Score:1

What does AES-GCM provide?

bm flag

I am wondering does AES-GCM which uses Authenticated Encryption provide us with all 3 properties (Authenticity, Confidentiality, and Integrity), or does it not provide integrity?

Maarten Bodewes avatar
in flag
Usually if message authenticity is provided it implies integrity. If it wasn't, an attacker would be able to construe a different authenticated message under the same key. So although they are different properties, they are closely related.
DannyNiu avatar
vu flag
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Score:2
in flag

AES-GCM (Galois Counter Mode) internally uses AES in CTR mode that can provide confidentiality and at most Ind-CPA security. AES-GCM also uses GHASH to provide integrity and authentication like any secure MAC.

In the end, AES-GCM constitutes an authenticated encryption (AE) mode with Associated Data ( AEAD).

One should be careful when using AES-GCM since there are many pitfalls and if you want to use it use AES-GCM-SIV which is safe from IV-reuse problems.

Keep in mind that the authentication is here mutual authentication ( both parties has the same right on the authentication, and should not be confused with the digital signature that can provide non-repudiation.

Hash MACs Digital signatures
Integrity Yes Yes yes
Authentication No Yes Yes
Non-Repuditiation No No Yes
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