Symmetric-Key Cryptography | Computer Security

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In this section, we will build symmetric-key encryption schemes that guarantee confidentiality. Because we are in the symmetric key setting, in this section we can assume that Alice and Bob share a secret key that is not known to anyone else. Later we will see how Alice and Bob might securely exchange a shared secret key over an insecure communication channel, but for now you can assume that only Alice and Bob know the value of the secret key. For modern schemes, we are going to assume that all messages are bitstrings, which is a sequence of bits, 0 or 1 (e.g. 1101100101010101). Text, images, and most other forms of communication can usually be converted into bitstrings before encryption, so this is a useful abstraction. Recall from the previous chapter that confidentiality was defined to mean that an attacker cannot read our messages. This definition, while intuitive, is quite open-ended. If the attacker can read the first half of our message but not the second half, is that confident

Symmetric-Key Cryptography | Computer Security Skip to main content Menu Expand (external link) Document Search Copy Copied Computer Security 6. Symmetric-Key Encryption In this section, we will build symmetric-key encryption schemes that guarantee confidentiality. Because we are in the symmetric key setting, in this section we can assume that Alice and Bob share a secret key that is not known to anyone else. Later we will see how Alice and Bob might securely exchange a shared secret key over an insecure communication channel, but for now you can assume that only Alice and Bob know the value o

Symmetric-Key Cryptography | Computer Security

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