Which statement about RC4 is true?

Which statement about RC4 is true?

• A. It is deprecated due to known vulnerabilities
• B. It is a block cipher used for streaming data
• C. It uses elliptic curves for key agreement
• D. It is the standard for digital signatures

Answer: (A)

RC4 is a stream cipher, and its ongoing deprecation comes from known weaknesses in the keystream it produces. Those weaknesses mean that, under certain conditions, patterns in the keystream can leak information about the plaintext, making it easier for an attacker to recover parts of the message. Because of these practical vulnerabilities, security standards and best practices have moved away from RC4 in favor of more secure algorithms like AES in modern modes. This makes the statement true: RC4 has been deprecated due to known vulnerabilities. It is not a block cipher, it does not use elliptic curves for key agreement, and it is not a standard for digital signatures.

RC4 is a stream cipher, and its ongoing deprecation comes from known weaknesses in the keystream it produces. Those weaknesses mean that, under certain conditions, patterns in the keystream can leak information about the plaintext, making it easier for an attacker to recover parts of the message. Because of these practical vulnerabilities, security standards and best practices have moved away from RC4 in favor of more secure algorithms like AES in modern modes.

This makes the statement true: RC4 has been deprecated due to known vulnerabilities. It is not a block cipher, it does not use elliptic curves for key agreement, and it is not a standard for digital signatures.