33 lines
922 B
Rust
33 lines
922 B
Rust
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use hmac::{Hmac, Mac};
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use sha2::Sha256;
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const NB_BYTES: usize = 5;
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pub fn generate_code(local_part: &str, separator: char, sub_addr: &str, key: &[u8]) -> Vec<u8> {
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// Compute the HMAC-SHA-256
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let mut hmac = Hmac::<Sha256>::new_from_slice(key).unwrap();
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hmac.update(local_part.as_bytes());
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hmac.update(separator.to_string().as_bytes());
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hmac.update(sub_addr.as_bytes());
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let result = hmac.finalize().into_bytes();
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// Reduce the result to NB_BYTES using a dynamic offset truncation
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let offset = (result[result.len() - 1] & 0xf) as usize;
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result[offset..offset + NB_BYTES].to_vec()
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}
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#[cfg(test)]
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mod tests {
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use super::generate_code;
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#[test]
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fn code_generation() {
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let key: &[u8] = &[
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0xd7, 0x5b, 0xe8, 0x89, 0xe7, 0xca, 0xe4, 0xf8, 0x02, 0x5f, 0x91, 0x75, 0x4d, 0x37,
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0x2e, 0xa1,
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];
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let code = generate_code("a", '+', "test", key);
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assert_eq!(code, vec![0x7d, 0xd8, 0xd7, 0x1c, 0x8e]);
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}
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}
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