diff -ru git-2.18.1/builtin/receive-pack.c git-2.18.1_patched/builtin/receive-pack.c
--- git-2.18.1/builtin/receive-pack.c	2018-09-27 22:44:44.000000000 +0200
+++ git-2.18.1_patched/builtin/receive-pack.c	2019-06-11 11:19:52.887797134 +0200
@@ -26,6 +26,8 @@
 #include "oidset.h"
 #include "packfile.h"
 #include "protocol.h"
+#include <openssl/hmac.h>
+#include <openssl/evp.h>
 
 static const char * const receive_pack_usage[] = {
 	N_("git receive-pack <git-dir>"),
@@ -419,43 +421,11 @@
 
 #define HMAC_BLOCK_SIZE 64
 
-static void hmac_sha1(unsigned char *out,
+static inline void hmac_sha1(unsigned char *out,
 		      const char *key_in, size_t key_len,
 		      const char *text, size_t text_len)
 {
-	unsigned char key[HMAC_BLOCK_SIZE];
-	unsigned char k_ipad[HMAC_BLOCK_SIZE];
-	unsigned char k_opad[HMAC_BLOCK_SIZE];
-	int i;
-	git_SHA_CTX ctx;
-
-	/* RFC 2104 2. (1) */
-	memset(key, '\0', HMAC_BLOCK_SIZE);
-	if (HMAC_BLOCK_SIZE < key_len) {
-		git_SHA1_Init(&ctx);
-		git_SHA1_Update(&ctx, key_in, key_len);
-		git_SHA1_Final(key, &ctx);
-	} else {
-		memcpy(key, key_in, key_len);
-	}
-
-	/* RFC 2104 2. (2) & (5) */
-	for (i = 0; i < sizeof(key); i++) {
-		k_ipad[i] = key[i] ^ 0x36;
-		k_opad[i] = key[i] ^ 0x5c;
-	}
-
-	/* RFC 2104 2. (3) & (4) */
-	git_SHA1_Init(&ctx);
-	git_SHA1_Update(&ctx, k_ipad, sizeof(k_ipad));
-	git_SHA1_Update(&ctx, text, text_len);
-	git_SHA1_Final(out, &ctx);
-
-	/* RFC 2104 2. (6) & (7) */
-	git_SHA1_Init(&ctx);
-	git_SHA1_Update(&ctx, k_opad, sizeof(k_opad));
-	git_SHA1_Update(&ctx, out, GIT_SHA1_RAWSZ);
-	git_SHA1_Final(out, &ctx);
+	HMAC(EVP_sha1(), key_in, key_len, text, text_len, out, NULL);
 }
 
 static char *prepare_push_cert_nonce(const char *path, timestamp_t stamp)
diff -ru git-2.18.1/Makefile git-2.18.1_patched/Makefile
--- git-2.18.1/Makefile	2018-09-27 22:44:44.000000000 +0200
+++ git-2.18.1_patched/Makefile	2019-06-10 17:28:26.137986964 +0200
@@ -1721,6 +1721,8 @@
 	BASIC_CFLAGS += -DHAVE_GETDELIM
 endif
 
+EXTLIBS += -lcrypto
+
 ifneq ($(PROCFS_EXECUTABLE_PATH),)
 	procfs_executable_path_SQ = $(subst ','\'',$(PROCFS_EXECUTABLE_PATH))
 	BASIC_CFLAGS += '-DPROCFS_EXECUTABLE_PATH="$(procfs_executable_path_SQ)"'