diff options
| -rw-r--r-- | src/modes/aead/ocb/ocb.cpp | 45 |
1 files changed, 20 insertions, 25 deletions
diff --git a/src/modes/aead/ocb/ocb.cpp b/src/modes/aead/ocb/ocb.cpp index 4cbd8bde8..a18a9c50e 100644 --- a/src/modes/aead/ocb/ocb.cpp +++ b/src/modes/aead/ocb/ocb.cpp @@ -159,7 +159,7 @@ secure_vector<byte> ocb_hash(const L_computer& L, 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) + m_ad_hash(BS), m_offset(BS), m_checksum(m_cipher->parallel_bytes()) { if(m_cipher->block_size() != BS) throw std::invalid_argument("OCB requires a 128 bit cipher so cannot be used with " + @@ -233,14 +233,9 @@ 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; + const size_t par_blocks = m_checksum.size() / BS; - secure_vector<byte> csum_accum(par_bytes); - secure_vector<byte> offsets(par_bytes); + std::vector<byte> offsets(m_checksum.size()); size_t blocks_left = blocks; @@ -251,25 +246,20 @@ void OCB_Encryption::encrypt(byte buffer[], size_t blocks) for(size_t i = 0; i != proc_blocks; ++i) { // could be done in parallel + //xor_buf(&m_offset[0], 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(&m_checksum[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) @@ -312,9 +302,15 @@ void OCB_Encryption::finish(secure_vector<byte>& buffer, size_t offset) } } + secure_vector<byte> checksum(BS); + + // fold checksum + for(size_t i = 0; i != m_checksum.size(); ++i) + checksum[i % checksum.size()] ^= m_checksum[i]; + // now compute the tag secure_vector<byte> mac = m_offset; - mac ^= m_checksum; + mac ^= checksum; mac ^= m_L->dollar(); m_cipher->encrypt(mac); @@ -338,7 +334,6 @@ void OCB_Decryption::decrypt(byte buffer[], size_t 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; @@ -355,20 +350,14 @@ void OCB_Decryption::decrypt(byte buffer[], size_t blocks) } 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); + xor_buf(&m_checksum[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) @@ -417,9 +406,15 @@ void OCB_Decryption::finish(secure_vector<byte>& buffer, size_t offset) } } + secure_vector<byte> checksum(BS); + + // fold checksum + for(size_t i = 0; i != m_checksum.size(); ++i) + checksum[i % checksum.size()] ^= m_checksum[i]; + // compute the mac secure_vector<byte> mac = m_offset; - mac ^= m_checksum; + mac ^= checksum; mac ^= m_L->dollar(); m_cipher->encrypt(mac); |