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Masui Masanori
Masui Masanori

Posted on

[Go] Try SHA-512 implementation

#go

Intro

I want to try authentications in Go.

Because I have tried in ASP.NET Core Identity before, I read its source code.

I thought I should know about password hashing first.
According to the "PasswordHasher.cs", it use HMAC-SHA512 by default.

So this time I decided to learn about SHA-512.

Although Go has sha512 package, but I will try implementing it by myself.

Examples

main.go

package main

import (
    "crypto/sha512"
    "log"
)

func main() {
    result := Hash("hello")
    result2 := sha512.Sum512([]byte("hello"))

    log.Println(result)
    log.Printf("%x", result2)
}
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sha512Hasher.go

package main

import (
    "fmt"
)

const (
    messageBlockSize = 128
)
/* eighty constant 64-bit words, K0, K1, ... K79 */
var K = []uint64{
    0x428a2f98d728ae22, 0x7137449123ef65cd, 0xb5c0fbcfec4d3b2f, 0xe9b5dba58189dbbc,
    0x3956c25bf348b538, 0x59f111f1b605d019, 0x923f82a4af194f9b, 0xab1c5ed5da6d8118,
    0xd807aa98a3030242, 0x12835b0145706fbe, 0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2,
    0x72be5d74f27b896f, 0x80deb1fe3b1696b1, 0x9bdc06a725c71235, 0xc19bf174cf692694,
    0xe49b69c19ef14ad2, 0xefbe4786384f25e3, 0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65,
    0x2de92c6f592b0275, 0x4a7484aa6ea6e483, 0x5cb0a9dcbd41fbd4, 0x76f988da831153b5,
    0x983e5152ee66dfab, 0xa831c66d2db43210, 0xb00327c898fb213f, 0xbf597fc7beef0ee4,
    0xc6e00bf33da88fc2, 0xd5a79147930aa725, 0x06ca6351e003826f, 0x142929670a0e6e70,
    0x27b70a8546d22ffc, 0x2e1b21385c26c926, 0x4d2c6dfc5ac42aed, 0x53380d139d95b3df,
    0x650a73548baf63de, 0x766a0abb3c77b2a8, 0x81c2c92e47edaee6, 0x92722c851482353b,
    0xa2bfe8a14cf10364, 0xa81a664bbc423001, 0xc24b8b70d0f89791, 0xc76c51a30654be30,
    0xd192e819d6ef5218, 0xd69906245565a910, 0xf40e35855771202a, 0x106aa07032bbd1b8,
    0x19a4c116b8d2d0c8, 0x1e376c085141ab53, 0x2748774cdf8eeb99, 0x34b0bcb5e19b48a8,
    0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb, 0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3,
    0x748f82ee5defb2fc, 0x78a5636f43172f60, 0x84c87814a1f0ab72, 0x8cc702081a6439ec,
    0x90befffa23631e28, 0xa4506cebde82bde9, 0xbef9a3f7b2c67915, 0xc67178f2e372532b,
    0xca273eceea26619c, 0xd186b8c721c0c207, 0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178,
    0x06f067aa72176fba, 0x0a637dc5a2c898a6, 0x113f9804bef90dae, 0x1b710b35131c471b,
    0x28db77f523047d84, 0x32caab7b40c72493, 0x3c9ebe0a15c9bebc, 0x431d67c49c100d4c,
    0x4cc5d4becb3e42b6, 0x597f299cfc657e2a, 0x5fcb6fab3ad6faec, 0x6c44198c4a475817,
}

func Hash(original string) string {
    inputValues := []byte(original)
    formattedMessage := formatInput(inputValues)
    computed := compute(formattedMessage)
    return computed
}

func formatInput(values []byte) []byte {
    // Calculate as binary 8-digit numbers
    L := len(values) * 8
    mod := len(values) % messageBlockSize
    padcount := messageBlockSize - mod
    /* 896 < L < 1024 */
    if mod > messageBlockSize-8 {
        padcount += messageBlockSize
    }
    results := make([]byte, len(values)+padcount)
    copy(results, values)
    // add 10000000
    results[len(values)] = 128
    // set L into the end of the message
    for i := 1; i <= 8; i++ {
        results[len(results)-i] = byte(L)
        L = L >> 8
    }
    return results
}
/*
* For t = 0 to 15
*     Wt = M(i)t
*/
func initFirst16Words(words []byte) []uint64 {
    W := make([]uint64, 16)
    for t := 0; t < 16; t++ {
        t8 := t * 8
        W[t] = uint64(words[t8])<<56 |
            uint64(words[t8+1])<<48 |
            uint64(words[t8+2])<<40 |
            uint64(words[t8+3])<<32 |
            uint64(words[t8+4])<<24 |
            uint64(words[t8+5])<<16 |
            uint64(words[t8+6])<<8 |
            uint64(words[t8+7])
    }
    return W
}

func generateMessageBlock(words []byte) [][]byte {
    var M [][]byte
    for i := 0; i < len(words); i += messageBlockSize {
        M = append(M, words[i:i+messageBlockSize])
    }
    return M
}

