TLS-DH-RSA-WITH-DES-CBC-SHA Cipher Suite

Key Exchange Mechanism

Diffie Hellman - DH

Grade - B

Static Diffie Hellman (DH) does not use emphemeral (temporary) keys, meaning it violates perfect forward secrecy. Ephemeral Diffie Hellman (EDH) should be used instead.

Authentication

Rivest, Shamir, Adleman - RSA

Grade - A

RSA as an authentication mechanism in cipher suites is secure because it relies on the difficulty of factoring large prime numbers. This makes it computationally infeasible for attackers to derive the private key from the public key, ensuring confidentiality and integrity in secure communications.

Cipher

Data Encryption Standard - DES

Grade - D

DES should not be used in cipher suites due to its weak 56-bit key size, making it highly vulnerable to brute-force attacks. Modern standards require stronger encryption, and DES’s vulnerabilities compromise security, making it unsuitable for protecting sensitive data in contemporary applications.

Hash

Secure Hash Algorithm - SHA

Grade - D

Chosen prefix attacks for SHA1 are feasible at an accessible cost to a well-funded adversary. This level of expense, while significant, does not pose a substantial barrier to attackers with sufficient resources, making such attacks a credible threat.

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.