Remove Go code in favor of upstream libscrypt-kdf

Adapt build to handle cgo shenanigans.

1 files changed, 55 insertions, 302 deletions

diff --git a/src/scrypt.go b/src/scrypt.go
index fe6cb8d..a4f03d2 100644
--- a/src/scrypt.go
+++ b/src/scrypt.go
@@ -1,28 +1,30 @@
 package scrypt
 
 import (
-	"crypto/hmac"
 	"crypto/rand"
-	"crypto/sha256"
-	"encoding/binary"
 	"encoding/hex"
 	"errors"
 	"fmt"
-	"hash"
 	"io"
-	"math/bits"
 	"os"
 	"slices"
 )
 
 
 
+/*
+#define _XOPEN_SOURCE 700
+#include <stdlib.h>
+#include <scrypt-kdf.h>
+*/
+import "C"
+
+
+
 const (
-	saltMinLength = 32
-	desiredLength = 32
-	maxInt                = int((^uint(0)) >> 1)
 	MinimumPasswordLength = 16
-
+	_SALT_MIN_LENGTH = 32
+	_DESIRED_LENGTH = 32
 	_N = 1 << 15
 	r  = 8
 	p  = 1
@@ -30,274 +32,12 @@ const (
 
 
 var (
-	ErrBadN           = errors.New("scrypt: N must be > 1 and a power of 2")
-	ErrParamsTooLarge = errors.New("scrypt: parameters are too large")
-	ErrSaltTooSmall   = errors.New("scrypt: salt is too small")
+	ErrSaltTooSmall = errors.New("scrypt: salt is too small")
+	ErrInternal     = errors.New("scrypt: internal error")
 )
 
 
 
