Cryptographic Objectives Cryptographic Concepts Flashcards

CA may use a third-party Registration Authority to perform the necessary checks on the person or company requesting the certificate to confirm their identity. The RA may appear to the client as a CA, but they do not actually sign the certificate that is issued. As discussed above, the CA issues certificate to a client and assist other users to verify the certificate. For analogy, a certificate can be considered as the ID card issued to the person. People use ID cards such as a driver’s license, passport to prove their identity.

Create another file secret2.txt with the text “ Hello All” in it. This protocol is versatile for the needs of the internet, and is currently used in the SSH2 software. The protocol is used to secure terminal sessions and TCP connections. GnuPG – The GNU Privacy Guard – is compliant with the proposed OpenPGP Internet standard as described in RFC2440. Encryption is the transformation of data into a form that is as close to impossible as possible to read without the appropriate knowledge (e.g. a key). Its purpose is to ensure privacy by keeping information hidden from anyone for whom it is not intended.

Cryptography Objectives

Pre-decided IV is initially loaded at the start of decryption. Unlike DES, the number of rounds in AES is variable and depends on the length of the key. AES uses 10 rounds for 128-bit keys, 12 rounds for 192-bit keys and 14 rounds for 256-bit keys. Each of these rounds uses a different 128-bit round key, which is calculated from the original AES key.

Cryptography Fundamentals

The process is said to be almost similar and not exactly same. In the case of decryption, the only difference is that the subkeys used in encryption are used in the reverse order. The encryption process uses the Feistel structure consisting multiple rounds of processing of the plaintext, each round consisting of a “substitution” step followed by a permutation step. Digital Encryption Standard − The popular block cipher of the 1990s.

Man in Middle Attack − The targets of this attack are mostly public key cryptosystems where key exchange is involved before communication takes place. In a public-key cryptosystem, the encryption key is in open domain and is known to any potential attacker. Using this key, he can generate pairs of corresponding plaintexts and ciphertexts. We know that once the plaintext is encrypted into ciphertext, it is put on unsecure public channel for transmission.

  • Several methods for making and verifying digital signatures are freely available but the most widely known algorithm is the RSA public-key algorithm.
  • To obtain the plaintext, the attacker only needs to find out the secret decryption key, as the algorithm is already in public domain.
  • Decrypting the Playfair cipher is as simple as doing the same process in reverse.
  • OpenCryptoKi is an opensource project that provides a cryptography library with a focus on security and portability.
  • Interestingly, the different modes result in different properties being achieved which add to the security of the underlying block cipher.
  • Symmetric algorithms use the same key for encryption and decryption .

Digital signature is a cryptographic value that is calculated from the data and a secret key known only by the signer. In real world, the receiver of message needs assurance that the message belongs to the sender and he should not be able to repudiate the origination of that message. Second is, when only message digest is encrypted using sender’s private key.

With the advances taking place in this field, government organizations, military units, and some corporate houses started adopting the applications of cryptography. Now, the arrival of computers and the Internet has brought effective cryptography within the reach of common people. In steganography, an unintended recipient or an intruder is unaware of the fact that observed data contains hidden information.

Types Of Cryptography

This “mangling” of code makes it impossible to easily understand, copy, fix, or maintain. Get in touch with our team at Triskele Labs and discover how we can help you protect your data and integrate cryptography into your security strategies and systems. Information security is one of the biggest concerns for businesses operating competitively in the modern business environment. When executed via the right strategies, cryptography helps you safeguard your intellectual property, preventing it from falling prey to cyber threats and threat actors.

Although MD5 was initially designed to be used as a cryptographic hash function, it has been found to suffer from extensive vulnerabilities. It can still be used as a checksum to verify data integrity, but only against unintentional corruption. Data Integrity − The cryptographic hash functions are playing vital role in assuring the users about the data integrity. This makes it essential for users employing PKC for encryption to seek digital signatures along with encrypted data to be assured of message authentication and non-repudiation.

If the attacker is able to find two different inputs that give the same hash value, it is a collision and that hash function is said to be broken. Similarly, if the hash function produces 64 bit hash values, the possible hash values are 1.8×1019. By repeatedly evaluating the function for different inputs, the same output is expected to be obtained after about 5.1×109 random inputs. Hence, he applies maximum effort towards finding out the secret key used in the cryptosystem. Once the attacker is able to determine the key, the attacked system is considered as broken or compromised. The receiver may divulge the plaintext to the attacker inadvertently.

Cryptography Objectives

Thus, it has an advantage for those applications that require both symmetric encryption and data origin authentication. The user takes the first block of plaintext and encrypts it with the key to produce the first block of ciphertext. Due to this design of Triple DES as an encrypt–decrypt–encrypt process, it is possible to use a 3TDES implementation for single DES by setting K1, K2, and K3 to be the same value. In the next sections, we will first discuss the model of block cipher followed by DES and AES, two of the most influential modern block ciphers. There is a vast number of block ciphers schemes that are in use. Multiples of 8 bit − A preferred block size is a multiple of 8 as it is easy for implementation as most computer processor handle data in multiple of 8 bits.

