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Support for TLS 1.2 PRF (#232)
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@skmcgrail
skmcgrail authored Oct 11, 2023
1 parent 976a029 commit 5b0faa6
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1 change: 1 addition & 0 deletions aws-lc-rs/src/lib.rs
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Expand Up @@ -127,6 +127,7 @@ mod fips;
pub mod iv;
mod ptr;
mod rsa;
pub mod tls_prf;

pub(crate) use debug::derive_debug_via_id;

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333 changes: 333 additions & 0 deletions aws-lc-rs/src/tls_prf.rs
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// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0 OR ISC

//! TLS 1.2 PRF API's for usage in [RFC 5246](https://www.rfc-editor.org/rfc/rfc5246) and [RFC 7627](https://www.rfc-editor.org/rfc/rfc7627).
use crate::{
digest::match_digest_type, digest::AlgorithmID, error::Unspecified, fips::indicator_check,
};
use core::ptr::null;

use aws_lc::CRYPTO_tls1_prf;

/// The TLS PRF `P_hash` Algorithm
pub struct Algorithm(AlgorithmID);

/// SHA-256 `P_hash` algorithm
pub const P_SHA256: Algorithm = Algorithm(AlgorithmID::SHA256);

/// SHA-384 `P_hash` algorithm
pub const P_SHA384: Algorithm = Algorithm(AlgorithmID::SHA384);

/// SHA-512 `P_hash` algorithm
pub const P_SHA512: Algorithm = Algorithm(AlgorithmID::SHA512);

/// Encapsulates a PRF algorithm and secret bytes to be used to derive output.
pub struct Secret {
algorithm: &'static Algorithm,
secret: Box<[u8]>,
}

impl Secret {
/// Constructs a new `Secret` for use with the associated `P_hash` `Algorithm`.
///
/// # Errors
/// * `Unspecified`: If `secret.is_empty() == true`.
pub fn new(algorithm: &'static Algorithm, secret: &[u8]) -> Result<Self, Unspecified> {
if secret.is_empty() {
return Err(Unspecified);
}

let secret = Vec::from(secret).into_boxed_slice();

Ok(Self { algorithm, secret })
}

/// Calculates `len` bytes of TLS PRF using the configured [`Algorithm`], and returns [`Secret`] of length `len`.
/// See [RFC5246](https://datatracker.ietf.org/doc/html/rfc5246#section-5)
///
/// # Errors
/// * `Unspecified`: Returned if the PRF derivation fails.
pub fn derive(self, label: &[u8], seed: &[u8], output: usize) -> Result<Secret, Unspecified> {
prf(self.algorithm, &self.secret, label, seed, None, output)
}

/// Calculates `len` bytes of TLS PRF using the configured [`Algorithm`], and returns [`Secret`] of length `len`.
///
/// In this function calling convention `seed1` and `seed2` will be concatenated together: `seed1 || seed2`.
///
/// See [RFC5246](https://datatracker.ietf.org/doc/html/rfc5246#section-5)
///
/// # Errors
/// * `Unspecified`: Returned if the PRF derivation fails.
pub fn derive_with_seed_concatination(
self,
label: &[u8],
seed1: &[u8],
seed2: &[u8],
len: usize,
) -> Result<Secret, Unspecified> {
prf(self.algorithm, &self.secret, label, seed1, Some(seed2), len)
}
}

impl Drop for Secret {
fn drop(&mut self) {
use zeroize::Zeroize;
self.secret.zeroize();
}
}

impl AsRef<[u8]> for Secret {
fn as_ref(&self) -> &[u8] {
&self.secret
}
}

impl<const L: usize> TryFrom<Secret> for [u8; L] {
type Error = Unspecified;

fn try_from(value: Secret) -> Result<Self, Self::Error> {
if value.secret.len() != L {
return Err(Unspecified);
}

let mut ret = [0u8; L];
ret.copy_from_slice(&value.secret);

