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Last minute modifications to DES/3DES enc/dec routines for data that …
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…is not a multiple of the resp. block size
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@maxieds
maxieds committed Feb 12, 2022
1 parent e15f8c7 commit bcf68d0
Showing 1 changed file with 30 additions and 2 deletions.
32 changes: 30 additions & 2 deletions Firmware/Chameleon-Mini/Application/CryptoTDEA.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ void EncryptDESBuffer(uint16_t Count, const void *Plaintext, void *Ciphertext, c
.blockSize = CRYPTO_DES_BLOCK_SIZE
};
uint16_t numBlocks = (Count + CryptoSpec.blockSize - 1) / CryptoSpec.blockSize;
bool dataNeedsPadding = (Count % CryptoSpec.blockSize) != 0;
uint16_t blockIndex = 0;
uint8_t *ctBuf = (uint8_t *) Ciphertext;
uint8_t inputBlock[CRYPTO_DES_BLOCK_SIZE];
Expand All @@ -25,8 +26,13 @@ void EncryptDESBuffer(uint16_t Count, const void *Plaintext, void *Ciphertext, c
}
while (blockIndex < numBlocks) {
if (blockIndex == 0) {
memset(inputBlock, 0x00, CRYPTO_DES_BLOCK_SIZE);
memcpy(inputBlock, &Plaintext[0], CRYPTO_DES_BLOCK_SIZE);
CryptoMemoryXOR(IV, inputBlock, CRYPTO_DES_BLOCK_SIZE);
} else if (dataNeedsPadding && blockIndex + 1 == numBlocks) {
memset(inputBlock, 0x00, CRYPTO_DES_BLOCK_SIZE);
memcpy(inputBlock, &Ciphertext[(blockIndex - 1) * CRYPTO_DES_BLOCK_SIZE], Count % CryptoSpec.blockSize);
CryptoMemoryXOR(&Plaintext[blockIndex * CRYPTO_DES_BLOCK_SIZE], inputBlock, CRYPTO_DES_BLOCK_SIZE);
} else {
memcpy(inputBlock, &Ciphertext[(blockIndex - 1) * CRYPTO_DES_BLOCK_SIZE], CRYPTO_DES_BLOCK_SIZE);
CryptoMemoryXOR(&Plaintext[blockIndex * CRYPTO_DES_BLOCK_SIZE], inputBlock, CRYPTO_DES_BLOCK_SIZE);
Expand All @@ -43,6 +49,7 @@ void DecryptDESBuffer(uint16_t Count, void *Plaintext, const void *Ciphertext, c
.blockSize = CRYPTO_DES_BLOCK_SIZE
};
uint16_t numBlocks = (Count + CryptoSpec.blockSize - 1) / CryptoSpec.blockSize;
bool dataNeedsPadding = (Count % CryptoSpec.blockSize) != 0;
uint16_t blockIndex = 0;
uint8_t inputBlock[CRYPTO_DES_BLOCK_SIZE];
uint8_t IV[CRYPTO_DES_BLOCK_SIZE];
Expand All @@ -53,9 +60,16 @@ void DecryptDESBuffer(uint16_t Count, void *Plaintext, const void *Ciphertext, c
}
while (blockIndex < numBlocks) {
CryptoSpec.cryptFunc(inputBlock, Ciphertext + blockIndex * CRYPTO_DES_BLOCK_SIZE, Keys);
if (blockIndex == 0) {
if (blockIndex == 0 && !dataNeedsPadding) {
memcpy(Plaintext, inputBlock, CRYPTO_DES_BLOCK_SIZE);
CryptoMemoryXOR(IV, Plaintext, CRYPTO_DES_BLOCK_SIZE);
} else if (blockIndex == 0 && dataNeedsPadding && numBlocks == 0x01) {
memcpy(Plaintext, inputBlock, Count % CryptoSpec.blockSize);
CryptoMemoryXOR(IV, Plaintext, Count % CryptoSpec.blockSize);
} else if (dataNeedsPadding && blockIndex + 1 == numBlocks) {
memcpy(Plaintext + blockIndex * CRYPTO_DES_BLOCK_SIZE, inputBlock, Count % CryptoSpec.blockSize);
CryptoMemoryXOR(&Ciphertext[(blockIndex - 1) * CRYPTO_DES_BLOCK_SIZE],
Plaintext + blockIndex * CRYPTO_DES_BLOCK_SIZE, Count % CryptoSpec.blockSize);
