diff options
Diffstat (limited to 'comm/third_party/botan/src/lib/modes/aead/ccm/ccm.cpp')
-rw-r--r-- | comm/third_party/botan/src/lib/modes/aead/ccm/ccm.cpp | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/modes/aead/ccm/ccm.cpp b/comm/third_party/botan/src/lib/modes/aead/ccm/ccm.cpp new file mode 100644 index 0000000000..ab2cfcb950 --- /dev/null +++ b/comm/third_party/botan/src/lib/modes/aead/ccm/ccm.cpp @@ -0,0 +1,279 @@ +/* +* CCM Mode Encryption +* (C) 2013,2018 Jack Lloyd +* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity +* +* Botan is released under the Simplified BSD License (see license.txt) +*/ + +#include <botan/ccm.h> +#include <botan/loadstor.h> + +namespace Botan { + +// 128-bit cipher is intrinsic to CCM definition +static const size_t CCM_BS = 16; + +/* +* CCM_Mode Constructor +*/ +CCM_Mode::CCM_Mode(BlockCipher* cipher, size_t tag_size, size_t L) : + m_tag_size(tag_size), + m_L(L), + m_cipher(cipher) + { + if(m_cipher->block_size() != CCM_BS) + throw Invalid_Argument(m_cipher->name() + " cannot be used with CCM mode"); + + if(L < 2 || L > 8) + throw Invalid_Argument("Invalid CCM L value " + std::to_string(L)); + + if(tag_size < 4 || tag_size > 16 || tag_size % 2 != 0) + throw Invalid_Argument("invalid CCM tag length " + std::to_string(tag_size)); + } + +void CCM_Mode::clear() + { + m_cipher->clear(); + reset(); + } + +void CCM_Mode::reset() + { + m_nonce.clear(); + m_msg_buf.clear(); + m_ad_buf.clear(); + } + +std::string CCM_Mode::name() const + { + return (m_cipher->name() + "/CCM(" + std::to_string(tag_size()) + "," + std::to_string(L())) + ")"; + } + +bool CCM_Mode::valid_nonce_length(size_t n) const + { + return (n == (15-L())); + } + +size_t CCM_Mode::default_nonce_length() const + { + return (15-L()); + } + +size_t CCM_Mode::update_granularity() const + { + /* + This value does not particularly matter as regardless CCM_Mode::update + buffers all input, so in theory this could be 1. However as for instance + Transform_Filter creates update_granularity() uint8_t buffers, use a + somewhat large size to avoid bouncing on a tiny buffer. + */ + return m_cipher->parallel_bytes(); + } + +Key_Length_Specification CCM_Mode::key_spec() const + { + return m_cipher->key_spec(); + } + +void CCM_Mode::key_schedule(const uint8_t key[], size_t length) + { + m_cipher->set_key(key, length); + } + +void CCM_Mode::set_associated_data(const uint8_t ad[], size_t length) + { + m_ad_buf.clear(); + + if(length) + { + // FIXME: support larger AD using length encoding rules + BOTAN_ARG_CHECK(length < (0xFFFF - 0xFF), "Supported CCM AD length"); + + m_ad_buf.push_back(get_byte(0, static_cast<uint16_t>(length))); + m_ad_buf.push_back(get_byte(1, static_cast<uint16_t>(length))); + m_ad_buf += std::make_pair(ad, length); + while(m_ad_buf.size() % CCM_BS) + m_ad_buf.push_back(0); // pad with zeros to full block size + } + } + +void CCM_Mode::start_msg(const uint8_t nonce[], size_t nonce_len) + { + if(!valid_nonce_length(nonce_len)) + throw Invalid_IV_Length(name(), nonce_len); + + m_nonce.assign(nonce, nonce + nonce_len); + m_msg_buf.clear(); + } + +size_t CCM_Mode::process(uint8_t buf[], size_t sz) + { + BOTAN_STATE_CHECK(m_nonce.size() > 0); + m_msg_buf.insert(m_msg_buf.end(), buf, buf + sz); + return 0; // no output until finished + } + +void CCM_Mode::encode_length(uint64_t len, uint8_t out[]) + { + const size_t len_bytes = L(); + + BOTAN_ASSERT_NOMSG(len_bytes >= 2 && len_bytes <= 8); + + for(size_t i = 0; i != len_bytes; ++i) + out[len_bytes-1-i] = get_byte(sizeof(uint64_t)-1-i, len); + + if(len_bytes < 8 && (len >> (len_bytes*8)) > 0) + throw Encoding_Error("CCM message length too long to encode in L field"); + } + +void CCM_Mode::inc(secure_vector<uint8_t>& C) + { + for(size_t i = 0; i != C.size(); ++i) + if(++C[C.size()-i-1]) + break; + } + +secure_vector<uint8_t> CCM_Mode::format_b0(size_t sz) + { + if(m_nonce.size() != 15-L()) + throw Invalid_State("CCM mode must set nonce"); + secure_vector<uint8_t> B0(CCM_BS); + + const uint8_t b_flags = + static_cast<uint8_t>((m_ad_buf.size() ? 