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Fix key wrapping mode with padding to conform to RFC 5649.

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According to RFC 5649 section 4.1 step 1) we should not add padding
if plaintext length is multiply of 8 ockets.

This matches pseudo-code in http://dx.doi.org/10.6028/NIST.SP.800-38F
on page 15, section 6.3 KWP, algorithm 5 KWP-AE, step 2.

PR#3675

Reviewed-by: Stephen Henson <steve@openssl.org>
Reviewed-by: Andy Polyakov <appro@openssl.org>
This commit is contained in:
Petr Spacek 2015-01-26 14:39:50 +01:00 committed by Dr. Stephen Henson
parent b5f07d6a66
commit ffa75828dd
1 changed files with 7 additions and 2 deletions
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9
crypto/modes/wrap128.c
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@ -230,8 +230,13 @@ size_t CRYPTO_128_wrap_pad(void *key, const unsigned char *icv,
const unsigned char *in, size_t inlen,
block128_f block)
{
/* n: number of 64-bit blocks in the padded key data */
const size_t blocks_padded = (inlen + 8) / 8;
/* n: number of 64-bit blocks in the padded key data
*
* If length of plain text is not a multiple of 8, pad the plain text octet
* string on the right with octets of zeros, where final length is the
* smallest multiple of 8 that is greater than length of plain text.
* If length of plain text is a multiple of 8, then there is no padding. */
const size_t blocks_padded = (inlen + 7) / 8; /* CEILING(m/8) */
const size_t padded_len = blocks_padded * 8;
const size_t padding_len = padded_len - inlen;
/* RFC 5649 section 3: Alternative Initial Value */