13258120944

Committed 11 Feb 2025 07:48AM UTC coverage: 91.661% (+0.002%) from 91.659%

Build # 13258120944

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Pull #4647

github

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web-flow

Commit Message

Merge 311224e67 into f372b5a9e

Pull Request Pull Request #4647: Avoid using mem_ops.h or assert.h in public headers

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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/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(31);
         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() == false; }

      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(size_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_ctz32(static_cast<uint32_t>(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_ctz32(static_cast<uint32_t>(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_ctz32(static_cast<uint32_t>(i + 1)));
      buf = offset;
      xor_buf(buf.data(), &ad[BS * i], BS);
      cipher.encrypt(buf);
      sum ^= buf;
   }

   if(ad_remainder) {
      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();
}

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[0], 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) {
      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) {
      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) {
         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) {
      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) {
      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) {
         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()) {
      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/mem_ops.h>
13	#include <botan/internal/bit_ops.h>
14	#include <botan/internal/ct_utils.h>
15	#include <botan/internal/poly_dbl.h>
16
17	namespace Botan {
18
19	// Has to be in Botan namespace so unique_ptr can reference it
20	class L_computer final {
21	public:
22	explicit L_computer(const BlockCipher& cipher) :	245✔
23	m_BS(cipher.block_size()), m_max_blocks(cipher.parallel_bytes() / m_BS) {	490✔
24	m_L_star.resize(m_BS);	245✔
25	cipher.encrypt(m_L_star);	245✔
26	m_L_dollar = poly_double(star());	245✔
27
28	// Preallocate the m_L vector to the maximum expected size to avoid
29	// re-allocations during runtime. This had caused a use-after-free in
30	// earlier versions, due to references into this buffer becoming stale
31	// in `compute_offset()`, after calling `get()` in the hot path.
32	//
33	// Note, that the list member won't be pre-allocated, so the expected
34	// memory overhead is negligible.
35	//
36	// See also https://github.com/randombit/botan/issues/3812
37	m_L.reserve(31);	245✔
38	m_L.push_back(poly_double(dollar()));	245✔
39
40	while(m_L.size() < 8) {	1,960✔
41	m_L.push_back(poly_double(m_L.back()));	3,430✔
42	}
43
44	m_offset_buf.resize(m_BS * m_max_blocks);	245✔
45	}	245✔
46
47	void init(const secure_vector<uint8_t>& offset) { m_offset = offset; }	9,467✔
48
49	bool initialized() const { return m_offset.empty() == false; }	16,624✔
50
