src/hash256.rs - incubator-milagro-crypto-rust - Git at Google

 /*
 Licensed to the Apache Software Foundation (ASF) under one
 or more contributor license agreements.  See the NOTICE file
 distributed with this work for additional information
 regarding copyright ownership.  The ASF licenses this file
 to you under the Apache License, Version 2.0 (the
 "License"); you may not use this file except in compliance
 with the License.  You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing,
 software distributed under the License is distributed on an
 "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 KIND, either express or implied.  See the License for the
 specific language governing permissions and limitations
 under the License.
 */

 const HASH256_H0: u32 = 0x6A09_E667;
 const HASH256_H1: u32 = 0xBB67_AE85;
 const HASH256_H2: u32 = 0x3C6E_F372;
 const HASH256_H3: u32 = 0xA54F_F53A;
 const HASH256_H4: u32 = 0x510E_527F;
 const HASH256_H5: u32 = 0x9B05_688C;
 const HASH256_H6: u32 = 0x1F83_D9AB;
 const HASH256_H7: u32 = 0x5BE0_CD19;

 const HASH256_K: [u32; 64] = [
     0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
     0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
     0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
     0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
     0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
     0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
     0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
     0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
 ];

 /// The block size of each round.
 pub const BLOCK_SIZE: usize = 64;
 /// Hash Length in Bytes
 pub const HASH_BYTES: usize = 32;
 // Ipad Byte
 const IPAD_BYTE: u8 = 0x36;
 // Opad Byte
 const OPAD_BYTE: u8 = 0x5c;

 pub struct HASH256 {
     length: [u32; 2],
     h: [u32; 8],
     w: [u32; 64],
 }

 impl HASH256 {
     fn s(n: u32, x: u32) -> u32 {
         return ((x) >> n) | ((x) << (32 - n));
     }
     fn r(n: u32, x: u32) -> u32 {
         return (x) >> n;
     }

     fn ch(x: u32, y: u32, z: u32) -> u32 {
         return (x & y) ^ (!(x) & z);
     }

     fn maj(x: u32, y: u32, z: u32) -> u32 {
         return (x & y) ^ (x & z) ^ (y & z);
     }
     fn sig0(x: u32) -> u32 {
         return HASH256::s(2, x) ^ HASH256::s(13, x) ^ HASH256::s(22, x);
     }

     fn sig1(x: u32) -> u32 {
         return HASH256::s(6, x) ^ HASH256::s(11, x) ^ HASH256::s(25, x);
     }

     fn theta0(x: u32) -> u32 {
         return HASH256::s(7, x) ^ HASH256::s(18, x) ^ HASH256::r(3, x);
     }

     fn theta1(x: u32) -> u32 {
         return HASH256::s(17, x) ^ HASH256::s(19, x) ^ HASH256::r(10, x);
     }

     fn transform(&mut self) {
         // basic transformation step
         for j in 16..64 {
             self.w[j] = HASH256::theta1(self.w[j - 2])
                 .wrapping_add(self.w[j - 7])
                 .wrapping_add(HASH256::theta0(self.w[j - 15]))
                 .wrapping_add(self.w[j - 16]);
         }
         let mut a = self.h[0];
         let mut b = self.h[1];
         let mut c = self.h[2];
         let mut d = self.h[3];
         let mut e = self.h[4];
         let mut f = self.h[5];
         let mut g = self.h[6];
         let mut hh = self.h[7];
         for j in 0..64 {
             // 64 times - mush it up
             let t1 = hh
                 .wrapping_add(HASH256::sig1(e))
                 .wrapping_add(HASH256::ch(e, f, g))
                 .wrapping_add(HASH256_K[j])
                 .wrapping_add(self.w[j]);
             let t2 = HASH256::sig0(a).wrapping_add(HASH256::maj(a, b, c));
             hh = g;
             g = f;
             f = e;
             e = d.wrapping_add(t1);
             d = c;
             c = b;
             b = a;
             a = t1.wrapping_add(t2);
         }
         self.h[0] = self.h[0].wrapping_add(a);
         self.h[1] = self.h[1].wrapping_add(b);
         self.h[2] = self.h[2].wrapping_add(c);
         self.h[3] = self.h[3].wrapping_add(d);
         self.h[4] = self.h[4].wrapping_add(e);
         self.h[5] = self.h[5].wrapping_add(f);
         self.h[6] = self.h[6].wrapping_add(g);
         self.h[7] = self.h[7].wrapping_add(hh);
     }

