Galois/Counter Mode
Galois/Counter Mode is an authenticated-encryption mode that combines counter-mode encryption with authentication of ciphertext and associated data.
Software Security for Developers
AES-GCM is an authenticated-encryption mode of AES that provides confidentiality and message integrity with associated data support.
- How it is used
- Protects application data and messages with confidentiality, integrity, authenticity, and optional authenticated associated data.
- How deep it goes
- Explains inputs, outputs, failure modes, Java configuration, AEAD, and safeguards, but defers GCM’s mathematical details.
- Examples
- Demonstrates Java Cipher code, Tink, associated-data messages, encrypted refunds files, and Nimbus JWE objects.
- What you can do after
- Build it from scratch or apply it through Java, Tink, or Nimbus while avoiding nonce reuse and authentication failures.
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Real-World Cryptography
An authenticated-encryption construction that combines AES in Galois/Counter Mode with authentication of ciphertext and associated data.
- How it is used
- Protects communications by combining confidentiality with authentication of ciphertext and associated data.
- How deep it goes
- Explains CTR, GMAC, nonce requirements, and practical Web Crypto use, but stops short of implementation-level details.
- Examples
- Uses Alice-and-Bob message flow, AES-GCM JavaScript, a random 12-byte IV, associated data, and altered-message rejection.
- What you can do after
- Apply it via the Web Crypto API to encrypt and decrypt messages while avoiding nonce reuse.
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Related concepts
- cipher block chaining modealternative to · Cipher block chaining is a block-cipher mode that XORs each plaintext block with the preceding ciphertext block before encryption, using an initialization vector for the first block.
- authenticated encryption with associated datakind of · Authenticated encryption with associated data is a cryptographic construction that encrypts plaintext while authenticating the ciphertext and optional unencrypted associated data.
- GMACuses · GMAC is an authentication-only construction based on Galois-field multiplication that produces an authentication tag for data.
- counter mode encryptionimplements · Counter mode encryption generates a keystream by encrypting successive counter values with a block cipher and combines it with plaintext to produce ciphertext.
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