[FD] KETAMINE: Multiple vulnerabilities in SecureRandom(), numerous cryptocurrency products affected.

A significant number of past and current cryptocurrency products contain a JavaScript class named SecureRandom(), containing both entropy collection and a PRNG. The entropy collection and the RNG itself are both deficient to the degree that key material can be recovered by a third party with medium complexity. There are a substantial number of variations of this SecureRandom() class in various pieces of software, some with bugs fixed, some with additional bugs added. Products that aren't today vulnerable due to moving to other libraries may be using old keys that have been previously compromised by usage of SecureRandom(). The most common variations of the library attempts to collect entropy from window.crypto's CSPRNG, but due to a type error in a comparison this function is silently stepped over without failing. Entropy is subsequently gathered from math.Random (a 48bit linear congruential generator, seeded by the time in some browsers), and a single execution of a medium resolution timer. In some known configurations this system has substantially less than 48 bits of entropy. The core of the RNG is an implementation of RC4 ("arcfour random"), and the output is often directly used for the creation of private key material as well as cryptographic nonces for ECDSA signatures. RC4 is publicly known to have biases of several bits, which are likely sufficient for a lattice solver to recover a ECDSA private key given a number of signatures. One popular Bitcoin web wallet re-initialized the RC4 state for every signature which makes the biases bit-aligned, but in other cases the Special K would be manifest itself over multiple transactions. Necessary action: * identify and move all funds stored using SecureRandom() * rotate all key material generated by, or has come into contact with any piece of software using SecureRandom() * do not write cryptographic tools in non-type safe languages * don't take the output of a CSPRNG and pass it through RC4 - 3CJ99vSipFi9z11UdbdZWfNKjywJnY8sT8

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