24053024312

Committed 06 Apr 2026 09:51PM UTC coverage: 91.831% (+2.4%) from 89.454%

Build # 24053024312

Build Type

Pull #5521

github

Committed by

web-flow

Commit Message

Merge 89fecf072 into 417709dd7

Pull Request Pull Request #5521: Rollup of small fixes

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/src/lib/modes/aead/ocb/ocb.cpp

/*
* OCB Mode
* (C) 2013,2017 Jack Lloyd
* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/internal/ocb.h>

#include <botan/block_cipher.h>
#include <botan/exceptn.h>
#include <botan/mem_ops.h>
#include <botan/internal/bit_ops.h>
#include <botan/internal/ct_utils.h>
#include <botan/internal/poly_dbl.h>

namespace Botan {

// Has to be in Botan namespace so unique_ptr can reference it
class L_computer final {
   public:
      explicit L_computer(const BlockCipher& cipher) :
            m_BS(cipher.block_size()), m_max_blocks(cipher.parallel_bytes() / m_BS) {
         m_L_star.resize(m_BS);
         cipher.encrypt(m_L_star);
         m_L_dollar = poly_double(star());

         // Preallocate the m_L vector to the maximum expected size to avoid
         // re-allocations during runtime. This had caused a use-after-free in
         // earlier versions, due to references into this buffer becoming stale
         // in `compute_offset()`, after calling `get()` in the hot path.
         //
         // Note, that the list member won't be pre-allocated, so the expected
         // memory overhead is negligible.
         //
         // See also https://github.com/randombit/botan/issues/3812
         m_L.reserve(65);
         m_L.push_back(poly_double(dollar()));

         while(m_L.size() < 8) {
            m_L.push_back(poly_double(m_L.back()));
         }

         m_offset_buf.resize(m_BS * m_max_blocks);
      }

      void init(const secure_vector<uint8_t>& offset) { m_offset = offset; }

      bool initialized() const { return !m_offset.empty(); }

      const secure_vector<uint8_t>& star() const { return m_L_star; }

      const secure_vector<uint8_t>& dollar() const { return m_L_dollar; }

      const secure_vector<uint8_t>& offset() const { return m_offset; }

      const secure_vector<uint8_t>& get(size_t i) const {
         while(m_L.size() <= i) {
            m_L.push_back(poly_double(m_L.back()));
         }

         return m_L[i];
      }

      const uint8_t* compute_offsets(uint64_t block_index, size_t blocks) {
         BOTAN_ASSERT(blocks <= m_max_blocks, "OCB offsets");

         uint8_t* offsets = m_offset_buf.data();

         if(block_index % 4 == 0) {
            const secure_vector<uint8_t>& L0 = get(0);
            const secure_vector<uint8_t>& L1 = get(1);

            while(blocks >= 4) {
               // ntz(4*i+1) == 0
               // ntz(4*i+2) == 1
               // ntz(4*i+3) == 0
               block_index += 4;
               const size_t ntz4 = var_ctz64(block_index);

               xor_buf(offsets, m_offset.data(), L0.data(), m_BS);
               offsets += m_BS;

               xor_buf(offsets, offsets - m_BS, L1.data(), m_BS);
               offsets += m_BS;

               xor_buf(m_offset.data(), L1.data(), m_BS);
               copy_mem(offsets, m_offset.data(), m_BS);
               offsets += m_BS;

               xor_buf(m_offset.data(), get(ntz4).data(), m_BS);
               copy_mem(offsets, m_offset.data(), m_BS);
               offsets += m_BS;

               blocks -= 4;
            }
         }

         for(size_t i = 0; i != blocks; ++i) {  // could be done in parallel
            const size_t ntz = var_ctz64(block_index + i + 1);
            xor_buf(m_offset.data(), get(ntz).data(), m_BS);
            copy_mem(offsets, m_offset.data(), m_BS);
            offsets += m_BS;
         }

         return m_offset_buf.data();
      }

   private:
      static secure_vector<uint8_t> poly_double(const secure_vector<uint8_t>& in) {
         secure_vector<uint8_t> out(in.size());
         poly_double_n(out.data(), in.data(), out.size());
         return out;
      }

      const size_t m_BS, m_max_blocks;
      secure_vector<uint8_t> m_L_dollar, m_L_star;
      secure_vector<uint8_t> m_offset;
      mutable std::vector<secure_vector<uint8_t>> m_L;
      secure_vector<uint8_t> m_offset_buf;
};

namespace {

/*
* OCB's HASH
*/
secure_vector<uint8_t> ocb_hash(const L_computer& L, const BlockCipher& cipher, const uint8_t ad[], size_t ad_len) {
   const size_t BS = cipher.block_size();
   secure_vector<uint8_t> sum(BS);
   secure_vector<uint8_t> offset(BS);

   secure_vector<uint8_t> buf(BS);

   const size_t ad_blocks = (ad_len / BS);
   const size_t ad_remainder = (ad_len % BS);

   for(size_t i = 0; i != ad_blocks; ++i) {
      // this loop could run in parallel
      offset ^= L.get(var_ctz64(i + 1));
      buf = offset;
      xor_buf(buf.data(), &ad[BS * i], BS);
      cipher.encrypt(buf);
      sum ^= buf;
   }

   if(ad_remainder > 0) {
      offset ^= L.star();
      buf = offset;
      xor_buf(buf.data(), &ad[BS * ad_blocks], ad_remainder);
      buf[ad_remainder] ^= 0x80;
      cipher.encrypt(buf);
      sum ^= buf;
   }

   return sum;
}

}  // namespace

OCB_Mode::OCB_Mode(std::unique_ptr<BlockCipher> cipher, size_t tag_size) :
      m_cipher(std::move(cipher)),
      m_checksum(m_cipher->parallel_bytes()),
      m_ad_hash(m_cipher->block_size()),
      m_tag_size(tag_size),
      m_block_size(m_cipher->block_size()),
      m_par_blocks(m_cipher->parallel_bytes() / m_block_size) {
   const size_t BS = block_size();

