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crypto: ecdsa - Use ecc_digits_from_bytes to convert signature
Since ecc_digits_from_bytes will provide zeros when an insufficient number of bytes are passed in the input byte array, use it to convert the r and s components of the signature to digits directly from the input byte array. This avoids going through an intermediate byte array that has the first few bytes filled with zeros. Signed-off-by: Stefan Berger <stefanb@linux.ibm.com> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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@ -38,7 +38,6 @@ static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned char tag,
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size_t bufsize = ndigits * sizeof(u64);
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ssize_t diff = vlen - bufsize;
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const char *d = value;
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u8 rs[ECC_MAX_BYTES];
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if (!value || !vlen)
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return -EINVAL;
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@ -46,7 +45,7 @@ static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned char tag,
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/* diff = 0: 'value' has exacly the right size
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* diff > 0: 'value' has too many bytes; one leading zero is allowed that
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* makes the value a positive integer; error on more
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* diff < 0: 'value' is missing leading zeros, which we add
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* diff < 0: 'value' is missing leading zeros
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*/
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if (diff > 0) {
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/* skip over leading zeros that make 'value' a positive int */
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@ -61,14 +60,7 @@ static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned char tag,
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if (-diff >= bufsize)
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return -EINVAL;
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if (diff) {
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/* leading zeros not given in 'value' */
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memset(rs, 0, -diff);
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}
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memcpy(&rs[-diff], d, vlen);
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ecc_swap_digits((u64 *)rs, dest, ndigits);
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ecc_digits_from_bytes(d, vlen, dest, ndigits);
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return 0;
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}
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