// Decrypt data in vector
void RC5Simple::RC5_Decrypt(vector<unsigned char> &in, vector<unsigned char> &out)
{
RC5_LOG(( "\nDecrypt\n" ));
// Cleaning output vector
out.clear();
out.resize(in.size(), 0);
// No decrypt null data
if(in.size()==0)
return;
// Get IV
unsigned char iv[RC5_BLOCK_LEN];
for(int i=0; i<RC5_BLOCK_LEN; i++)
iv[i]=in[i];
// Set secret key for decrypt
RC5_Setup(rc5_key);
// Decode by blocks from block with index 1 (from 0 block already read IV)
unsigned int data_size=0;
unsigned int block=1;
while( (RC5_BLOCK_LEN*(block+1))<=in.size() )
{
unsigned int shift=block*RC5_BLOCK_LEN;
RC5_TWORD temp_word_1;
RC5_TWORD temp_word_2;
RC5_TWORD pt[RC5_WORDS_IN_BLOCK];
RC5_TWORD ct[RC5_WORDS_IN_BLOCK];
RC5_LOG(( "Block num %d, shift %d\n", block, shift ));
temp_word_1=RC5_GetWordFromByte(in[shift],
in[shift+1],
in[shift+2],
in[shift+3]);
temp_word_2=RC5_GetWordFromByte(in[shift+RC5_WORD_LEN],
in[shift+RC5_WORD_LEN+1],
in[shift+RC5_WORD_LEN+2],
in[shift+RC5_WORD_LEN+3]);
pt[0]=temp_word_1;
pt[1]=temp_word_2;
// Decode
RC5_DecryptBlock(pt, ct);
// ---------------------------
// Un XOR block with IV vector
// ---------------------------
// Convert block words to plain array
unsigned char ct_part[RC5_BLOCK_LEN];
for(int i=0; i<RC5_WORD_LEN; i++)
{
ct_part[i]=RC5_GetByteFromWord(ct[0], i);
ct_part[i+RC5_WORD_LEN]=RC5_GetByteFromWord(ct[1], i);
}
// Un XOR
for(int i=0; i<RC5_BLOCK_LEN; i++)
ct_part[i]^=iv[i];
if(block==1)
{
data_size=RC5_GetIntFromByte(ct_part[0], ct_part[1], ct_part[2], ct_part[3]);
RC5_LOG(( "Decrypt data size: %d\n", data_size ));
// Uncorrect decrypt data size
if((unsigned int)data_size>(unsigned int)in.size())
return;
}
#if RC5_ENABLE_DEBUG_PRINT==1
RC5_LOG(( "Pt %.8X, %.8X\n", pt[0], pt[1] ));
RC5_LOG(( "Ct %.8X, %.8X\n", ct[0], ct[1] ));
#endif
// Generate next IV for Cipher Block Chaining (CBC)
for(int i=0; i<RC5_BLOCK_LEN; i++)
iv[i]=in[shift+i];
// Save decrypt data
for(int i=0; i<RC5_BLOCK_LEN; i++)
out[shift-RC5_BLOCK_LEN+i]=ct_part[i];
block++;
}
// Cleaning IV
for(int i=0; i<RC5_BLOCK_LEN; i++)
iv[i]=0;
// Remove from output first byte with length
out.erase(out.begin(), out.begin()+RC5_BLOCK_LEN);
// Remove from output last byte with random byte for aligning
if(out.size()>data_size)
out.erase(out.begin()+data_size, out.end());
}
// Decrypt data in vector
void RC5Simple::RC5_Decrypt(vector<unsigned char> &in, vector<unsigned char> &out)
{
RC5_LOG(( "\nDecrypt\n" ));
RC5_LOG(( "\nInput data size: %d\n", in.size() ));
// No decrypt null data
if(in.size()==0)
{
errorCode=RC5_ERROR_CODE_6;
return;
}
// Detect format version
unsigned int formatVersion=0;
if(rc5_isSetFormatVersionForce==true)
formatVersion=rc5_formatVersion; // If format set force, format not autodetected
else
{
// Signature bytes
const char *signature=RC5_SIMPLE_SIGNATURE;
// Detect signature
bool isSignatureCorrect=true;
for(int i=0; i<(RC5_BLOCK_LEN-1); i++)
if(in[i]!=signature[i])
isSignatureCorrect=false;
// If not detect signature
if(isSignatureCorrect==false)
formatVersion=RC5_FORMAT_VERSION_1; // In first version can't signature
else
{
// Get format version
unsigned char readFormatVersion=in[RC5_BLOCK_LEN-1];
// If format version correct
if(readFormatVersion>=RC5_FORMAT_VERSION_2 && readFormatVersion<=RC5_FORMAT_VERSION_CURRENT)
formatVersion=readFormatVersion;
else
formatVersion=RC5_FORMAT_VERSION_1; // If version not correct, may be it format 1 ( probability 0.[hrendesyatih]1 )