   /*
   * draft-krovetz-ocb-wide-d1 specifies OCB for several other block
   * sizes but only 128, 192, 256 and 512 bit are currently supported
   * by this implementation.
   */
   BOTAN_ARG_CHECK(BS == 16 || BS == 24 || BS == 32 || BS == 64, "Invalid block size for OCB");

   BOTAN_ARG_CHECK(m_tag_size % 4 == 0 && m_tag_size >= 8 && m_tag_size <= BS && m_tag_size <= 32,
                   "Invalid OCB tag length");
}

OCB_Mode::~OCB_Mode() = default;

void OCB_Mode::clear() {
   m_cipher->clear();
   m_L.reset();  // add clear here?
   reset();
}

void OCB_Mode::reset() {
   m_block_index = 0;
   zeroise(m_ad_hash);
   zeroise(m_checksum);
   m_last_nonce.clear();
   m_stretch.clear();
   zeroise(m_nonce_buf);
   zeroise(m_offset);
}

bool OCB_Mode::valid_nonce_length(size_t length) const {
   if(length == 0) {
      return false;
   }
   if(block_size() == 16) {
      return length < 16;
   } else {
      return length < (block_size() - 1);
   }
}

std::string OCB_Mode::name() const {
   return m_cipher->name() + "/OCB";  // include tag size?
}

size_t OCB_Mode::update_granularity() const {
   return block_size();
}

size_t OCB_Mode::ideal_granularity() const {
   return (m_par_blocks * block_size());
}

Key_Length_Specification OCB_Mode::key_spec() const {
   return m_cipher->key_spec();
}

bool OCB_Mode::has_keying_material() const {
   return m_cipher->has_keying_material();
}

void OCB_Mode::key_schedule(std::span<const uint8_t> key) {
   m_cipher->set_key(key);
   m_L = std::make_unique<L_computer>(*m_cipher);
}

void OCB_Mode::set_associated_data_n(size_t idx, std::span<const uint8_t> ad) {
   BOTAN_ARG_CHECK(idx == 0, "OCB: cannot handle non-zero index in set_associated_data_n");
   assert_key_material_set();
   m_ad_hash = ocb_hash(*m_L, *m_cipher, ad.data(), ad.size());
}

const secure_vector<uint8_t>& OCB_Mode::update_nonce(const uint8_t nonce[], size_t nonce_len) {
   const size_t BS = block_size();

   BOTAN_ASSERT(BS == 16 || BS == 24 || BS == 32 || BS == 64, "OCB block size is supported");

   // NOLINTNEXTLINE(readability-avoid-nested-conditional-operator)
   const size_t MASKLEN = (BS == 16 ? 6 : ((BS == 24) ? 7 : 8));

   const uint8_t BOTTOM_MASK = static_cast<uint8_t>((static_cast<uint16_t>(1) << MASKLEN) - 1);

   m_nonce_buf.resize(BS);
   clear_mem(m_nonce_buf.data(), m_nonce_buf.size());

   copy_mem(&m_nonce_buf[BS - nonce_len], nonce, nonce_len);
   m_nonce_buf[0] = static_cast<uint8_t>(((tag_size() * 8) % (BS * 8)) << (BS <= 16 ? 1 : 0));

   m_nonce_buf[BS - nonce_len - 1] ^= 1;

   const uint8_t bottom = m_nonce_buf[BS - 1] & BOTTOM_MASK;
   m_nonce_buf[BS - 1] &= ~BOTTOM_MASK;

   const bool need_new_stretch = (m_last_nonce != m_nonce_buf);

   if(need_new_stretch) {
      m_last_nonce = m_nonce_buf;

      m_cipher->encrypt(m_nonce_buf);

      /*
      The loop bounds (BS vs BS/2) are derived from the relation
      between the block size and the MASKLEN. Using the terminology
      of draft-krovetz-ocb-wide, we have to derive enough bits in
      ShiftedKtop to read up to BLOCKLEN+bottom bits from Stretch.