64 : 0) + (((tag_size()/2)-1) << 3) + (L()-1)); + + B0[0] = b_flags; + copy_mem(&B0[1], m_nonce.data(), m_nonce.size()); + encode_length(sz, &B0[m_nonce.size()+1]); + + return B0; + } + +secure_vector<uint8_t> CCM_Mode::format_c0() + { + if(m_nonce.size() != 15-L()) + throw Invalid_State("CCM mode must set nonce"); + secure_vector<uint8_t> C(CCM_BS); + + const uint8_t a_flags = static_cast<uint8_t>(L() - 1); + + C[0] = a_flags; + copy_mem(&C[1], m_nonce.data(), m_nonce.size()); + + return C; + } + +void CCM_Encryption::finish(secure_vector<uint8_t>& buffer, size_t offset) + { + BOTAN_ARG_CHECK(buffer.size() >= offset, "Offset is sane"); + + buffer.insert(buffer.begin() + offset, msg_buf().begin(), msg_buf().end()); + + const size_t sz = buffer.size() - offset; + uint8_t* buf = buffer.data() + offset; + + const secure_vector<uint8_t>& ad = ad_buf(); + BOTAN_ARG_CHECK(ad.size() % CCM_BS == 0, "AD is block size multiple"); + + const BlockCipher& E = cipher(); + + secure_vector<uint8_t> T(CCM_BS); + E.encrypt(format_b0(sz), T); + + for(size_t i = 0; i != ad.size(); i += CCM_BS) + { + xor_buf(T.data(), &ad[i], CCM_BS); + E.encrypt(T); + } + + secure_vector<uint8_t> C = format_c0(); + secure_vector<uint8_t> S0(CCM_BS); + E.encrypt(C, S0); + inc(C); + + secure_vector<uint8_t> X(CCM_BS); + + const uint8_t* buf_end = &buf[sz]; + + while(buf != buf_end) + { + const size_t to_proc = std::min<size_t>(CCM_BS, buf_end - buf); + + xor_buf(T.data(), buf, to_proc); + E.encrypt(T); + + E.encrypt(C, X); + xor_buf(buf, X.data(), to_proc); + inc(C); + + buf += to_proc; + } + + T ^= S0; + + buffer += std::make_pair(T.data(), tag_size()); + + reset(); + } + +void CCM_Decryption::finish(secure_vector<uint8_t>& buffer, size_t offset) + { + BOTAN_ARG_CHECK(buffer.size() >= offset, "Offset is sane"); + + buffer.insert(buffer.begin() + offset, msg_buf().begin(), msg_buf().end()); + + const size_t sz = buffer.size() - offset; + uint8_t* buf = buffer.data() + offset; + + BOTAN_ASSERT(sz >= tag_size(), "We have the tag"); + + const secure_vector<uint8_t>& ad = ad_buf(); + BOTAN_ARG_CHECK(ad.size() % CCM_BS == 0, "AD is block size multiple"); + + const BlockCipher& E = cipher(); + + secure_vector<uint8_t> T(CCM_BS); + E.encrypt(format_b0(sz - tag_size()), T); + + for(size_t i = 0; i != ad.size(); i += CCM_BS) + { + xor_buf(T.data(), &ad[i], CCM_BS); + E.encrypt(T); + } + + secure_vector<uint8_t> C = format_c0(); + + secure_vector<uint8_t> S0(CCM_BS); + E.encrypt(C, S0); + inc(C); + + secure_vector<uint8_t> X(CCM_BS); + + const uint8_t* buf_end = &buf[sz - tag_size()]; + + while(buf != buf_end) + { + const size_t to_proc = std::min<size_t>(CCM_BS, buf_end - buf); + + E.encrypt(C, X); + xor_buf(buf, X.data(), to_proc); + inc(C); + + xor_buf(T.data(), buf, to_proc); + E.encrypt(T); + + buf += to_proc; + } + + T ^= S0; + + if(!constant_time_compare(T.data(), buf_end, tag_size())) + throw Invalid_Authentication_Tag("CCM tag check failed"); + + buffer.resize(buffer.size() - tag_size()); + + reset(); + } + +} |