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Correct serious bug in AES-CBC decryption when the message length isn't

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a multiple of AES_BLOCK_SIZE.
Optimize decryption of all complete blocks in AES-CBC by removing an
unnecessary memcpy().

The error was notified by James Fernandes <jf210032@exchange.DAYTONOH.NCR.com>.
The unnecessary memcpy() was found as an effect of investigating that error.
This commit is contained in:
Richard Levitte 2003-10-15 09:00:18 +00:00
parent 79e4022a33
commit fa5846e58b
1 changed files with 4 additions and 5 deletions
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9
crypto/aes/aes_cbc.c
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@ -91,21 +91,20 @@ void AES_cbc_encrypt(const unsigned char *in, unsigned char *out,
}
} else {
while (len >= AES_BLOCK_SIZE) {
memcpy(tmp, in, AES_BLOCK_SIZE);
AES_decrypt(in, out, key);
for(n=0; n < AES_BLOCK_SIZE; ++n)
out[n] ^= ivec[n];
memcpy(ivec, tmp, AES_BLOCK_SIZE);
memcpy(ivec, in, AES_BLOCK_SIZE);
len -= AES_BLOCK_SIZE;
in += AES_BLOCK_SIZE;
out += AES_BLOCK_SIZE;
}
if (len) {
memcpy(tmp, in, AES_BLOCK_SIZE);
AES_decrypt(tmp, tmp, key);
AES_decrypt(in, tmp, key);
for(n=0; n < len; ++n)
out[n] ^= ivec[n];
memcpy(ivec, tmp, AES_BLOCK_SIZE);
out[n] = tmp[n] ^ ivec[n];
memcpy(ivec, in, AES_BLOCK_SIZE);
}
}
}