51	const secure_vector<uint8_t>& star() const { return m_L_star; }	6,083✔
52
53	const secure_vector<uint8_t>& dollar() const { return m_L_dollar; }	9,620✔
54
55	const secure_vector<uint8_t>& offset() const { return m_offset; }	9,375✔
56
57	const secure_vector<uint8_t>& get(size_t i) const {	121,751✔
58	while(m_L.size() <= i) {	121,838✔
59	m_L.push_back(poly_double(m_L.back()));	174✔
60	}
61
62	return m_L[i];	121,751✔
63	}
64
65	const uint8_t* compute_offsets(size_t block_index, size_t blocks) {	14,532✔
66	BOTAN_ASSERT(blocks <= m_max_blocks, "OCB offsets");	14,532✔
67
68	uint8_t* offsets = m_offset_buf.data();	14,532✔
69
70	if(block_index % 4 == 0) {	14,532✔
71	const secure_vector<uint8_t>& L0 = get(0);	14,078✔
72	const secure_vector<uint8_t>& L1 = get(1);	14,078✔
73
74	while(blocks >= 4) {	65,068✔
75	// ntz(4*i+1) == 0
76	// ntz(4*i+2) == 1
77	// ntz(4*i+3) == 0
78	block_index += 4;	36,912✔
79	const size_t ntz4 = var_ctz32(static_cast<uint32_t>(block_index));	36,912✔
80
81	xor_buf(offsets, m_offset.data(), L0.data(), m_BS);	36,912✔
82	offsets += m_BS;	36,912✔
83
84	xor_buf(offsets, offsets - m_BS, L1.data(), m_BS);	36,912✔
85	offsets += m_BS;	36,912✔
86
87	xor_buf(m_offset.data(), L1.data(), m_BS);	36,912✔
88	copy_mem(offsets, m_offset.data(), m_BS);	36,912✔
89	offsets += m_BS;	36,912✔
90
91	xor_buf(m_offset.data(), get(ntz4).data(), m_BS);	36,912✔
92	copy_mem(offsets, m_offset.data(), m_BS);	36,912✔
93	offsets += m_BS;	36,912✔
94
95	blocks -= 4;	36,912✔
96	}
97	}
98
99	for(size_t i = 0; i != blocks; ++i) { // could be done in parallel	24,189✔
100	const size_t ntz = var_ctz32(static_cast<uint32_t>(block_index + i + 1));	9,657✔
101	xor_buf(m_offset.data(), get(ntz).data(), m_BS);	9,657✔
102	copy_mem(offsets, m_offset.data(), m_BS);	9,657✔
103	offsets += m_BS;	9,657✔
104	}
105
106	return m_offset_buf.data();	14,532✔
107	}
108
109	private:
110	static secure_vector<uint8_t> poly_double(const secure_vector<uint8_t>& in) {	2,292✔
111	secure_vector<uint8_t> out(in.size());	2,292✔
112	poly_double_n(out.data(), in.data(), out.size());	2,292✔
113	return out;	2,292✔
114	}	×
115
116	const size_t m_BS, m_max_blocks;
117	secure_vector<uint8_t> m_L_dollar, m_L_star;
118	secure_vector<uint8_t> m_offset;
119	mutable std::vector<secure_vector<uint8_t>> m_L;
120	secure_vector<uint8_t> m_offset_buf;
121	};
122
123	namespace {
124
125	/*
126	* OCB's HASH
127	*/
128	secure_vector<uint8_t> ocb_hash(const L_computer& L, const BlockCipher& cipher, const uint8_t ad[], size_t ad_len) {	9,515✔
129	const size_t BS = cipher.block_size();	9,515✔
130	secure_vector<uint8_t> sum(BS);	9,515✔
131	secure_vector<uint8_t> offset(BS);	9,515✔
132
133	secure_vector<uint8_t> buf(BS);	9,515✔
134
135	const size_t ad_blocks = (ad_len / BS);	9,515✔
136	const size_t ad_remainder = (ad_len % BS);	9,515✔
137
138	for(size_t i = 0; i != ad_blocks; ++i) {	56,541✔
139	// this loop could run in parallel
140	offset ^= L.get(var_ctz32(static_cast<uint32_t>(i + 1)));	94,052✔
141	buf = offset;	47,026✔
142	xor_buf(buf.data(), &ad[BS * i], BS);	47,026✔
143	cipher.encrypt(buf);	47,026✔
144	sum ^= buf;	47,026✔
