Networking & Security
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| Group | Key size | Security level | Notes |
|---|---|---|---|
| Group 1 | 768 bits | Weak | Deprecated, unsafe today |
| Group 2 | 1024 bits | Moderate | Phased out, not recommended |
| Group 5 | 1536 bits | Better | Legacy support |
| Group 14 | 2048 bits | Strong | Common default today |
| Group 15 | 3072 bits | Stronger | Rarely used |
| Group 16 | 4096 bits | Very strong | Slow, rarely used |
| Group 18 | 8192 bits | Extremely strong | Mostly academic, very slow |
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Why DH groups matter
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Security
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Small groups (like 768-bit) are vulnerable to attacks.
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Large groups are much harder for an attacker to break.
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Performance
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Bigger groups = slower key generation.
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In TLS, VPNs, or SSH, the server needs to compute DH every handshake.
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Compatibility
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Older clients may only support smaller groups.
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Modern systems prefer 2048-bit+ or elliptic curves.
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Posted : 09/02/2026 10:36 pm
