H3C Technologies H3C S12500-X Series Switches - Manual (Page 130)

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Managing public keys
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Overview
This chapter describes public key management for the asymmetric key algorithms including the
Revest-Shamir-Adleman Algorithm (RSA), the Digital Signature Algorithm (DSA), and the Elliptic Curve
Digital Signature Algorithm (ECDSA).
Many security applications, for example, SSH, use asymmetric key algorithms to secure communications
between two parties, as shown in
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Figure 37 . Asymmetric key algorithms use two separate keys (one
public and one private) for encryption and decryption, in contrast to the symmetric key algorithms, which
use only one key.
Figure 37 Encryption and decryption
A key owner can distribute the public key in plain text on the network but must keep the private key in
privacy. It is mathematically infeasible to calculate the private key even if an attacker knows the algorithm
and the public key.
The security applications use the asymmetric key algorithms for the following purposes:
• Encryption and decryption—Any public key receiver can use the public key to encrypt information,
but only the private key owner can decrypt the information.
• Digital signature—The key owner uses the private key to "sign" information to be sent, and the
receiver decrypts the information with the sender's public key to verify information authenticity.
RSA, DSA, and ECDSA can all perform digital signature, but only RSA can perform encryption and
decryption.
Asymmetric key algorithms enables secure key distribution on an insecure network, but the security
strength of an asymmetric key algorithm still depends on key size as with any symmetric key algorithm.
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FIPS compliance
The device supports the FIPS mode that complies with NIST FIPS 140-2 requirements. Support for features,
commands, and parameters might differ in FIPS mode (see "
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Configuring FIPS ") and non-FIPS mode.
Receiver
Key
Plain text Cipher text Plain text
Sender
Encryption Decryption
Key