145	}
146
147	if(ad_remainder) {	9,515✔
148	offset ^= L.star();	5,884✔
149	buf = offset;	5,884✔
150	xor_buf(buf.data(), &ad[BS * ad_blocks], ad_remainder);	5,884✔
151	buf[ad_remainder] ^= 0x80;	5,884✔
152	cipher.encrypt(buf);	5,884✔
153	sum ^= buf;	5,884✔
154	}
155
156	return sum;	9,515✔
157	}	19,030✔
158
159	} // namespace
160
161	OCB_Mode::OCB_Mode(std::unique_ptr<BlockCipher> cipher, size_t tag_size) :	337✔
162	m_cipher(std::move(cipher)),	337✔
163	m_checksum(m_cipher->parallel_bytes()),	674✔
164	m_ad_hash(m_cipher->block_size()),	337✔
165	m_tag_size(tag_size),	337✔
166	m_block_size(m_cipher->block_size()),	337✔
167	m_par_blocks(m_cipher->parallel_bytes() / m_block_size) {	1,011✔
168	const size_t BS = block_size();	337✔
169
170	/*
171	* draft-krovetz-ocb-wide-d1 specifies OCB for several other block
172	* sizes but only 128, 192, 256 and 512 bit are currently supported
173	* by this implementation.
174	*/
175	BOTAN_ARG_CHECK(BS == 16 \|\| BS == 24 \|\| BS == 32 \|\| BS == 64, "Invalid block size for OCB");	337✔
176
177	BOTAN_ARG_CHECK(m_tag_size % 4 == 0 && m_tag_size >= 8 && m_tag_size <= BS && m_tag_size <= 32,	337✔
178	"Invalid OCB tag length");
179	}	337✔
180
181	OCB_Mode::~OCB_Mode() = default;	1,991✔
182
183	void OCB_Mode::clear() {	92✔
184	m_cipher->clear();	92✔
185	m_L.reset(); // add clear here?	92✔
186	reset();	92✔
187	}	92✔
188
189	void OCB_Mode::reset() {	410✔
190	m_block_index = 0;	410✔
191	zeroise(m_ad_hash);	410✔
192	zeroise(m_checksum);	410✔
193	m_last_nonce.clear();	410✔
194	m_stretch.clear();	410✔
195	}	410✔
196
197	bool OCB_Mode::valid_nonce_length(size_t length) const {	9,513✔
198	if(length == 0) {	9,513✔
199	return false;
200	}
201	if(block_size() == 16) {	9,513✔
202	return length < 16;	7,911✔
203	} else {
204	return length < (block_size() - 1);	1,602✔
205	}
206	}
207
208	std::string OCB_Mode::name() const {	506✔
209	return m_cipher->name() + "/OCB"; // include tag size?	1,012✔
210	}
211
212	size_t OCB_Mode::update_granularity() const {	1,321✔
213	return block_size();	1,321✔
214	}
215
216	size_t OCB_Mode::ideal_granularity() const {	276✔
217	return (m_par_blocks * block_size());	276✔
218	}
219
220	Key_Length_Specification OCB_Mode::key_spec() const {	245✔
221	return m_cipher->key_spec();	245✔
222	}
223
224	bool OCB_Mode::has_keying_material() const {	36,388✔
225	return m_cipher->has_keying_material();	36,388✔
226	}
227
228	void OCB_Mode::key_schedule(std::span<const uint8_t> key) {	245✔
229	m_cipher->set_key(key);	245✔
230	m_L = std::make_unique<L_computer>(*m_cipher);	245✔
231	}	245✔
232
233	void OCB_Mode::set_associated_data_n(size_t idx, std::span<const uint8_t> ad) {	9,699✔
234	BOTAN_ARG_CHECK(idx == 0, "OCB: cannot handle non-zero index in set_associated_data_n");	9,699✔
235	assert_key_material_set();	9,699✔
236	m_ad_hash = ocb_hash(m_L, m_cipher, ad.data(), ad.size());	9,515✔
237	}	9,515✔
238
239	const secure_vector<uint8_t>& OCB_Mode::update_nonce(const uint8_t nonce[], size_t nonce_len) {	9,467✔
240	const size_t BS = block_size();	9,467✔
241
242	BOTAN_ASSERT(BS == 16 \|\| BS == 24 \|\| BS == 32 \|\| BS == 64, "OCB block size is supported");	9,467✔
