Digest.BLAKE128(3)

💖 Digest.BLAKE128 — the OCaml library page, but make it make sense 💖

okay so bestie, welcome to Digest.BLAKE128 from the OCaml library (Digest.BLAKE128(3), section 3, iykyk). this whole page is literally about one little module and it's lowkey iconic, let's go 🫶

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✨ NAME ✨

Digest.BLAKE128 — BLAKE128 is the BLAKE2b hash function producing 128-bit (16-byte) digests. no cap, that's the whole vibe of the page 🎀

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🦋 Module 🦋

Module Digest.BLAKE128

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🌸 Documentation 🌸

Module BLAKE128 : S

ok so BLAKE128 is the BLAKE2b hash function producing 128-bit (16-byte) digests. it is cryptographically secure — slay — BUT (and this is the important part, bestie, don't skip it) the small size of the digests enables brute-force attacks in 2{^64} attempts. so like, secure, but the tiny digest size is giving "crackable with enough brute force" energy 💀

Since 5.2

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💅 the types and values 💅

• type t = string — the type of digests. that's it, that's the type. a digest is literally a string around here ✨
• val hash_length : int — the length of digests, in bytes. this number matters later, remember it 🧚
• val compare : t -> t -> int — compare two digests, with the same specification as compare. (yes, that compare, the one you already know and love.)
• val equal : t -> t -> bool — test two digests for equality. simple. clean. iconic.
• val string : string -> t — return the digest of the given string. feed it a string, get a digest back 🍓
• val bytes : bytes -> t — return the digest of the given byte sequence. same deal but with bytes.
• val substring : string -> int -> int -> t — substring s ofs len returns the digest of the substring of s starting at index ofs and containing len characters. yes, characters, not bytes, because it's a string.
• val subbytes : bytes -> int -> int -> t — subbytes s ofs len returns the digest of the subsequence of s starting at index ofs and containing len bytes. this one's the bytes twin, and it counts bytes, okay? don't mix them up 🫶

val substring : string -> int -> int -> t
val subbytes : bytes -> int -> int -> t

• val channel : in_channel -> int -> t — read characters from the channel and return their digest. for the full specification, go look at Digest.channel — it's the main character, this one's just the BLAKE128 version of it 💜
• val file : string -> t — return the digest of the file whose name is given. just hand it a filename, that's the whole thing.
• val output : out_channel -> t -> unit — write a digest on the given output channel.
• val input : in_channel -> t — read a digest from the given input channel. (see how it's the mirror of output? obsessed with the symmetry honestly)
• val to_hex : t -> string — return the printable hexadecimal representation of the given digest. so your digest becomes a cute lil readable hex string ✨

raises Invalid_argument if the length of the argument is not hash_length. note that trailing comma in the original, it's part of the lore lmaoo 😭

• val of_hex : string -> t — convert a hexadecimal representation back into the corresponding digest. the reverse trip, we love a round-trip 🎀

raises Invalid_argument if the length of the argument is not 2 * hash_length, or if the arguments contains non-hexadecimal characters. so like — wrong length or wrong characters and it's a no from it 🙈

val to_hex : t -> string
val of_hex : string -> t

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that's genuinely every single value on the page, bestie, nothing skipped, nothing invented, we ate and left no crumbs 👑

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✨ cute lil sign-off ✨

this page was brought to you by OCamldoc, dated 2026-06-22 — that's the source/version and the date, right at the bottom where the footer always lives. go forth and hash responsibly, 128 bits at a time 💖🦋🌸