From eadd6510088f87b012361bfc80332cafd5af7615 Mon Sep 17 00:00:00 2001 From: siddharth Date: Sat, 5 Mar 2022 16:20:14 -0500 Subject: lib: add sha256 implementation --- lib/sha256.go | 192 +++++++++++++++++++++++++++++++++++++++++++++++++++++ lib/sha256_test.go | 31 +++++++++ 2 files changed, 223 insertions(+) create mode 100644 lib/sha256.go create mode 100644 lib/sha256_test.go diff --git a/lib/sha256.go b/lib/sha256.go new file mode 100644 index 0000000..da6dd7c --- /dev/null +++ b/lib/sha256.go @@ -0,0 +1,192 @@ +// Copyright © 2022 siddharth +// SPDX-License-Identifier: ISC + +package lib + +// SHA-256 implementation. +// Reference https://csrc.nist.gov/publications/detail/fips/180/4/final + +type Sha256 struct { + hvs []uint32 + Msg []byte + MsgLen int +} + +// SHA-256 Constants +var sha256K []uint32 = []uint32{ + 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, +} + +// SHA-256 initial hash values. +var sha256HashValues []uint32 = []uint32{ + 0x6a09e667, + 0xbb67ae85, + 0x3c6ef372, + 0xa54ff53a, + 0x510e527f, + 0x9b05688c, + 0x1f83d9ab, + 0x5be0cd19, +} + +// Ch(x,y,z) function. +func sha256FCh(x, y, z uint32) uint32 { + return (x & y) ^ (^x & z) +} + +// Maj(x,y,z) function. +func sha256FMaj(x, y, z uint32) uint32 { + return (x & y) ^ (x & z) ^ (y & z) +} + +// Σ0(x) function. +func sha256FΣ0(x uint32) uint32 { + return shaRotr(x, 2) ^ shaRotr(x, 13) ^ shaRotr(x, 22) +} + +// Σ1(x) function. +func sha256FΣ1(x uint32) uint32 { + return shaRotr(x, 6) ^ shaRotr(x, 11) ^ shaRotr(x, 25) +} + +// σ0(x) function. +func sha256Fσ0(x uint32) uint32 { + return shaRotr(x, 7) ^ shaRotr(x, 18) ^ shaShr(x, 3) +} + +// σ1(x) function. +func sha256Fσ1(x uint32) uint32 { + return shaRotr(x, 17) ^ shaRotr(x, 19) ^ shaShr(x, 10) +} + +// Returns the message schedule W_t for a message block `mb` +// The message schedule has 64 32-bit words. +func sha256MessageSchedule(mb []uint32) []uint32 { + // Message schedule. + w := make([]uint32, 0) + + // Generate message schedule. + for t := 0; t < 64; t++ { + if t <= 15 { + w = append(w, mb[t]) + } else { + w = append(w, shaAdd( + sha256Fσ1(w[t-2]), + w[t-7], + sha256Fσ0(w[t-15]), + w[t-16], + )) + } + } + return w +} + +func (s *Sha256) Init(hvs []uint32) { + // Set initial hash values. + h := make([]uint32, 8) + if len(hvs) == 8 { + copy(h, hvs) + s.hvs = h + } else { + copy(h, sha256HashValues) + s.hvs = h + } +} + +func (s *Sha256) Message(m []byte) { + s.Msg = m + s.MsgLen = len(m) +} + +// SHA-256 - Pad message such that its length is a multiple of 512. +func (s *Sha256) Pad() []byte { + // Initialize padded message. + pm := make([]byte, len(s.Msg)) + copy(pm, s.Msg) + + // Add padding. + pm = append(pm, MDPadding(s.MsgLen)...) + + return pm +} + +func (s *Sha256) Hash() []byte { + // Pad message. + pm := s.Pad() + + // Break int message blocks. + mbs := shaMessageBlocks(pm) + + // Initialize hash values. + hvs := make([]uint32, 8) + copy(hvs, s.hvs) // Initial hash values. + + // Process each message block. + for _, mb := range mbs { + // Get message schedule. + w := sha256MessageSchedule(mb) + + // Initialize working variables. + a := hvs[0] + b := hvs[1] + c := hvs[2] + d := hvs[3] + e := hvs[4] + f := hvs[5] + g := hvs[6] + h := hvs[7] + + for t := 0; t <= 63; t++ { + t1 := shaAdd( + h, + sha256FΣ1(e), + sha256FCh(e, f, g), + sha256K[t], + w[t], + ) + t2 := shaAdd(sha256FΣ0(a), sha256FMaj(a, b, c)) + h = g + g = f + f = e + e = shaAdd(d, t1) + d = c + c = b + b = a + a = shaAdd(t1, t2) + } + + // Compute intermediate hash values. + hvs[0] = shaAdd(a, hvs[0]) + hvs[1] = shaAdd(b, hvs[1]) + hvs[2] = shaAdd(c, hvs[2]) + hvs[3] = shaAdd(d, hvs[3]) + hvs[4] = shaAdd(e, hvs[4]) + hvs[5] = shaAdd(f, hvs[5]) + hvs[6] = shaAdd(g, hvs[6]) + hvs[7] = shaAdd(h, hvs[7]) + } + + // Slurp sha256 digest from hash values. + d := make([]byte, 0) // sha256 digest + for i := 0; i < 8; i++ { + // Break 32-bit hash value into 4 bytes. + hb := make([]byte, 4) + for j := 3; j >= 0; j-- { + // Get last 8 bits. + hb[j] = byte(hvs[i] & 0xFF) + + // Get rid of last 8 bits. + hvs[i] = hvs[i] >> 8 + } + d = append(d, hb...) + } + + return d +} diff --git a/lib/sha256_test.go b/lib/sha256_test.go new file mode 100644 index 0000000..ca429fd --- /dev/null +++ b/lib/sha256_test.go @@ -0,0 +1,31 @@ +// Copyright © 2022 siddharth +// SPDX-License-Identifier: ISC + +package lib + +import "testing" + +// Tests from +// https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Standards-and-Guidelines/documents/examples/SHA256.pdf +func TestSha256Hash(t *testing.T) { + sha256 := Sha256{} + sha256.Init([]uint32{}) + + // Test 1 + m := "abc" + sha256.Message(StrToBytes(m)) + h := sha256.Hash() + e := "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad" + if BytesToHexStr(h) != e { + t.Errorf("sha256 test 1 failed: %x != %s\n", h, e) + } + + // Test 2 + m = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq" + sha256.Message(StrToBytes(m)) + h = sha256.Hash() + e = "248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1" + if BytesToHexStr(h) != e { + t.Errorf("sha256 test 1 failed: %x != %s\n", h, e) + } +} -- cgit v1.2.3