Can somebody explain to me why using addresses more than once is insecure and whether this will always be an issue or can it be mitigated in wallet or software updates? Thanks.
I'm quoting Wikipedia here, so keep that in mind. But I believe that the way they encrypt data is based on this. Thus making it quantum proof as well.
In cryptography, a Lamport signature or Lamport one-time signature scheme is a method for constructing a digital signature. Lamport signatures can be built from any cryptographically secure one-way function; usually, a cryptographic hash function is used. Although the potential development of quantum computers threatens the security of many common forms of cryptography such as RSA, it is believed that Lamport signatures with large hash functions would still be secure in that event. Unfortunately, each Lamport key can only be used to sign a single message. However, combined with hash trees, a single key could be used for many messages, making this a fairly efficient digital signature scheme. The Lamport signature cryptosystem was invented in 1979 and named after its inventor, Leslie Lamport.