Ok(ret)
}
}

fn prf(
algorithm: &'static Algorithm,
secret: &[u8],
label: &[u8],
seed1: &[u8],
seed2: Option<&[u8]>,
output: usize,
) -> Result<Secret, Unspecified> {
if output == 0 {
return Err(Unspecified);
}

let mut output = vec![0u8; output];

let digest = match_digest_type(&algorithm.0);

let (seed2, seed2_len) = if let Some(seed2) = seed2 {
(seed2.as_ptr(), seed2.len())
} else {
(null(), 0usize)
};

if 1 != indicator_check!(unsafe {
CRYPTO_tls1_prf(
*digest,
output.as_mut_ptr(),
output.len(),
secret.as_ptr(),
secret.len(),
label.as_ptr().cast(),
label.len(),
seed1.as_ptr(),
seed1.len(),
seed2,
seed2_len,
)
}) {
return Err(Unspecified);
}

Ok(Secret {
algorithm,
secret: output.into_boxed_slice(),
})
}

#[cfg(test)]
mod tests {
use std::ffi::CString;

use super::{Secret, P_SHA256, P_SHA384, P_SHA512};

#[cfg(feature = "fips")]
mod fips;

#[test]
fn aws_lc_kat() {
// Testings constants from https://github.com/aws/aws-lc/blob/c5ef1079b605acac1068ac362a7008f30fd8c100/crypto/fipsmodule/self_check/self_check.c#L1130
const TLS_SECRET: &[u8; 32] = &[
0xab, 0xc3, 0x65, 0x7b, 0x09, 0x4c, 0x76, 0x28, 0xa0, 0xb2, 0x82, 0x99, 0x6f, 0xe7,
0x5a, 0x75, 0xf4, 0x98, 0x4f, 0xd9, 0x4d, 0x4e, 0xcc, 0x2f, 0xcf, 0x53, 0xa2, 0xc4,
0x69, 0xa3, 0xf7, 0x31,
];

const TLS_LABEL: &str = "FIPS self test";

const TLS_SEED1: &[u8; 16] = &[
0x8f, 0x0d, 0xe8, 0xb6, 0x90, 0x8f, 0xb1, 0xd2, 0x6d, 0x51, 0xf4, 0x79, 0x18, 0x63,
0x51, 0x65,
];

const TLS_SEED2: &[u8; 16] = &[
0x7d, 0x24, 0x1a, 0x9d, 0x3c, 0x59, 0xbf, 0x3c, 0x31, 0x1e, 0x2b, 0x21, 0x41, 0x8d,
0x32, 0x81,
];

const TLS_OUTPUT_P_SHA256: &[u8; 32] = &[
0xe2, 0x1d, 0xd6, 0xc2, 0x68, 0xc7, 0x57, 0x03, 0x2c, 0x2c, 0xeb, 0xbb, 0xb8, 0xa9,
0x7d, 0xe9, 0xee, 0xe6, 0xc9, 0x47, 0x83, 0x0a, 0xbd, 0x11, 0x60, 0x5d, 0xd5, 0x2c,
0x47, 0xb6, 0x05, 0x88,
];

let secret = Secret::new(&P_SHA256, TLS_SECRET).expect("secret created");

// The AWS-LC KAT annoyingly includes the null terminator in its KAT, so using CString here to handle that for us.
let label = CString::new(TLS_LABEL).expect("failed to create CString");

let output = secret
.derive_with_seed_concatination(
label.as_bytes_with_nul(),
TLS_SEED1,
TLS_SEED2,
TLS_OUTPUT_P_SHA256.len(),
)
.unwrap();

assert_eq!(TLS_OUTPUT_P_SHA256, output.as_ref());

let mut seed = Vec::<u8>::with_capacity(TLS_SEED1.len() + TLS_SEED2.len());
seed.extend(TLS_SEED1);
seed.extend(TLS_SEED2);

let secret = Secret::new(&P_SHA256, TLS_SECRET).expect("secret created");
let output = secret
.derive(label.as_bytes_with_nul(), &seed, TLS_OUTPUT_P_SHA256.len())
.unwrap();

assert_eq!(TLS_OUTPUT_P_SHA256, output.as_ref());
}

#[test]
fn sha256() {
// KAT Sourced from https://csrc.nist.gov/Projects/cryptographic-algorithm-validation-program/Component-Testing

