diff --git a/src/digest.cc b/src/digest.cc
index 71b14eee53..bb75e22596 100644
--- a/src/digest.cc
+++ b/src/digest.cc
@@ -63,12 +63,18 @@ void hash_final(EVP_MD_CTX* c, u_char* md)
 
 unsigned char* internal_md5(const unsigned char* data, unsigned long len, unsigned char* out)
 	{
-	static unsigned char static_out[MD5_DIGEST_LENGTH];
+	return calculate_digest(Hash_MD5, data, len, out);
+	}
+
+unsigned char* calculate_digest(HashAlgorithm Alg, const unsigned char* data, uint64_t len, unsigned char* out)
+	{
+	// maximum possible length for supported hashes
+	static unsigned char static_out[SHA512_DIGEST_LENGTH];
 
 	if ( ! out )
 		out = static_out; // use static array for return, see OpenSSL man page
 
-	EVP_MD_CTX* c = hash_init(Hash_MD5);
+	EVP_MD_CTX* c = hash_init(Alg);
 	hash_update(c, data, len);
 	hash_final(c, out);
 	return out;
diff --git a/src/digest.h b/src/digest.h
index e102828c7c..f5569179ff 100644
--- a/src/digest.h
+++ b/src/digest.h
@@ -22,6 +22,8 @@ inline void* EVP_MD_CTX_md_data(const EVP_MD_CTX* ctx)
 	}
 #endif
 
+// if you add something here, note that you might have to make sure that the
+// static_out member in calculate_digest is still long enough.
 enum HashAlgorithm { Hash_MD5, Hash_SHA1, Hash_SHA224, Hash_SHA256, Hash_SHA384, Hash_SHA512 };
 
 inline const char* digest_print(const u_char* digest, size_t n)
@@ -54,3 +56,13 @@ void hash_update(EVP_MD_CTX* c, const void* data, unsigned long len);
 void hash_final(EVP_MD_CTX* c, u_char* md);
 
 unsigned char* internal_md5(const unsigned char* data, unsigned long len, unsigned char* out);
+
+/**
+ * Calculates the selected digest.
+ * @param Alg Digest algorithm to use.
+ * @param data Data to hash.
+ * @param len Length of data to hash.
+ * @param out Buffer to write data to. If set to nullptr, a static buffer will be used
+ * @return Buffer that the hash was written to. Length is deoendent on the chosen hash function.
+ */
+unsigned char* calculate_digest(HashAlgorithm Alg, const unsigned char* data, uint64_t len, unsigned char* out);