                 +----------+---------+-------+---------+
                 | BLOCKLEN | RESIDUE | SHIFT | MASKLEN |
                 +----------+---------+-------+---------+
                 |       32 |     141 |    17 |    4    |
                 |       64 |      27 |    25 |    5    |
                 |       96 |    1601 |    33 |    6    |
                 |      128 |     135 |     8 |    6    |
                 |      192 |     135 |    40 |    7    |
                 |      256 |    1061 |     1 |    8    |
                 |      384 |    4109 |    80 |    8    |
                 |      512 |     293 |   176 |    8    |
                 |     1024 |  524355 |   352 |    9    |
                 +----------+---------+-------+---------+
      */
      if(BS == 16) {
         for(size_t i = 0; i != BS / 2; ++i) {
            m_nonce_buf.push_back(m_nonce_buf[i] ^ m_nonce_buf[i + 1]);
         }
      } else if(BS == 24) {
         for(size_t i = 0; i != 16; ++i) {
            m_nonce_buf.push_back(m_nonce_buf[i] ^ m_nonce_buf[i + 5]);
         }
      } else if(BS == 32) {
         for(size_t i = 0; i != BS; ++i) {
            m_nonce_buf.push_back(m_nonce_buf[i] ^ (m_nonce_buf[i] << 1) ^ (m_nonce_buf[i + 1] >> 7));
         }
      } else if(BS == 64) {
         for(size_t i = 0; i != BS / 2; ++i) {
            m_nonce_buf.push_back(m_nonce_buf[i] ^ m_nonce_buf[i + 22]);
         }
      }

      m_stretch = m_nonce_buf;
   }

   // now set the offset from stretch and bottom
   const size_t shift_bytes = bottom / 8;
   const size_t shift_bits = bottom % 8;

   BOTAN_ASSERT(m_stretch.size() >= BS + shift_bytes + 1, "Size ok");

   m_offset.resize(BS);
   for(size_t i = 0; i != BS; ++i) {
      m_offset[i] = (m_stretch[i + shift_bytes] << shift_bits);
      m_offset[i] |= (m_stretch[i + shift_bytes + 1] >> (8 - shift_bits));
   }

   return m_offset;
}

void OCB_Mode::start_msg(const uint8_t nonce[], size_t nonce_len) {
   if(!valid_nonce_length(nonce_len)) {
      throw Invalid_IV_Length(name(), nonce_len);
   }

   assert_key_material_set();

   m_L->init(update_nonce(nonce, nonce_len));
   zeroise(m_checksum);
   m_block_index = 0;
}

void OCB_Encryption::encrypt(uint8_t buffer[], size_t blocks) {
   assert_key_material_set();
   BOTAN_STATE_CHECK(m_L->initialized());

   const size_t BS = block_size();

   while(blocks > 0) {
      const size_t proc_blocks = std::min(blocks, par_blocks());
      const size_t proc_bytes = proc_blocks * BS;

      const uint8_t* offsets = m_L->compute_offsets(m_block_index, proc_blocks);

      xor_buf(m_checksum.data(), buffer, proc_bytes);

      xor_buf(buffer, offsets, proc_bytes);
      m_cipher->encrypt_n(buffer, buffer, proc_blocks);
      xor_buf(buffer, offsets, proc_bytes);

      buffer += proc_bytes;
      blocks -= proc_blocks;
      m_block_index += proc_blocks;
   }
}

size_t OCB_Encryption::process_msg(uint8_t buf[], size_t sz) {
   BOTAN_ARG_CHECK(sz % update_granularity() == 0, "Invalid OCB input size");
   encrypt(buf, sz / block_size());
   return sz;
}

void OCB_Encryption::finish_msg(secure_vector<uint8_t>& buffer, size_t offset) {
   assert_key_material_set();
   BOTAN_STATE_CHECK(m_L->initialized());

   const size_t BS = block_size();

   BOTAN_ARG_CHECK(buffer.size() >= offset, "Offset is out of range");
   const size_t sz = buffer.size() - offset;
   uint8_t* buf = buffer.data() + offset;

   secure_vector<uint8_t> mac(BS);

   if(sz > 0) {
      const size_t final_full_blocks = sz / BS;
      const size_t remainder_bytes = sz - (final_full_blocks * BS);

      encrypt(buf, final_full_blocks);
      mac = m_L->offset();

      if(remainder_bytes > 0) {
         BOTAN_ASSERT(remainder_bytes < BS, "Only a partial block left");
         uint8_t* remainder = &buf[sz - remainder_bytes];

         xor_buf(m_checksum.data(), remainder, remainder_bytes);
         m_checksum[remainder_bytes] ^= 0x80;

         // Offset_*
         mac ^= m_L->star();

         secure_vector<uint8_t> pad(BS);
         m_cipher->encrypt(mac, pad);
         xor_buf(remainder, pad.data(), remainder_bytes);
      }
   } else {
      mac = m_L->offset();
   }

   // now compute the tag

   // fold checksum
   for(size_t i = 0; i != m_checksum.size(); i += BS) {
      xor_buf(mac.data(), m_checksum.data() + i, BS);
   }

   xor_buf(mac.data(), m_L->dollar().data(), BS);
   m_cipher->encrypt(mac);
   xor_buf(mac.data(), m_ad_hash.data(), BS);

   buffer += std::make_pair(mac.data(), tag_size());

   zeroise(m_checksum);
   m_block_index = 0;
}

void OCB_Decryption::decrypt(uint8_t buffer[], size_t blocks) {
   assert_key_material_set();
   BOTAN_STATE_CHECK(m_L->initialized());

   const size_t BS = block_size();

   while(blocks > 0) {
      const size_t proc_blocks = std::min(blocks, par_blocks());
      const size_t proc_bytes = proc_blocks * BS;

      const uint8_t* offsets = m_L->compute_offsets(m_block_index, proc_blocks);

      xor_buf(buffer, offsets, proc_bytes);
      m_cipher->decrypt_n(buffer, buffer, proc_blocks);
      xor_buf(buffer, offsets, proc_bytes);

      xor_buf(m_checksum.data(), buffer, proc_bytes);

      buffer += proc_bytes;
      blocks -= proc_blocks;
      m_block_index += proc_blocks;
   }
}

size_t OCB_Decryption::process_msg(uint8_t buf[], size_t sz) {
   BOTAN_ARG_CHECK(sz % update_granularity() == 0, "Invalid OCB input size");
   decrypt(buf, sz / block_size());
   return sz;
}

void OCB_Decryption::finish_msg(secure_vector<uint8_t>& buffer, size_t offset) {
   assert_key_material_set();
   BOTAN_STATE_CHECK(m_L->initialized());

   const size_t BS = block_size();

