TeaSpeak/tomcrypt
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ltc: ctr: update pt and ct after acceleration

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Problem occurs in the condition of the following case:

1st decryption:
Decrypt a ciphertext whose length is a multiple of the block size (16B)
(len = n * block_size)
2nd decryption:
Decrypt the continuing ciphertext whose length is not a multiple of the
block size
(len = m * block_size + l)

In this case accel_ctr_encrypt() is firstly used at the 2nd decryption.
If pt and ct are not updated, the top (l = len % block_size) bytes of
decryption result are sometimes destroyed.

From: Tetsuya Yoshizaki <yoshizaki.tetsuya@socionext.com>
Signed-off-by: Tetsuya Yoshizaki <yoshizaki.tetsuya@socionext.com>
Signed-off-by: Victor Chong <victor.chong@linaro.org>
(cherry picked from commit d1d3ae2d1e705f36e7d313aa4a9b61c0a146ee44)
This commit is contained in:
Tetsuya Yoshizaki 2018-01-19 06:23:16 +00:00 committed by Steffen Jaeckel
parent 5501572b35
commit 144839a8db
1 changed files with 2 additions and 0 deletions
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2
src/modes/ctr/ctr_encrypt.c
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@ -53,6 +53,8 @@ int ctr_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, s
if ((err = cipher_descriptor[ctr->cipher].accel_ctr_encrypt(pt, ct, len/ctr->blocklen, ctr->ctr, ctr->mode, &ctr->key)) != CRYPT_OK) {
return err;
}
pt += (len / ctr->blocklen) * ctr->blocklen;
ct += (len / ctr->blocklen) * ctr->blocklen;
len %= ctr->blocklen;
}