Digest.MD5(3)

💅 Digest.MD5(3) 💅

Ok bestie, welcome to the Digest.MD5(3) page from the OCaml library — we're talking about the Digest.MD5 module, and yes, it's giving very specific hash-function energy. Let's get into it 💖

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✨ NAME ✨

Digest.MD5 — MD5 is the MD5 hash function. No cap, that's literally the name and the job 🌸

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🧩 Module 🧩

• Module: Digest.MD5 — that's the module we're living in, bestie 🫶

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💖 Documentation 💖

• Module MD5 : S — the signature situation, exactly as written.

MD5 is the MD5 hash function. It produces 128-bit (16-byte) digests, and it is not cryptographically secure at all. Like, do not use it for security, fr fr 😭 It should be used only for compatibility with earlier designs that mandate the use of MD5. That's the whole vibe: legacy compatibility, not main character security energy 💀

✨ Since 5.2 ✨

• type t = string — the type of digests. That's the digest representation right there 🎀
• val hash_length : int — the length of digests, in bytes. Short, sweet, and exactly what it says 💅
• val compare : t -> t -> int — compare two digests, with the same specification as compare. Bestie, it's the comparison behavior you already know and love 🌈
• val equal : t -> t -> bool — test two digests for equality. Simple vibe check: equal or not equal 🦋
• val string : string -> t — return the digest of the given string. String goes in, digest comes out ✨
• val bytes : bytes -> t — return the digest of the given byte sequence. Byte-sequence bestie gets the same treatment 💜
• 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. Slice that string, hash that slice, periodt 🍓
• 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. Same idea, but the byte-sequence edition 🧚
• val channel : in_channel -> int -> t — read characters from the channel and return their digest. See Digest.channel for the full specification. Go check that one for the whole story, iykyk 👑
• val file : string -> t — return the digest of the file whose name is given. Give it a filename, get a digest 🎀
• val output : out_channel -> t -> unit — write a digest on the given output channel. Digest goes out through the channel, slay 💅
• val input : in_channel -> t — read a digest from the given input channel. Digest comes in from the channel, iconic 🦋
• val to_hex : t -> string — return the printable hexadecimal representation of the given digest. Hex string era ✨

Raises Invalid_argument if the length of the argument is not hash_length, 😭

• val of_hex : string -> t — convert a hexadecimal representation back into the corresponding digest. Hex string goes back to digest form, no cap 💖

Raises Invalid_argument if the length of the argument is not 2 * hash_length, or if the arguments contains non-hexadecimal characters. That's the guardrail, bestie 🚧

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Cute sign-off time 🫶: this little page came from OCamldoc, dated 2026-06-22, and it's the Digest.MD5(3) manual page. Bye bestie, stay hashing responsibly 💜✨