243
244	// NOLINTNEXTLINE(readability-avoid-nested-conditional-operator)
245	const size_t MASKLEN = (BS == 16 ? 6 : ((BS == 24) ? 7 : 8));	9,467✔
246
247	const uint8_t BOTTOM_MASK = static_cast<uint8_t>((static_cast<uint16_t>(1) << MASKLEN) - 1);	9,467✔
248
249	m_nonce_buf.resize(BS);	9,467✔
250	clear_mem(&m_nonce_buf[0], m_nonce_buf.size());	9,467✔
251
252	copy_mem(&m_nonce_buf[BS - nonce_len], nonce, nonce_len);	9,467✔
253	m_nonce_buf[0] = static_cast<uint8_t>(((tag_size() * 8) % (BS * 8)) << (BS <= 16 ? 1 : 0));	11,065✔
254
255	m_nonce_buf[BS - nonce_len - 1] ^= 1;	9,467✔
256
257	const uint8_t bottom = m_nonce_buf[BS - 1] & BOTTOM_MASK;	9,467✔
258	m_nonce_buf[BS - 1] &= ~BOTTOM_MASK;	9,467✔
259
260	const bool need_new_stretch = (m_last_nonce != m_nonce_buf);	9,467✔
261
262	if(need_new_stretch) {	9,467✔
263	m_last_nonce = m_nonce_buf;	683✔
264
265	m_cipher->encrypt(m_nonce_buf);	683✔
266
267	/*
268	The loop bounds (BS vs BS/2) are derived from the relation
269	between the block size and the MASKLEN. Using the terminology
270	of draft-krovetz-ocb-wide, we have to derive enough bits in
271	ShiftedKtop to read up to BLOCKLEN+bottom bits from Stretch.
272
273	+----------+---------+-------+---------+
274	\| BLOCKLEN \| RESIDUE \| SHIFT \| MASKLEN \|
275	+----------+---------+-------+---------+
276	\| 32 \| 141 \| 17 \| 4 \|
277	\| 64 \| 27 \| 25 \| 5 \|
278	\| 96 \| 1601 \| 33 \| 6 \|
279	\| 128 \| 135 \| 8 \| 6 \|
280	\| 192 \| 135 \| 40 \| 7 \|
281	\| 256 \| 1061 \| 1 \| 8 \|
282	\| 384 \| 4109 \| 80 \| 8 \|
283	\| 512 \| 293 \| 176 \| 8 \|
284	\| 1024 \| 524355 \| 352 \| 9 \|
285	+----------+---------+-------+---------+
286	*/
287	if(BS == 16) {	683✔
288	for(size_t i = 0; i != BS / 2; ++i) {	5,535✔
289	m_nonce_buf.push_back(m_nonce_buf[i] ^ m_nonce_buf[i + 1]);	4,920✔
290	}
291	} else if(BS == 24) {	68✔
292	for(size_t i = 0; i != 16; ++i) {	408✔
293	m_nonce_buf.push_back(m_nonce_buf[i] ^ m_nonce_buf[i + 5]);	384✔
294	}
295	} else if(BS == 32) {	44✔
296	for(size_t i = 0; i != BS; ++i) {	1,089✔
297	m_nonce_buf.push_back(m_nonce_buf[i] ^ (m_nonce_buf[i] << 1) ^ (m_nonce_buf[i + 1] >> 7));	1,056✔
298	}
299	} else if(BS == 64) {
300	for(size_t i = 0; i != BS / 2; ++i) {	363✔
301	m_nonce_buf.push_back(m_nonce_buf[i] ^ m_nonce_buf[i + 22]);	352✔
302	}
303	}
304
305	m_stretch = m_nonce_buf;	683✔
306	}
307
308	// now set the offset from stretch and bottom
309	const size_t shift_bytes = bottom / 8;	9,467✔
310	const size_t shift_bits = bottom % 8;	9,467✔
311
312	BOTAN_ASSERT(m_stretch.size() >= BS + shift_bytes + 1, "Size ok");	9,467✔
313
314	m_offset.resize(BS);	9,467✔
315	for(size_t i = 0; i != BS; ++i) {	195,875✔
316	m_offset[i] = (m_stretch[i + shift_bytes] << shift_bits);	186,408✔
317	m_offset[i] \|= (m_stretch[i + shift_bytes + 1] >> (8 - shift_bits));	186,408✔
318	}
319
320	return m_offset;	9,467✔
321	}
322
323	void OCB_Mode::start_msg(const uint8_t nonce[], size_t nonce_len) {	9,467✔
324	if(!valid_nonce_length(nonce_len)) {	9,467✔
325	throw Invalid_IV_Length(name(), nonce_len);	×
326	}
327
