Which sequence of RSA key lengths is correct?

Which sequence of RSA key lengths is correct?

• A. 2048, 3072, 4096
• B. 512, 1024, 2048
• C. 128, 256, 512
• D. 1024, 2048, 4096

Answer: (A)

RSA key length determines how hard it is to factor the modulus, so security improves as the number of bits increases. Today, 2048 bits is the minimum recommended for new keys, with 3072 and 4096 bits offering progressively stronger protection for data that must stay confidential longer. The sequence 2048, 3072, 4096 matches a common, practical upgrade path: start at 2048, increase to 3072 for better long-term security without excessive performance impact, and use 4096 when the highest level of protection is needed over many years. Other options include sizes that are considered insecure or obsolete: very small sizes like 512 or 128/256/512 are easily broken with modern hardware, and starting with 1024 is discouraged in current guidelines. A sequence that begins with 1024 (like 1024, 2048, 4096) isn’t the standard recommended progression today.

RSA key length determines how hard it is to factor the modulus, so security improves as the number of bits increases. Today, 2048 bits is the minimum recommended for new keys, with 3072 and 4096 bits offering progressively stronger protection for data that must stay confidential longer. The sequence 2048, 3072, 4096 matches a common, practical upgrade path: start at 2048, increase to 3072 for better long-term security without excessive performance impact, and use 4096 when the highest level of protection is needed over many years.

Other options include sizes that are considered insecure or obsolete: very small sizes like 512 or 128/256/512 are easily broken with modern hardware, and starting with 1024 is discouraged in current guidelines. A sequence that begins with 1024 (like 1024, 2048, 4096) isn’t the standard recommended progression today.