gleam/crypto

Set of cryptographic functions.

Types

HashAlgorithm

pub type HashAlgorithm {
  Sha224
  Sha256
  Sha384
  Sha512
  Md5
}

Constructors

```
Sha224
```
```
Sha256
```
```
Sha384
```
```
Sha512
```
```
Md5
```
The MD5 hash algorithm is considered weak and should not be used for security purposes. It may still be useful for non-security purposes or for compatibility with existing systems.

Functions

hash

</>

pub fn hash(a: HashAlgorithm, b: BitArray) -> BitArray

Computes a digest of the input bit string.

hmac

</>

pub fn hmac(
  data: BitArray,
  algorithm: HashAlgorithm,
  key: BitArray,
) -> BitArray

Calculates the HMAC (hash-based message authentication code) for a bit string.

Based on the Erlang crypto:mac function, or the node:crypto.createHmac function on JavaScript.

secure_compare

</>

pub fn secure_compare(left: BitArray, right: BitArray) -> Bool

Compares the two binaries in constant-time to avoid timing attacks.

For more details see: http://codahale.com/a-lesson-in-timing-attacks/

sign_message

</>

pub fn sign_message(
  message: BitArray,
  secret: BitArray,
  digest_type: HashAlgorithm,
) -> String

Sign a message which can later be verified using the verify_signed_message function to detect if the message has been tampered with.

A web application could use this verifier to sign HTTP cookies. The data can be read by the user, but cannot be tampered with.

strong_random_bytes

</>

pub fn strong_random_bytes(a: Int) -> BitArray

Generates a specified number of bytes randomly uniform 0..255, and returns the result in a binary.

On Erlang this uses a cryptographically secure prng seeded and periodically mixed with / operating system provided entropy. By default this is the RAND_bytes method from OpenSSL. https://erlang.org/doc/man/crypto.html#strong_rand_bytes-1

On JavaScript the WebCrypto API is used.

verify_signed_message

</>

pub fn verify_signed_message(
  message: String,
  secret: BitArray,
) -> Result(BitArray, Nil)

Verify a message created by the sign_message function.