diff options
author | lloyd <[email protected]> | 2013-12-05 02:09:41 +0000 |
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committer | lloyd <[email protected]> | 2013-12-05 02:09:41 +0000 |
commit | 9e4c7395029bb672d208c9c5cb2936ba397cbf20 (patch) | |
tree | 2545668dd8a16b5acc1d124b616668ebe67f0287 /src | |
parent | 7de7b04b3c9684dae02d069f04e33ad59129da1e (diff) |
Add SIV
Diffstat (limited to 'src')
-rw-r--r-- | src/modes/aead/aead.cpp | 17 | ||||
-rw-r--r-- | src/modes/aead/siv/info.txt | 3 | ||||
-rw-r--r-- | src/modes/aead/siv/siv.cpp | 183 | ||||
-rw-r--r-- | src/modes/aead/siv/siv.h | 114 |
4 files changed, 316 insertions, 1 deletions
diff --git a/src/modes/aead/aead.cpp b/src/modes/aead/aead.cpp index d913c7c3a..26a7091fd 100644 --- a/src/modes/aead/aead.cpp +++ b/src/modes/aead/aead.cpp @@ -20,6 +20,10 @@ #include <botan/gcm.h> #endif +#if defined(BOTAN_HAS_AEAD_SIV) + #include <botan/siv.h> +#endif + #if defined(BOTAN_HAS_AEAD_OCB) #include <botan/ocb.h> #endif @@ -59,7 +63,7 @@ AEAD_Mode* get_aead(const std::string& algo_spec, Cipher_Dir direction) return new CCM_Decryption(cipher->clone(), 8, 3); } - if(mode_name == "CCM") + if(mode_name == "CCM" || mode_name == "CCM-8") { const size_t L = (mode_info.size() > 2) ? to_u32bit(mode_info[2]) : 3; @@ -80,6 +84,17 @@ AEAD_Mode* get_aead(const std::string& algo_spec, Cipher_Dir direction) } #endif +#if defined(BOTAN_HAS_AEAD_SIV) + if(mode_name == "SIV") + { + BOTAN_ASSERT(tag_size == 16, "Valid tag size for SIV"); + if(direction == ENCRYPTION) + return new SIV_Encryption(cipher->clone()); + else + return new SIV_Decryption(cipher->clone()); + } +#endif + #if defined(BOTAN_HAS_AEAD_GCM) if(mode_name == "GCM") { diff --git a/src/modes/aead/siv/info.txt b/src/modes/aead/siv/info.txt new file mode 100644 index 000000000..b1e38568e --- /dev/null +++ b/src/modes/aead/siv/info.txt @@ -0,0 +1,3 @@ +define AEAD_SIV 20131202 + +load_on auto diff --git a/src/modes/aead/siv/siv.cpp b/src/modes/aead/siv/siv.cpp new file mode 100644 index 000000000..15fb16aa0 --- /dev/null +++ b/src/modes/aead/siv/siv.cpp @@ -0,0 +1,183 @@ +/* +* SIV Mode Encryption +* (C) 2013 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#include <botan/siv.h> +#include <botan/cmac.h> +#include <botan/ctr.h> +#include <botan/parsing.h> +#include <botan/internal/xor_buf.h> +#include <algorithm> + +#include <iostream> +#include <botan/hex.h> + +namespace Botan { + +SIV_Mode::SIV_Mode(BlockCipher* cipher) : + m_name(cipher->name() + "/SIV"), + m_ctr(new CTR_BE(cipher->clone())), + m_cmac(new CMAC(cipher)) + { + } + +void SIV_Mode::clear() + { + m_ctr.reset(); + m_nonce.clear(); + m_msg_buf.clear(); + m_ad_macs.clear(); + } + +std::string SIV_Mode::name() const + { + return m_name; + } + +bool SIV_Mode::valid_nonce_length(size_t) const + { + return true; + } + +size_t SIV_Mode::update_granularity() const + { + /* + This value does not particularly matter as regardless SIV_Mode::update + buffers all input, so in theory this could be 1. However as for instance + Transformation_Filter creates update_granularity() byte buffers, use a + somewhat large size to avoid bouncing on a tiny buffer. + */ + return 128; + } + +Key_Length_Specification SIV_Mode::key_spec() const + { + return m_cmac->key_spec().multiple(2); + } + +void SIV_Mode::key_schedule(const byte key[], size_t length) + { + const size_t keylen = length / 2; + m_cmac->set_key(key, keylen); + m_ctr->set_key(key + keylen, keylen); + m_ad_macs.clear(); + } + +void SIV_Mode::set_associated_data_n(size_t n, const byte ad[], size_t length) + { + if(n >= m_ad_macs.size()) + m_ad_macs.resize(n+1); + + m_ad_macs[n] = m_cmac->process(ad, length); + } + +secure_vector<byte> SIV_Mode::start(const byte nonce[], size_t nonce_len) + { + if(!valid_nonce_length(nonce_len)) + throw Invalid_IV_Length(name(), nonce_len); + + if(nonce_len) + m_nonce = m_cmac->process(nonce, nonce_len); + else + m_nonce.clear(); + + m_msg_buf.clear(); + + return secure_vector<byte>(); + } + +void SIV_Mode::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]; + + m_msg_buf.insert(m_msg_buf.end(), buf, buf + sz); + buffer.resize(offset); // truncate msg + } + +secure_vector<byte> SIV_Mode::S2V(const byte* text, size_t text_len) + { + const byte zero[16] = { 0 }; + + secure_vector<byte> V = cmac().process(zero, 16); + + for(size_t i = 0; i != m_ad_macs.size(); ++i) + { + V = CMAC::poly_double(V, 0x87); + V ^= m_ad_macs[i]; + } + + if(m_nonce.size()) + { + V = CMAC::poly_double(V, 0x87); + V ^= m_nonce; + } + + if(text_len < 16) + { + V = CMAC::poly_double(V, 0x87); + xor_buf(&V[0], text, text_len); + V[text_len] ^= 0x80; + return cmac().process(V); + } + + cmac().update(text, text_len - 16); + xor_buf(&V[0], &text[text_len - 16], 16); + cmac().update(V); + + return cmac().final(); + } + +void SIV_Mode::set_ctr_iv(secure_vector<byte> V) + { + V[8] &= 0x7F; + V[12] &= 0x7F; + + ctr().set_iv(&V[0], V.size()); + } + +void SIV_Encryption::finish(secure_vector<byte>& buffer, size_t offset) + { + BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane"); + + buffer.insert(buffer.begin() + offset, msg_buf().begin(), msg_buf().end()); + + secure_vector<byte> V = S2V(&buffer[offset], buffer.size() - offset); + + buffer.insert(buffer.begin() + offset, V.begin(), V.end()); + + set_ctr_iv(V); + ctr().cipher1(&buffer[offset + V.size()], buffer.size() - offset - V.size()); + } + +void SIV_Decryption::finish(secure_vector<byte>& buffer, size_t offset) + { + BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane"); + + buffer.insert(buffer.begin() + offset, msg_buf().begin(), msg_buf().end()); + + const size_t sz = buffer.size() - offset; + + BOTAN_ASSERT(sz >= tag_size(), "We have the tag"); + + secure_vector<byte> V(&buffer[offset], &buffer[offset + 16]); + + set_ctr_iv(V); + + ctr().cipher(&buffer[offset + V.size()], + &buffer[offset], + buffer.size() - offset - V.size()); + + secure_vector<byte> T = S2V(&buffer[offset], buffer.size() - offset - V.size()); + + if(T != V) + throw Integrity_Failure("SIV tag check failed"); + + buffer.resize(buffer.size() - tag_size()); + } + +} diff --git a/src/modes/aead/siv/siv.h b/src/modes/aead/siv/siv.h new file mode 100644 index 000000000..612d29bb7 --- /dev/null +++ b/src/modes/aead/siv/siv.h @@ -0,0 +1,114 @@ +/* +* SIV Mode +* (C) 2013 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#ifndef BOTAN_AEAD_SIV_H__ +#define BOTAN_AEAD_SIV_H__ + +#include <botan/aead.h> +#include <botan/block_cipher.h> +#include <botan/stream_cipher.h> +#include <botan/mac.h> +#include <memory> + +namespace Botan { + +/** +* Base class for SIV encryption and decryption (@see RFC 5297) +*/ +class BOTAN_DLL SIV_Mode : public AEAD_Mode + { + public: + secure_vector<byte> start(const byte nonce[], size_t nonce_len) override; + + void update(secure_vector<byte>& blocks, size_t offset) override; + + void set_associated_data_n(size_t n, const byte ad[], size_t ad_len); + + void set_associated_data(const byte ad[], size_t ad_len) override + { + set_associated_data_n(0, ad, ad_len); + } + + std::string name() const override; + + size_t update_granularity() const; + + Key_Length_Specification key_spec() const override; + + bool valid_nonce_length(size_t) const override; + + void clear(); + + size_t tag_size() const { return 16; } + + protected: + SIV_Mode(BlockCipher* cipher); + + StreamCipher& ctr() { return *m_ctr; } + + void set_ctr_iv(secure_vector<byte> V); + + secure_vector<byte>& msg_buf() { return m_msg_buf; } + + secure_vector<byte> S2V(const byte text[], size_t text_len); + private: + MessageAuthenticationCode& cmac() { return *m_cmac; } + + void key_schedule(const byte key[], size_t length) override; + + const std::string m_name; + + std::unique_ptr<StreamCipher> m_ctr; + std::unique_ptr<MessageAuthenticationCode> m_cmac; + secure_vector<byte> m_nonce, m_msg_buf; + std::vector<secure_vector<byte>> m_ad_macs; + }; + +/** +* SIV Encryption +*/ +class BOTAN_DLL SIV_Encryption : public SIV_Mode + { + public: + /** + * @param cipher a block cipher + */ + SIV_Encryption(BlockCipher* cipher) : SIV_Mode(cipher) {} + + void finish(secure_vector<byte>& final_block, size_t offset) override; + + size_t output_length(size_t input_length) const override + { return input_length + tag_size(); } + + size_t minimum_final_size() const override { return 0; } + }; + +/** +* SIV Decryption +*/ +class BOTAN_DLL SIV_Decryption : public SIV_Mode + { + public: + /** + * @param cipher a 128-bit block cipher + */ + SIV_Decryption(BlockCipher* cipher) : SIV_Mode(cipher) {} + + void finish(secure_vector<byte>& final_block, size_t offset) override; + + size_t output_length(size_t input_length) const override + { + BOTAN_ASSERT(input_length > tag_size(), "Sufficient input"); + return input_length - tag_size(); + } + + size_t minimum_final_size() const override { return tag_size(); } + }; + +} + +#endif |