}
}
unsigned int ivShift=0;
unsigned int firstDataBlock=0;
unsigned int removeBlocksFromOutput=0;
unsigned int blockWithDataSize=0;
if(formatVersion==RC5_FORMAT_VERSION_1)
{
ivShift=0;
firstDataBlock=1; // Start decode from block with index 1 (from block 0 read IV)
removeBlocksFromOutput=1;
blockWithDataSize=1;
}
if(formatVersion==RC5_FORMAT_VERSION_2)
{
ivShift=RC5_BLOCK_LEN;
firstDataBlock=2; // Start decode from block with index 2 (0 - signature and version, 1 - IV)
removeBlocksFromOutput=2; // Random data block and size data block
blockWithDataSize=3;
}
if(formatVersion==RC5_FORMAT_VERSION_3)
{
ivShift=RC5_BLOCK_LEN;
firstDataBlock=2; // Start decode from block with index 2 (0 - signature and version, 1 - IV)
removeBlocksFromOutput=3; // Two random data block and size data block
blockWithDataSize=4;
}
// Get IV
unsigned char iv[RC5_BLOCK_LEN];
for(int i=0; i<RC5_BLOCK_LEN; i++)
iv[i]=in[i+ivShift];
// Set secret key for decrypt
RC5_Setup(rc5_key);
// Cleaning output vector
out.clear();
out.resize(in.size(), 0);
// Decode by blocks from started data block
unsigned int data_size=0;
unsigned int block=firstDataBlock;
while( (RC5_BLOCK_LEN*(block+1))<=in.size() )
{
unsigned int shift=block*RC5_BLOCK_LEN;
RC5_TWORD temp_word_1;
RC5_TWORD temp_word_2;
RC5_TWORD pt[RC5_WORDS_IN_BLOCK];
RC5_TWORD ct[RC5_WORDS_IN_BLOCK];
RC5_LOG(( "Block num %d, shift %d\n", block, shift ));
temp_word_1=RC5_GetWordFromByte(in[shift],
in[shift+1],
in[shift+2],
in[shift+3]);
temp_word_2=RC5_GetWordFromByte(in[shift+RC5_WORD_LEN],
in[shift+RC5_WORD_LEN+1],
in[shift+RC5_WORD_LEN+2],
in[shift+RC5_WORD_LEN+3]);
pt[0]=temp_word_1;
pt[1]=temp_word_2;
RC5_LOG(( "Block data. Word 1: %.2X, Word 2: %.2X\n", temp_word_1, temp_word_2 ));
// Decode
RC5_DecryptBlock(pt, ct);
// ---------------------------
// Un XOR block with IV vector
// ---------------------------
// Convert block words to plain array
unsigned char ct_part[RC5_BLOCK_LEN];
for(int i=0; i<RC5_WORD_LEN; i++)
{
ct_part[i]=RC5_GetByteFromWord(ct[0], i);
ct_part[i+RC5_WORD_LEN]=RC5_GetByteFromWord(ct[1], i);
}
// Un XOR
for(int i=0; i<RC5_BLOCK_LEN; i++)
ct_part[i]^=iv[i];
if(block==blockWithDataSize)
{
data_size=RC5_GetIntFromByte(ct_part[0], ct_part[1], ct_part[2], ct_part[3]);
RC5_LOG(( "Decrypt data size: %d\n", data_size ));
// Uncorrect decrypt data size
if((unsigned int)data_size>(unsigned int)in.size())
{
// RC5_LOG(( "Incorrect data size. Decrypt data size: %d, estimate data size: ~%d\n", data_size, in.size() ));
errorCode=RC5_ERROR_CODE_7;
return;
}
}
#if RC5_ENABLE_DEBUG_PRINT==1
RC5_LOG(( "Pt %.8X, %.8X\n", pt[0], pt[1] ));
RC5_LOG(( "Ct %.8X, %.8X\n", ct[0], ct[1] ));
#endif
// Generate next IV for Cipher Block Chaining (CBC)
for(int i=0; i<RC5_BLOCK_LEN; i++)
iv[i]=in[shift+i];
// Save decrypt data
for(int i=0; i<RC5_BLOCK_LEN; i++)
{
RC5_LOG(( "Put decrypt data to vector out[%d] = %.2X\n", shift-(removeBlocksFromOutput*RC5_BLOCK_LEN)+i, ct_part[i] ));
out[shift-(firstDataBlock*RC5_BLOCK_LEN)+i]=ct_part[i];
}
block++;
}
// Cleaning IV
for(int i=0; i<RC5_BLOCK_LEN; i++)
iv[i]=0;
// Remove from output a blocks with technical data (random blocks, size, etc...)
out.erase(out.begin(), out.begin()+removeBlocksFromOutput*RC5_BLOCK_LEN);
// Remove from output a last byte with random byte for aligning
if(out.size()>data_size)
out.erase(out.begin()+data_size, out.end());
}
