Naming scheme

All custom engines follow the naming scheme nex<L><T><C><V>. Each character has a fixed meaning, so the name of an engine can be read off to determine its output length class, type, core algorithm, and version.

Format

nex <L> <T> <C> <V>
│   │   │   │   │
│   │   │   │   └─ Version
│   │   │   └──── Core algorithm
│   │   └────── Type
│   └──────── Length class
└──────────── NexHash prefix

Total length: seven characters (nex + four). All characters are lowercase.

Fields

<L> — Length class

A single digit indicating the order of magnitude of the output hex length.

Digit	Range (hex chars)	Range (bits)
1	1 – 9	4 – 36
2	10 – 99	40 – 396
3	100 – 999	400 – 3 996
4	1 000 – 9 999	4 000 – 39 996
5	10 000+	40 000+

External standards (argon2, bcrypt) do not follow this scheme — their names are reserved for compatibility with existing PHC strings.

<T> — Type

A single letter indicating what the engine hashes.

Letter	Meaning	Input
P	Password	A single secret string
F	File	A path to a file (streamed)
M	Message	A password (key) plus arbitrary text
K	Key	Key derivation (reserved for future use)
B	Blob	Arbitrary byte buffer (reserved)

<C> — Core algorithm

A single letter identifying the underlying cryptographic primitive.

Letter	Meaning
A	Argon2 family (memory-hard)
B	bcrypt / Blowfish
H	SHA-512
S	SHA-256
X	Mixed (combination of primitives)

<V> — Version

A single digit (1 – 9) tracking breaking changes within an engine. Incremented when the produced output for the same input changes — for example, when the iteration formula or output length changes. Performance optimisations and bug fixes that leave the output identical do not increment the version.

Decoding examples

Name	Length class	Type	Core	Version	Decoded meaning
nex3ph1	3 (100–999)	Password	SHA-512	1	432-hex password hash, SHA-512 based
nex4px1	4 (1k–10k)	Password	Mixed	1	1240-hex password hash, mixed SHA-256/512
nex3fh1	3 (100–999)	File	SHA-512	1	256-hex file hash, SHA-512 streaming
nex4px2	4 (1k–10k)	Password	Mixed	2	8743-hex password hash, mixed SHA, version 2
nex4mx1	4 (1k–10k)	Message	Mixed	1	2048-hex keyed-message hash, mixed SHA
nex5mx1	5 (10k+)	Message	Mixed	1	16384-hex keyed-message hash, Argon2id + mixed SHA

Reserved future names

The scheme leaves room for additional engines. Examples of names that may appear in later releases:

Name	Possible meaning
nex5pk1	10000+ hex password key, SHA-256 based
nex4fa1	~5000 hex file hash, Argon2-based (memory-hard file hashing)
nex4ma1	~5000 hex keyed-message hash, Argon2-based
nex2mb1	~50 hex short-message hash, bcrypt-based
nex3ks1	~300 hex key derivation, SHA-256 based

If a future engine produces output that cannot be described by the existing fields, the scheme will be extended rather than reused with a conflicting meaning.