What is Cryptography?
Cryptography comes from the Greek words kryptós, meaning hidden, and graphein, meaning writing.
Cryptography is a set of mathematical methods that work to provide information security concepts such as privacy, authentication and integrity. These methods aim to protect the information (thus its sender and receiver infos along with it) from active or passive attacks that may be encountered during the transmission of information.
In other words, cryptography can be seen as all of the techniques used to transform readable information into an unreadable form by unwanted parties.
It's the usage area of cryptology known as the science of ciphering. In short, it's a science and technique that goes back to the beginning of human history. Its main purposes are; confidentiality, identification, integrity and constancy. And I'll tell that the computer part in general and the part that you can use mostly on the internet.
If we try tı divide the crypto process into two pieces, basically it'ld be encryption and decryption. This can also be with a key between sender and receiver. Sender encrypts the message with the key and sends it to receiver. Receiver also decrypts it with the same key and receives the message. Thus, no information is leaked from the message, even in case of being captured by another person. This is where hackers steps in. There are solution methods of basic crypto systems. The simplest of these is to try and compare the encryption technique according to all possibilities to open the message we have. However, this is almost impossible in cases encoded with very difficult techniques.
Symmetrical - Asymmetrical
Basic cryptology is divided into two main groups, symmetric and asymmetric. In symmetric encryptions, the message exchange between the receiver and the sender takes place with the same key. The receiver can decrypt the message with the key used while sender sending it. In asymmetric encryption, there are 2 keys. The sender encrypts with one of these two keys, but the receiver has to use the other key that the sender didn't use for encryption.
Basic bit operations and usage
In fact, cryptology is a perfect fit for someone who loves mathematics. Basically it's the conversion of large numbers into bits for operational convenience. So for example, 4 bits are equivalent to 128 characters. The basis for this is the residual class of 2 (0 and 1). Likewise, a 4-bit character is a form of 4 0s and 1s written next to each other.
Possibilities for a password to be cracked
For passwords that are completely made up of numbers, there are shortcut solutions outside of the standards, but if we evaluate the exact times according to bits:
As you can see, as it increases in multiples of 2, the solving time progresses towards the impossible. Of course, if the machine speed increases in the same way by 2 times. These speeds would decrease by dividing by half at the same rates.
One Time Pad
In short, it's a key as long as the message we have. In the randomly selected encryption process, each letter in the message and the corresponding letter of that letter on the pad are converted into numbers and added. Sequence numbers in the alphabet can be used when converting letters to numbers. If the total exceeds the number of letters in the alphabet, the number of letters in the alphabet is subtracted from the total. The resulting number is either typed directly or translated into a letter. For decryption, however, the process is reversed with the same key strip. This time, the letters on the pad are removed from the letters in the encrypted message, and if the total falls below zero, the number of letters in the alphabet is added.
It's very important that the letters on the pad are chosen at random. If we add a message with regular letters to a randomly selected pad, the letters we get will again be random. Therefore, we have no choice but to guess which lane was used to decrypt this encrypted message. Since the pad and the message are the same length (which requires one pad to be used only once), if we try all the pads, we get all the messages of that length. Therefore, the safety of the disposable strip has been proven. The only information leaked from the streamed-encrypted message is its presence and length.
Public-Key Cryptography
As I wrote above, there are basically 2 keys: symmetric and asymmetric keys. The symmetric key consists of a single key and can decipher the information if someone else has this key during the exchange of information. Therefore, the first asymmetric encryption methods created the public key phenomenon. One of them is called the public key and the other is called the private key. It's known and doesn't need to be hidden. It's used in the encryption process, but since it requires a private key in the decryption process, it's only found in the receiver and decrypted with its help.
Trapdoor
As far as we know, both one-way and pseudorandom permutations do not help us to get public key encryption schemes. The way we obtain these is by using trapdoor functions (also known as trapdoor permutations). These are keyed collections with the following property: there are two keys for each function: one to compute it in the forward direction and one to compute it in the reverse direction (invert it). Now the key for the forward direction can be given to the adversary (not inside a black box but really given to him) and still this will not help him invert the function (that is, the function is a one-way permutation to someone not knowing the invertion key or trapdoor).
Hacking and Usage Area (everyone is probably waiting this part)
The science of cryptology has been used and will be used in private conversations between banks and companies with important data exchange, and it will be used in confidential communications as well. So it's a basic science that hackers stand on. It has been used for years to produce solutions. It's possible to solve it, but as in the example I gave above, I don't think anyone will live for 292000 years. So basically we have to develop our technique. There are many encryption techniques and they all have different solutions. That's why you have to go beyond being a simple computer user to decrypt a password. With the digital signature event that is now becoming widespread, it's possible to prevent hackers, but nothing is impossible. Digital signatures are data encyrpt with 128-bit encryption techniques. To identify ourselves, we must have our digital signature under it. Even if a stranger (possibly hacker) gets our digital signature, he'll not be able to solve it and reliability will be guaranteed. That's why cryptology is important.
Cryptography comes from the Greek words kryptós, meaning hidden, and graphein, meaning writing.
Cryptography is a set of mathematical methods that work to provide information security concepts such as privacy, authentication and integrity. These methods aim to protect the information (thus its sender and receiver infos along with it) from active or passive attacks that may be encountered during the transmission of information.
In other words, cryptography can be seen as all of the techniques used to transform readable information into an unreadable form by unwanted parties.
