Recently, I have read some article where was a discussion about multiple use of cryptographically strong hash for a password. That discussion has pushed me to a math topic. The essence of the problem arises from the idea of multiple (1,000 or more times) password processing before storing by any cryptographically strong algorithm (typically, it is a hash function) in order to get a slow algorithm of verification that effectively resists brute force in case of interception or theft of this value by an intruder . This idea is not new, and it is used by the developers of Cisco, RAR and many others. But, as far as hashing is an operation that compresses many values, there is a logical question - don’t we damage the resistance of system? I will try to answer this question.
U.S. chemists have devised a method of genetic marking of proteins so that they start lighting up using one of the seven colors in the visible range. The seven colors come out as 49 color pairs, which is enough to encode the letters, numbers and other characters. Scientists have demonstrated a new technology on the bacteria Escherichia coli.
In order to protect the encrypted text is used an additional gene that is resistant to the particular antibiotic. That is that the sensible text of the color pairs appears only after the antibiotic treatment of bacteria, when the "extra" bacteria die. It turns out that the antibiotic plays a role as a key to decrypt the message. The potential attacker will have only one attempt to find the right key.
It has been a long time that the idea of a full-fledged quantum computer thrill the minds of scientists and people that are interested in the field of cryptography. Indeed, the forthcoming of the computer is able to solve the complex problems as well it questions the existence of cryptography in the form in which it is now. Cryptographic protocols with public key will no longer make sense, because one-way functions are no longer remain unchanged. Sun goes down, the world will overturn, the river will flow backwards ... But we do not hurry to give up, right?