1 /*
2 * CTR-BE Mode
3 * (C) 1999-2007 Jack Lloyd
4 *
5 * Botan is released under the Simplified BSD License (see license.txt)
6 */
7 
8 #ifndef BOTAN_CTR_BE_H_
9 #define BOTAN_CTR_BE_H_
10 
11 #include <botan/block_cipher.h>
12 #include <botan/stream_cipher.h>
13 
14 BOTAN_FUTURE_INTERNAL_HEADER(ctr.h)
15 
16 namespace Botan {
17 
18 /**
19 * CTR-BE (Counter mode, big-endian)
20 */
21 class BOTAN_PUBLIC_API(2,0) CTR_BE final : public StreamCipher
22    {
23    public:
24       void cipher(const uint8_t in[], uint8_t out[], size_t length) override;
25 
26       void set_iv(const uint8_t iv[], size_t iv_len) override;
27 
28       size_t default_iv_length() const override;
29 
30       bool valid_iv_length(size_t iv_len) const override;
31 
32       Key_Length_Specification key_spec() const override;
33 
34       std::string name() const override;
35 
36       CTR_BE* clone() const override;
37 
38       void clear() override;
39 
40       /**
41       * @param cipher the block cipher to use
42       */
43       explicit CTR_BE(BlockCipher* cipher);
44 
45       CTR_BE(BlockCipher* cipher, size_t ctr_size);
46 
47       void seek(uint64_t offset) override;
48    private:
49       void key_schedule(const uint8_t key[], size_t key_len) override;
50       void add_counter(const uint64_t counter);
51 
52       std::unique_ptr<BlockCipher> m_cipher;
53 
54       const size_t m_block_size;
55       const size_t m_ctr_size;
56       const size_t m_ctr_blocks;
57 
58       secure_vector<uint8_t> m_counter, m_pad;
59       std::vector<uint8_t> m_iv;
60       size_t m_pad_pos;
61    };
62 
63 }
64 
65 #endif
66