     /// Initialise Hash function
     pub fn init(&mut self) {
         // initialise
         for i in 0..64 {
             self.w[i] = 0
         }
         self.length[0] = 0;
         self.length[1] = 0;
         self.h[0] = HASH256_H0;
         self.h[1] = HASH256_H1;
         self.h[2] = HASH256_H2;
         self.h[3] = HASH256_H3;
         self.h[4] = HASH256_H4;
         self.h[5] = HASH256_H5;
         self.h[6] = HASH256_H6;
         self.h[7] = HASH256_H7;
     }

     pub fn new() -> HASH256 {
         let mut nh = HASH256 {
             length: [0; 2],
             h: [0; 8],
             w: [0; 64],
         };
         nh.init();
         return nh;
     }

     /// Process a single byte
     pub fn process(&mut self, byt: u8) {
         /* process the next message byte */
         let cnt = ((self.length[0] / 32) % 16) as usize;
         self.w[cnt] <<= 8;
         self.w[cnt] |= (byt & 0xFF) as u32;
         self.length[0] += 8;
         if self.length[0] == 0 {
             self.length[1] += 1;
             self.length[0] = 0
         }
         if (self.length[0] % 512) == 0 {
             self.transform()
         }
     }

     /// Process an array of bytes
     pub fn process_array(&mut self, b: &[u8]) {
         for i in 0..b.len() {
             self.process(b[i])
         }
     }

     /// Process a 32-bit integer
     pub fn process_num(&mut self, n: i32) {
         self.process(((n >> 24) & 0xff) as u8);
         self.process(((n >> 16) & 0xff) as u8);
         self.process(((n >> 8) & 0xff) as u8);
         self.process((n & 0xff) as u8);
     }

     /// Generate 32-byte Hash
     pub fn hash(&mut self) -> [u8; HASH_BYTES] {
         // pad message and finish - supply digest
         let mut digest: [u8; 32] = [0; 32];
         let len0 = self.length[0];
         let len1 = self.length[1];
         self.process(0x80);
         while (self.length[0] % 512) != 448 {
             self.process(0)
         }
         self.w[14] = len1;
         self.w[15] = len0;
         self.transform();
         for i in 0..32 {
             // convert to bytes
             digest[i] = ((self.h[i / 4] >> (8 * (3 - i % 4))) & 0xff) as u8;
         }
         self.init();
         return digest;
     }

     /// Generate a HMAC
     ///
     /// https://tools.ietf.org/html/rfc2104
     pub fn hmac(key: &[u8], text: &[u8]) -> [u8; HASH_BYTES] {
         let mut k = key.to_vec();

         // Verify length of key < BLOCK_SIZE
         if k.len() > BLOCK_SIZE {
             // Reduce key to 32 bytes by hashing
             let mut hash256 = HASH256::new();
             hash256.init();
             hash256.process_array(&k);
             k = hash256.hash().to_vec();
         }

         // Prepare inner and outer paddings
         // inner = (ipad XOR k)
         // outer = (opad XOR k)
         let mut inner = vec![IPAD_BYTE; BLOCK_SIZE];
         let mut outer = vec![OPAD_BYTE; BLOCK_SIZE];
         for (i, byte) in k.iter().enumerate() {
             inner[i] = inner[i] ^ byte;
             outer[i] = outer[i] ^ byte;
         }

         // Concatenate inner with text = (ipad XOR k || text)
         inner.extend_from_slice(text);

         // hash inner = H(ipad XOR k || text)
         let mut hash256 = HASH256::new();
         hash256.init();
         hash256.process_array(&inner);
         let inner = hash256.hash();

         // Concatenate outer with hash of inner = (opad XOR k) || H(ipad XOR k || text)
         outer.extend_from_slice(&inner);

         // Final hash = H((opad XOR k) || H(ipad XOR k || text))
         let mut hash256 = HASH256::new();
         hash256.init();
         hash256.process_array(&outer);
         hash256.hash()
     }