   BOTAN_ARG_CHECK(buffer.size() >= offset, "Offset is out of range");
   const size_t sz = buffer.size() - offset;
   uint8_t* buf = buffer.data() + offset;

   BOTAN_ARG_CHECK(sz >= tag_size(), "input did not include the tag");

   const size_t remaining = sz - tag_size();

   secure_vector<uint8_t> mac(BS);

   if(remaining > 0) {
      const size_t final_full_blocks = remaining / BS;
      const size_t final_bytes = remaining - (final_full_blocks * BS);

      decrypt(buf, final_full_blocks);
      mac ^= m_L->offset();

      if(final_bytes > 0) {
         BOTAN_ASSERT(final_bytes < BS, "Only a partial block left");

         uint8_t* remainder = &buf[remaining - final_bytes];

         mac ^= m_L->star();
         secure_vector<uint8_t> pad(BS);
         m_cipher->encrypt(mac, pad);  // P_*
         xor_buf(remainder, pad.data(), final_bytes);

         xor_buf(m_checksum.data(), remainder, final_bytes);
         m_checksum[final_bytes] ^= 0x80;
      }
   } else {
      mac = m_L->offset();
   }

   // compute the mac

   // fold checksum
   for(size_t i = 0; i != m_checksum.size(); i += BS) {
      xor_buf(mac.data(), m_checksum.data() + i, BS);
   }

   mac ^= m_L->dollar();
   m_cipher->encrypt(mac);
   mac ^= m_ad_hash;

   // reset state
   zeroise(m_checksum);
   m_block_index = 0;

   // compare mac
   const uint8_t* included_tag = &buf[remaining];

   if(!CT::is_equal(mac.data(), included_tag, tag_size()).as_bool()) {
      clear_mem(std::span{buffer}.subspan(offset, remaining));
      throw Invalid_Authentication_Tag("OCB tag check failed");
   }

