Jędrzej Stuczyński
31 lines
813 B
Rust
31 lines
813 B
Rust
// Copyright 2021 - Nym Technologies SA <contact@nymtech.net>
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// SPDX-License-Identifier: Apache-2.0
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use hkdf::{
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hmac::{
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digest::{crypto_common::BlockSizeUser, Digest},
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SimpleHmac,
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},
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Hkdf,
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};
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/// Perform HKDF `extract` then `expand` as a single step.
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pub fn extract_then_expand<D>(
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salt: Option<&[u8]>,
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ikm: &[u8],
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info: Option<&[u8]>,
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okm_length: usize,
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) -> Result<Vec<u8>, hkdf::InvalidLength>
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where
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D: Digest + BlockSizeUser + Clone,
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{
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// TODO: this would need to change if we ever needed the generated pseudorandom key, but
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// realistically I don't see any reasons why we might need it
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let hkdf = Hkdf::<D, SimpleHmac<D>>::new(salt, ikm);
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let mut okm = vec![0u8; okm_length];
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hkdf.expand(info.unwrap_or(&[]), &mut okm)?;
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Ok(okm)
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}
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