328	assert_key_material_set();	9,467✔
329
330	m_L->init(update_nonce(nonce, nonce_len));	9,467✔
331	zeroise(m_checksum);	9,467✔
332	m_block_index = 0;	9,467✔
333	}	9,467✔
334
335	void OCB_Encryption::encrypt(uint8_t buffer[], size_t blocks) {	4,204✔
336	assert_key_material_set();	4,204✔
337	BOTAN_STATE_CHECK(m_L->initialized());	4,158✔
338
339	const size_t BS = block_size();	4,112✔
340
341	while(blocks) {	11,790✔
342	const size_t proc_blocks = std::min(blocks, par_blocks());	7,678✔
343	const size_t proc_bytes = proc_blocks * BS;	7,678✔
344
345	const uint8_t* offsets = m_L->compute_offsets(m_block_index, proc_blocks);	7,678✔
346
347	xor_buf(m_checksum.data(), buffer, proc_bytes);	7,678✔
348
349	xor_buf(buffer, offsets, proc_bytes);	7,678✔
350	m_cipher->encrypt_n(buffer, buffer, proc_blocks);	7,678✔
351	xor_buf(buffer, offsets, proc_bytes);	7,678✔
352
353	buffer += proc_bytes;	7,678✔
354	blocks -= proc_blocks;	7,678✔
355	m_block_index += proc_blocks;	7,678✔
356	}
357	}	4,112✔
358
359	size_t OCB_Encryption::process_msg(uint8_t buf[], size_t sz) {	500✔
360	BOTAN_ARG_CHECK(sz % update_granularity() == 0, "Invalid OCB input size");	500✔
361	encrypt(buf, sz / block_size());	500✔
362	return sz;	408✔
363	}
364
365	void OCB_Encryption::finish_msg(secure_vector<uint8_t>& buffer, size_t offset) {	5,713✔
366	assert_key_material_set();	5,713✔
367	BOTAN_STATE_CHECK(m_L->initialized());	5,621✔
368
369	const size_t BS = block_size();	5,575✔
370
371	BOTAN_ARG_CHECK(buffer.size() >= offset, "Offset is out of range");	5,575✔
372	const size_t sz = buffer.size() - offset;	5,575✔
373	uint8_t* buf = buffer.data() + offset;	5,575✔
374
375	secure_vector<uint8_t> mac(BS);	5,575✔
376
377	if(sz) {	5,575✔
378	const size_t final_full_blocks = sz / BS;	3,704✔
379	const size_t remainder_bytes = sz - (final_full_blocks * BS);	3,704✔
380
381	encrypt(buf, final_full_blocks);	3,704✔
382	mac = m_L->offset();	3,704✔
383
384	if(remainder_bytes) {	3,704✔
385	BOTAN_ASSERT(remainder_bytes < BS, "Only a partial block left");	3,501✔
386	uint8_t* remainder = &buf[sz - remainder_bytes];	3,501✔
387
388	xor_buf(m_checksum.data(), remainder, remainder_bytes);	3,501✔
389	m_checksum[remainder_bytes] ^= 0x80;	3,501✔
390
391	// Offset_*
392	mac ^= m_L->star();	3,501✔
393
394	secure_vector<uint8_t> pad(BS);	3,501✔
395	m_cipher->encrypt(mac, pad);	3,501✔
396	xor_buf(remainder, pad.data(), remainder_bytes);	3,501✔
397	}	3,501✔
398	} else {
399	mac = m_L->offset();	1,871✔
400	}
401
402	// now compute the tag
403
404	// fold checksum
405	for(size_t i = 0; i != m_checksum.size(); i += BS) {	131,119✔
406	xor_buf(mac.data(), m_checksum.data() + i, BS);	125,544✔
407	}
408
409	xor_buf(mac.data(), m_L->dollar().data(), BS);	5,575✔
410	m_cipher->encrypt(mac);	5,575✔
411	xor_buf(mac.data(), m_ad_hash.data(), BS);	5,575✔
412
413	buffer += std::make_pair(mac.data(), tag_size());	5,575✔
414
415	zeroise(m_checksum);	5,575✔
416	m_block_index = 0;	5,575✔
417	}	5,575✔
418
419	void OCB_Decryption::decrypt(uint8_t buffer[], size_t blocks) {	3,045✔
420	assert_key_material_set();	3,045✔
421	BOTAN_STATE_CHECK(m_L->initialized());	2,999✔
