WGU Updated Introduction-to-Cryptography Exam Questions and Answers by gurbaaz

Large-scale quantum computers threaten many widely deployed public-key algorithms because quantum algorithms can solve their underlying hard math problems efficiently. In particular, Shor’s algorithm can factor large integers and compute discrete logarithms in polynomial time, which directly breaks the security assumptions of RSA (factoring) and traditional Diffie–Hellman/ECC (discrete log). That makes RSA the clearest target among the options. By comparison, symmetric algorithms like AES are affected mainly by Grover’s algorithm, which provides a quadratic speedup for brute force; this can be mitigated by using larger keys (e.g., AES-256). Hash functions like SHA-256 also face Grover-style speedups for preimage search, again mitigated by output length/security margin, and collision resistance is impacted differently. ECB is a mode of operation, not a standalone algorithm, and its issues are classical (pattern leakage), not specifically quantum. Therefore, the algorithm most directly threatened by quantum computing among the choices is RSA.

TLS is the modern successor to SSL. SSL (notably SSL 2.0 and SSL 3.0) was an early protocol family for securing network communications, providing encryption, integrity, and endpoint authentication for applications like HTTPS. Over time, weaknesses were discovered in SSL’s design and in the cryptographic mechanisms commonly used with it. TLS was introduced as an improved, standardized evolution (starting with TLS 1.0, based on SSL 3.0 but with important fixes), and later versions (TLS 1.2 and TLS 1.3) significantly strengthened security by removing weak ciphers, improving key exchange, and tightening handshake and record protections. In practice, when people say “SSL” today, they often mean “TLS,” but true SSL is deprecated and should not be used. SSL is not a replacement of TLS, and the two are not identical in security—TLS versions incorporate substantial improvements and modern cryptographic best practices. SSL is also not limited to email; it was widely used for web traffic and other protocols. Therefore, the correct relationship is that TLS replaced SSL to provide improved security.

When securely distributing a symmetric key over an untrusted network, a common approach is hybrid cryptography: use asymmetric cryptography to protect the symmetric key, then use the symmetric key for bulk encryption. To ensure only Employee B can recover the symmetric key, Employee A encrypts (wraps) that symmetric key using Employee B’s public key. Because only Employee B should possess the matching private key, only B can decrypt the wrapped symmetric key. This is the same principle used in TLS key exchange (in older RSA key transport) and in secure email: encrypt the session key to the recipient’s public key. Encrypting the symmetric key with Employee A’s private key would not provide confidentiality—anyone with A’s public key could reverse it, and it functions more like a signature than encryption. Employee B’s private key should never be shared and is used only by B to decrypt. Therefore, for confidentiality of the shared symmetric key, the correct encryption key is Employee B’s public key.

Web browsers rely on PKI to establish trust in secure connections, primarily through X.509 certificates and a built-in set of trusted root Certificate Authorities (CAs). When a browser connects to an HTTPS site, the server presents a certificate chain. The browser validates that chain up to a trusted root, checks that the certificate is valid for the domain (SAN/CN matching), confirms validity dates, and may check revocation status. This PKI process allows browsers to authenticate the website’s identity and negotiate encrypted session keys for TLS, enabling confidentiality and integrity for the connection. In practical terms, the browser’s PKI components include certificate stores, validation logic, and mechanisms for handling intermediates, trust policies, and revocation. While PKI supports authentication as an outcome, the best description of how browsers utilize PKI is that they manage and validate digital certificates and associated keys to establish trust. PKI is not about compressing messages or encrypting data at rest; it is about identity binding and trust chains that make secure web communication possible.