TLS-ECDHE-PSK-WITH-AES-128-CBC-SHA256 Cipher Suite

Key Exchange Mechanism

Elliptic Curve Diffie Hellman Ephemeral - ECDHE

Grade - A

ECDHE (Elliptic Curve Diffie-Hellman Ephemeral) is used because it enhances security through the use of ephemeral keys, which are temporary and unique for each session. This ensures that even if one session’s key is compromised, past and future sessions remain secure. ECDHE provides perfect forward secrecy, meaning that the compromise of long-term keys does not affect the confidentiality of past communications. The ephemeral nature of the keys significantly reduces the risk of long-term data breaches and enhances the overall robustness of the cryptographic protocol.

Authentication

Pre-Shared Key - PSK

Grade - A

PSK (Pre-Shared Key) cipher suites are used for authentication in secure communication protocols like TLS. They allow parties to establish a shared secret beforehand, ensuring confidentiality and integrity of data exchanges without the overhead of public key infrastructure (PKI), suitable for constrained environments or specific security requirements.

Cipher

Advanced Encryption Standard - AES

Grade - A

AES should be used in cipher suites because it offers strong security with efficient performance, large block size (128 bits), and resistance to known attacks. Its widespread adoption and thorough analysis by the cryptographic community ensure reliability and robustness for encrypting sensitive data.

Hash

Secure Hash Algorithm 256 Bit - SHA256

Grade - A

Improving greatly from SHA1, SHA-256 and above create secure hashes through robust cryptographic algorithms that ensure collision resistance and preimage resistance. They process input data in fixed-size blocks, applying complex mathematical transformations that make it computationally impractical to reverse-engineer the original data from its hash.

Key Size

128 Bit - 128

Grade - A

128-bit symmetric encryption keys are considered secure because they provide an astronomically large number of possible combinations (2^128), making brute-force attacks computationally infeasible with current technology. This level of security is sufficient for most practical purposes and is widely adopted in various encryption protocols.

Cipher Mode

Cipher Block Chaining - CBC

Grade - D

Cipher Block Chaining (CBC) mode is vulnerable to the Lucky13 and POODLE (in TLS v1.2 and below) attacks. The Lucky13 attack exploits timing discrepancies in padding validation, allowing attackers to gradually reveal plaintext. The POODLE attack leverages padding errors to decrypt ciphertext by repeatedly modifying and sending it to the server, observing the error responses. These vulnerabilities arise from CBC’s handling of padding and error messages, making it less secure than modern encryption modes like Galois Counter Mode (GCM), which offer stronger integrity and confidentiality guarantees.