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Symmetric Key: Strengths & Weaknesses

CISSP, GIAC GSEC, Security+ Review


Speed: Very quick, allowing for large amounts of data to be encrypted in very little time

Very difficult to break encoded data using large key sizes
Smaller keys sizes considered weak and are more vulnerable to attack
Algorithms used to encode data are freely available
Same key used to both encrypt and decrypt
Requires very secure mechanism for key distribution
Keys and data must be delivered separately
Since a unique symmetric key must be used between the sender and each recipient, number of keys grows geometrically with the number of users
10 users = 45 keys
1000 users = 499,500 keys

Limited security
Symmetric keys only encode data and restrict its access
Do not provide other elements of security e.g., authentication, non-repudiation