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Adiantum
General
Designers	Paul Crowley and Eric Biggers at Google
First published	October 12, 2018; 5 years ago (2018-10-12)
Related to	HPolyC
Cipher detail
Key sizes	8192 bits
Block sizes	no practical limit; intended for 4096-byte disk sectors
Structure	HBSH (hash, block cipher, stream cipher, hash)

Adiantum is a cipher composition for disk encryption. It uses a new cipher construction called HBSH (hash, block cipher, stream cipher, hash), specifically choosing NH, 256-bit Advanced Encryption Standard (AES-256), ChaCha12, Poly1305 for the four elements. HPolyC is an earlier variant which does not use NH.^[1]

It was designed in 2018 by Paul Crowley and Eric Biggers at Google specifically for low-powered mobile devices running Android Go. It has been included in the Linux kernel since version 5.0.^[2] The construct is designed to be "wide-block", where any change in the plaintext causes the entire ciphertext to be unrecognizably changed.^[3]

Adiantum is implemented in Android 10 as an alternative cipher for device encryption, particularly on low-end devices lacking hardware-accelerated support for AES. (Adiantum only invokes AES once per plaintext.) The company stated that Adiantum ran five times faster than AES-256-XTS on ARM Cortex-A7 CPUs.^[1] Google had previously exempted devices from mandatory device encryption if their specifications affected system performance if enabled. Due to the introduction of Adiantum, device encryption becomes mandatory on all Android devices beginning on Android 10.^[4]^[5]

References

External links

Block ciphers (security summary)

Block ciphers (security summary)
Common algorithms	AES Blowfish DES (internal mechanics, Triple DES) Serpent SM4 Twofish
Less common algorithms	ARIA Camellia CAST-128 GOST IDEA LEA RC5 RC6 SEED Skipjack TEA XTEA
Other algorithms	3-Way Adiantum Akelarre Anubis Ascon BaseKing BassOmatic BATON BEAR and LION CAST-256 Chiasmus CIKS-1 CIPHERUNICORN-A CIPHERUNICORN-E CLEFIA CMEA Cobra COCONUT98 Crab Cryptomeria/C2 CRYPTON CS-Cipher DEAL DES-X DFC E2 FEAL FEA-M FROG G-DES Grand Cru Hasty Pudding cipher Hierocrypt ICE IDEA NXT Intel Cascade Cipher Iraqi Kalyna KASUMI KeeLoq KHAZAD Khufu and Khafre KN-Cipher Kuznyechik Ladder-DES LOKI (97, 89/91) Lucifer M6 M8 MacGuffin Madryga MAGENTA MARS Mercy MESH MISTY1 MMB MULTI2 MultiSwap New Data Seal NewDES Nimbus NOEKEON NUSH PRESENT Prince Q RC2 REDOC Red Pike S-1 SAFER SAVILLE SC2000 SHACAL SHARK Simon Speck Spectr-H64 Square SXAL/MBAL Threefish Treyfer UES xmx XXTEA Zodiac
Design	Feistel network Key schedule Lai–Massey scheme Product cipher S-box P-box SPN Confusion and diffusion Round Avalanche effect Block size Key size Key whitening (Whitening transformation)
Attack (cryptanalysis)	Brute-force (EFF DES cracker) MITM Biclique attack 3-subset MITM attack Linear (Piling-up lemma) Differential Impossible Truncated Higher-order Differential-linear Distinguishing (Known-key) Integral/Square Boomerang Mod n Related-key Slide Rotational Side-channel Timing Power-monitoring Electromagnetic Acoustic Differential-fault XSL Interpolation Partitioning Rubber-hose Black-bag Davies Rebound Weak key Tau Chi-square Time/memory/data tradeoff
Standardization	AES process CRYPTREC NESSIE
Utilization	Initialization vector Mode of operation Padding

v t e Cryptography
General	History of cryptography Outline of cryptography Cryptographic protocol Authentication protocol Cryptographic primitive Cryptanalysis Cryptocurrency Cryptosystem Cryptographic nonce Cryptovirology Hash function Cryptographic hash function Key derivation function Digital signature Kleptography Key (cryptography) Key exchange Key generator Key schedule Key stretching Keygen Cryptojacking malware Ransomware Random number generation Cryptographically secure pseudorandom number generator (CSPRNG) Pseudorandom noise (PRN) Secure channel Insecure channel Subliminal channel Encryption Decryption End-to-end encryption Harvest now, decrypt later Information-theoretic security Plaintext Codetext Ciphertext Shared secret Trapdoor function Trusted timestamping Key-based routing Onion routing Garlic routing Kademlia Mix network
Mathematics	Cryptographic hash function Block cipher Stream cipher Symmetric-key algorithm Authenticated encryption Public-key cryptography Quantum key distribution Quantum cryptography Post-quantum cryptography Message authentication code Random numbers Steganography
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