diff options
Diffstat (limited to 'src/lib/mac/cmac')
| -rw-r--r-- | src/lib/mac/cmac/cmac.cpp | 34 |
1 files changed, 28 insertions, 6 deletions
diff --git a/src/lib/mac/cmac/cmac.cpp b/src/lib/mac/cmac/cmac.cpp index 16524faec..b4c9cb129 100644 --- a/src/lib/mac/cmac/cmac.cpp +++ b/src/lib/mac/cmac/cmac.cpp @@ -16,9 +16,7 @@ namespace Botan { */ secure_vector<byte> CMAC::poly_double(const secure_vector<byte>& in) { - const byte polynomial = (in.size() == 16) ? 0x87 : 0x1B; - - const byte poly_xor = (in[0] & 0x80) ? polynomial : 0; + const bool top_carry = (in[0] & 0x80); secure_vector<byte> out = in; @@ -30,7 +28,26 @@ secure_vector<byte> CMAC::poly_double(const secure_vector<byte>& in) carry = (temp >> 7); } - out[out.size()-1] ^= poly_xor; + if(top_carry) + { + switch(in.size()) + { + case 8: + out[out.size()-1] ^= 0x1B; + break; + case 16: + out[out.size()-1] ^= 0x87; + break; + case 32: + out[out.size()-2] ^= 0x4; + out[out.size()-1] ^= 0x25; + break; + case 64: + out[out.size()-2] ^= 0x1; + out[out.size()-1] ^= 0x25; + break; + } + } return out; } @@ -133,8 +150,13 @@ MessageAuthenticationCode* CMAC::clone() const */ CMAC::CMAC(BlockCipher* cipher) : m_cipher(cipher) { - if(m_cipher->block_size() != 8 && m_cipher->block_size() != 16) - throw Invalid_Argument("CMAC cannot use the cipher " + m_cipher->name()); + if(m_cipher->block_size() != 8 && m_cipher->block_size() != 16 && + m_cipher->block_size() != 32 && m_cipher->block_size() != 64) + { + throw Invalid_Argument("CMAC cannot use the " + + std::to_string(m_cipher->block_size() * 8) + + " bit cipher " + m_cipher->name()); + } m_state.resize(output_length()); m_buffer.resize(output_length()); |