   // remove tag from end of message
   buffer.resize(remaining + offset);
}

}  // namespace Botan

1	/*
2	* OCB Mode
3	* (C) 2013,2017 Jack Lloyd
4	* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
5	*
6	* Botan is released under the Simplified BSD License (see license.txt)
7	*/
8
9	#include <botan/internal/ocb.h>
10
11	#include <botan/block_cipher.h>
12	#include <botan/exceptn.h>
13	#include <botan/mem_ops.h>
14	#include <botan/internal/bit_ops.h>
15	#include <botan/internal/ct_utils.h>
16	#include <botan/internal/poly_dbl.h>
17
18	namespace Botan {
19
20	// Has to be in Botan namespace so unique_ptr can reference it
21	class L_computer final {
22	public:
23	explicit L_computer(const BlockCipher& cipher) :	225✔
24	m_BS(cipher.block_size()), m_max_blocks(cipher.parallel_bytes() / m_BS) {	450✔
25	m_L_star.resize(m_BS);	225✔
26	cipher.encrypt(m_L_star);	225✔
27	m_L_dollar = poly_double(star());	225✔
28
29	// Preallocate the m_L vector to the maximum expected size to avoid
30	// re-allocations during runtime. This had caused a use-after-free in
31	// earlier versions, due to references into this buffer becoming stale
32	// in `compute_offset()`, after calling `get()` in the hot path.
33	//
34	// Note, that the list member won't be pre-allocated, so the expected
35	// memory overhead is negligible.
36	//
37	// See also https://github.com/randombit/botan/issues/3812
38	m_L.reserve(65);	225✔
39	m_L.push_back(poly_double(dollar()));	225✔
40
41	while(m_L.size() < 8) {	1,800✔
42	m_L.push_back(poly_double(m_L.back()));	3,150✔
43	}
44
45	m_offset_buf.resize(m_BS * m_max_blocks);	225✔
46	}	225✔
47
48	void init(const secure_vector<uint8_t>& offset) { m_offset = offset; }	9,439✔
49
50	bool initialized() const { return !m_offset.empty(); }	16,572✔
51
52	const secure_vector<uint8_t>& star() const { return m_L_star; }	6,047✔
53
54	const secure_vector<uint8_t>& dollar() const { return m_L_dollar; }	9,572✔
55
56	const secure_vector<uint8_t>& offset() const { return m_offset; }	9,347✔
57
58	const secure_vector<uint8_t>& get(size_t i) const {	121,863✔
59	while(m_L.size() <= i) {	121,950✔
60	m_L.push_back(poly_double(m_L.back()));	174✔
61	}
62
63	return m_L[i];	121,863✔
64	}
65
66	const uint8_t* compute_offsets(uint64_t block_index, size_t blocks) {	14,528✔
67	BOTAN_ASSERT(blocks <= m_max_blocks, "OCB offsets");	14,528✔
68
69	uint8_t* offsets = m_offset_buf.data();	14,528✔
70
71	if(block_index % 4 == 0) {	14,528✔
72	const secure_vector<uint8_t>& L0 = get(0);	14,074✔
73	const secure_vector<uint8_t>& L1 = get(1);	14,074✔
74
75	while(blocks >= 4) {	65,227✔
76	// ntz(4*i+1) == 0
77	// ntz(4*i+2) == 1
78	// ntz(4*i+3) == 0
79	block_index += 4;	37,079✔
80	const size_t ntz4 = var_ctz64(block_index);	37,079✔
81
82	xor_buf(offsets, m_offset.data(), L0.data(), m_BS);	37,079✔
83	offsets += m_BS;	37,079✔
84
85	xor_buf(offsets, offsets - m_BS, L1.data(), m_BS);	37,079✔
86	offsets += m_BS;	37,079✔
87
88	xor_buf(m_offset.data(), L1.data(), m_BS);	37,079✔
89	copy_mem(offsets, m_offset.data(), m_BS);	37,079✔
90	offsets += m_BS;	37,079✔
91
92	xor_buf(m_offset.data(), get(ntz4).data(), m_BS);	37,079✔
93	copy_mem(offsets, m_offset.data(), m_BS);	37,079✔
94	offsets += m_BS;	37,079✔
95
96	blocks -= 4;	37,079✔
97	}
98	}
99
100	for(size_t i = 0; i != blocks; ++i) { // could be done in parallel	24,159✔
101	const size_t ntz = var_ctz64(block_index + i + 1);	9,631✔
102	xor_buf(m_offset.data(), get(ntz).data(), m_BS);	9,631✔
103	copy_mem(offsets, m_offset.data(), m_BS);	9,631✔
104	offsets += m_BS;	9,631✔
105	}
106
107	return m_offset_buf.data();	14,528✔
108	}
109
110	private:
111	static secure_vector<uint8_t> poly_double(const secure_vector<uint8_t>& in) {	2,112✔
112	secure_vector<uint8_t> out(in.size());	2,112✔
113	poly_double_n(out.data(), in.data(), out.size());	2,112✔
114	return out;	2,112✔
115	}	×
116
117	const size_t m_BS, m_max_blocks;
118	secure_vector<uint8_t> m_L_dollar, m_L_star;
119	secure_vector<uint8_t> m_offset;
120	mutable std::vector<secure_vector<uint8_t>> m_L;
121	secure_vector<uint8_t> m_offset_buf;
122	};
123
124	namespace {
125
126	/*
127	* OCB's HASH
128	*/
129	secure_vector<uint8_t> ocb_hash(const L_computer& L, const BlockCipher& cipher, const uint8_t ad[], size_t ad_len) {	9,495✔
130	const size_t BS = cipher.block_size();	9,495✔
131	secure_vector<uint8_t> sum(BS);	9,495✔
