TLS_DHE_RSA_WITH_AES_128_CBC_SHA
Breakdown of the TLS_DHE_RSA_WITH_AES_128_CBC_SHA cipher suite
Cyber Security Rating for TLS_DHE_RSA_WITH_AES_128_CBC_SHA - D
B
Key Exchange Mechanism
Diffie-Hellman Ephemeral (DHE) in cipher suites refers to a key exchange method where each session generates temporary, one-time-use (ephemeral) keys. This ensures forward secrecy, meaning if one session's key is compromised, past and future sessions remain secure. DHE provides an added layer of protection against decryption by ensuring keys are used briefly and then discarded, enhancing security in TLS communications.
A
Authentication
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.
A
Cipher
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.
D
Hash
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.
A
Key Size
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.
D
Cipher Mode
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.
Web infrastructure owners must ensure they only allow secure cipher suites to protect against potential security threats. Cipher suites determine the encryption algorithms and key exchange mechanisms used in HTTPS connections. Insecure cipher suites can leave data vulnerable to interception, decryption, and manipulation by malicious actors. By restricting to secure cipher suites, owners mitigate risks such as data breaches, unauthorized access, and compromise of sensitive information. This proactive measure helps maintain trust with users, ensures compliance with security standards, and safeguards the integrity and confidentiality of data transmitted over the web.
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