     /// HKDF-Extract
     ///
     /// https://tools.ietf.org/html/rfc5869
     pub fn hkdf_extract(salt: &[u8], ikm: &[u8]) -> [u8; HASH_BYTES] {
         HASH256::hmac(salt, ikm)
     }

     /// HKDF-Extend
     ///
     /// https://tools.ietf.org/html/rfc5869
     pub fn hkdf_extend(prk: &[u8], info: &[u8], l: u8) -> Vec<u8> {
         // n = cieling(l / 32)
         let mut n = l / (HASH_BYTES as u8);
         if n * (HASH_BYTES as u8) < l {
             n += 1;
         }

         let mut okm: Vec<u8> = vec![];
         let mut previous = vec![]; // T(0) = []

         for i in 0..n as usize {
             // Concatenate (T(i) || info || i)
             let mut text: Vec<u8> = previous;
             text.extend_from_slice(info);
             text.push((i + 1) as u8); // Note: i <= 254

             // T(i+1) = HMAC(PRK, T(i) || info || i)
             previous = HASH256::hmac(prk, &text).to_vec();
             okm.extend_from_slice(&previous);
         }

         // Reduce length to size L
         okm.resize(l as usize, 0);
         okm
     }
 }

 #[cfg(test)]
 mod tests {
     use super::*;

     #[test]
     fn test_hmac_simple() {
         let text = [0x0a];
         let key = [0x0b];
         let expected =
             hex::decode("b1746117c186405d121d52866f48270fdeb2177d67f6922f0a031e0101658624")
                 .unwrap();

         let output = HASH256::hmac(&key, &text);
         assert_eq!(expected, output);
     }

     #[test]
     fn test_hmac_empty() {
         let text = [];
         let key = [];
         let expected =
             hex::decode("b613679a0814d9ec772f95d778c35fc5ff1697c493715653c6c712144292c5ad")
                 .unwrap();

         let output = HASH256::hmac(&key, &text);
         assert_eq!(expected, output);
     }

     #[test]
     fn test_hmac_32_byte_key() {
         let text = [0x0a];
         let key = hex::decode("abababababababababababababababababababababababababababababababab")
             .unwrap();
         let expected =
             hex::decode("43997a72e7b3b1c19e5566c940d5f2961c96802b58a3da2acd19dcc1a90a8d05")
                 .unwrap();

         let output = HASH256::hmac(&key, &text);
         assert_eq!(expected, output);
     }

     #[test]
     fn test_hmac_64_byte_key() {
         let text = [0x0a];
         let key = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b").unwrap();
         let expected =
             hex::decode("93a88773df742079e3512f3d10f4f8ac674e24c4eda78df46c2376dd3946750b")
                 .unwrap();

         let output = HASH256::hmac(&key, &text);
         assert_eq!(expected, output);
     }

     #[test]
     fn test_hmac_65_byte_key() {
         let text = [0x0a];
         let key = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0B").unwrap();
         let expected =
             hex::decode("7c8dd5068bcff3347dd13a7493247444635b51cf000b18f37a74a55cec3413fb")
                 .unwrap();

         let output = HASH256::hmac(&key, &text);
         assert_eq!(expected, output);
     }

     #[test]
     fn test_hmac_65_byte_text() {
         let text = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0B").unwrap();
         let key = [0x0b];
         let expected =
             hex::decode("f04344808f2fcdafe1c20272a29b1ce4be00c916a2c14700b82b81c6eae9dd96")
                 .unwrap();

         let output = HASH256::hmac(&key, &text);
         assert_eq!(expected, output);
     }

     #[test]
     fn test_hkdf_case_1() {
         // From https://tools.ietf.org/html/rfc5869
         let ikm = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b").unwrap();
         let salt = hex::decode("000102030405060708090a0b0c").unwrap();
         let expected_prk =
             hex::decode("077709362c2e32df0ddc3f0dc47bba6390b6c73bb50f9c3122ec844ad7c2b3e5")
                 .unwrap();

         let output_prk = HASH256::hkdf_extract(&salt, &ikm).to_vec();
         assert_eq!(expected_prk, output_prk);

         let info = hex::decode("f0f1f2f3f4f5f6f7f8f9").unwrap();
         let l = 42;
         let expected_okm = hex::decode(
             "3cb25f25faacd57a90434f64d0362f2a2d2d0a90cf1a5a4c5db02d56ecc4c5bf34007208d5b887185865",
         )
         .unwrap();

         let output_okm = HASH256::hkdf_extend(&expected_prk, &info, l);
         assert_eq!(expected_okm, output_okm);
     }

