silk.crypto.sha1.

When to use#

Use Sha1 only when an existing format needs SHA-1, such as a Git object ID or the WebSocket handshake. For new designs, use SHA-256 from silk.crypto.sha2 or SHA-3 from silk.crypto.sha3. For the keys of a hash map, use silk.collections.hash.

Details#

Sha1.hash returns the digest of one slice. For a message that arrives in parts, call Sha1.make, then Sha1.update for each part, then Sha1.finish. Nothing allocates.

Gotchas#

SHA-1 is broken: an attacker can make two different messages with the same digest. Do not use it for signatures, certificates, or checks against tampering.

Examples#

Hash a message in one call and in parts#

import silk.crypto.sha1 { Sha1 }

pub fn main() -> i32 {
  let oneShot = Sha1.hash(b"abc")
  let mut state = Sha1.make()
  state.update(b"a")
  state.update(b"bc")
  let streamed = state.finish()

  // SHA-1("abc") is a9993e36...d89d.
  if oneShot[0] != 0xa9 || oneShot[19] != 0x9d || streamed[0] != oneShot[0] {
    return 1
  }
  return 0
}

Import as Sha1 with import silk.crypto.sha1 { Sha1 }.

Public declarations: 1.

Sha1#

pub struct Sha1

A streaming SHA-1 state that returns a 20-byte digest.

Call Sha1.update for each part of the message, then Sha1.finish. The state is a fixed-size value and does not allocate.

Gotchas#

SHA-1 is broken. Use it only where an existing format needs it.

Implementation Sha1#

impl Sha1

Associated function make#

pub fn make() -> Self

Returns a SHA-1 state for an empty message.

Method update#

pub fn update(self: &mut Self, bytes: &[u8]) -> ()

Adds bytes to the end of the message.

Any split of the message into parts gives the same digest. An empty slice changes nothing.

Gotchas#

The program traps if the full message is longer than 2^64 - 1 bits.

Method finish#

pub fn finish(self: Self) -> [u8; 20]

Returns the 20-byte SHA-1 digest of the message and consumes the state.

Associated function hash#

pub fn hash(bytes: &[u8]) -> [u8; 20]

Returns the 20-byte SHA-1 digest of bytes.

Gotchas#

The program traps if bytes is longer than 2^64 - 1 bits.

Category: Cryptography.

Profiles: aarch64-apple-darwin, aarch64-unknown-linux-gnu, aarch64-unknown-linux-gnu-no-libc, x86_64-unknown-linux-gnu, x86_64-unknown-linux-gnu-no-libc, wasm32-unknown-unknown, wasm32-wasip1, wasm32-wasip2.