hashlib

hashlib

hashlib provides cryptographic hash primitives for Starlark — MD5, SHA-1, SHA-256, and SHA-512 digests of string or bytes input, returned as lowercase hex. Capability profile: pure (no filesystem, network, process, or log side effects).

Migrated from qri-io/starlib.

Functions

All four share the same signature and behavior; only the algorithm differs. data is a required positional argument (also accepted as the keyword data). It must be a Starlark string or bytes; the two encode identically, so a string and the equivalent bytes produce the same digest. The return is the digest hex-encoded as a lowercase string.

Errors: each function takes exactly one argument — passing more raises got N arguments, want at most 1. Passing a non-string/bytes value (e.g. an int) raises for parameter data: got <type>, want string or bytes.

Examples

md5

load("hashlib", "md5")
print(md5(""))
print(md5("Aloha!"))
print(md5(b"Aloha!"))
# Output:
# d41d8cd98f00b204e9800998ecf8427e
# de424bf3e7dcba091c27d652ada485fb
# de424bf3e7dcba091c27d652ada485fb

The string and bytes forms of "Aloha!" hash to the same value.

sha1

load("hashlib", "sha1")
print(sha1(""))
print(sha1("Aloha!"))
# Output:
# da39a3ee5e6b4b0d3255bfef95601890afd80709
# c3dd37312ba987e1cc40ae021bc202c4a52d8afe

sha256

load("hashlib", "sha256")
print(sha256(""))
print(sha256("Aloha!"))
# Output:
# e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
# dea7e28aee505f2dd033de1427a517793e38b7605e8fc24da40151907e52cea3

sha512

load("hashlib", "sha512")
print(sha512(""))
print(sha512("Aloha!"))
# Output:
# cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e
# d9cb95ad9d916a0781b3339424d5eb11c476405dfba7af7fabf4981fdd3291c27e8006e4cca617beae70dd00ab86a0213c44ed461229b16b45db45f64691049e

Error: wrong argument count

load("hashlib", "md5")
md5("Aloha!", "Hello!")
# Output:
# Error: hash.md5: got 2 arguments, want at most 1

Error: wrong input type

load("hashlib", "md5")
md5(123)
# Output:
# Error: hash.md5: for parameter data: got int, want string or bytes

Notes / boundaries

• Engine: Go standard library crypto/md5, crypto/sha1, crypto/sha256, crypto/sha512; output is encoding/hex lowercase.
• Deterministic: identical input always yields identical output; no salt, no randomness.
• Pure: no host effects of any kind.
• No streaming/incremental API: each call hashes the full data value in one shot; there is no reusable hasher object or update/hexdigest protocol like CPython's hashlib. The module exposes only the four one-shot functions above — no constants and no custom types.
• MD5 and SHA-1 are not collision-resistant. They are provided for checksums and legacy interop; do not use them for security-sensitive integrity or signatures — prefer sha256 or sha512.