} else {
memcpy(Plaintext + blockIndex * CRYPTO_DES_BLOCK_SIZE, inputBlock, CRYPTO_DES_BLOCK_SIZE);
CryptoMemoryXOR(&Ciphertext[(blockIndex - 1) * CRYPTO_DES_BLOCK_SIZE],
Expand All @@ -71,6 +85,7 @@ void Encrypt3DESBuffer(uint16_t Count, const void *Plaintext, void *Ciphertext,
.blockSize = CRYPTO_3KTDEA_BLOCK_SIZE
};
uint16_t numBlocks = (Count + CryptoSpec.blockSize - 1) / CryptoSpec.blockSize;
bool dataNeedsPadding = (Count % CryptoSpec.blockSize) != 0;
uint8_t *ctBuf = (uint8_t *) Ciphertext;
uint16_t blockIndex = 0;
uint8_t inputBlock[CRYPTO_3KTDEA_BLOCK_SIZE];
Expand All @@ -82,8 +97,13 @@ void Encrypt3DESBuffer(uint16_t Count, const void *Plaintext, void *Ciphertext,
}
while (blockIndex < numBlocks) {
if (blockIndex == 0) {
memset(inputBlock, 0x00, CRYPTO_3KTDEA_BLOCK_SIZE);
memcpy(inputBlock, &Plaintext[0], CRYPTO_3KTDEA_BLOCK_SIZE);
CryptoMemoryXOR(IV, inputBlock, CRYPTO_3KTDEA_BLOCK_SIZE);
} else if (dataNeedsPadding && blockIndex + 1 == numBlocks) {
memset(inputBlock, 0x00, CRYPTO_3KTDEA_BLOCK_SIZE);
memcpy(inputBlock, &Ciphertext[(blockIndex - 1) * CRYPTO_3KTDEA_BLOCK_SIZE], Count % CryptoSpec.blockSize);
CryptoMemoryXOR(&Plaintext[blockIndex * CRYPTO_3KTDEA_BLOCK_SIZE], inputBlock, CRYPTO_3KTDEA_BLOCK_SIZE);
} else {
memcpy(inputBlock, &Ciphertext[(blockIndex - 1) * CRYPTO_3KTDEA_BLOCK_SIZE], CRYPTO_3KTDEA_BLOCK_SIZE);
CryptoMemoryXOR(&Plaintext[blockIndex * CRYPTO_3KTDEA_BLOCK_SIZE], inputBlock, CRYPTO_3KTDEA_BLOCK_SIZE);
Expand All @@ -100,6 +120,7 @@ void Decrypt3DESBuffer(uint16_t Count, void *Plaintext, const void *Ciphertext,
.blockSize = CRYPTO_3KTDEA_BLOCK_SIZE
};
uint16_t numBlocks = (Count + CryptoSpec.blockSize - 1) / CryptoSpec.blockSize;
bool dataNeedsPadding = (Count % CryptoSpec.blockSize) != 0;
uint16_t blockIndex = 0;
uint8_t inputBlock[CRYPTO_3KTDEA_BLOCK_SIZE];
uint8_t IV[CRYPTO_3KTDEA_BLOCK_SIZE];
Expand All @@ -110,9 +131,16 @@ void Decrypt3DESBuffer(uint16_t Count, void *Plaintext, const void *Ciphertext,
}
while (blockIndex < numBlocks) {
CryptoSpec.cryptFunc(inputBlock, Ciphertext + blockIndex * CRYPTO_3KTDEA_BLOCK_SIZE, Keys);
if (blockIndex == 0) {
if (blockIndex == 0 && !dataNeedsPadding) {
memcpy(Plaintext, inputBlock, CRYPTO_3KTDEA_BLOCK_SIZE);
CryptoMemoryXOR(IV, Plaintext, CRYPTO_3KTDEA_BLOCK_SIZE);
} else if (blockIndex == 0 && dataNeedsPadding && numBlocks == 0x01) {
memcpy(Plaintext, inputBlock, Count % CryptoSpec.blockSize);
CryptoMemoryXOR(IV, Plaintext, Count % CryptoSpec.blockSize);
} else if (dataNeedsPadding && blockIndex + 1 == numBlocks) {
memcpy(Plaintext + blockIndex * CRYPTO_3KTDEA_BLOCK_SIZE, inputBlock, Count % CryptoSpec.blockSize);
CryptoMemoryXOR(&Ciphertext[(blockIndex - 1) * CRYPTO_3KTDEA_BLOCK_SIZE],
Plaintext + blockIndex * CRYPTO_3KTDEA_BLOCK_SIZE, Count % CryptoSpec.blockSize);
} else {
memcpy(Plaintext + blockIndex * CRYPTO_3KTDEA_BLOCK_SIZE, inputBlock, CRYPTO_3KTDEA_BLOCK_SIZE);
CryptoMemoryXOR(&Ciphertext[(blockIndex - 1) * CRYPTO_3KTDEA_BLOCK_SIZE],
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