| freeqsay: Nim port of the Clojure implementation fa53aa2 nandi 6h ago | 1 | ## Pure-Nim SHA-256, HMAC-SHA256 and HKDF-SHA256. |
| 2 | ## |
| 3 | ## No dependencies: the avatar seed has to be derivable anywhere the port runs, |
| 4 | ## including builds with no OpenSSL to bind against. |
| 5 | |
| 6 | import std/strutils |
| 7 | |
| 8 | type Sha256Digest* = array[32, byte] |
| 9 | |
| 10 | const K: array[64, uint32] = [ |
| 11 | 0x428a2f98'u32, 0x71374491'u32, 0xb5c0fbcf'u32, 0xe9b5dba5'u32, |
| 12 | 0x3956c25b'u32, 0x59f111f1'u32, 0x923f82a4'u32, 0xab1c5ed5'u32, |
| 13 | 0xd807aa98'u32, 0x12835b01'u32, 0x243185be'u32, 0x550c7dc3'u32, |
| 14 | 0x72be5d74'u32, 0x80deb1fe'u32, 0x9bdc06a7'u32, 0xc19bf174'u32, |
| 15 | 0xe49b69c1'u32, 0xefbe4786'u32, 0x0fc19dc6'u32, 0x240ca1cc'u32, |
| 16 | 0x2de92c6f'u32, 0x4a7484aa'u32, 0x5cb0a9dc'u32, 0x76f988da'u32, |
| 17 | 0x983e5152'u32, 0xa831c66d'u32, 0xb00327c8'u32, 0xbf597fc7'u32, |
| 18 | 0xc6e00bf3'u32, 0xd5a79147'u32, 0x06ca6351'u32, 0x14292967'u32, |
| 19 | 0x27b70a85'u32, 0x2e1b2138'u32, 0x4d2c6dfc'u32, 0x53380d13'u32, |
| 20 | 0x650a7354'u32, 0x766a0abb'u32, 0x81c2c92e'u32, 0x92722c85'u32, |
| 21 | 0xa2bfe8a1'u32, 0xa81a664b'u32, 0xc24b8b70'u32, 0xc76c51a3'u32, |
| 22 | 0xd192e819'u32, 0xd6990624'u32, 0xf40e3585'u32, 0x106aa070'u32, |
| 23 | 0x19a4c116'u32, 0x1e376c08'u32, 0x2748774c'u32, 0x34b0bcb5'u32, |
| 24 | 0x391c0cb3'u32, 0x4ed8aa4a'u32, 0x5b9cca4f'u32, 0x682e6ff3'u32, |
| 25 | 0x748f82ee'u32, 0x78a5636f'u32, 0x84c87814'u32, 0x8cc70208'u32, |
| 26 | 0x90befffa'u32, 0xa4506ceb'u32, 0xbef9a3f7'u32, 0xc67178f2'u32] |
| 27 | |
| 28 | const H0: array[8, uint32] = [ |
| 29 | 0x6a09e667'u32, 0xbb67ae85'u32, 0x3c6ef372'u32, 0xa54ff53a'u32, |
| 30 | 0x510e527f'u32, 0x9b05688c'u32, 0x1f83d9ab'u32, 0x5be0cd19'u32] |
| 31 | |
| 32 | func rotr(x: uint32, n: int): uint32 {.inline.} = |
| 33 | (x shr n) or (x shl (32 - n)) |
| 34 | |
| 35 | func toBytes*(s: string): seq[byte] = |
| 36 | ## UTF-8 bytes of a string. |
| 37 | result = newSeq[byte](s.len) |
| 38 | for i, c in s: |
| 39 | result[i] = byte(c) |
| 40 | |
| 41 | func digest*(input: openArray[byte]): Sha256Digest = |
| 42 | let |
| 43 | n = input.len |
| 44 | bitlen = uint64(n) * 8 |
| 45 | blocks = (n + 9 + 63) div 64 |
| 46 | var padded = newSeq[byte](blocks * 64) |
| 47 | for i, b in input: |
| 48 | padded[i] = b |
| 49 | padded[n] = 0x80 |
| 50 | for i in 0 ..< 8: |
| 51 | padded[padded.len - 1 - i] = byte((bitlen shr (8 * i)) and 0xff) |
| 52 | |
| 53 | var h = H0 |
| 54 | var w: array[64, uint32] |
| 55 | for blk in 0 ..< blocks: |
| 56 | let off = blk * 64 |
| 57 | for i in 0 ..< 16: |