Encryption With Digital Signature

We will see two aspects of the RSA cryptosystem, firstly generation of key pair and secondly encryption-decryption algorithms. The key stream generated is XOR-ed with the plaintext blocks. The OFB mode requires an IV as the initial random n-bit input block.

Falling of the cryptosystem in the hands of an intruder should not lead to any compromise of the system, preventing any inconvenience to the user. Processing power of computer system required to run symmetric algorithm is less. Non-repudiation is a property that is most desirable in situations where there are chances of a dispute over the exchange of data. For example, once an order is placed electronically, a purchaser cannot deny the purchase order, if non-repudiation service was enabled in this transaction.

Cryptography Objectives

AES-NI is used in a variety of applications, including email, file sharing, and secure communications. Diffie-Hellman is used in a variety of applications, including email, file sharing, and secure communications. RSA is used in a variety of applications, including email, file sharing, and secure communications. DES is used in a variety of applications, including email, file sharing, and secure communications.

Block Size

A digital certificate does the same basic thing in the electronic world, but with one difference. Since the public keys are in open domain, they are likely to be abused. It is, thus, necessary to establish and maintain some kind of trusted infrastructure to manage these keys. Instead of storing password in clear, mostly all logon processes store the hash values of passwords in the file. There also exist 256, and 320-bit versions of this algorithm.

Then we will define Kerckhoff’s principle which gives the attacker the knowledge of the system and the design. This gives the attacker greater capability and is generally a good practice when designing your cryptographic scheme. Lastly, we will describe the security by obscurity principle and contrast it with Kerckhoff’s principle. Security experts rarely rely on security by obscurity when designing cryptosystems.

It is during and after the European Renaissance, various Italian and Papal states led the rapid proliferation of cryptographic techniques. Various analysis and attack techniques were researched in this era to break the secret codes. Protecting data-at-rest is the most prominent use of encryption, and is typically referred to as data encryption. Whole disk encryption of laptop data to provide security in the event of device loss is an example of data-at-rest protection.

Cryptography Objectives

The degree of confidentiality determines the secrecy of the information. The principle specifies that only the sender and receiver will be able to access the information shared between them. Now the confidential information is in the hands of an intruder C.

An examination of the OSI networking model shows a layer dedicated to transport, and this abstraction can be used to manage end-to-end cryptographic functions for a communication channel. When utilizing the TCP/IP protocol, Transport Layer Security is one specific method of managing security at the transport What Is Cryptography level. Public Key Cryptography, or asymmetric cryptography, uses two keys to encrypt data. One is used for encryption, while the other key can decrypts the message. Unlike symmetric cryptography, if one key is used to encrypt, that same key cannot decrypt the message, rather the other key shall be used.

With 26 letters in alphabet, the possible permutations are 26! The sender and the receiver may choose any one of these possible permutation as a ciphertext alphabet. Known Plaintext Attack − In this method, the attacker knows the plaintext for some parts of the ciphertext. The task is to decrypt the rest of the ciphertext using this information. This may be done by determining the key or via some other method. The best example of this attack is linear cryptanalysis against block ciphers.

Triple Des

Today’s algorithms can be deciphered, but it would require years and sometimes decades to decipher the meaning of just one message. Thus, the race to create newer and more advanced cryptography techniques continues. Symmetric cryptography, known also as secret-key cryptography, is the use of a single shared secret to share encrypted data between parties. Ciphers in this category are called symmetric because you use the same key to encrypt and decrypt the data. The two main types of algorithms used in encryption are symmetric and asymmetric.

Technically, stream ciphers are block ciphers with a block size of one bit. Ciphertext Only Attacks − In this method, the attacker has access to a set of ciphertext. COA is said to be successful when the corresponding plaintext can be determined from a given set of ciphertext. Occasionally, the encryption key can be determined from this attack. Modern cryptosystems are guarded against ciphertext-only attacks. Decryption Algorithm, It is a mathematical process, that produces a unique plaintext for any given ciphertext and decryption key.

Cryptographic Objectives Cryptographic Concepts

Financial transactions, security-related information, administration, law, and more, wherever electronic communication occurs, cryptography has a major role in the play. Without the detection of any suspicious activity, the data cannot be altered in storage or transit with respect to the sender and the intended receiver. By identifying confidential information, a hacker can misuse it and drive it to commit severe fraud.


The attacker has access to corresponding ciphertext gathered from open channel. Thus, the first assumption about security environment is that the encryption algorithm is known to the attacker. While considering possible attacks on the cryptosystem, it is necessary to know the cryptosystems environment. The attacker’s assumptions and knowledge about the environment decides his capabilities.

Generation Of Elgamal Key Pair

Obscurity has a role, making it hard for an attacker to easily guess critical pieces of information, but should not be relied upon as a singular method of protection. A cryptographic service provider is a software library that implements cryptographic functions. CSPs implement encoding and decoding functions, which computer application programs may use, for example, to implement strong user authentication or for secure e-mail. For cryptographic purposes, the importance of the unpredictability cannot be overstated.

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