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authorlloyd <[email protected]>2014-01-10 03:41:59 +0000
committerlloyd <[email protected]>2014-01-10 03:41:59 +0000
commit6894dca64c04936d07048c0e8cbf7e25858548c3 (patch)
tree5d572bfde9fe667dab14e3f04b5285a85d8acd95 /src/lib/modes/cfb/cfb.cpp
parent9efa3be92442afb3d0b69890a36c7f122df18eda (diff)
Move lib into src
Diffstat (limited to 'src/lib/modes/cfb/cfb.cpp')
-rw-r--r--src/lib/modes/cfb/cfb.cpp150
1 files changed, 150 insertions, 0 deletions
diff --git a/src/lib/modes/cfb/cfb.cpp b/src/lib/modes/cfb/cfb.cpp
new file mode 100644
index 000000000..7721e1487
--- /dev/null
+++ b/src/lib/modes/cfb/cfb.cpp
@@ -0,0 +1,150 @@
+/*
+* CFB Mode
+* (C) 1999-2007,2013 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/cfb.h>
+#include <botan/parsing.h>
+#include <botan/internal/xor_buf.h>
+
+namespace Botan {
+
+CFB_Mode::CFB_Mode(BlockCipher* cipher, size_t feedback_bits) :
+ m_cipher(cipher),
+ m_feedback_bytes(feedback_bits ? feedback_bits / 8 : cipher->block_size())
+ {
+ if(feedback_bits % 8 || feedback() > cipher->block_size())
+ throw std::invalid_argument(name() + ": feedback bits " +
+ std::to_string(feedback_bits) + " not supported");
+ }
+
+void CFB_Mode::clear()
+ {
+ m_cipher->clear();
+ m_shift_register.clear();
+ }
+
+std::string CFB_Mode::name() const
+ {
+ if(feedback() == cipher().block_size())
+ return cipher().name() + "/CFB";
+ else
+ return cipher().name() + "/CFB(" + std::to_string(feedback()*8) + ")";
+ }
+
+size_t CFB_Mode::output_length(size_t input_length) const
+ {
+ return input_length;
+ }
+
+size_t CFB_Mode::update_granularity() const
+ {
+ return feedback();
+ }
+
+size_t CFB_Mode::minimum_final_size() const
+ {
+ return 0;
+ }
+
+Key_Length_Specification CFB_Mode::key_spec() const
+ {
+ return cipher().key_spec();
+ }
+
+size_t CFB_Mode::default_nonce_length() const
+ {
+ return cipher().block_size();
+ }
+
+bool CFB_Mode::valid_nonce_length(size_t n) const
+ {
+ return (n == cipher().block_size());
+ }
+
+void CFB_Mode::key_schedule(const byte key[], size_t length)
+ {
+ m_cipher->set_key(key, length);
+ }
+
+secure_vector<byte> CFB_Mode::start(const byte nonce[], size_t nonce_len)
+ {
+ if(!valid_nonce_length(nonce_len))
+ throw Invalid_IV_Length(name(), nonce_len);
+
+ m_shift_register.assign(nonce, nonce + nonce_len);
+ m_keystream_buf.resize(m_shift_register.size());
+ cipher().encrypt(m_shift_register, m_keystream_buf);
+
+ return secure_vector<byte>();
+ }
+
+void CFB_Encryption::update(secure_vector<byte>& buffer, size_t offset)
+ {
+ BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
+ size_t sz = buffer.size() - offset;
+ byte* buf = &buffer[offset];
+
+ const size_t BS = cipher().block_size();
+
+ secure_vector<byte>& state = shift_register();
+ const size_t shift = feedback();
+
+ while(sz)
+ {
+ const size_t took = std::min(shift, sz);
+ xor_buf(&buf[0], &keystream_buf()[0], took);
+
+ // Assumes feedback-sized block except for last input
+ copy_mem(&state[0], &state[shift], BS - shift);
+ copy_mem(&state[BS-shift], &buf[0], shift);
+ cipher().encrypt(state, keystream_buf());
+
+ buf += took;
+ sz -= took;
+ }
+ }
+
+void CFB_Encryption::finish(secure_vector<byte>& buffer, size_t offset)
+ {
+ update(buffer, offset);
+ }
+
+void CFB_Decryption::update(secure_vector<byte>& buffer, size_t offset)
+ {
+ BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
+ size_t sz = buffer.size() - offset;
+ byte* buf = &buffer[offset];
+
+ const size_t BS = cipher().block_size();
+
+ secure_vector<byte>& state = shift_register();
+ const size_t shift = feedback();
+
+ while(sz)
+ {
+ const size_t took = std::min(shift, sz);
+
+ // first update shift register with ciphertext
+ copy_mem(&state[0], &state[shift], BS - shift);
+ copy_mem(&state[BS-shift], &buf[0], took);
+
+ // then decrypt
+ xor_buf(&buf[0], &keystream_buf()[0], took);
+
+ // then update keystream
+ cipher().encrypt(state, keystream_buf());
+
+ buf += took;
+ sz -= took;
+ }
+ }
+
+void CFB_Decryption::finish(secure_vector<byte>& buffer, size_t offset)
+ {
+ update(buffer, offset);
+ }
+
+}