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:lock: Cryptographic Services :lock: - Coggle Diagram
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Cryptographic Services
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Secure communications
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Securing network infrastructure involves device hardening, access control, threat monitoring, endpoint protection, and email/web security.
There are 3 primary objectives of securing communications.
Authentication
: The message comes from an authentic source.
Integrity:
No one intercepted the message and altered it.
Confidentiality:
If the message is captured it cannot be deciphered.
The most popular symmetric encryption algorithm is the Advanced Encryption Standard (AES).
Authentication
Guarantees that a message comes from a source that it claims to come from.
It is similar to put a PIN on a device or banking a ATM.
Data nonrepudiation is a similar service that allows the sender of a message to be uniquely identified. With nonrepudiation services in place, a sender cannot deny having been the source of that message.
Data integrity
Ensures that messages are not altered in transit.
European nobility ensured the data integrity of documents by creating a wax seal to close an envelope.
Data confidentiality
ensures privacy so that only the receiver can read the message. This can be achieved through encryption.
When enabling encryption, readable data is called plaintext, or cleartext, while the encrypted version is called encrypted text.
Using a hash function is another way to ensure data confidentiality. A hash function transforms a string of characters into a usually shorter, fixed-length value or key that represents the original string.
Cryptography
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Creating cipher text
A scytale is a device used to generate a transposition cipher. A strip of paper or other material is wrapped around a rod of a known diameter.
Caesar Cipher: The Caesar Cipher is a type of substitution cipher in which each letter is replaced by another letter that is a set number of places away in the alphabet.
Vigenere Cipher: The Vigenère cipher is a type of polyalphabetic substitution cipher. It was considered unbreakable until 1863. To use the cipher a key text is generated that repeats for the length of the message to be encrypted.
Enigma Machine: The Enigma machine was an electromechanical encryption device that was developed and used by Nazi Germany during World War II. The device depended on the distribution of pre-shared keys that were used to encrypt and decrypt messages
Transposition ciphers
In transposition ciphers, no letters are replaced; they are simply rearranged
Modern encryption block cipher algorithms, such as AES and the legacy 3DES, still use transposition as part of the algorithm.
Substitution ciphers
Substitution ciphers substitute one letter for another. In their simplest form, substitution ciphers retain the letter frequency of the original message.
Because the entire message relied on the same single key shift, the Caesar cipher is referred to as a monoalphabetic substitution cipher. It is also fairly easy to crack
For this reason, polyalphabetic ciphers, such as the Vigenère cipher, were invented.
One-Time Pad Ciphers
proposed a teletype cipher in which a prepared key consisting of an arbitrarily long, non-repeating sequence of numbers was kept on paper tape, shown in the figure. It was then combined character by character with the plaintext message to produce the ciphertext.
Cryptanalysis
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. Cryptanalysis is the practice and study of determining the meaning of encrypted information (cracking the code), without access to the shared secret key.
The Vigenère cipher had been absolutely secure until it was broken in the 19th century by English cryptographer Charles Babbage.
Mary, Queen of Scots, was plotting to overthrow Queen Elizabeth I from the throne and sent encrypted messages to her co-conspirators. The cracking of the code used in this plot led to the beheading of Mary in 1587
The Enigma-encrypted communications were used by the Germans to navigate and direct their U-boats in the Atlantic. Polish and British cryptanalysts broke the German Enigma code
Methods of cracking code
Brute-force method: The attacker tries every possible key knowing that eventually one of them will work.
Ciphertext method: The attacker has the ciphertext of several encrypted messages but no knowledge of the underlying plaintext.
Known-plaintext method: The attacker has access to the ciphertext of several messages and knows something about the plaintext underlying that ciphertext.
Choosen-plaintext method: The attacker chooses which data the encryption device encrypts and observes the ciphertext output.
Choosen ciphertext method: The attacker can choose different ciphertext to be decrypted and has access to the decrypted plaintext.
Meet-in-the-middle: The attacker knows a portion of the plaintext and the corresponding ciphertext.
Cryptology
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Cryptology is the science of making and breaking secret codes.
It combines the:
-Cryptography: development and use of codes.
-Cryptoanalisis: breaking of thode codes.
Cryptanalists
Cryptanalysis is often used by governments in military and diplomatic surveillance, by enterprises in testing the strength of security procedures, and by malicious hackers in exploiting weaknesses in websites.
it is actually a necessity. It is an ironic fact of cryptography that it is impossible to prove that any algorithm is secure. It can only be proven that it is not vulnerable to known cryptanalytic attacks
In the world of communications and networking, authentication, integrity, and data confidentiality are implemented in many ways using various protocols and algorithms.
Integrity:
MD5(legacy), SHA
Authenticity:
HMAC-MD5 (legacy), HMAC-SHA-256, RSA and DSA
Confidentiality:
3DES(Legacy), AES