     #[test]
     fn test_hkdf_case_2() {
         // From https://tools.ietf.org/html/rfc5869
         let ikm = hex::decode("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f")
             .unwrap();
         let salt = hex::decode("606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeaf")
             .unwrap();
         let expected_prk =
             hex::decode("06a6b88c5853361a06104c9ceb35b45cef760014904671014a193f40c15fc244")
                 .unwrap();

         let output_prk = HASH256::hkdf_extract(&salt, &ikm).to_vec();
         assert_eq!(expected_prk, output_prk);

         let info = hex::decode("b0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff")
             .unwrap();
         let l = 82;
         let expected_okm = hex::decode("b11e398dc80327a1c8e7f78c596a49344f012eda2d4efad8a050cc4c19afa97c59045a99cac7827271cb41c65e590e09da3275600c2f09b8367793a9aca3db71cc30c58179ec3e87c14c01d5c1f3434f1d87")
             .unwrap();

         let output_okm = HASH256::hkdf_extend(&expected_prk, &info, l);
         assert_eq!(expected_okm, output_okm);
     }

     #[test]
     fn test_hkdf_case_3() {
         // From https://tools.ietf.org/html/rfc5869
         let ikm = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b").unwrap();
         let salt = vec![];
         let expected_prk =
             hex::decode("19ef24a32c717b167f33a91d6f648bdf96596776afdb6377ac434c1c293ccb04")
                 .unwrap();

         let output_prk = HASH256::hkdf_extract(&salt, &ikm).to_vec();
         assert_eq!(expected_prk, output_prk);

         let info = vec![];
         let l = 42;
         let expected_okm = hex::decode(
             "8da4e775a563c18f715f802a063c5a31b8a11f5c5ee1879ec3454e5f3c738d2d9d201395faa4b61a96c8",
         )
         .unwrap();

         let output_okm = HASH256::hkdf_extend(&expected_prk, &info, l);
         assert_eq!(expected_okm, output_okm);
     }
 }
	/*
	Licensed to the Apache Software Foundation (ASF) under one
	or more contributor license agreements. See the NOTICE file
	distributed with this work for additional information
	regarding copyright ownership. The ASF licenses this file
	to you under the Apache License, Version 2.0 (the
	"License"); you may not use this file except in compliance
	with the License. You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing,
	software distributed under the License is distributed on an
	"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	KIND, either express or implied. See the License for the
	specific language governing permissions and limitations
	under the License.
	*/

	const HASH256_H0: u32 = 0x6A09_E667;
	const HASH256_H1: u32 = 0xBB67_AE85;
	const HASH256_H2: u32 = 0x3C6E_F372;
	const HASH256_H3: u32 = 0xA54F_F53A;
	const HASH256_H4: u32 = 0x510E_527F;
	const HASH256_H5: u32 = 0x9B05_688C;
	const HASH256_H6: u32 = 0x1F83_D9AB;
	const HASH256_H7: u32 = 0x5BE0_CD19;

	const HASH256_K: [u32; 64] = [
	0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
	0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
	0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
	0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
	0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
	0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
	0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
	0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
	];

	/// The block size of each round.
	pub const BLOCK_SIZE: usize = 64;
	/// Hash Length in Bytes
	pub const HASH_BYTES: usize = 32;
	// Ipad Byte
	const IPAD_BYTE: u8 = 0x36;
	// Opad Byte
	const OPAD_BYTE: u8 = 0x5c;

	pub struct HASH256 {
	length: [u32; 2],
	h: [u32; 8],
	w: [u32; 64],
	}

	impl HASH256 {
	fn s(n: u32, x: u32) -> u32 {
	return ((x) >> n) \| ((x) << (32 - n));
	}
	fn r(n: u32, x: u32) -> u32 {
	return (x) >> n;
	}

	fn ch(x: u32, y: u32, z: u32) -> u32 {
	return (x & y) ^ (!(x) & z);
	}

	fn maj(x: u32, y: u32, z: u32) -> u32 {
	return (x & y) ^ (x & z) ^ (y & z);
	}
	fn sig0(x: u32) -> u32 {
	return HASH256::s(2, x) ^ HASH256::s(13, x) ^ HASH256::s(22, x);
	}