422
423	const size_t BS = block_size();	2,953✔
424
425	while(blocks) {	9,807✔
426	const size_t proc_blocks = std::min(blocks, par_blocks());	6,854✔
427	const size_t proc_bytes = proc_blocks * BS;	6,854✔
428
429	const uint8_t* offsets = m_L->compute_offsets(m_block_index, proc_blocks);	6,854✔
430
431	xor_buf(buffer, offsets, proc_bytes);	6,854✔
432	m_cipher->decrypt_n(buffer, buffer, proc_blocks);	6,854✔
433	xor_buf(buffer, offsets, proc_bytes);	6,854✔
434
435	xor_buf(m_checksum.data(), buffer, proc_bytes);	6,854✔
436
437	buffer += proc_bytes;	6,854✔
438	blocks -= proc_blocks;	6,854✔
439	m_block_index += proc_blocks;	6,854✔
440	}
441	}	2,953✔
442
443	size_t OCB_Decryption::process_msg(uint8_t buf[], size_t sz) {	513✔
444	BOTAN_ARG_CHECK(sz % update_granularity() == 0, "Invalid OCB input size");	513✔
445	decrypt(buf, sz / block_size());	513✔
446	return sz;	421✔
447	}
448
449	void OCB_Decryption::finish_msg(secure_vector<uint8_t>& buffer, size_t offset) {	3,938✔
450	assert_key_material_set();	3,938✔
451	BOTAN_STATE_CHECK(m_L->initialized());	3,846✔
452
453	const size_t BS = block_size();	3,800✔
454
455	BOTAN_ARG_CHECK(buffer.size() >= offset, "Offset is out of range");	3,800✔
456	const size_t sz = buffer.size() - offset;	3,800✔
457	uint8_t* buf = buffer.data() + offset;	3,800✔
458
459	BOTAN_ARG_CHECK(sz >= tag_size(), "input did not include the tag");	3,800✔
460
461	const size_t remaining = sz - tag_size();	3,800✔
462
463	secure_vector<uint8_t> mac(BS);	3,800✔
464
465	if(remaining) {	3,800✔
466	const size_t final_full_blocks = remaining / BS;	2,532✔
467	const size_t final_bytes = remaining - (final_full_blocks * BS);	2,532✔
468
469	decrypt(buf, final_full_blocks);	2,532✔
470	mac ^= m_L->offset();	2,532✔
471
472	if(final_bytes) {	2,532✔
473	BOTAN_ASSERT(final_bytes < BS, "Only a partial block left");	2,337✔
474
475	uint8_t* remainder = &buf[remaining - final_bytes];	2,337✔
476
477	mac ^= m_L->star();	2,337✔
478	secure_vector<uint8_t> pad(BS);	2,475✔
479	m_cipher->encrypt(mac, pad); // P_*	2,337✔
480	xor_buf(remainder, pad.data(), final_bytes);	2,337✔
481
482	xor_buf(m_checksum.data(), remainder, final_bytes);	2,337✔
483	m_checksum[final_bytes] ^= 0x80;	2,337✔
484	}	2,337✔
485	} else {
486	mac = m_L->offset();	1,268✔
487	}
488
489	// compute the mac
490
491	// fold checksum
492	for(size_t i = 0; i != m_checksum.size(); i += BS) {	124,556✔
493	xor_buf(mac.data(), m_checksum.data() + i, BS);	120,756✔
494	}
495
496	mac ^= m_L->dollar();	3,800✔
497	m_cipher->encrypt(mac);	3,800✔
498	mac ^= m_ad_hash;	3,800✔
499
500	// reset state
501	zeroise(m_checksum);	3,800✔
502	m_block_index = 0;	3,800✔
503
504	// compare mac
505	const uint8_t* included_tag = &buf[remaining];	3,800✔
506
507	if(!CT::is_equal(mac.data(), included_tag, tag_size()).as_bool()) {	7,600✔
508	throw Invalid_Authentication_Tag("OCB tag check failed");	138✔
509	}
510
511	// remove tag from end of message
512	buffer.resize(remaining + offset);	3,662✔
513	}	3,662✔
514
515	} // namespace Botan

randombit / botan / 13258120944

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