It's the usage area of cryptology known as the science of ciphering. In short, it's a science and technique that goes back to the beginning of human history. Its main purposes are; confidentiality, identification, integrity and constancy. And I'll tell that the computer part in general and the part that you can use mostly on the internet.
If we try tı divide the crypto process into two pieces, basically it'ld be encryption and decryption. This can also be with a key between sender and receiver. Sender encrypts the message with the key and sends it to receiver. Receiver also decrypts it with the same key and receives the message. Thus, no information is leaked from the message, even in case of being captured by another person. This is where hackers steps in. There are solution methods of basic crypto systems. The simplest of these is to try and compare the encryption technique according to all possibilities to open the message we have. However, this is almost impossible in cases encoded with very difficult techniques.
Symmetrical - Asymmetrical
Basic cryptology is divided into two main groups, symmetric and asymmetric. In symmetric encryptions, the message exchange between the receiver and the sender takes place with the same key. The receiver can decrypt the message with the key used while sender sending it. In asymmetric encryption, there are 2 keys. The sender encrypts with one of these two keys, but the receiver has to use the other key that the sender didn't use for encryption.
Basic bit operations and usage
In fact, cryptology is a perfect fit for someone who loves mathematics. Basically it's the conversion of large numbers into bits for operational convenience. So for example, 4 bits are equivalent to 128 characters. The basis for this is the residual class of 2 (0 and 1). Likewise, a 4-bit character is a form of 4 0s and 1s written next to each other.
Possibilities for a password to be cracked
For passwords that are completely made up of numbers, there are shortcut solutions outside of the standards, but if we evaluate the exact times according to bits:
Kod:
It takes 36 minutes to crack 32 bit encryption in 10^6/sec speed.
It takes 6 days to crack 40 bit encryption in 10^6/sec speed.
It takes 292000 years to crack 64 bit encryption in 10^6/sec speed.
It takes 54*10^23 years to crack 128 bit encryption in 10^6/sec speed.As you can see, as it increases in multiples of 2, the solving time progresses towards the impossible. Of course, if the machine speed increases in the same way by 2 times. These speeds would decrease by dividing by half at the same rates.
One Time Pad
In short, it's a key as long as the message we have. In the randomly selected encryption process, each letter in the message and the corresponding letter of that letter on the pad are converted into numbers and added. Sequence numbers in the alphabet can be used when converting letters to numbers. If the total exceeds the number of letters in the alphabet, the number of letters in the alphabet is subtracted from the total. The resulting number is either typed directly or translated into a letter. For decryption, however, the process is reversed with the same key strip. This time, the letters on the pad are removed from the letters in the encrypted message, and if the total falls below zero, the number of letters in the alphabet is added.
Kod:
Plain Text: BUMESAJTEKKULLANIMLIKSERITILESIFRELENMISTIR
Pad: DOKPEZRHOCVSVMLNDTKBJTSDSULEPLSSZCHEBZMQCHJ + (mod 26)
Encrypted Text: EIWTWZAASMFMGXLALFVJTLWUANTPTD***GSIOLUIVPAIt's very important that the letters on the pad are chosen at random. If we add a message with regular letters to a randomly selected pad, the letters we get will again be random. Therefore, we have no choice but to guess which lane was used to decrypt this encrypted message. Since the pad and the message are the same length (which requires one pad to be used only once), if we try all the pads, we get all the messages of that length. Therefore, the safety of the disposable strip has been proven. The only information leaked from the streamed-encrypted message is its presence and length.
Public-Key Cryptography
As I wrote above, there are basically 2 keys: symmetric and asymmetric keys. The symmetric key consists of a single key and can decipher the information if someone else has this key during the exchange of information. Therefore, the first asymmetric encryption methods created the public key phenomenon. One of them is called the public key and the other is called the private key. It's known and doesn't need to be hidden. It's used in the encryption process, but since it requires a private key in the decryption process, it's only found in the receiver and decrypted with its help.
Trapdoor
As far as we know, both one-way and pseudorandom permutations do not help us to get public key encryption schemes. The way we obtain these is by using trapdoor functions (also known as trapdoor permutations). These are keyed collections with the following property: there are two keys for each function: one to compute it in the forward direction and one to compute it in the reverse direction (invert it). Now the key for the forward direction can be given to the adversary (not inside a black box but really given to him) and still this will not help him invert the function (that is, the function is a one-way permutation to someone not knowing the invertion key or trapdoor).
Hacking and Usage Area (everyone is probably waiting this part)
The science of cryptology has been used and will be used in private conversations between banks and companies with important data exchange, and it will be used in confidential communications as well. So it's a basic science that hackers stand on. It has been used for years to produce solutions. It's possible to solve it, but as in the example I gave above, I don't think anyone will live for 292000 years. So basically we have to develop our technique. There are many encryption techniques and they all have different solutions. That's why you have to go beyond being a simple computer user to decrypt a password. With the digital signature event that is now becoming widespread, it's possible to prevent hackers, but nothing is impossible. Digital signatures are data encyrpt with 128-bit encryption techniques. To identify ourselves, we must have our digital signature under it. Even if a stranger (possibly hacker) gets our digital signature, he'll not be able to solve it and reliability will be guaranteed. That's why cryptology is important.
Source: https://www.turkhackteam.org/kriptografi-sifreleme/847927-kriptografiye-giris.html
Translator: R4V3N
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