Some builds (depends on crypto engine support?) of OpenSSL
0.9.7x have EVP_DigestFinal function which which clears all of
EVP_MD_CTX. This makes pgcrypto crash in functions which
re-use one digest context several times: hmac() and crypt()
with md5 algorithm.
Following patch fixes it by carring the digest info around
EVP_DigestFinal and re-initializing cipher.
Please apply this also to stable branches (8.0 / 7.4).
Note that this can be blamed on OpenSSL 0.9.7x backwards-
compatibility functions: 0.9.6x and new 0.9.7x API
(EVP_DigestFinal_ex) do clear the "secret data" but keep the
general algorithm info.
But still, the fact is that pgcrypto was relying on
undocumented beheviour.
--
marko
Index: contrib/pgcrypto/openssl.c
===================================================================
RCS file: /opt/cvs2/pgsql/contrib/pgcrypto/openssl.c,v
retrieving revision 1.13
diff -u -c -r1.13 openssl.c
*** contrib/pgcrypto/openssl.c 29 Nov 2003 22:39:28 -0000 1.13
--- contrib/pgcrypto/openssl.c 11 Mar 2005 15:39:34 -0000
***************
*** 73,80 ****
--- 73,87 ----
digest_finish(PX_MD * h, uint8 *dst)
{
EVP_MD_CTX *ctx = (EVP_MD_CTX *) h->p.ptr;
+ const EVP_MD *md = EVP_MD_CTX_md(ctx);
EVP_DigestFinal(ctx, dst, NULL);
+
+ /*
+ * Some builds of 0.9.7x clear all of ctx in EVP_DigestFinal.
+ * Fix it by reinitializing ctx.
+ */
+ EVP_DigestInit(ctx, md);
}
static void
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