
CompTIA CASP+ CAS-004 Certification Guide
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Symmetric encryption provides confidentiality by provisioning bulk encryption. It is highly efficient at encrypting data at rest and data in transit. Due to the relatively small key sizes that are used, it is very fast (in comparison to asymmetric encryption). Symmetric encryption uses a single key to encrypt (or lock) the data and the same key is used to decrypt (unlock) the data.
Symmetric algorithms are divided into two main categories: block and stream ciphers.
These ciphers are used to encrypt data in blocks, typically 64 or 128 bits. They offer the most robust security but lack the outright speed that's offered by stream ciphers. The following are some examples of block ciphers:
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