48 lines
1.4 KiB
Markdown
48 lines
1.4 KiB
Markdown
# Implementation of the TOTP algorithm in Rust
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```Rust
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use base32::decode;
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use chrono::Utc;
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use sha1::{digest::Update, Digest, Sha1};
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const INTERVAL: u64 = 30;
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const TOTP_KEY: &str = "BOMY6BV5BWVJEWJ4ZLDYKN3LSIS736B3";
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fn generate() {
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// Pre-process data
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let epoch = Utc::now().timestamp() as u64;
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let msg = epoch / INTERVAL;
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let bytes_msg = msg.to_be_bytes();
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let key_decoded = decode(base32::Alphabet::RFC4648 { padding: false }, TOTP_KEY).unwrap();
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// HMAC-SHA1
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let mut key_pad = key_decoded.clone();
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key_pad.resize(64, 0);
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let i_key_pad: Vec<u8> = key_pad.iter().map(|&x| x ^ 0x36).collect();
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let o_key_pad: Vec<u8> = key_pad.iter().map(|&x| x ^ 0x5C).collect();
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let mut i_key_pad_msg = Vec::new();
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i_key_pad_msg.extend_from_slice(&i_key_pad);
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i_key_pad_msg.extend_from_slice(&bytes_msg);
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let i_key_pad_msg_hashed = Sha1::new().chain(&i_key_pad_msg).finalize();
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let mut o_key_pad_msg = Vec::new();
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o_key_pad_msg.extend_from_slice(&o_key_pad);
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o_key_pad_msg.extend_from_slice(&i_key_pad_msg_hashed);
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let hmac_result = Sha1::new().chain(&o_key_pad_msg).finalize();
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// TOTP Algorithm
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let start = (hmac_result[19] & 0xF) as usize;
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let raw_bytes: [u8; 4] = hmac_result[start..start + 4].try_into().unwrap();
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let raw_token = u32::from_be_bytes(raw_bytes);
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let raw_token = raw_token & 0x7F_FF_FF_FF;
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let token = raw_token % 1_000_000;
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println!("{:06}", token);
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}
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``` |