Read a Cipher Suite — TechKnowSurge

About this interactive

Not every device can do the same cryptography. There are different ciphers, key lengths and modes of encryption, different hashing algorithms and different ways to exchange keys. A cipher suite is a preconfigured set of those options, so two devices can agree on one name instead of every parameter separately. The name lists the parts in order. Take TLS_DHE_RSA_WITH_AES_256_GCM_SHA384. DHE is the key exchange (Diffie-Hellman; ECDHE is the elliptic-curve version). RSA is the authentication (ECDSA is another). After WITH comes the symmetric cipher that encrypts the session, AES, then its key length, 256 bits, then its mode, GCM (CBC is an older one). Last is the hashing algorithm, SHA384, which is SHA-384. Where a name has only one method before WITH, as in TLS_RSA_WITH_AES_128_CBC_SHA, RSA does the key exchange and the authentication. The traffic itself is always encrypted with the symmetric cipher, because asymmetric encryption is too slow and resource-intensive for the bulk of the data. RSA in a suite name is not what encrypts your page. The client sends the list of suites it supports, the server matches it against its own and picks the best one both can use, and tells the client. Suites are dropped as weaknesses are found: TLS 1.3 does not support Triple DES at all. TLS 1.3 names are also shorter, such as TLS_AES_256_GCM_SHA384, because the key exchange and authentication are no longer part of the suite.

What you'll learn

Read a cipher suite name and pick out each component: the key exchange method, the authentication method, the symmetric cipher, its key length, its mode of operation and the hashing algorithm
Recall how a cipher suite is chosen (the client lists the suites it supports and the server picks one) and that suites are dropped over time, as TLS 1.3 dropped Triple DES

Aligned to

CompTIA Security+

1.4 Explain the importance of using appropriate cryptographic solutions.

CompTIA SecurityX

2.3 Given a scenario, implement appropriate cryptographic protocols and algorithms.

ISC2 CISSP

3.6 Select and determine cryptographic solutions

4.3 Implement secure communication channels according to design

Cisco CCST Cybersecurity

1.4 Explain encryption methods and applications

NIST 800-53

SC-8 Transmission Confidentiality and Integrity

ISC2 CC

5.1 Understand data security

Key terms

Cipher Suite: A preconfigured set of algorithms specifying the symmetric cipher, key length, mode of operation, hashing algorithm, and key exchange method used to secure TLS communication.
Key Exchange: A method used to securely share cryptographic keys between parties over an insecure channel.
Diffie-Hellman: A key exchange algorithm that allows two parties to independently generate a shared secret over an insecure channel using two private keys, two public keys, and a shared value, without ever transmitting the secret itself.
Elliptic Curve Diffie-Hellman Ephemeral: ECDHE combines elliptic curve cryptography with ephemeral key exchange to provide perfect forward secrecy in TLS and other protocols while requiring smaller key sizes than classical DHE.
RSA: An asymmetric encryption algorithm based on the difficulty of factoring large prime numbers, widely used for secure data transmission.
Elliptic Curve Digital Signature Algorithm: ECDSA is an asymmetric digital signature algorithm based on elliptic curve cryptography, providing equivalent security to RSA/DSA with significantly smaller key sizes.
Advanced Encryption Standard: A symmetric encryption algorithm widely used to secure data, supporting key sizes of 128, 192, and 256 bits.
Key Length: The size of a cryptographic key measured in bits, where each additional bit doubles the number of possible key combinations and increases encryption strength.
Galois Counter Mode: Galois Counter Mode is an authenticated encryption cipher mode that provides both confidentiality and integrity verification using AES combined with a Galois field authentication tag.
Cipher Block Chaining: Cipher Block Chaining is a block cipher mode that XORs each plaintext block with the previous ciphertext block before encryption, making identical plaintext blocks produce different ciphertext; it is vulnerable to padding oracle attacks if not implemented carefully.
Secure Hash Algorithm: Secure Hash Algorithm is a family of cryptographic hash functions standardized by NIST, including SHA-1 (deprecated for most uses), SHA-256, and SHA-3, used for data integrity verification, digital signatures, and certificate validation.
Symmetric Encryption: An encryption method that uses the same key for both encryption and decryption.
Authentication: The process of verifying the identity of a user, device, or system.

Topics

Cipher Suite Transport Layer Security Interactive Fill In

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