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TLS-RSA-WITH-RC4-128-MD5 Cipher Suite
A breakdown of the Cipher Suite TLS_RSA_WITH_RC4_128_MD5, its strengths, and its weaknesses.
Key Exchange Mechanism
Rivest, Shamir, Adleman - RSA
Grade - B
RSA key exchange does not provide perfect forward secrecy because if an attacker captures the RSA private key, they can decrypt all past communications encrypted with the corresponding public key. This is due to the static nature of the key pairs used in RSA, which contrasts with protocols like Diffie-Hellman, where ephemeral keys ensure that past sessions remain secure even if current keys are compromised.
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
Rivest Cipher 4 - RC4
Grade - D
RC4 should not be used as a cipher due to several vulnerabilities, including biases in its keystream and susceptibility to various attacks such as the Fluhrer-Mantin-Shamir attack. These weaknesses compromise the confidentiality and integrity of encrypted data, making RC4 unsuitable for secure communications in modern cryptographic applications. Deprecated in RFC 7465.
Hash
Message Digest 5 - MD5
Grade - F
MD5 is considered highly insecure because chosen prefixes can be generated with minimal computing power. This vulnerability allows attackers to create different inputs that produce the same hash, leading to potential data breaches and integrity issues. Consequently, MD5 is unsuitable for modern cryptographic needs and should be avoided in favor of more secure algorithms.
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.
