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check that there are no extra bytes in the checksum and that the

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parameters are NULL or the NULL-type. All to avoid having excess data
that can be used to fake the signature.


git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@18031 ec53bebd-3082-4978-b11e-865c3cabbd6b
This commit is contained in:
Love Hörnquist Åstrand
2006-09-05 21:38:44 +00:00
parent 3d82dd78b7
commit f62a5620c6
1 changed files with 21 additions and 6 deletions
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27
lib/hx509/crypto.c
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@@ -130,7 +130,7 @@ rsa_verify_signature(const struct signature_alg *sig_alg,
const SubjectPublicKeyInfo *spi;
DigestInfo di;
unsigned char *to;
int tosize;
int tosize, retsize;
int ret;
RSA *rsa;
RSAPublicKey pk;
@@ -167,21 +167,27 @@ rsa_verify_signature(const struct signature_alg *sig_alg,
goto out;
}
ret = RSA_public_decrypt(sig->length, (unsigned char *)sig->data,
to, rsa, RSA_PKCS1_PADDING);
if (ret == -1) {
retsize = RSA_public_decrypt(sig->length, (unsigned char *)sig->data,
to, rsa, RSA_PKCS1_PADDING);
if (retsize == -1) {
ret = HX509_CRYPTO_SIG_INVALID_FORMAT;
free(to);
goto out;
}
if (ret > tosize)
if (retsize > tosize)
_hx509_abort("internal rsa decryption failure: ret > tosize");
ret = decode_DigestInfo(to, ret, &di, &size);
ret = decode_DigestInfo(to, retsize, &di, &size);
free(to);
if (ret) {
goto out;
}
/* Check for extra data inside the sigature */
if (size != retsize) {
ret = HX509_CRYPTO_SIG_INVALID_FORMAT;
goto out;
}
if (sig_alg->digest_oid &&
heim_oid_cmp(&di.digestAlgorithm.algorithm,
(*sig_alg->digest_oid)()) != 0)
@@ -190,6 +196,15 @@ rsa_verify_signature(const struct signature_alg *sig_alg,
goto out;
}
/* verify that the parameters are NULL or the NULL-type */
if (di.digestAlgorithm.parameters != NULL &&
(di.digestAlgorithm.parameters->length != 2 ||
memcmp(di.digestAlgorithm.parameters->data, "\x05\x00", 2) != 0))
{
ret = HX509_CRYPTO_SIG_INVALID_FORMAT;
goto out;
}
ret = _hx509_verify_signature(NULL,
&di.digestAlgorithm,
data,