Encrypting traffic
Symmetric, asymmetric and hybrid encryption seen through use; in transit, at rest, end to end; pairs of plain-text and encrypted protocols; the VPN tunnel.
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Symmetric encryption: what is it?
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Encryption where the same secret key is used to encrypt and to decrypt.
It is fast, so suited to large volumes, but raises the problem of sharing the key without a third party intercepting it.
An attacker on the same Wi-Fi captures this session. What can they read?
```text
220 FTP server ready
USER alice
331 Password required for alice
PASS soleil2024
230 Login successful`- The username and the password, exactly as typed
- Only the username, since FTP then protects the password
- A hash of the password, which the attacker still has to crack
- Nothing usable, since port 21 encrypts the commands
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The username and the password, exactly as typed
FTP sends commands in clear text: the
PASSline contains the password itself. The same flaw affects Telnet, HTTP, IMAP or LDAP without encryption.… encryption uses the same key to encrypt and decrypt; asymmetric uses a pair made of a … key and a private key.
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Symmetric encryption uses the same key to encrypt and decrypt; asymmetric uses a pair made of a public key and a private key.
The private key never leaves its owner. The public key can be given to anyone at no risk.
Asymmetric encryption: what is it?
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Encryption based on a key pair: what one key encrypts, only the other can decrypt, and one of the two can be published.
It solves the key exchange problem, since the public key does not need to be kept secret, but it is far slower than symmetric encryption.