| use ring::digest; |
| use ring::hmac; |
| |
| use std::io::Write; |
| |
| fn convert_digest_to_hmac_alg(hash: &'static digest::Algorithm) -> hmac::Algorithm { |
| if hash == &digest::SHA256 { |
| hmac::HMAC_SHA256 |
| } else if hash == &digest::SHA384 { |
| hmac::HMAC_SHA384 |
| } else if hash == &digest::SHA512 { |
| hmac::HMAC_SHA512 |
| } else { |
| panic!("bad digest for prf"); |
| } |
| } |
| |
| fn concat_sign(key: &hmac::Key, a: &[u8], b: &[u8]) -> hmac::Tag { |
| let mut ctx = hmac::Context::with_key(key); |
| ctx.update(a); |
| ctx.update(b); |
| ctx.sign() |
| } |
| |
| fn p(out: &mut [u8], hashalg: &'static digest::Algorithm, secret: &[u8], seed: &[u8]) { |
| let hmac_key = hmac::Key::new(convert_digest_to_hmac_alg(hashalg), secret); |
| |
| // A(1) |
| let mut current_a = hmac::sign(&hmac_key, seed); |
| |
| let mut offs = 0; |
| |
| while offs < out.len() { |
| // P_hash[i] = HMAC_hash(secret, A(i) + seed) |
| let p_term = concat_sign(&hmac_key, current_a.as_ref(), seed); |
| offs += out[offs..].as_mut().write(p_term.as_ref()).unwrap(); |
| |
| // A(i+1) = HMAC_hash(secret, A(i)) |
| current_a = hmac::sign(&hmac_key, current_a.as_ref()); |
| } |
| } |
| |
| fn concat(a: &[u8], b: &[u8]) -> Vec<u8> { |
| let mut ret = Vec::new(); |
| ret.extend_from_slice(a); |
| ret.extend_from_slice(b); |
| ret |
| } |
| |
| pub fn prf(out: &mut [u8], |
| hashalg: &'static digest::Algorithm, |
| secret: &[u8], |
| label: &[u8], |
| seed: &[u8]) { |
| let joined_seed = concat(label, seed); |
| p(out, hashalg, secret, &joined_seed); |
| } |
| |
| #[cfg(test)] |
| mod tests { |
| use ring::digest::{SHA256, SHA512}; |
| |
| #[test] |
| fn check_sha256() { |
| let secret = b"\x9b\xbe\x43\x6b\xa9\x40\xf0\x17\xb1\x76\x52\x84\x9a\x71\xdb\x35"; |
| let seed = b"\xa0\xba\x9f\x93\x6c\xda\x31\x18\x27\xa6\xf7\x96\xff\xd5\x19\x8c"; |
| let label = b"test label"; |
| let expect = include_bytes!("testdata/prf-result.1.bin"); |
| let mut output = [0u8; 100]; |
| |
| super::prf(&mut output, &SHA256, secret, label, seed); |
| assert_eq!(expect.len(), output.len()); |
| assert_eq!(expect.to_vec(), output.to_vec()); |
| } |
| |
| #[test] |
| fn check_sha512() { |
| let secret = b"\xb0\x32\x35\x23\xc1\x85\x35\x99\x58\x4d\x88\x56\x8b\xbb\x05\xeb"; |
| let seed = b"\xd4\x64\x0e\x12\xe4\xbc\xdb\xfb\x43\x7f\x03\xe6\xae\x41\x8e\xe5"; |
| let label = b"test label"; |
| let expect = include_bytes!("testdata/prf-result.2.bin"); |
| let mut output = [0u8; 196]; |
| |
| super::prf(&mut output, &SHA512, secret, label, seed); |
| assert_eq!(expect.len(), output.len()); |
| assert_eq!(expect.to_vec(), output.to_vec()); |
| } |
| } |