132	secure_vector<uint8_t> offset(BS);	9,495✔
133
134	secure_vector<uint8_t> buf(BS);	9,495✔
135
136	const size_t ad_blocks = (ad_len / BS);	9,495✔
137	const size_t ad_remainder = (ad_len % BS);	9,495✔
138
139	for(size_t i = 0; i != ad_blocks; ++i) {	56,500✔
140	// this loop could run in parallel
141	offset ^= L.get(var_ctz64(i + 1));	94,010✔
142	buf = offset;	47,005✔
143	xor_buf(buf.data(), &ad[BS * i], BS);	47,005✔
144	cipher.encrypt(buf);	47,005✔
145	sum ^= buf;	47,005✔
146	}
147
148	if(ad_remainder > 0) {	9,495✔
149	offset ^= L.star();	5,869✔
150	buf = offset;	5,869✔
151	xor_buf(buf.data(), &ad[BS * ad_blocks], ad_remainder);	5,869✔
152	buf[ad_remainder] ^= 0x80;	5,869✔
153	cipher.encrypt(buf);	5,869✔
154	sum ^= buf;	5,869✔
155	}
156
157	return sum;	9,495✔
158	}	18,990✔
159
160	} // namespace
161
162	OCB_Mode::OCB_Mode(std::unique_ptr<BlockCipher> cipher, size_t tag_size) :	317✔
163	m_cipher(std::move(cipher)),	317✔
164	m_checksum(m_cipher->parallel_bytes()),	634✔
165	m_ad_hash(m_cipher->block_size()),	317✔
166	m_tag_size(tag_size),	317✔
167	m_block_size(m_cipher->block_size()),	317✔
168	m_par_blocks(m_cipher->parallel_bytes() / m_block_size) {	951✔
169	const size_t BS = block_size();	317✔
170
171	/*
172	* draft-krovetz-ocb-wide-d1 specifies OCB for several other block
173	* sizes but only 128, 192, 256 and 512 bit are currently supported
174	* by this implementation.
175	*/
176	BOTAN_ARG_CHECK(BS == 16 \|\| BS == 24 \|\| BS == 32 \|\| BS == 64, "Invalid block size for OCB");	317✔
177
178	BOTAN_ARG_CHECK(m_tag_size % 4 == 0 && m_tag_size >= 8 && m_tag_size <= BS && m_tag_size <= 32,	317✔
179	"Invalid OCB tag length");
180	}	317✔
181
182	OCB_Mode::~OCB_Mode() = default;	1,851✔
183
184	void OCB_Mode::clear() {	92✔
185	m_cipher->clear();	92✔
186	m_L.reset(); // add clear here?	92✔
187	reset();	92✔
188	}	92✔
189
190	void OCB_Mode::reset() {	410✔
191	m_block_index = 0;	410✔
192	zeroise(m_ad_hash);	410✔
193	zeroise(m_checksum);	410✔
194	m_last_nonce.clear();	410✔
195	m_stretch.clear();	410✔
196	zeroise(m_nonce_buf);	410✔
197	zeroise(m_offset);	410✔
198	}	410✔
199
200	bool OCB_Mode::valid_nonce_length(size_t length) const {	9,485✔
201	if(length == 0) {	9,485✔
202	return false;
203	}
204	if(block_size() == 16) {	9,485✔
205	return length < 16;	7,883✔
206	} else {
207	return length < (block_size() - 1);	1,602✔
208	}
209	}
210
211	std::string OCB_Mode::name() const {	506✔
212	return m_cipher->name() + "/OCB"; // include tag size?	1,012✔
213	}
214
215	size_t OCB_Mode::update_granularity() const {	1,597✔
216	return block_size();	1,597✔
217	}
218
219	size_t OCB_Mode::ideal_granularity() const {	276✔
220	return (m_par_blocks * block_size());	276✔
221	}
222
223	Key_Length_Specification OCB_Mode::key_spec() const {	225✔
224	return m_cipher->key_spec();	225✔
225	}
226
227	bool OCB_Mode::has_keying_material() const {	36,288✔
228	return m_cipher->has_keying_material();	36,288✔
229	}
230
231	void OCB_Mode::key_schedule(std::span<const uint8_t> key) {	225✔
232	m_cipher->set_key(key);	225✔
233	m_L = std::make_unique<L_computer>(*m_cipher);	225✔
234	}	225✔
235
236	void OCB_Mode::set_associated_data_n(size_t idx, std::span<const uint8_t> ad) {	9,679✔
237	BOTAN_ARG_CHECK(idx == 0, "OCB: cannot handle non-zero index in set_associated_data_n");	9,679✔
238	assert_key_material_set();	9,679✔
239	m_ad_hash = ocb_hash(m_L, m_cipher, ad.data(), ad.size());	9,495✔
240	}	9,495✔
241
242	const secure_vector<uint8_t>& OCB_Mode::update_nonce(const uint8_t nonce[], size_t nonce_len) {	9,439✔
243	const size_t BS = block_size();	9,439✔
244
245	BOTAN_ASSERT(BS == 16 \|\| BS == 24 \|\| BS == 32 \|\| BS == 64, "OCB block size is supported");	9,439✔
246
247	// NOLINTNEXTLINE(readability-avoid-nested-conditional-operator)
248	const size_t MASKLEN = (BS == 16 ? 6 : ((BS == 24) ? 7 : 8));	9,439✔
249
250	const uint8_t BOTTOM_MASK = static_cast<uint8_t>((static_cast<uint16_t>(1) << MASKLEN) - 1);	9,439✔
251
252	m_nonce_buf.resize(BS);	9,439✔
253	clear_mem(m_nonce_buf.data(), m_nonce_buf.size());	9,439✔
254
255	copy_mem(&m_nonce_buf[BS - nonce_len], nonce, nonce_len);	9,439✔
256	m_nonce_buf[0] = static_cast<uint8_t>(((tag_size() * 8) % (BS * 8)) << (BS <= 16 ? 1 : 0));	11,037✔
257
258	m_nonce_buf[BS - nonce_len - 1] ^= 1;	9,439✔
259
260	const uint8_t bottom = m_nonce_buf[BS - 1] & BOTTOM_MASK;	9,439✔
