commit 8d16023c31e4b7626d44757bd0f47ad1ad1eb8ab
Author: Jared Jennings <jared.jennings.ctr@us.af.mil>
Date:   Thu Mar 27 18:42:23 2014 -0500

    use OpenSSL EVP API instead of MD5 API to perform MD5 hashes using OpenSSL in ext/digest

diff --git a/ext/digest/md5/md5ossl.c b/ext/digest/md5/md5ossl.c
index 97c7902..fdde089 100644
--- a/ext/digest/md5/md5ossl.c
+++ b/ext/digest/md5/md5ossl.c
@@ -2,8 +2,15 @@
 
 #include "md5ossl.h"
 
-void
-MD5_Finish(MD5_CTX *pctx, unsigned char *digest)
+int
+rb_digest_md5osslevp_Init(EVP_MD_CTX *pctx)
 {
-    MD5_Final(digest, pctx);
+  return EVP_DigestInit_ex(pctx, EVP_md5(), NULL);
+}
+
+int
+rb_digest_md5osslevp_Finish(EVP_MD_CTX *pctx, unsigned char *digest)
+{
+  /* if EVP_DigestFinal_ex fails, we ignore that */
+  return EVP_DigestFinal_ex(pctx, digest, NULL);
 }
diff --git a/ext/digest/md5/md5ossl.h b/ext/digest/md5/md5ossl.h
index c50e20c..96eee63 100644
--- a/ext/digest/md5/md5ossl.h
+++ b/ext/digest/md5/md5ossl.h
@@ -4,10 +4,22 @@
 #define MD5OSSL_H_INCLUDED
 
 #include <stddef.h>
-#include <openssl/md5.h>
+#include <openssl/evp.h>
 
-#define MD5_BLOCK_LENGTH	MD5_CBLOCK
+#define MD5_Init   rb_digest_md5osslevp_Init
+#define MD5_Update EVP_DigestUpdate
+#define MD5_Finish rb_digest_md5osslevp_Finish
+#define MD5_CTX    EVP_MD_CTX
 
-void MD5_Finish(MD5_CTX *pctx, unsigned char *digest);
+/* We should use EVP_MD_size(3) and EVP_MD_block_size(3), but the
+   advantage of these is that they are flexible across digest
+   algorithms and we are fixing the digest algorithm here; and these
+   numbers must be constants because the rb_digest_metadata_t
+   structure is declared const. Simplest way is to write literals. */
+#define MD5_BLOCK_LENGTH		64
+#define MD5_DIGEST_LENGTH		16
+
+int MD5_Init(MD5_CTX *pctx);
+int MD5_Finish(MD5_CTX *pctx, unsigned char *digest);
 
 #endif