Expand description
The message digest context.
Examples
Compute the SHA256 checksum of data
use openssl::md::Md;
use openssl::md_ctx::MdCtx;
let mut ctx = MdCtx::new().unwrap();
ctx.digest_init(Md::sha256()).unwrap();
ctx.digest_update(b"Some Crypto Text").unwrap();
let mut digest = [0; 32];
ctx.digest_final(&mut digest).unwrap();
assert_eq!(
digest,
*b"\x60\x78\x56\x38\x8a\xca\x5c\x51\x83\xc4\xd1\x4d\xc8\xf9\xcc\xf2\
\xa5\x21\xb3\x10\x93\x72\xfa\xd6\x7c\x55\xf5\xc9\xe3\xd1\x83\x19",
);Sign and verify data with RSA and SHA256
use openssl::md::Md;
use openssl::md_ctx::MdCtx;
use openssl::pkey::PKey;
use openssl::rsa::Rsa;
// Generate a random RSA key.
let key = Rsa::generate(4096).unwrap();
let key = PKey::from_rsa(key).unwrap();
let text = b"Some Crypto Text";
// Create the signature.
let mut ctx = MdCtx::new().unwrap();
ctx.digest_sign_init(Some(Md::sha256()), &key).unwrap();
ctx.digest_sign_update(text).unwrap();
let mut signature = vec![];
ctx.digest_sign_final_to_vec(&mut signature).unwrap();
// Verify the signature.
let mut ctx = MdCtx::new().unwrap();
ctx.digest_verify_init(Some(Md::sha256()), &key).unwrap();
ctx.digest_verify_update(text).unwrap();
let valid = ctx.digest_verify_final(&signature).unwrap();
assert!(valid);
Compute and verify an HMAC-SHA256
use openssl::md::Md;
use openssl::md_ctx::MdCtx;
use openssl::memcmp;
use openssl::pkey::PKey;
// Create a key with the HMAC secret.
let key = PKey::hmac(b"my secret").unwrap();
let text = b"Some Crypto Text";
// Compute the HMAC.
let mut ctx = MdCtx::new().unwrap();
ctx.digest_sign_init(Some(Md::sha256()), &key).unwrap();
ctx.digest_sign_update(text).unwrap();
let mut hmac = vec![];
ctx.digest_sign_final_to_vec(&mut hmac).unwrap();
// Verify the HMAC. You can't use MdCtx to do this; instead use a constant time equality check.
let valid = memcmp::eq(&hmac, &target);
assert!(valid);