+ let hmacSize = 256 / 8 // [byte].
+ let signatureSize = Crypto.rsaKeySize / 8 // [byte].
+ let keysSize = Crypto.rsaKeySize / 8 // [byte].
+
+ let generatKeysPair () : Key * Key = Crypto.generateRSAKeysPair ()
+
+ /// Format of the container:
+ /// <mac><signature><encrypted keys><cyphertext>
+ /// Where the sizes of the three first parts are given by 'hmacSize', 'signatureSize' and 'keysSize'.