const SECRET: &[u8] = &[
0xf8, 0x93, 0x8e, 0xcc, 0x9e, 0xde, 0xbc, 0x50, 0x30, 0xc0, 0xc6, 0xa4, 0x41, 0xe2,
0x13, 0xcd, 0x24, 0xe6, 0xf7, 0x70, 0xa5, 0x0d, 0xda, 0x07, 0x87, 0x6f, 0x8d, 0x55,
0xda, 0x06, 0x2b, 0xca, 0xdb, 0x38, 0x6b, 0x41, 0x1f, 0xd4, 0xfe, 0x43, 0x13, 0xa6,
0x04, 0xfc, 0xe6, 0xc1, 0x7f, 0xbc,
];
const LABEL: &[u8] = b"master secret";
const SEED1: &[u8] = &[
0x36, 0xc1, 0x29, 0xd0, 0x1a, 0x32, 0x00, 0x89, 0x4b, 0x91, 0x79, 0xfa, 0xac, 0x58,
0x9d, 0x98, 0x35, 0xd5, 0x87, 0x75, 0xf9, 0xb5, 0xea, 0x35, 0x87, 0xcb, 0x8f, 0xd0,
0x36, 0x4c, 0xae, 0x8c,
];
const SEED2: &[u8] = &[
0xf6, 0xc9, 0x57, 0x5e, 0xd7, 0xdd, 0xd7, 0x3e, 0x1f, 0x7d, 0x16, 0xec, 0xa1, 0x15,
0x41, 0x58, 0x12, 0xa4, 0x3c, 0x2b, 0x74, 0x7d, 0xaa, 0xaa, 0xe0, 0x43, 0xab, 0xfb,
0x50, 0x05, 0x3f, 0xce,
];
const EXPECT: &[u8] = &[
0x20, 0x2c, 0x88, 0xc0, 0x0f, 0x84, 0xa1, 0x7a, 0x20, 0x02, 0x70, 0x79, 0x60, 0x47,
0x87, 0x46, 0x11, 0x76, 0x45, 0x55, 0x39, 0xe7, 0x05, 0xbe, 0x73, 0x08, 0x90, 0x60,
0x2c, 0x28, 0x9a, 0x50, 0x01, 0xe3, 0x4e, 0xeb, 0x3a, 0x04, 0x3e, 0x5d, 0x52, 0xa6,
0x5e, 0x66, 0x12, 0x51, 0x88, 0xbf,
];

let secret = Secret::new(&P_SHA256, SECRET).expect("secret created");

let output = secret
.derive_with_seed_concatination(LABEL, SEED1, SEED2, EXPECT.len())
.expect("derive successful");

assert_eq!(EXPECT, output.as_ref());
}

#[test]
fn sha384() {
// KAT Sourced from https://csrc.nist.gov/Projects/cryptographic-algorithm-validation-program/Component-Testing

const SECRET: &[u8] = &[
0xa5, 0xe2, 0x64, 0x26, 0x33, 0xf5, 0xb8, 0xc8, 0x1a, 0xd3, 0xfe, 0x0c, 0x2f, 0xe3,
0xa8, 0xe5, 0xef, 0x80, 0x6b, 0x06, 0x12, 0x1d, 0xd1, 0x0d, 0xf4, 0xbb, 0x0f, 0xe8,
0x57, 0xbf, 0xdc, 0xf5, 0x22, 0x55, 0x8e, 0x05, 0xd2, 0x68, 0x2c, 0x9a, 0x80, 0xc7,
0x41, 0xa3, 0xaa, 0xb1, 0x71, 0x6f,
];
const LABEL: &[u8] = b"master secret";
const SEED1: &[u8] = &[
0xab, 0xe4, 0xbf, 0x55, 0x27, 0x42, 0x9a, 0xc8, 0xeb, 0x13, 0x57, 0x4d, 0x27, 0x09,
0xe8, 0x01, 0x2b, 0xd1, 0xa1, 0x13, 0xc6, 0xd3, 0xb1, 0xd3, 0xaa, 0x2c, 0x38, 0x40,
0x51, 0x87, 0x78, 0xac,
];
const SEED2: &[u8] = &[
0xcb, 0x6e, 0x0b, 0x3e, 0xb0, 0x29, 0x76, 0xb6, 0x46, 0x6d, 0xfa, 0x96, 0x51, 0xc2,
0x91, 0x94, 0x14, 0xf1, 0x64, 0x8f, 0xd3, 0xa7, 0x83, 0x8d, 0x02, 0x15, 0x3e, 0x5b,
0xd3, 0x95, 0x35, 0xb6,
];
const EXPECT: &[u8] = &[
0xb4, 0xd4, 0x9b, 0xfa, 0x87, 0x74, 0x7f, 0xe8, 0x15, 0x45, 0x7b, 0xc3, 0xda, 0x15,
0x07, 0x3d, 0x6a, 0xc7, 0x33, 0x89, 0xe7, 0x03, 0x07, 0x9a, 0x35, 0x03, 0xc0, 0x9e,
0x14, 0xbd, 0x55, 0x9a, 0x5b, 0x3c, 0x7c, 0x60, 0x1c, 0x73, 0x65, 0xf6, 0xea, 0x8c,
0x68, 0xd3, 0xd9, 0x59, 0x68, 0x27,
];

