TLS_DHE_PSK_WITH_ARIA_128_CBC_SHA256

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.

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.

Cryptographic algorithms with low adoption should be avoided due to several critical reasons. They often lack rigorous scrutiny and testing by the broader cryptographic community, which increases the risk of undetected vulnerabilities. Moreover, their limited deployment means fewer opportunities for real-world validation and feedback, hindering confidence in their security and interoperability with existing systems. High adoption indicates robustness from extensive scrutiny and successful implementation in diverse environments.

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.

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 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.