261	m_nonce_buf[BS - 1] &= ~BOTTOM_MASK;	9,439✔
262
263	const bool need_new_stretch = (m_last_nonce != m_nonce_buf);	9,439✔
264
265	if(need_new_stretch) {	9,439✔
266	m_last_nonce = m_nonce_buf;	663✔
267
268	m_cipher->encrypt(m_nonce_buf);	663✔
269
270	/*
271	The loop bounds (BS vs BS/2) are derived from the relation
272	between the block size and the MASKLEN. Using the terminology
273	of draft-krovetz-ocb-wide, we have to derive enough bits in
274	ShiftedKtop to read up to BLOCKLEN+bottom bits from Stretch.
275
276	+----------+---------+-------+---------+
277	\| BLOCKLEN \| RESIDUE \| SHIFT \| MASKLEN \|
278	+----------+---------+-------+---------+
279	\| 32 \| 141 \| 17 \| 4 \|
280	\| 64 \| 27 \| 25 \| 5 \|
281	\| 96 \| 1601 \| 33 \| 6 \|
282	\| 128 \| 135 \| 8 \| 6 \|
283	\| 192 \| 135 \| 40 \| 7 \|
284	\| 256 \| 1061 \| 1 \| 8 \|
285	\| 384 \| 4109 \| 80 \| 8 \|
286	\| 512 \| 293 \| 176 \| 8 \|
287	\| 1024 \| 524355 \| 352 \| 9 \|
288	+----------+---------+-------+---------+
289	*/
290	if(BS == 16) {	663✔
291	for(size_t i = 0; i != BS / 2; ++i) {	5,355✔
292	m_nonce_buf.push_back(m_nonce_buf[i] ^ m_nonce_buf[i + 1]);	4,760✔
293	}
294	} else if(BS == 24) {	68✔
295	for(size_t i = 0; i != 16; ++i) {	408✔
296	m_nonce_buf.push_back(m_nonce_buf[i] ^ m_nonce_buf[i + 5]);	384✔
297	}
298	} else if(BS == 32) {	44✔
299	for(size_t i = 0; i != BS; ++i) {	1,089✔
300	m_nonce_buf.push_back(m_nonce_buf[i] ^ (m_nonce_buf[i] << 1) ^ (m_nonce_buf[i + 1] >> 7));	1,056✔
301	}
302	} else if(BS == 64) {
303	for(size_t i = 0; i != BS / 2; ++i) {	363✔
304	m_nonce_buf.push_back(m_nonce_buf[i] ^ m_nonce_buf[i + 22]);	352✔
305	}
306	}
307
308	m_stretch = m_nonce_buf;	663✔
309	}
310
311	// now set the offset from stretch and bottom
312	const size_t shift_bytes = bottom / 8;	9,439✔
313	const size_t shift_bits = bottom % 8;	9,439✔
314
315	BOTAN_ASSERT(m_stretch.size() >= BS + shift_bytes + 1, "Size ok");	9,439✔
316
317	m_offset.resize(BS);	9,439✔
318	for(size_t i = 0; i != BS; ++i) {	195,399✔
319	m_offset[i] = (m_stretch[i + shift_bytes] << shift_bits);	185,960✔
320	m_offset[i] \|= (m_stretch[i + shift_bytes + 1] >> (8 - shift_bits));	185,960✔
321	}
322
323	return m_offset;	9,439✔
324	}
325
326	void OCB_Mode::start_msg(const uint8_t nonce[], size_t nonce_len) {	9,439✔
327	if(!valid_nonce_length(nonce_len)) {	9,439✔
328	throw Invalid_IV_Length(name(), nonce_len);	×
329	}
330
331	assert_key_material_set();	9,439✔
332
333	m_L->init(update_nonce(nonce, nonce_len));	9,439✔
334	zeroise(m_checksum);	9,439✔
335	m_block_index = 0;	9,439✔
336	}	9,439✔
337
338	void OCB_Encryption::encrypt(uint8_t buffer[], size_t blocks) {	4,193✔
339	assert_key_material_set();	4,193✔
340	BOTAN_STATE_CHECK(m_L->initialized());	4,147✔
341
342	const size_t BS = block_size();	4,101✔
343
344	while(blocks > 0) {	11,778✔
345	const size_t proc_blocks = std::min(blocks, par_blocks());	7,677✔
346	const size_t proc_bytes = proc_blocks * BS;	7,677✔
347
348	const uint8_t* offsets = m_L->compute_offsets(m_block_index, proc_blocks);	7,677✔
349
350	xor_buf(m_checksum.data(), buffer, proc_bytes);	7,677✔
351
352	xor_buf(buffer, offsets, proc_bytes);	7,677✔
353	m_cipher->encrypt_n(buffer, buffer, proc_blocks);	7,677✔
354	xor_buf(buffer, offsets, proc_bytes);	7,677✔
355
356	buffer += proc_bytes;	7,677✔
357	blocks -= proc_blocks;	7,677✔
358	m_block_index += proc_blocks;	7,677✔
359	}
360	}	4,101✔
361
362	size_t OCB_Encryption::process_msg(uint8_t buf[], size_t sz) {	500✔
363	BOTAN_ARG_CHECK(sz % update_granularity() == 0, "Invalid OCB input size");	500✔
364	encrypt(buf, sz / block_size());	500✔
365	return sz;	408✔
366	}
367
368	void OCB_Encryption::finish_msg(secure_vector<uint8_t>& buffer, size_t offset) {	5,699✔
369	assert_key_material_set();	5,699✔
370	BOTAN_STATE_CHECK(m_L->initialized());	5,607✔
371
372	const size_t BS = block_size();	5,561✔
373
374	BOTAN_ARG_CHECK(buffer.size() >= offset, "Offset is out of range");	5,561✔
375	const size_t sz = buffer.size() - offset;	5,561✔
376	uint8_t* buf = buffer.data() + offset;	5,561✔
377
378	secure_vector<uint8_t> mac(BS);	5,561✔
379
380	if(sz > 0) {	5,561✔
381	const size_t final_full_blocks = sz / BS;	3,693✔
382	const size_t remainder_bytes = sz - (final_full_blocks * BS);	3,693✔
383
384	encrypt(buf, final_full_blocks);	3,693✔
385	mac = m_L->offset();	3,693✔
386
387	if(remainder_bytes > 0) {	3,693✔
