The crypto hook flags weak cryptographic primitives at the call site: a deprecated cipher, an insecure mode, or a broken digest. It is language-aware, reading each file by its own rules so a Python construct is never flagged on a Rust file, and it is the deterministic engine behind the crypto sub-skill, which you can run yourself in scan or check mode.

Run it

Scan the codebase

node ./.lagune/hooks/crypto.mjs           # scans the whole project
node ./.lagune/hooks/crypto.mjs -d src    # scans a directory
node ./.lagune/hooks/crypto.mjs -f hash.ts # scans a single file

Check a snippet

node ./.lagune/hooks/crypto.mjs -l javascript -p 'createCipher("aes-256-cbc", k)' # => weak
node ./.lagune/hooks/crypto.mjs -l python -p 'hashlib.md5(data)'                   # => review
node ./.lagune/hooks/crypto.mjs -l go -p 'sha256.Sum256(data)'                     # => safe

The scan prints up to two sections. Weak cryptography found is the finding set (DES/3DES/RC4/Blowfish/RC2, ECB mode): each is a broken cipher primitive, so the hook exits non-zero. Cryptography to review manually is a lead set it cannot judge alone: an MD5/SHA-1 digest (broken for security use, but legitimate as a plain checksum, so intent decides), a non-cryptographic RNG in a security context, or a timing-unsafe comparison. A clean run prints no weak cryptography found.

How to read the verdict

Verdict	Meaning
weak	The snippet uses a broken cipher primitive (DES/3DES, RC4, Blowfish, RC2, or ECB mode).
review	An intent-dependent primitive: an MD5/SHA-1 digest, or a non-cryptographic RNG in a security context.
safe	The snippet uses crypto, and no weak primitive was found.
invalid	The snippet contains no recognizable cryptographic construct to judge.

CLI options

Option	Alias	Value	Description
--pattern	-p	a code snippet	Check one snippet. Repeat to check several, one verdict per line.
--lang	-l	a language	Required with -p: one of javascript, python, go, java, kotlin, php, ruby, rust, csharp, c, cpp.
--dir	-d	a directory	Scope a scan to a directory. Repeats and combines with -f.
--file	-f	a file	Scope a scan to a single file. Repeats and combines with -d.

With no option it scans the whole project. -p needs -l and cannot be combined with -d or -f.

Supported languages

The scan reads these languages, keyed by file extension, each checked against its own cryptographic APIs.

Language	Weak ciphers (finding) & digests/RNG (review)
JavaScript / TypeScript	createCipher, CryptoJS.DES/RC4, quoted *-ecb; MD5/SHA-1 createHash/subtle.digest; Math.random()
Python	pycryptodome DES/ARC4/Blowfish.new, algorithms.TripleDES, MODE_ECB; hashlib.md5/sha1; random.*
Go	des.NewCipher, rc4.NewCipher, blowfish.NewCipher, NewECBEncrypter; md5/sha1.Sum; math/rand
Java / Kotlin	Cipher.getInstance("DES"/…/ECB"); MessageDigest.getInstance("MD5"), HmacMD5; java.util.Random
PHP	openssl_encrypt("des-…"/…-ecb"), mcrypt_*; md5()/sha1(), hash("md5", …); rand()/mt_rand()
Ruby	OpenSSL::Cipher.new("des-…"), :ECB; Digest::MD5/SHA1; rand()/Random
Rust	Rc4::, Blowfish::, des::, ecb::; Md5::, Sha1::, Hmac<Md5>; SmallRng/XorShiftRng
C#	DES/TripleDES/RC2.Create, CipherMode.ECB; MD5/SHA1.Create, HMACMD5; new Random()
C / C++	OpenSSL DES_*/RC4/EVP_des_*, EVP_*_ecb; MD5()/SHA1(), EVP_md5; rand()/random()

Best-effort, not exhaustive

It reads source as text, so a primitive assembled at runtime, hidden behind an alias, or written in a form it does not recognize can slip past. Treat the table as a strong starting point, not a complete inventory.

tip

The hook guarantees the floor (these constructs exist): key management, IV reuse, and RSA padding are judgment the crypto sub-skill still covers.

Frequently Asked Questions

Run the crypto hook with no flag. Broken ciphers and ECB mode are findings that exit non-zero. An MD5/SHA-1 digest is a review lead, since it is broken for security use but legitimate as a plain checksum.

Only as a review lead in a security context, never as an automatic finding, since randomness is legitimate for jitter or UI ordering.