-// Package pbkdf2 implements the key derivation function PBKDF2 as defined in
-// RFC 2898 / PKCS #5 v2.0.
-//
-// A key derivation function is useful when encrypting data based on a password
-// or any other not-fully-random data. It uses a pseudorandom function to derive
-// a secure encryption key based on the password.
-//
-// While v2.0 of the standard defines only one pseudorandom function to use,
-// HMAC-SHA1, the drafted v2.1 specification allows use of all five FIPS
-// Approved Hash Functions SHA-1, SHA-224, SHA-256, SHA-384 and SHA-512 for
-// HMAC. To choose, you can pass the `New` functions from the different SHA
-// packages to pbkdf2.Key.
-//
-//
-// Key derives a key from the password, salt and iteration count, returning a
-// []byte of length keylen that can be used as cryptographic key. The key is
-// derived based on the method described as PBKDF2 with the HMAC variant using
-// the supplied hash function.
-//
-// For example, to use a HMAC-SHA-1 based PBKDF2 key derivation function, you
-// can get a derived key for e.g. AES-256 (which needs a 32-byte key) by
-// doing:
-//
-//	dk := pbkdf2.Key([]byte("some password"), salt, 4096, 32, sha1.New)
-//
-// Remember to get a good random salt. At least 8 bytes is recommended by the
-// RFC.
-//
-// Using a higher iteration count will increase the cost of an exhaustive
-// search but will also make derivation proportionally slower.
-func _PBKDF2Key(
-	password []byte,
-	salt []byte,
-	iter int,
-	keyLen int,
-	h func() hash.Hash,
-) []byte {
-	prf := hmac.New(h, password)
-	hashLen := prf.Size()
-	numBlocks := (keyLen + hashLen - 1) / hashLen
-
-	var buffer [4]byte
-	dk := make([]byte, 0, numBlocks*hashLen)
-	U := make([]byte, hashLen)
-	for block := 1; block <= numBlocks; block++ {
-		// N.B.: || means concatenation, ^ means XOR
-		// for each block T_i = U_1 ^ U_2 ^ ... ^ U_iter
-		// U_1 = PRF(password, salt || uint(i))
-		prf.Reset()
-		prf.Write(salt)
-		buffer[0] = byte(block >> 24)
-		buffer[1] = byte(block >> 16)
-		buffer[2] = byte(block >> 8)
-		buffer[3] = byte(block >> 0)
-		prf.Write(buffer[:4])
-		dk = prf.Sum(dk)
-		T := dk[len(dk) - hashLen:]
-		copy(U, T)
-
-		// U_n = PRF(password, U_(n - 1))
-		for n := 2; n <= iter; n++ {
-			prf.Reset()
-			prf.Write(U)
-			U = U[:0]
-			U = prf.Sum(U)
-			for x := range U {
-				T[x] ^= U[x]
-			}
-		}
-	}
-	return dk[:keyLen]
-}
-
-// blockCopy copies n numbers from src into dst.
-func blockCopy(dst []uint32, src []uint32, n int) {
-	copy(dst, src[:n])
-}
-
-// blockXOR XORs numbers from dst with n numbers from src.
-func blockXOR(dst []uint32, src []uint32, n int) {
-	for i, v := range src[:n] {
-		dst[i] ^= v
-	}
-}
-
-// salsaXOR applies Salsa20/8 to the XOR of 16 numbers from tmp and in,
-// and puts the result into both tmp and out.
-func salsaXOR(tmp *[16]uint32, in []uint32, out []uint32) {
-	w0  := tmp[0]  ^ in[0]
-	w1  := tmp[1]  ^ in[1]
-	w2  := tmp[2]  ^ in[2]
-	w3  := tmp[3]  ^ in[3]
-	w4  := tmp[4]  ^ in[4]
-	w5  := tmp[5]  ^ in[5]
-	w6  := tmp[6]  ^ in[6]
-	w7  := tmp[7]  ^ in[7]
-	w8  := tmp[8]  ^ in[8]
-	w9  := tmp[9]  ^ in[9]
-	w10 := tmp[10] ^ in[10]
-	w11 := tmp[11] ^ in[11]
-	w12 := tmp[12] ^ in[12]
-	w13 := tmp[13] ^ in[13]
-	w14 := tmp[14] ^ in[14]
-	w15 := tmp[15] ^ in[15]
-
-	x0  := w0