	fn sig1(x: u32) -> u32 {
	return HASH256::s(6, x) ^ HASH256::s(11, x) ^ HASH256::s(25, x);
	}

	fn theta0(x: u32) -> u32 {
	return HASH256::s(7, x) ^ HASH256::s(18, x) ^ HASH256::r(3, x);
	}

	fn theta1(x: u32) -> u32 {
	return HASH256::s(17, x) ^ HASH256::s(19, x) ^ HASH256::r(10, x);
	}

	fn transform(&mut self) {
	// basic transformation step
	for j in 16..64 {
	self.w[j] = HASH256::theta1(self.w[j - 2])
	.wrapping_add(self.w[j - 7])
	.wrapping_add(HASH256::theta0(self.w[j - 15]))
	.wrapping_add(self.w[j - 16]);
	}
	let mut a = self.h[0];
	let mut b = self.h[1];
	let mut c = self.h[2];
	let mut d = self.h[3];
	let mut e = self.h[4];
	let mut f = self.h[5];
	let mut g = self.h[6];
	let mut hh = self.h[7];
	for j in 0..64 {
	// 64 times - mush it up
	let t1 = hh
	.wrapping_add(HASH256::sig1(e))
	.wrapping_add(HASH256::ch(e, f, g))
	.wrapping_add(HASH256_K[j])
	.wrapping_add(self.w[j]);
	let t2 = HASH256::sig0(a).wrapping_add(HASH256::maj(a, b, c));
	hh = g;
	g = f;
	f = e;
	e = d.wrapping_add(t1);
	d = c;
	c = b;
	b = a;
	a = t1.wrapping_add(t2);
	}
	self.h[0] = self.h[0].wrapping_add(a);
	self.h[1] = self.h[1].wrapping_add(b);
	self.h[2] = self.h[2].wrapping_add(c);
	self.h[3] = self.h[3].wrapping_add(d);
	self.h[4] = self.h[4].wrapping_add(e);
	self.h[5] = self.h[5].wrapping_add(f);
	self.h[6] = self.h[6].wrapping_add(g);
	self.h[7] = self.h[7].wrapping_add(hh);
	}

	/// Initialise Hash function
	pub fn init(&mut self) {
	// initialise
	for i in 0..64 {
	self.w[i] = 0
	}
	self.length[0] = 0;
	self.length[1] = 0;
	self.h[0] = HASH256_H0;
	self.h[1] = HASH256_H1;
	self.h[2] = HASH256_H2;
	self.h[3] = HASH256_H3;
	self.h[4] = HASH256_H4;
	self.h[5] = HASH256_H5;
	self.h[6] = HASH256_H6;
	self.h[7] = HASH256_H7;
	}

	pub fn new() -> HASH256 {
	let mut nh = HASH256 {
	length: [0; 2],
	h: [0; 8],
	w: [0; 64],
	};
	nh.init();
	return nh;
	}

	/// Process a single byte
	pub fn process(&mut self, byt: u8) {
	/* process the next message byte */
	let cnt = ((self.length[0] / 32) % 16) as usize;
	self.w[cnt] <<= 8;
	self.w[cnt] \|= (byt & 0xFF) as u32;
	self.length[0] += 8;
	if self.length[0] == 0 {
	self.length[1] += 1;
	self.length[0] = 0
	}
	if (self.length[0] % 512) == 0 {
	self.transform()
	}
	}

	/// Process an array of bytes
	pub fn process_array(&mut self, b: &[u8]) {
	for i in 0..b.len() {
	self.process(b[i])
	}
	}

	/// Process a 32-bit integer
	pub fn process_num(&mut self, n: i32) {
	self.process(((n >> 24) & 0xff) as u8);
	self.process(((n >> 16) & 0xff) as u8);
	self.process(((n >> 8) & 0xff) as u8);
	self.process((n & 0xff) as u8);
	}

