diff options
Diffstat (limited to 'content/blog/2020-02-09-cryptography-basics.md')
| -rw-r--r-- | content/blog/2020-02-09-cryptography-basics.md | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/content/blog/2020-02-09-cryptography-basics.md b/content/blog/2020-02-09-cryptography-basics.md new file mode 100644 index 0000000..dee2174 --- /dev/null +++ b/content/blog/2020-02-09-cryptography-basics.md @@ -0,0 +1,180 @@ ++++ +date = 2020-02-09 +title = "Cryptography Basics" +description = "" +draft = false ++++ + +# Similar Article Available + +If you haven\'t already, feel free to read my post on [AES +Encryption](../aes-encryption/). + +# What is Cryptography? + +In layman\'s terms, cryptography is a process that can change data from +a readable format into an unreadable format (and vice-versa) through a +series of processes and secrets. More technically, this is the Internet +Security Glossary\'s definition: + +> \[Cryptography is\] the mathematical science that deals with +> transforming data to render its meaning unintelligible (i.e., to hide +> its semantic content), prevent its undetected alteration, or prevent +> its unauthorized use. If the transformation is reversible, +> cryptography also deals with restoring encrypted data to an +> intelligible form. +> +> - [Internet Security Glossary +> (2000)](https://tools.ietf.org/html/rfc2828) + +Cryptography cannot offer protection against the loss of data; it simply +offers encryption methods to protect data at-rest and data in-traffic. +At a high-level, encrypted is when plaintext data is encrypted to +ciphertext (a secure form of text that cannot be understood unless +decrypted back to plaintext). The encryption process is completed +through the use of a mathematical function that utilizes one or more +values called keys to encrypt or decrypt the data. + +# Key Elements of Cryptographic Systems + +To create or evaluate a cryptographic system, you need to know the +essential pieces to the system: + +- **Encryption Algorithm (Primitive):\*** A mathematical process that + encrypts and decrypts data. +- **Encryption Key:\*** A string of bits used within the encryption + algorithm as the secret that allows successful encryption or + decryption of data. +- **Key Length (Size):\*** The maximum number of bits within the + encryption key. It\'s important to remember that key size is + regulated in many countries. +- **Message Digest:\*** A smaller, fixed-size bit string version of + the original message. This is practically infeasible to reverse, + which is why it\'s commonly used to verify integrity. + +# Symmetric Systems (Secret Key Cryptography) + +Symmetric cryptography utilizes a secret, bidirectional key to perform +both encryption and decryption of the data. The most common +implementation of symmetric cryptography is the Advanced Encryption +Standard, which uses keys that are 128 bits to 256 bits in size. This +standard came after the National Institute of Standards and Technology +(NIST) decided to retire the Data Encryption Standard (DES) in 2001. + +Since brute force attacks strongly correlate with key length, the 56-bit +key length of DES was considered insecure after it was publicly broken +in under 24 hours. However, there is a modern implementation of DES +called Triple DES where the DES method is applied three times to each +data block. + +The main advantages to symmetric systems are the ease of use, since only +one key is required for both encryption and decryption, and the +simplicity of the algorithms. This helps with bulk data encryption that +may unnecessarily waste time and power using asymmetric systems. + +However, symmetric systems have disadvantages to keep in mind. Since the +key is private, it can be difficult to safely distribute keys to +communication partners. Additionally, the key cannot be used to sign +messages since it\'s necessary to keep the key private. + +# Asymmetric Systems (Public Key Cryptography) + +Asymmetric cryptography utilizes two keys within the system: a secret +key that is privately-held and a public key that can be distributed +freely. The interesting aspect of asymmetric cryptography is that either +key can be used to encrypt the data, there\'s no rule that dictates +which key must be used for encryption. Once one key is used to encrypt +the data, only the other key can be used to decrypt the data. This means +that if the private key encrypts the data, only the public key can +decrypt the data. + +An advantage of this system is that if you successfully decrypt data +using one of the keys, you can be sure of the sender since only the +other key could have encrypted the data. + +One of the major implementations of an asymmetric system is a digital +signature. A digital signature can be generated using the sender\'s +private key, or a one-way hash function and is used to provide assurance +for the integrity and authenticity of the message. A couple common +message digest algorithms are SHA-256 and SHA-512, which securely +compress data and produce a 128-bit message digest. + +It should be noted that man-in-the-middle attacks are one of the risks +with digital signatures and public keys. To combat this, applications +often use a public key infrastructure (PKI) to independently +authenticate the validity of signatures and keys. + +Due to the large key size and [inefficient mathematical +functions](https://crypto.stackexchange.com/a/591) of asymmetric +encryption, elliptical curve cryptography (ECC) is often used to +increase security while using fewer resources. + +# Applications of Cryptographic Systems + +There are quite a few implementations of cryptographic systems around +the world. Here are a few popular examples: + +**Transport Layer Security (TLS):\*** One of the most famous +cryptographic solutions created is TLS, a session-layered or +connection-layered internet protocol that allows for secure +communications between browsers and servers. Using handshakes, peer +negotiation, and authentication allows TLS to prevent eavesdropping and +malicious transformation of data. The major reason for TLS popularity is +that a major vulnerability was found in the SSL protocol in 2014. +Instead of SSL, TLS can be used with HTTP to form HTTPS and is the +preferred method for modern web development due to its increased +security. + +**Secure Hypertext Transfer Protocol (HTTPS):\*** An application layer +protocol that allows for secure transport of data between servers and +web clients. One of the unique parts of HTTPS is that it uses a secured +port number instead of the default web port address. + +**Virtual Private Network (VPN):\*** VPNs are made to securely extend a +private network across public networks by utilizing an encrypted layered +tunneling protocol paired with an authentication method, such as +usernames and passwords. This technology originally allowed remote +employees to access their company\'s data but have evolved into one of +the top choices for anyone who wishes to mask their sensitive personal +data. + +**Internet Protocol Security (IPSec):\*** This protocol suite +facilitates communication between two or more hosts or subnets by +authenticating and encrypting the data packets. IPSec is used in a lot +of VPNs to establish the VPN connection through the transport and tunnel +mode encryption methods. IPSec encrypts just the data portion of packets +in the transport methods, but it encrypts both the data and headers in +the tunnel method (introducing an additional header for authentication). + +**Secure Shell (SSH):\*** SSH is another network protocol used to +protect network services by authenticating users through a secure +channel. This protocol is often used for command-line (shell) functions +such as remote shell commands, logins, and file transfers. + +**Kerberos:\*** Developed by MIT, Kerberos is a computer-network +authentication protocol that works on the basis of tickets to allow +nodes communicating over a non-secure network to prove their identity to +one another securely. This is most commonly used in business +environments when used as the authentication and encryption method for +Windows Active Directory (AD). + +# Cybersecurity Controls + +If you\'re someone who needs solutions on how to control risks +associated with utilizing a crytograhpic system, start with a few basic +controls: + +- **Policies:\*** A policy on the use of cryptographic controls for + protection of information is implemented and is in accordance with + organizational objectives. +- **Key management:\*** A policy on the use, protection and lifetime + of cryptographic keys is implemented through the entire application + lifecycle. +- **Key size:\*** The organization has researched the optimal key size + for their purposes, considering national laws, required processing + power, and longevity of the solution. +- **Algorithm selection:\*** Implemented algorithms are sufficiently + appropriate for the business of the organization, robust, and align + with recommended guidelines. +- **Protocol configuration:\*** Protocols have been reviewed and + configured suitable to the purpose of the business. |