/* SHR^n(x) = x>>n */
func SHR(bits, word uint64) uint64 {
    return word >> bits
}

/* ROTR^n(x) = (x>>n) OR (x<<(w-n)) */
func ROTR(bits, word uint64) uint64 {
    return (word >> bits) | (word << (64 - bits))
}

/* CH( x, y, z) = (x AND y) XOR ( (NOT x) AND z) */
func CH(x, y, z uint64) uint64 {
    return (x & y) ^ ((^x) & z)
}

/* MAJ( x, y, z) = (x AND y) XOR (x AND z) XOR (y AND z) */
func MAJ(x, y, z uint64) uint64 {
    return (x & y) ^ (x & z) ^ (y & z)
}

/* BSIG0(x) = ROTR^28(x) XOR ROTR^34(x) XOR ROTR^39(x) */
func BSIG0(x uint64) uint64 {
    return ROTR(28, x) ^ ROTR(34, x) ^ ROTR(39, x)
}

/* BSIG1(x) = ROTR^14(x) XOR ROTR^18(x) XOR ROTR^41(x) */
func BSIG1(x uint64) uint64 {
    return ROTR(14, x) ^ ROTR(18, x) ^ ROTR(41, x)
}

/* SSIG0(x) = ROTR^1(x) XOR ROTR^8(x) XOR SHR^7(x) */
func SSIG0(x uint64) uint64 {
    return ROTR(1, x) ^ ROTR(8, x) ^ SHR(7, x)
}

/* SSIG1(x) = ROTR^19(x) XOR ROTR^61(x) XOR SHR^6(x) */
func SSIG1(x uint64) uint64 {
    return ROTR(19, x) ^ ROTR(61, x) ^ SHR(6, x)
}
func compute(messages []byte) string {
    /* initial H(0) hash values */
    H := [8]uint64{
        0x6a09e667f3bcc908,
        0xbb67ae8584caa73b,
        0x3c6ef372fe94f82b,
        0xa54ff53a5f1d36f1,
        0x510e527fade682d1,
        0x9b05688c2b3e6c1f,
        0x1f83d9abfb41bd6b,
        0x5be0cd19137e2179,
    }

    for _, block := range generateMessageBlock(messages) {
        // init W[0]~W[15]
        words := initFirst16Words(block)
        for t := 16; t <= 79; t++ {
            words = append(words, SSIG1(words[t-2])+words[t-7]+SSIG0(words[t-15])+words[t-16])
        }
        a := H[0]
        b := H[1]
        c := H[2]
        d := H[3]
        e := H[4]
        f := H[5]
        g := H[6]
        h := H[7]

        for t, w := range words {
            T1 := h + BSIG1(e) + CH(e, f, g) + K[t] + w
            T2 := BSIG0(a) + MAJ(a, b, c)
            h = g
            g = f
            f = e
            e = d + T1
            d = c
            c = b
            b = a
            a = T1 + T2
        }

        H[0] = a + H[0]
        H[1] = b + H[1]
        H[2] = c + H[2]
        H[3] = d + H[3]
        H[4] = e + H[4]
        H[5] = f + H[5]
        H[6] = g + H[6]
        H[7] = h + H[7]
    }
    // get H[N]
    result := ""
    for _, h := range H {
        // Fill with 0s and align to 16 digits
        result += fmt.Sprintf("%016x", h)
    }
    return result
}
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0 padding

To get final result, I wrote like below.

...
    // get H[N]
    result := ""
    for _, h := range H {
        result += fmt.Sprintf("%x", h)
    }
    return result
}
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But it wasn't as same as the result of crypto/sha512.

// the result of my code
9b71d224bd62f3785d96d46ad3ea3d73319bfbc2890caadae2dff72519673ca72323c3d99ba5c11d7c7acc6e14b8c5dac4663475c2e5c3adef46f73bcdec043

// the result of crypto/sha512
9b71d224bd62f3785d96d46ad3ea3d73319bfbc2890caadae2dff72519673ca72323c3d99ba5c11d7c7acc6e14b8c5da0c4663475c2e5c3adef46f73bcdec043
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Because one of the H[N] started from "0" and it was omitted.

9b71d224bd62f378
5d96d46ad3ea3d73
319bfbc2890caada
e2dff72519673ca7
2323c3d99ba5c11d
7c7acc6e14b8c5da
c4663475c2e5c3a
def46f73bcdec043
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So I fill with 0s like below.

...
    // get H[N]
    result := ""
    for _, h := range H {
        log.Printf("%x", h)
        // Fill with 0s and align to 16 digits
        result += fmt.Sprintf("%016x", h)
    }
    return result
}
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Resources

Discussion (2)

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jonasbn profile image
jonasbn

Absolutely marvellous post. I will spend some time reading though your code - thank you for making the effort.

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masanori_msl profile image
Masui Masanori Author

Thank you for reading my post.
I wish it will help you :)