This tutorial covers hashing with std/crypto. Because sometimes you really, really don't want people reading your data.
Hashing strings
std/crypto provides MD5, SHA1, and SHA256 wrappers that return raw bytes, plus hex helpers for display.
module main
import "std/crypto"
import "std/str"
fn main() -> int {
secret := "password123"
md5 := crypto.Md5Hex(secret)
sha256 := crypto.Sha256Hex(secret)
print("MD5: {md5}")
print("SHA256: {sha256}")
return 0
}
HMAC
HMAC combines a secret key with a message digest. It is useful for authenticating messages:
key := "my-secret-key"
message := "transfer $100"
mac := crypto.HmacSha256(key, message)
macHex := crypto.HexEncode(mac, 32)
print("HMAC: {macHex}")
What not to do
MD5 and SHA1 are not safe for password storage. They are fine for checksums.
SHA256 is still not appropriate for passwords without salting.
Use HMAC when you need to verify message integrity with a secret key. Don't invent your own crypto. Just don't.
Exercises
- Write a program that computes the SHA256 hash of a file and prints it.
- Compare the HMAC of a message using two different keys.
- Verify that changing one character in the input changes the hash completely.
