Introduction-to-Cryptography Exam Dumps : WGU Introduction to Cryptography HNO1

A digital signature is a cryptographic mechanism that enables a recipient to verify who created a message (authenticity) and that the message has not been altered (integrity). It is typically built using asymmetric cryptography: the signer uses a private key to sign a hash (digest) of the message, producing a signature. Anyone with the signer’s public key can verify that the signature matches the message digest, confirming the signature was created by the corresponding private key and that the content remains unchanged. Digital signatures do not primarily provide confidentiality; the signed message may still be readable unless separately encrypted. They also support nonrepudiation in many operational contexts because a valid signature can be strong evidence that the private key holder authorized the signed data, assuming key protection and policy controls. Common digital signature algorithms include RSA-PSS, ECDSA, and EdDSA. Certificates (X.509) are often used to bind public keys to identities, allowing verifiers to trust the claimed signer. Therefore, the best definition is a technique to verify authenticity and integrity.

SHA-1 (Secure Hash Algorithm 1) produces a fixed-size output of 160 bits (20 bytes). Hash output size matters in cryptography because it influences collision resistance and the effort required for various attacks. For an ideal n-bit hash, finding a collision by generic means is expected around 2^(n/2) operations (birthday bound). With SHA-1’s 160-bit output, that generic bound would be about 2^80, which was once considered strong; however, SHA-1 has been broken in practice with significantly less work due to cryptanalytic advances, and it is now deprecated for most security uses. Still, the question is strictly about output length, not current suitability. The other options do not match SHA-1: 40 bits would be far too small for a modern hash, 80 bits is not SHA-1’s output, and 320 bits would imply a much larger digest (closer to SHA-256’s 256 bits or SHA-384’s 384 bits). Therefore, the correct SHA-1 output length is 160 bits.

In AES, the number of rounds is explicitly tied to the key length. AES-128 uses 10 rounds, AES-192 uses 12 rounds, and AES-256 uses 14 rounds. The purpose of additional rounds is to increase diffusion and confusion, strengthening resistance against cryptanalysis as the key schedule and state transformations iterate more times. Although key length primarily affects brute-force resistance, AES’s designers and standardization parameters link longer keys with more rounds to maintain security margins across variants, especially considering differences in the key schedule structure. Thus, as key length increases from 128 to 192 to 256 bits, the number of rounds increases correspondingly from 10 to 12 to 14. This relationship is fixed by the AES specification and does not vary dynamically at runtime. Therefore, the correct correlation is that the number of rounds increases as the key length increases.