let secret = Secret::new(&P_SHA384, SECRET).expect("secret created");

let output = secret
.derive_with_seed_concatination(LABEL, SEED1, SEED2, EXPECT.len())
.expect("derive successful");

assert_eq!(EXPECT, output.as_ref());
}

#[test]
fn sha512() {
// KAT Sourced from https://csrc.nist.gov/Projects/cryptographic-algorithm-validation-program/Component-Testing

const SECRET: &[u8] = &[
0xdf, 0xef, 0x39, 0xaf, 0x25, 0xc1, 0x26, 0x63, 0xa9, 0x1e, 0xe5, 0xd2, 0x70, 0x42,
0xb9, 0x64, 0x4a, 0x16, 0xef, 0x55, 0xb8, 0x10, 0x55, 0xd1, 0xbd, 0x7d, 0xcb, 0x0b,
0x8f, 0x06, 0xeb, 0x00, 0x17, 0x08, 0xcd, 0xef, 0xcf, 0x82, 0x59, 0x1d, 0xef, 0xca,
0x1a, 0x6f, 0x1a, 0xc6, 0x93, 0xab,
];
const LABEL: &[u8] = b"master secret";
const SEED1: &[u8] = &[
0x78, 0xbc, 0x52, 0x98, 0xdf, 0xe9, 0xcf, 0x8e, 0xd3, 0x36, 0xc2, 0xe2, 0xf0, 0xf6,
0xb4, 0x6e, 0x24, 0x56, 0xf3, 0x9f, 0x35, 0xf1, 0x14, 0x3c, 0xd2, 0x1e, 0xaa, 0x16,
0x27, 0x70, 0x25, 0xb2,
];
const SEED2: &[u8] = &[
0xe2, 0x33, 0x9a, 0x6c, 0x68, 0x1e, 0xb3, 0x08, 0x08, 0x88, 0x39, 0x71, 0xb1, 0xce,
0x5b, 0x9b, 0x1e, 0xce, 0x0f, 0x3d, 0x01, 0x1a, 0x96, 0xa7, 0xff, 0xf1, 0xf5, 0xf9,
0xd8, 0x0f, 0xfd, 0x4b,
];
const EXPECT: &[u8] = &[
0xa7, 0x0c, 0x5f, 0xe8, 0xd3, 0x4b, 0x64, 0x5a, 0x20, 0xce, 0x98, 0x96, 0x9b, 0xd3,
0x08, 0x58, 0xe7, 0x29, 0xc7, 0x7c, 0x8a, 0x5f, 0x05, 0xd3, 0xe2, 0x89, 0x21, 0x9d,
0x6b, 0x57, 0x52, 0xb7, 0x5b, 0x75, 0xe1, 0xca, 0x00, 0xd3, 0x32, 0x96, 0x58, 0xd7,
0xf1, 0x88, 0xed, 0x1a, 0xb7, 0xe0,
];

let secret = Secret::new(&P_SHA512, SECRET).expect("secret created");

let output = secret
.derive_with_seed_concatination(LABEL, SEED1, SEED2, EXPECT.len())
.expect("derive successful");

assert_eq!(EXPECT, output.as_ref());
}

#[test]
fn try_into_array() {
let secret = Secret::new(&P_SHA256, &[42u8; 32]).expect("secret creation to succeed");

let secret = secret
.derive("master secret".as_bytes(), &[7u8; 3], 7)
.expect("derive to succeed");

let _secret: [u8; 7] = secret.try_into().expect("try_into to succeed");
}
}
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