diff options
author | lloyd <[email protected]> | 2013-08-14 19:31:00 +0000 |
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committer | lloyd <[email protected]> | 2013-08-14 19:31:00 +0000 |
commit | fea5a34379a62bfadac4b8601db4b54198b47acd (patch) | |
tree | 5971a4de1060a59ebd4e8dbecb25d5feebabaafe /src/aead/ocb/ocb.cpp | |
parent | f71a892cec86340321accff6ee06b9ab9774b89c (diff) |
Make XTS a Transformation under src/modes
Move AEAD modes to src/modes/aead
Add filters for Transformations (based on original AEAD filters)
Diffstat (limited to 'src/aead/ocb/ocb.cpp')
-rw-r--r-- | src/aead/ocb/ocb.cpp | 444 |
1 files changed, 0 insertions, 444 deletions
diff --git a/src/aead/ocb/ocb.cpp b/src/aead/ocb/ocb.cpp deleted file mode 100644 index 4cbd8bde8..000000000 --- a/src/aead/ocb/ocb.cpp +++ /dev/null @@ -1,444 +0,0 @@ -/* -* OCB Mode -* (C) 2013 Jack Lloyd -* -* Distributed under the terms of the Botan license -*/ - -#include <botan/ocb.h> -#include <botan/cmac.h> -#include <botan/internal/xor_buf.h> -#include <botan/internal/bit_ops.h> -#include <algorithm> - -namespace Botan { - -// Has to be in Botan namespace so unique_ptr can reference it -class L_computer - { - public: - L_computer(const BlockCipher& cipher) - { - m_L_star.resize(cipher.block_size()); - cipher.encrypt(m_L_star); - m_L_dollar = poly_double(star()); - m_L.push_back(poly_double(dollar())); - } - - const secure_vector<byte>& star() const { return m_L_star; } - - const secure_vector<byte>& dollar() const { return m_L_dollar; } - - const secure_vector<byte>& operator()(size_t i) const { return get(i); } - - const secure_vector<byte>& get(size_t i) const - { - while(m_L.size() <= i) - m_L.push_back(poly_double(m_L.back())); - - return m_L.at(i); - } - - private: - secure_vector<byte> poly_double(const secure_vector<byte>& in) const - { - return CMAC::poly_double(in, 0x87); - } - - secure_vector<byte> m_L_dollar, m_L_star; - mutable std::vector<secure_vector<byte>> m_L; - }; - -class Nonce_State - { - public: - Nonce_State(const BlockCipher& cipher) : m_cipher(cipher) {} - - secure_vector<byte> update_nonce(const byte nonce[], - size_t nonce_len); - private: - const BlockCipher& m_cipher; - secure_vector<byte> m_last_nonce; - secure_vector<byte> m_stretch; - }; - -secure_vector<byte> -Nonce_State::update_nonce(const byte nonce[], size_t nonce_len) - { - const size_t BS = 16; - - BOTAN_ASSERT(nonce_len < BS, "Nonce is less than 128 bits"); - - secure_vector<byte> nonce_buf(BS); - - copy_mem(&nonce_buf[BS - nonce_len], nonce, nonce_len); - nonce_buf[BS - nonce_len - 1] = 1; - - const byte bottom = nonce_buf[15] & 0x3F; - nonce_buf[15] &= 0xC0; - - const bool need_new_stretch = (m_last_nonce != nonce_buf); - - if(need_new_stretch) - { - m_last_nonce = nonce_buf; - - m_cipher.encrypt(nonce_buf); - - for(size_t i = 0; i != 8; ++i) - nonce_buf.push_back(nonce_buf[i] ^ nonce_buf[i+1]); - - m_stretch = nonce_buf; - } - - // now set the offset from stretch and bottom - - const size_t shift_bytes = bottom / 8; - const size_t shift_bits = bottom % 8; - - secure_vector<byte> offset(BS); - for(size_t i = 0; i != BS; ++i) - { - offset[i] = (m_stretch[i+shift_bytes] << shift_bits); - offset[i] |= (m_stretch[i+shift_bytes+1] >> (8-shift_bits)); - } - - return offset; - } - -namespace { - -/* -* OCB's HASH -*/ -secure_vector<byte> ocb_hash(const L_computer& L, - const BlockCipher& cipher, - const byte ad[], size_t ad_len) - { - const size_t BS = cipher.block_size(); - - secure_vector<byte> sum(BS); - secure_vector<byte> offset(BS); - - secure_vector<byte> 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(ctz(i+1)); - - buf = offset; - xor_buf(&buf[0], &ad[BS*i], BS); - - cipher.encrypt(buf); - - sum ^= buf; - } - - if(ad_remainder) - { - offset ^= L.star(); - - buf = offset; - xor_buf(&buf[0], &ad[BS*ad_blocks], ad_remainder); - buf[ad_len % BS] ^= 0x80; - - cipher.encrypt(buf); - - sum ^= buf; - } - - return sum; - } - -} - -OCB_Mode::OCB_Mode(BlockCipher* cipher, size_t tag_size) : - m_cipher(cipher), - m_tag_size(tag_size), - m_ad_hash(BS), m_offset(BS), m_checksum(BS) - { - if(m_cipher->block_size() != BS) - throw std::invalid_argument("OCB requires a 128 bit cipher so cannot be used with " + - m_cipher->name()); - - if(m_tag_size != 16) // fixme: 64, 96 bits also supported - throw std::invalid_argument("OCB cannot produce a " + std::to_string(m_tag_size) + - " byte tag"); - - } - -OCB_Mode::~OCB_Mode() { /* for unique_ptr destructor */ } - -void OCB_Mode::clear() - { - m_cipher.reset(); - m_L.reset(); - zeroise(m_ad_hash); - zeroise(m_offset); - zeroise(m_checksum); - } - -bool OCB_Mode::valid_nonce_length(size_t length) const - { - return (length > 0 && length < 16); - } - -std::string OCB_Mode::name() const - { - return m_cipher->name() + "/OCB"; // include tag size - } - -size_t OCB_Mode::update_granularity() const - { - return 8 * m_cipher->parallel_bytes(); - } - -Key_Length_Specification OCB_Mode::key_spec() const - { - return m_cipher->key_spec(); - } - -void OCB_Mode::key_schedule(const byte key[], size_t length) - { - m_cipher->set_key(key, length); - m_L.reset(new L_computer(*m_cipher)); - m_nonce_state.reset(new Nonce_State(*m_cipher)); - } - -void OCB_Mode::set_associated_data(const byte ad[], size_t ad_len) - { - BOTAN_ASSERT(m_L, "A key was set"); - m_ad_hash = ocb_hash(*m_L, *m_cipher, &ad[0], ad_len); - } - -secure_vector<byte> OCB_Mode::start(const byte nonce[], size_t nonce_len) - { - if(!valid_nonce_length(nonce_len)) - throw Invalid_IV_Length(name(), nonce_len); - - BOTAN_ASSERT(m_nonce_state, "A key was set"); - - m_offset = m_nonce_state->update_nonce(nonce, nonce_len); - zeroise(m_checksum); - m_block_index = 0; - - return secure_vector<byte>(); - } - -void OCB_Encryption::encrypt(byte buffer[], size_t blocks) - { - const L_computer& L = *m_L; // convenient name - - const size_t par_bytes = m_cipher->parallel_bytes(); - - BOTAN_ASSERT(par_bytes % BS == 0, "Cipher is parallel in full blocks"); - - const size_t par_blocks = par_bytes / BS; - - secure_vector<byte> csum_accum(par_bytes); - secure_vector<byte> offsets(par_bytes); - - size_t blocks_left = blocks; - - while(blocks_left) - { - const size_t proc_blocks = std::min(blocks_left, par_blocks); - const size_t proc_bytes = proc_blocks * BS; - - for(size_t i = 0; i != proc_blocks; ++i) - { // could be done in parallel - m_offset ^= L(ctz(++m_block_index)); - copy_mem(&offsets[BS*i], &m_offset[0], BS); - } - - xor_buf(&csum_accum[0], &buffer[0], proc_bytes); - - xor_buf(&buffer[0], &offsets[0], proc_bytes); - - m_cipher->encrypt_n(&buffer[0], &buffer[0], proc_blocks); - - xor_buf(&buffer[0], &offsets[0], proc_bytes); - - buffer += proc_bytes; - blocks_left -= proc_blocks; - } - - // fold into checksum - for(size_t i = 0; i != csum_accum.size(); ++i) - m_checksum[i % BS] ^= csum_accum[i]; - } - -void OCB_Encryption::update(secure_vector<byte>& buffer, size_t offset) - { - BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane"); - const size_t sz = buffer.size() - offset; - byte* buf = &buffer[offset]; - - BOTAN_ASSERT(sz % BS == 0, "Input length is an even number of blocks"); - - encrypt(buf, sz / BS); - } - -void OCB_Encryption::finish(secure_vector<byte>& buffer, size_t offset) - { - BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane"); - const