388	BOTAN_ASSERT(remainder_bytes < BS, "Only a partial block left");	3,493✔
389	uint8_t* remainder = &buf[sz - remainder_bytes];	3,493✔
390
391	xor_buf(m_checksum.data(), remainder, remainder_bytes);	3,493✔
392	m_checksum[remainder_bytes] ^= 0x80;	3,493✔
393
394	// Offset_*
395	mac ^= m_L->star();	3,493✔
396
397	secure_vector<uint8_t> pad(BS);	3,493✔
398	m_cipher->encrypt(mac, pad);	3,493✔
399	xor_buf(remainder, pad.data(), remainder_bytes);	3,493✔
400	}	3,493✔
401	} else {
402	mac = m_L->offset();	1,868✔
403	}
404
405	// now compute the tag
406
407	// fold checksum
408	for(size_t i = 0; i != m_checksum.size(); i += BS) {	152,553✔
409	xor_buf(mac.data(), m_checksum.data() + i, BS);	146,992✔
410	}
411
412	xor_buf(mac.data(), m_L->dollar().data(), BS);	5,561✔
413	m_cipher->encrypt(mac);	5,561✔
414	xor_buf(mac.data(), m_ad_hash.data(), BS);	5,561✔
415
416	buffer += std::make_pair(mac.data(), tag_size());	5,561✔
417
418	zeroise(m_checksum);	5,561✔
419	m_block_index = 0;	5,561✔
420	}	5,561✔
421
422	void OCB_Decryption::decrypt(uint8_t buffer[], size_t blocks) {	3,032✔
423	assert_key_material_set();	3,032✔
424	BOTAN_STATE_CHECK(m_L->initialized());	2,986✔
425
426	const size_t BS = block_size();	2,940✔
427
428	while(blocks > 0) {	9,791✔
429	const size_t proc_blocks = std::min(blocks, par_blocks());	6,851✔
430	const size_t proc_bytes = proc_blocks * BS;	6,851✔
431
432	const uint8_t* offsets = m_L->compute_offsets(m_block_index, proc_blocks);	6,851✔
433
434	xor_buf(buffer, offsets, proc_bytes);	6,851✔
435	m_cipher->decrypt_n(buffer, buffer, proc_blocks);	6,851✔
436	xor_buf(buffer, offsets, proc_bytes);	6,851✔
437
438	xor_buf(m_checksum.data(), buffer, proc_bytes);	6,851✔
439
440	buffer += proc_bytes;	6,851✔
441	blocks -= proc_blocks;	6,851✔
442	m_block_index += proc_blocks;	6,851✔
443	}
444	}	2,940✔
445
446	size_t OCB_Decryption::process_msg(uint8_t buf[], size_t sz) {	513✔
447	BOTAN_ARG_CHECK(sz % update_granularity() == 0, "Invalid OCB input size");	513✔
448	decrypt(buf, sz / block_size());	513✔
449	return sz;	421✔
450	}
451
452	void OCB_Decryption::finish_msg(secure_vector<uint8_t>& buffer, size_t offset) {	3,924✔
453	assert_key_material_set();	3,924✔
454	BOTAN_STATE_CHECK(m_L->initialized());	3,832✔
455
456	const size_t BS = block_size();	3,786✔
457
458	BOTAN_ARG_CHECK(buffer.size() >= offset, "Offset is out of range");	3,786✔
459	const size_t sz = buffer.size() - offset;	3,786✔
460	uint8_t* buf = buffer.data() + offset;	3,786✔
461
462	BOTAN_ARG_CHECK(sz >= tag_size(), "input did not include the tag");	3,786✔
463
464	const size_t remaining = sz - tag_size();	3,786✔
465
466	secure_vector<uint8_t> mac(BS);	3,786✔
467
468	if(remaining > 0) {	3,786✔
469	const size_t final_full_blocks = remaining / BS;	2,519✔
470	const size_t final_bytes = remaining - (final_full_blocks * BS);	2,519✔
471
472	decrypt(buf, final_full_blocks);	2,519✔
473	mac ^= m_L->offset();	2,519✔
474
475	if(final_bytes > 0) {	2,519✔
476	BOTAN_ASSERT(final_bytes < BS, "Only a partial block left");	2,329✔
477
478	uint8_t* remainder = &buf[remaining - final_bytes];	2,329✔
479
480	mac ^= m_L->star();	2,329✔
481	secure_vector<uint8_t> pad(BS);	2,467✔
482	m_cipher->encrypt(mac, pad); // P_*	2,329✔
483	xor_buf(remainder, pad.data(), final_bytes);	2,329✔
484
485	xor_buf(m_checksum.data(), remainder, final_bytes);	2,329✔
486	m_checksum[final_bytes] ^= 0x80;	2,329✔
487	}	2,329✔
488	} else {
489	mac = m_L->offset();	1,267✔
490	}
491
492	// compute the mac
493
494	// fold checksum
495	for(size_t i = 0; i != m_checksum.size(); i += BS) {	125,046✔
496	xor_buf(mac.data(), m_checksum.data() + i, BS);	121,260✔
497	}
498
499	mac ^= m_L->dollar();	3,786✔
500	m_cipher->encrypt(mac);	3,786✔
501	mac ^= m_ad_hash;	3,786✔
502
503	// reset state
504	zeroise(m_checksum);	3,786✔
505	m_block_index = 0;	3,786✔
506
507	// compare mac
508	const uint8_t* included_tag = &buf[remaining];	3,786✔
509
510	if(!CT::is_equal(mac.data(), included_tag, tag_size()).as_bool()) {	3,786✔
511	clear_mem(std::span{buffer}.subspan(offset, remaining));	138✔
512	throw Invalid_Authentication_Tag("OCB tag check failed");	138✔
513	}
514
515	// remove tag from end of message
516	buffer.resize(remaining + offset);	3,648✔
517	}	3,648✔
518
519	} // namespace Botan

randombit / botan / 24053024312

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