	/// Generate 32-byte Hash
	pub fn hash(&mut self) -> [u8; HASH_BYTES] {
	// pad message and finish - supply digest
	let mut digest: [u8; 32] = [0; 32];
	let len0 = self.length[0];
	let len1 = self.length[1];
	self.process(0x80);
	while (self.length[0] % 512) != 448 {
	self.process(0)
	}
	self.w[14] = len1;
	self.w[15] = len0;
	self.transform();
	for i in 0..32 {
	// convert to bytes
	digest[i] = ((self.h[i / 4] >> (8 * (3 - i % 4))) & 0xff) as u8;
	}
	self.init();
	return digest;
	}

	/// Generate a HMAC
	///
	/// https://tools.ietf.org/html/rfc2104
	pub fn hmac(key: &[u8], text: &[u8]) -> [u8; HASH_BYTES] {
	let mut k = key.to_vec();

	// Verify length of key < BLOCK_SIZE
	if k.len() > BLOCK_SIZE {
	// Reduce key to 32 bytes by hashing
	let mut hash256 = HASH256::new();
	hash256.init();
	hash256.process_array(&k);
	k = hash256.hash().to_vec();
	}

	// Prepare inner and outer paddings
	// inner = (ipad XOR k)
	// outer = (opad XOR k)
	let mut inner = vec![IPAD_BYTE; BLOCK_SIZE];
	let mut outer = vec![OPAD_BYTE; BLOCK_SIZE];
	for (i, byte) in k.iter().enumerate() {
	inner[i] = inner[i] ^ byte;
	outer[i] = outer[i] ^ byte;
	}

	// Concatenate inner with text = (ipad XOR k \|\| text)
	inner.extend_from_slice(text);

	// hash inner = H(ipad XOR k \|\| text)
	let mut hash256 = HASH256::new();
	hash256.init();
	hash256.process_array(&inner);
	let inner = hash256.hash();

	// Concatenate outer with hash of inner = (opad XOR k) \|\| H(ipad XOR k \|\| text)
	outer.extend_from_slice(&inner);

	// Final hash = H((opad XOR k) \|\| H(ipad XOR k \|\| text))
	let mut hash256 = HASH256::new();
	hash256.init();
	hash256.process_array(&outer);
	hash256.hash()
	}

	/// HKDF-Extract
	///
	/// https://tools.ietf.org/html/rfc5869
	pub fn hkdf_extract(salt: &[u8], ikm: &[u8]) -> [u8; HASH_BYTES] {
	HASH256::hmac(salt, ikm)
	}

	/// HKDF-Extend
	///
	/// https://tools.ietf.org/html/rfc5869
	pub fn hkdf_extend(prk: &[u8], info: &[u8], l: u8) -> Vec<u8> {
	// n = cieling(l / 32)
	let mut n = l / (HASH_BYTES as u8);
	if n * (HASH_BYTES as u8) < l {
	n += 1;
	}

	let mut okm: Vec<u8> = vec![];
	let mut previous = vec![]; // T(0) = []

	for i in 0..n as usize {
	// Concatenate (T(i) \|\| info \|\| i)
	let mut text: Vec<u8> = previous;
	text.extend_from_slice(info);
	text.push((i + 1) as u8); // Note: i <= 254

	// T(i+1) = HMAC(PRK, T(i) \|\| info \|\| i)
	previous = HASH256::hmac(prk, &text).to_vec();
	okm.extend_from_slice(&previous);
	}

	// Reduce length to size L
	okm.resize(l as usize, 0);
	okm
	}
	}

	#[cfg(test)]
	mod tests {
	use super::*;

	#[test]
	fn test_hmac_simple() {
	let text = [0x0a];
	let key = [0x0b];
	let expected =
	hex::decode("b1746117c186405d121d52866f48270fdeb2177d67f6922f0a031e0101658624")
	.unwrap();

	let output = HASH256::hmac(&key, &text);
	assert_eq!(expected, output);
	}

	#[test]
	fn test_hmac_empty() {
	let text = [];
	let key = [];
	let expected =
	hex::decode("b613679a0814d9ec772f95d778c35fc5ff1697c493715653c6c712144292c5ad")
	.unwrap();

	let output = HASH256::hmac(&key, &text);
	assert_eq!(expected, output);
	}

	#[test]
	fn test_hmac_32_byte_key() {
	let text = [0x0a];
	let key = hex::decode("abababababababababababababababababababababababababababababababab")
	.unwrap();
	let expected =
	hex::decode("43997a72e7b3b1c19e5566c940d5f2961c96802b58a3da2acd19dcc1a90a8d05")
	.unwrap();

