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use crypto::aes; use crypto::buffer::{ RefReadBuffer, RefWriteBuffer, BufferResult }; pub struct DrbgCtx{ pub reseed_counter: usize, pub key: [u8;32], pub ctr: [u8;16] } impl DrbgCtx { const CTR_LEN: usize = 16; const KEY_LEN: usize = 32; pub const fn new() -> Self { Self { reseed_counter: 0, key: [0; DrbgCtx::KEY_LEN], ctr: [0; DrbgCtx::CTR_LEN] } } fn inc(&mut self) { for i in 0..16 { let j = 15-i; if self.ctr[j] == 0xFF { self.ctr[j] = 0 } else { self.ctr[j] = self.ctr[j] + 1; break; } } } fn process_aes_block(&self, block: &mut [u8]) { let mut e = aes::ecb_encryptor( aes::KeySize::KeySize256, &self.key, crypto::blockmodes::NoPadding); let mut r = RefReadBuffer::new(&self.ctr); let mut w = RefWriteBuffer::new(block); match e.encrypt(&mut r, &mut w, true).unwrap() { BufferResult::BufferOverflow => panic!("Wrong implementation"), BufferResult::BufferUnderflow => {} } } fn update(&mut self, seed: &[u8]) { let mut t = vec![0;48]; for i in 0..3 { self.inc(); self.process_aes_block(&mut t[i*16..]); } for i in 0..seed.len() { t[i] ^= seed[i]; } for i in 0..32 { self.key[i] = t[i]; } for i in 32..48 { self.ctr[i-32] = t[i]; } } pub fn init(&mut self, entropy: &[u8], diversifier: Vec<u8>) { let mut m = vec![0;48]; for i in 0..48 { m[i] = entropy[i]; } if diversifier.len() >= 48 { for i in 0..48 { m[i] ^= diversifier[i]; } } self.key = [0; DrbgCtx::KEY_LEN]; self.ctr = [0; DrbgCtx::CTR_LEN]; self.update(m.as_slice()); self.reseed_counter = 1; } pub fn get_random(&mut self, data: &mut [u8]) { let mut i = 0; let mut b = vec![0; 16]; let mut l = data.len(); while l > 0 { self.inc(); self.process_aes_block(&mut b); if l > 15 { for k in 0..16 { data[i+k] = b[k]; } i += 16; l -= 16; } else { for k in 0..l { data[i+k] = b[k]; } l = 0; } } self.update(Vec::new().as_slice()); self.reseed_counter = self.reseed_counter+1; } }