| 58 | w[i] = (uint32(padded[off + i*4]) shl 24) or |
| 59 | (uint32(padded[off + i*4 + 1]) shl 16) or |
| 60 | (uint32(padded[off + i*4 + 2]) shl 8) or |
| 61 | uint32(padded[off + i*4 + 3]) |
| 62 | for i in 16 ..< 64: |
| 63 | let |
| 64 | w15 = w[i - 15] |
| 65 | w2 = w[i - 2] |
| 66 | s0 = rotr(w15, 7) xor rotr(w15, 18) xor (w15 shr 3) |
| 67 | s1 = rotr(w2, 17) xor rotr(w2, 19) xor (w2 shr 10) |
| 68 | w[i] = w[i - 16] + s0 + w[i - 7] + s1 |
| 69 | |
| 70 | var (a, b, c, d, e, f, g, hh) = (h[0], h[1], h[2], h[3], h[4], h[5], h[6], h[7]) |
| 71 | for i in 0 ..< 64: |
| 72 | let |
| 73 | s1 = rotr(e, 6) xor rotr(e, 11) xor rotr(e, 25) |
| 74 | ch = (e and f) xor ((not e) and g) |
| 75 | t1 = hh + s1 + ch + K[i] + w[i] |
| 76 | s0 = rotr(a, 2) xor rotr(a, 13) xor rotr(a, 22) |
| 77 | maj = (a and b) xor (a and c) xor (b and c) |
| 78 | t2 = s0 + maj |
| 79 | hh = g; g = f; f = e; e = d + t1 |
| 80 | d = c; c = b; b = a; a = t1 + t2 |
| 81 | |
| 82 | for i, v in [a, b, c, d, e, f, g, hh]: |
| 83 | h[i] = h[i] + v |
| 84 | |
| 85 | for i, v in h: |
| 86 | result[i*4] = byte((v shr 24) and 0xff) |
| 87 | result[i*4 + 1] = byte((v shr 16) and 0xff) |
| 88 | result[i*4 + 2] = byte((v shr 8) and 0xff) |
| 89 | result[i*4 + 3] = byte(v and 0xff) |
| 90 | |
| 91 | func digest*(s: string): Sha256Digest = digest(toBytes(s)) |
| 92 | |
| 93 | func hmac*(key, msg: openArray[byte]): Sha256Digest = |
| 94 | ## HMAC-SHA256. |
| 95 | var k = @key |
| 96 | if k.len > 64: |
| 97 | k = @(digest(k)) |
| 98 | var ipad, opad = newSeq[byte](64) |
| 99 | for i in 0 ..< 64: |
| 100 | let kb = if i < k.len: k[i] else: 0'u8 |
| 101 | ipad[i] = kb xor 0x36 |
| 102 | opad[i] = kb xor 0x5c |
| 103 | let inner = digest(ipad & @msg) |
| 104 | digest(opad & @inner) |
| 105 | |
| 106 | func hmac*(key, msg: string): Sha256Digest = hmac(toBytes(key), toBytes(msg)) |
| 107 | |
| 108 | func hkdf*(ikm, salt, info: openArray[byte], length = 32): seq[byte] = |
| 109 | ## HKDF-SHA256 (extract + expand). One expand block, so `length` <= 32. |
| 110 | doAssert length <= 32, "hkdf: only one expand block is implemented" |
| 111 | let prk = hmac(salt, ikm) |
| 112 | let t1 = hmac(prk, @info & @[1'u8]) |
| 113 | result = @(t1) |
| 114 | result.setLen(length) |
| 115 | |
| 116 | func hkdf*(ikm, salt, info: string, length = 32): seq[byte] = |
| 117 | hkdf(toBytes(ikm), toBytes(salt), toBytes(info), length) |
| 118 | |
| 119 | func toHex*(bs: openArray[byte]): string = |
| 120 | ## Lowercase hex. |
| 121 | result = newStringOfCap(bs.len * 2) |
| 122 | for b in bs: |
| 123 | result.add toHex(int(b), 2).toLowerAscii |