	let output = HASH256::hmac(&key, &text);
	assert_eq!(expected, output);
	}

	#[test]
	fn test_hmac_64_byte_key() {
	let text = [0x0a];
	let key = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b").unwrap();
	let expected =
	hex::decode("93a88773df742079e3512f3d10f4f8ac674e24c4eda78df46c2376dd3946750b")
	.unwrap();

	let output = HASH256::hmac(&key, &text);
	assert_eq!(expected, output);
	}

	#[test]
	fn test_hmac_65_byte_key() {
	let text = [0x0a];
	let key = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0B").unwrap();
	let expected =
	hex::decode("7c8dd5068bcff3347dd13a7493247444635b51cf000b18f37a74a55cec3413fb")
	.unwrap();

	let output = HASH256::hmac(&key, &text);
	assert_eq!(expected, output);
	}

	#[test]
	fn test_hmac_65_byte_text() {
	let text = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0B").unwrap();
	let key = [0x0b];
	let expected =
	hex::decode("f04344808f2fcdafe1c20272a29b1ce4be00c916a2c14700b82b81c6eae9dd96")
	.unwrap();

	let output = HASH256::hmac(&key, &text);
	assert_eq!(expected, output);
	}

	#[test]
	fn test_hkdf_case_1() {
	// From https://tools.ietf.org/html/rfc5869
	let ikm = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b").unwrap();
	let salt = hex::decode("000102030405060708090a0b0c").unwrap();
	let expected_prk =
	hex::decode("077709362c2e32df0ddc3f0dc47bba6390b6c73bb50f9c3122ec844ad7c2b3e5")
	.unwrap();

	let output_prk = HASH256::hkdf_extract(&salt, &ikm).to_vec();
	assert_eq!(expected_prk, output_prk);

	let info = hex::decode("f0f1f2f3f4f5f6f7f8f9").unwrap();
	let l = 42;
	let expected_okm = hex::decode(
	"3cb25f25faacd57a90434f64d0362f2a2d2d0a90cf1a5a4c5db02d56ecc4c5bf34007208d5b887185865",
	)
	.unwrap();

	let output_okm = HASH256::hkdf_extend(&expected_prk, &info, l);
	assert_eq!(expected_okm, output_okm);
	}

	#[test]
	fn test_hkdf_case_2() {
	// From https://tools.ietf.org/html/rfc5869
	let ikm = hex::decode("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f")
	.unwrap();
	let salt = hex::decode("606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeaf")
	.unwrap();
	let expected_prk =
	hex::decode("06a6b88c5853361a06104c9ceb35b45cef760014904671014a193f40c15fc244")
	.unwrap();

	let output_prk = HASH256::hkdf_extract(&salt, &ikm).to_vec();
	assert_eq!(expected_prk, output_prk);

	let info = hex::decode("b0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff")
	.unwrap();
	let l = 82;
	let expected_okm = hex::decode("b11e398dc80327a1c8e7f78c596a49344f012eda2d4efad8a050cc4c19afa97c59045a99cac7827271cb41c65e590e09da3275600c2f09b8367793a9aca3db71cc30c58179ec3e87c14c01d5c1f3434f1d87")
	.unwrap();

	let output_okm = HASH256::hkdf_extend(&expected_prk, &info, l);
	assert_eq!(expected_okm, output_okm);
	}

	#[test]
	fn test_hkdf_case_3() {
	// From https://tools.ietf.org/html/rfc5869
	let ikm = hex::decode("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b").unwrap();
	let salt = vec![];
	let expected_prk =
	hex::decode("19ef24a32c717b167f33a91d6f648bdf96596776afdb6377ac434c1c293ccb04")
	.unwrap();

	let output_prk = HASH256::hkdf_extract(&salt, &ikm).to_vec();
	assert_eq!(expected_prk, output_prk);

	let info = vec![];
	let l = 42;
	let expected_okm = hex::decode(
	"8da4e775a563c18f715f802a063c5a31b8a11f5c5ee1879ec3454e5f3c738d2d9d201395faa4b61a96c8",
	)
	.unwrap();

	let output_okm = HASH256::hkdf_extend(&expected_prk, &info, l);
	assert_eq!(expected_okm, output_okm);
	}
	}