size_t sz = buffer.size() - offset; - byte* buf = &buffer[offset]; - - 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); - - if(remainder_bytes) - { - BOTAN_ASSERT(remainder_bytes < BS, "Only a partial block left"); - byte* remainder = &buf[sz - remainder_bytes]; - - xor_buf(&m_checksum[0], &remainder[0], remainder_bytes); - m_checksum[remainder_bytes] ^= 0x80; - - m_offset ^= m_L->star(); // Offset_* - - secure_vector<byte> buf(BS); - m_cipher->encrypt(m_offset, buf); - xor_buf(&remainder[0], &buf[0], remainder_bytes); - } - } - - // now compute the tag - secure_vector<byte> mac = m_offset; - mac ^= m_checksum; - mac ^= m_L->dollar(); - - m_cipher->encrypt(mac); - - mac ^= m_ad_hash; - - buffer += std::make_pair(&mac[0], tag_size()); - - zeroise(m_checksum); - zeroise(m_offset); - m_block_index = 0; - } - -void OCB_Decryption::decrypt(byte buffer[], size_t blocks) - { - const L_computer& L = *m_L; // convenient name - - const size_t par_bytes = m_cipher->parallel_bytes(); - - BOTAN_ASSERT(par_bytes % BS == 0, "Cipher is parallel in full blocks"); - - const size_t par_blocks = par_bytes / BS; - - secure_vector<byte> csum_accum(par_bytes); - secure_vector<byte> offsets(par_bytes); - - size_t blocks_left = blocks; - - while(blocks_left) - { - const size_t proc_blocks = std::min(blocks_left, par_blocks); - const size_t proc_bytes = proc_blocks * BS; - - for(size_t i = 0; i != proc_blocks; ++i) - { // could be done in parallel - m_offset ^= L(ctz(++m_block_index)); - copy_mem(&offsets[BS*i], &m_offset[0], BS); - } - - xor_buf(&buffer[0], &offsets[0], proc_bytes); - - m_cipher->decrypt_n(&buffer[0], &buffer[0], proc_blocks); - - xor_buf(&buffer[0], &offsets[0], proc_bytes); - - xor_buf(&csum_accum[0], &buffer[0], proc_bytes); - - buffer += proc_bytes; - blocks_left -= proc_blocks; - } - - // fold into checksum - for(size_t i = 0; i != csum_accum.size(); ++i) - m_checksum[i % BS] ^= csum_accum[i]; - } - -void OCB_Decryption::update(secure_vector<byte>& buffer, size_t offset) - { - BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane"); - const size_t sz = buffer.size() - offset; - byte* buf = &buffer[offset]; - - BOTAN_ASSERT(sz % BS == 0, "Input length is an even number of blocks"); - - decrypt(buf, sz / BS); - } - -void OCB_Decryption::finish(secure_vector<byte>& buffer, size_t offset) - { - BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane"); - const size_t sz = buffer.size() - offset; - byte* buf = &buffer[offset]; - - BOTAN_ASSERT(sz >= tag_size(), "We have the tag"); - - const size_t remaining = sz - tag_size(); - - if(remaining) - { - const size_t final_full_blocks = remaining / BS; - const size_t final_bytes = remaining - (final_full_blocks * BS); - - decrypt(&buf[0], final_full_blocks); - - if(final_bytes) - { - BOTAN_ASSERT(final_bytes < BS, "Only a partial block left"); - - byte* remainder = &buf[remaining - final_bytes]; - - m_offset ^= m_L->star(); // Offset_* - - secure_vector<byte> pad(BS); - m_cipher->encrypt(m_offset, pad); // P_* - - xor_buf(&remainder[0], &pad[0], final_bytes); - - xor_buf(&m_checksum[0], &remainder[0], final_bytes); - m_checksum[final_bytes] ^= 0x80; - } - } - - // compute the mac - secure_vector<byte> mac = m_offset; - mac ^= m_checksum; - mac ^= m_L->dollar(); - - m_cipher->encrypt(mac); - - mac ^= m_ad_hash; - - // reset state - zeroise(m_checksum); - zeroise(m_offset); - m_block_index = 0; - - // compare mac - const byte* included_tag = &buf[remaining]; - - if(!same_mem(&mac[0], included_tag, tag_size())) - throw Integrity_Failure("OCB tag check failed"); - - // remove tag from end of message - buffer.resize(remaining + offset); - } - -} |