr, size_t n)
Definition: mem_ops.h:115