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An asymmetric-key algorithm uses a related pair of distinct keys: a public key that can be shared and a private key that is kept secret. Depending on the algorithm and protocol, the keys can support encryption and decryption, digital signatures, or key agreement. These are different operations, not one universal function.
What do the public and private keys do?
The public and private keys are mathematically related, but they have different roles. The public key may be distributed; its corresponding private key must remain secret. NIST’s glossary defines public-key cryptography as using two separate keys, one to encrypt or digitally sign data and another to decrypt it or verify the signature: NIST CSRC glossary: public key cryptography.
The particular operation depends on the algorithm. A public key is not automatically able to encrypt arbitrary data, and not every asymmetric algorithm provides encryption. NIST also describes public-key uses that include computing a shared secret: NIST CSRC glossary: public key.
How are encryption, signatures, and key agreement different?
| Operation | Typical key roles | Goal |
|---|---|---|
| Public-key encryption | Encrypt with the recipient’s public key; decrypt with the corresponding private key | Confidentiality for the protected material |
| Digital signature | Generate a signature with the private key; verify it with the corresponding public key | Authenticity and integrity, not confidentiality |
| Key agreement | Use related key material within an agreed protocol to compute a shared secret | Establish shared secret material |
The table describes common roles at a conceptual level; the exact operations depend on the algorithm and protocol.
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- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
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Encryption and decryption
For public-key encryption, a sender uses the recipient’s public key to protect material. The corresponding private key is used to decrypt it. The intended protection is confidentiality.
Signing and verification
A signer uses the private key to generate a digital signature. Other people can use the corresponding public key to verify it. A digital signature is not a message encrypted with the private key. NIST states that signatures provide authenticity and integrity protections, but not confidentiality: NIST SP 800-63-3.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Key agreement
In key agreement, participants use related key material in a protocol to compute shared secret material. This is distinct from encrypting a message or signing it.
Quick Recap
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
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- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
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- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
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- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
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