JWT: updated to make JWT algorithm support more flexible, and simple to extend with specific algorithm.

library/security/jwt/src/jwt_alg_hs256.e

@@ -0,0 +1,57 @@
+note
+	description: "Summary description for {JWT_ALG_HS256}."
+	author: ""
+	date: "$Date$"
+	revision: "$Revision$"
+
+class
+	JWT_ALG_HS256
+
+inherit
+	JWT_ALG
+
+feature -- Access
+
+	name: STRING = "hs256"
+
+	encoded_string (a_message: READABLE_STRING_8; a_secret: READABLE_STRING_8): STRING
+		do
+			Result := base64_hmacsha256 (a_message, a_secret)
+		end
+
+feature {NONE} -- Implementation		
+
+	base64_hmacsha256 (s: READABLE_STRING_8; a_secret: READABLE_STRING_8): STRING_8
+		local
+			hs256: HMAC_SHA256
+		do
+			create hs256.make_ascii_key (a_secret)
+			hs256.update_from_string (s)
+			-- if Version >= EiffelStudio 18.01 then
+			-- 	Result := hs256.base64_digest --lowercase_hexadecimal_string_digest
+			-- else
+			Result := base64_bytes_encoded_string (hs256.digest)
+			-- end
+		end
+
+	base64_bytes_encoded_string (a_bytes: SPECIAL [NATURAL_8]): STRING_8
+			-- Base64 string from `a_bytes`.
+			--| Note: to be removed when 18.01 is not latest release anymore.
+		local
+			s: STRING
+			i,n: INTEGER
+		do
+			from
+				i := 1
+				n := a_bytes.count
+				create s.make (n)
+			until
+				i > n
+			loop
+				s.append_code (a_bytes[i - 1])
+				i := i + 1
+			end
+			Result := (create {BASE64}).encoded_string (s)
+		end
+
+end