March 24, 2017

Use Cryptography Like The CIA

A recent wikileaks dump of CIA material included a file called “Network Operations Division Cryptographic Requirements“. Assuming it’s genuine, this 17-page PDF describes crypto policy that must be followed by developers of “tools used to advance the CIA’s intelligence collection activities”.

Since a government security agency has insight into the state of the art in non-public cryptanalysis, it’s interesting to see what government spies recommend as a secure policy for crypto usage. Here I’ve picked out a few of the highlights that were interesting to me, in particular in the ways they’re different from other public crypto standards like PCI or ECRYPT.

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February 23, 2017

Google Announces Full SHA-1 Collision: What It Means

Today Google announced the first public full SHA-1 collision, i.e. the first pair of distinct values that when hashed with the SHA-1 function produce the same digest. This should not come as a surprise – it follows the free-start collisions announced at the end of 2015, and many cryptographers had been anticipating full SHA-1 collisions imminently.

To understand what this means, it helps to look at what happened after collisions were found in the MD5 hash function.

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October 24, 2014

Algorithm Choice in PKCS#11 (part 6) – MAC modes

In previous posts we covered the state of the art cryptanalysis results on the RSA mechanisms, hash functions, block ciphers and block cipher modes available in PKCS#11. In this post we look at the message authentication code (MAC) mechanisms available.

Return of the MAC

There are essentially two ways to produce a MAC from a message and a shared secret: one is to use a block cipher in an appropriate MAC mode, the other is to used a keyed hash function (HMAC). During the 1990s, it was hard for US-based companies to export technology containing strong block ciphers, and the state of the art block ciphers were a lot slower than the widely used hash functions. Hence the HMAC construction became very popular.

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