Cryptography is a technique used to safeguard data and prevent unauthorized third parties from accessing or altering valuable information for their own benefit or to the detriment of others.
One of the oldest techniques used to protect information is cryptography. This technique is as old as writing. And one of the many examples that we find about its use is the interesting case of the history of the Enigma machine, used by the Nazis during World War II to encrypt messages on the battlefront.
The word cryptography comes from the Greek κριπτός (kryptós = covered, hidden), γραφειν (graphein = to write), and the suffix -ia (used to create abstract nouns). The encrypted message itself is in plain sight. It can be read, but its meaning is hidden. Thus, we can say that using cryptography a person can hide a text or information, so that only the sender and receiver can interpret it.
With the growing rise and development of computing, it was widely disclosed and modified for use. Now it is based on complex mathematical algorithms that are responsible for encrypting messages. They have the task of guaranteeing confidentiality between the parties and the integrity of the information, while offering authentication of both the sender and the receiver, it guarantees that the sender or the receiver can repudiate the message. And finally, it guarantees that the message is new, that is, that it is not repeated.
The foundations of computer cryptography are established in the articles «A Mathematical Theory of Communication» of 1948 and «Communication Theory of Secrecy Systems» 1949. Both published by Claude Shannon that lay the foundations of information theory and modern cryptography.
«New directions of Crytography», Developed by Whitfiled Diffie and Martin Hellman in 1976 establishes the concept of public key cryptography. Crypto consolidation comes in 1977 with the publication of the RSA algorithm, developed by mathematicians Ron Rivest, Adi Shamir y Leon Adleman.
Cryptography and security
Nowadays, cryptography is one of the fundamental pillars on which technology is based blockchain. This allows the operation of the network, guarantees the mechanisms of consent between users and the integrity of the blockchain.
To guarantee that no external person can access the data, the cryptography of public key (asymmetric cryptography) and secret key cryptography (symmetric cryptography) that we will develop later. Public key encryption generates a hash which makes the distribution of information easier while the private key encrypts and decrypts information between sender and receiver.
En Bitcoin, the public key is obtained using the private key, but the reverse process is impossible to perform. That is to say, unable to get private key from public key. The public key, after some subsequent modifications, is the address that we can share with all members of the community so that they send us money. Or in your case, the one that we will use from other users of the community to make some payment. There is no risk of theft, since the funds are only accessible through the private key.
The private key is similar to a PIN or password. that we use to access different web pages, but in this case it is encrypted, adding much more security. This means that we will introduce a series of terms or words and these will be encrypted and protect the wallet or purse. Only we have these words, so we must keep them safely and not share them with anyone. This way we can access our funds at any time.
Cryptography types
As we mentioned at the beginning, crypto can be symmetric or asymmetric, depending on the type of key you use. Let's look at this in more detail.
Symmetric
La symmetric cryptography it has been used since the beginning of history and for a very long time. It is also called private key cryptography or one key cryptography. To carry it out and to be able to encrypt and decrypt a message, a unique key is used that both the sender and the receiver must previously know. This is the weak point of this method, since the key is more likely to be intercepted by a third party when it is transmitted to the receiver by the sender.
In symmetric cryptography you must use a key that is very difficult to guess, because today's computers can guess keys very quickly. Therefore, we must consider that since cryptographic algorithms are public, it must be guaranteed that their strength depends on their internal complexity and the length of the key used, to avoid brute force attacks.
Asymmetric
Also known as public key cryptography. This method makes use of two keys, a public and a private one; so it is not necessary to know a password beforehand. The public key can be sent and made known to anyone, while the private key is the one that should not be shared with anyone. When a sender wants to send a message, the sender uses the public key to encrypt the message and sends it. And only the recipient with their private key can decrypt the message.
La asymmetric cryptography It provides an extraordinary level of security, to the point that even the person who encrypted the message cannot decrypt it without the private key. This is the method used in cryptocurrencies, and it is a fundamental piece in the blockchain to be able to carry out operations and information exchanges between equals with total security and without the need to trust each other.
hybrid
It is a method that uses both symmetric and asymmetric encryption. Using public key encryption to share a key for symmetric encryption.
Knowing the basics of symmetric crypto and asymmetric crypto, we can realize what their biggest difference is. The security provided by the first is of a very low level compared to the security provided by the second. But, the speed with which symmetric cryptography encrypts and decrypts a message is superior to that of asymmetric cryptography. So from there comes hybrid cryptography.
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