How deeply does Real-World Cryptography cover counter mode encryption?

Explains nonce construction, counters, keystream XOR, truncation, capacity, and nonce-reuse failure without implementation detail.

Counter mode encryption

As explained in Real-World Cryptography

AES-CTR is a counter-mode construction that applies AES to successive counter values to generate a keystream or pseudorandom-looking output.

Counter mode turns AES into a stream-like encryption method. AES encrypts a unique nonce joined to a counter, producing a keystream that is XORed with plaintext. section 4.5.2

The construction works in a few practical steps:

Choose a nonce that does not repeat; it need not be unpredictable. section 4.5.2
Concatenate the nonce with a counter beginning at 1, then encrypt each block with AES. section 4.5.2
XOR the resulting keystream with plaintext; truncate excess keystream so padding is unnecessary. section 4.5.2
Never reuse a nonce: repeated keystreams let an observer XOR ciphertexts and recover the XOR of the plaintexts. section 4.5.2

A typical AES-CTR layout

AES-CTR uses a 96-bit nonce and a 32-bit counter inside each 16-byte AES block. The counter increments for each block and permits less than 69 GB with one nonce. section 4.5.2

How Real-World Cryptography covers it

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Also explained in

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Hacking CryptographyCounter mode encrypts successive counter values with a block cipher to generate a keystream that is combined with plaintext.

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Related concepts

stream cipherimplements · A stream cipher is an encryption algorithm that combines plaintext sequentially with a generated keystream, typically using XOR.
Galois/Counter Modeimplemented by · Galois/Counter Mode is an authenticated-encryption mode that combines counter-mode encryption with authentication of ciphertext and associated data.
CCMPused by · CCMP is an IEEE 802.11 wireless security protocol that combines AES counter-mode encryption with CBC-MAC-based message authentication.
GCMPused by · GCMP is a wireless data-protection protocol that combines AES counter-mode encryption with GMAC integrity protection.
encryptionkind of · Encryption is the cryptographic transformation of readable data into ciphertext to conceal its contents, reversible through decryption with appropriate information.
pseudo-random number generatorproduces · A pseudorandom number generator is a deterministic computational process that uses an initial seed or internal state to produce a sequence with random-like statistical properties.

This explainer was generated by Manning's knowledge graph from the text of Real-World Cryptography. The section links point to the parts of the book it draws on.