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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?

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    $\begingroup$ 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. $\endgroup$
    – Maarten Bodewes
    Oct 26, 2022 at 10:39
  • $\begingroup$ A piece of recommended reading from our picked list $\endgroup$
    – DannyNiu
    Oct 26, 2022 at 11:31

1 Answer 1

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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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