There&#x27;s been some good work in Merkle Signatures in recent times. I posted a bunch on Schneier&#x27;s blog here:<p><a href="https:&#x2F;&#x2F;www.schneier.com&#x2F;blog&#x2F;archives&#x2F;2015&#x2F;03&#x2F;friday_squid_bl_470.html#c6692293" rel="nofollow">https:&#x2F;&#x2F;www.schneier.com&#x2F;blog&#x2F;archives&#x2F;2015&#x2F;03&#x2F;friday_squid_...</a>