-	x1  := w1
-	x2  := w2
-	x3  := w3
-	x4  := w4
-	x5  := w5
-	x6  := w6
-	x7  := w7
-	x8  := w8
-	x9  := w9
-	x10 := w10
-	x11 := w11
-	x12 := w12
-	x13 := w13
-	x14 := w14
-	x15 := w15
-
-	for i := 0; i < 8; i += 2 {
-		x4  ^= bits.RotateLeft32(x0  + x12, 7)
-		x8  ^= bits.RotateLeft32(x4  + x0,  9)
-		x12 ^= bits.RotateLeft32(x8  + x4,  13)
-		x0  ^= bits.RotateLeft32(x12 + x8,  18)
-
-		x9  ^= bits.RotateLeft32(x5  + x1,  7)
-		x13 ^= bits.RotateLeft32(x9  + x5,  9)
-		x1  ^= bits.RotateLeft32(x13 + x9,  13)
-		x5  ^= bits.RotateLeft32(x1  + x13, 18)
-
-		x14 ^= bits.RotateLeft32(x10 + x6,  7)
-		x2  ^= bits.RotateLeft32(x14 + x10, 9)
-		x6  ^= bits.RotateLeft32(x2  + x14, 13)
-		x10 ^= bits.RotateLeft32(x6  + x2,  18)
-
-		x3  ^= bits.RotateLeft32(x15 + x11, 7)
-		x7  ^= bits.RotateLeft32(x3  + x15, 9)
-		x11 ^= bits.RotateLeft32(x7  + x3,  13)
-		x15 ^= bits.RotateLeft32(x11 + x7,  18)
-
-		x1  ^= bits.RotateLeft32(x0  + x3,  7)
-		x2  ^= bits.RotateLeft32(x1  + x0,  9)
-		x3  ^= bits.RotateLeft32(x2  + x1,  13)
-		x0  ^= bits.RotateLeft32(x3  + x2,  18)
-
-		x6  ^= bits.RotateLeft32(x5  + x4,  7)
-		x7  ^= bits.RotateLeft32(x6  + x5,  9)
-		x4  ^= bits.RotateLeft32(x7  + x6,  13)
-		x5  ^= bits.RotateLeft32(x4  + x7,  18)
-
-		x11 ^= bits.RotateLeft32(x10 + x9,  7)
-		x8  ^= bits.RotateLeft32(x11 + x10, 9)
-		x9  ^= bits.RotateLeft32(x8  + x11, 13)
-		x10 ^= bits.RotateLeft32(x9  + x8,  18)
-
-		x12 ^= bits.RotateLeft32(x15 + x14, 7)
-		x13 ^= bits.RotateLeft32(x12 + x15, 9)
-		x14 ^= bits.RotateLeft32(x13 + x12, 13)
-		x15 ^= bits.RotateLeft32(x14 + x13, 18)
-	}
-
-	x0  += w0
-	x1  += w1
-	x2  += w2
-	x3  += w3
-	x4  += w4
-	x5  += w5
-	x6  += w6
-	x7  += w7
-	x8  += w8
-	x9  += w9
-	x10 += w10
-	x11 += w11
-	x12 += w12
-	x13 += w13
-	x14 += w14
-	x15 += w15
-
-	out[0],  tmp[0]  = x0,  x0
-	out[1],  tmp[1]  = x1,  x1
-	out[2],  tmp[2]  = x2,  x2
-	out[3],  tmp[3]  = x3,  x3
-	out[4],  tmp[4]  = x4,  x4
-	out[5],  tmp[5]  = x5,  x5
-	out[6],  tmp[6]  = x6,  x6
-	out[7],  tmp[7]  = x7,  x7
-	out[8],  tmp[8]  = x8,  x8
-	out[9],  tmp[9]  = x9,  x9
-	out[10], tmp[10] = x10, x10
-	out[11], tmp[11] = x11, x11
-	out[12], tmp[12] = x12, x12
-	out[13], tmp[13] = x13, x13
-	out[14], tmp[14] = x14, x14
-	out[15], tmp[15] = x15, x15
-}
-
-func blockMix(tmp *[16]uint32, in []uint32, out []uint32, r int) {
-	blockCopy(tmp[:], in[(2 * r - 1) * 16:], 16)
-	for i := 0; i < 2 * r; i += 2 {
-		salsaXOR(tmp, in[i * 16:],      out[i * 8:])
-		salsaXOR(tmp, in[i * 16 + 16:], out[i * 8 + r * 16:])
-	}
-}
-
-func integer(b []uint32, r int) uint64 {
-	j := (2 * r - 1) * 16
-	return uint64(b[j]) | (uint64(b[j + 1]) << 32)
-}
-
-func smix(b []byte, r int, N int, v []uint32, xy []uint32) {
-	var tmp [16]uint32
-	R := 32 * r
-	x := xy
-	y := xy[R:]
-
-	j := 0
-	for i := 0; i < R; i++ {
-		x[i] = binary.LittleEndian.Uint32(b[j:])
-		j += 4
-	}
-	for i := 0; i < N; i += 2 {
-		blockCopy(v[i * R:], x, R)
-		blockMix(&tmp, x, y, r)
-
-		blockCopy(v[(i + 1) * R:], y, R)
-		blockMix(&tmp, y, x, r)
-	}
-	for i := 0; i < N; i += 2 {
-		j := int(integer(x, r) & uint64(N - 1))
-		blockXOR(x, v[j * R:], R)
-		blockMix(&tmp, x, y, r)
-
-		j = int(integer(y, r) & uint64(N - 1))
-		blockXOR(y, v[j * R:], R)
-		blockMix(&tmp, y, x, r)
-	}
-	j = 0
-	for _, v := range x[:R] {
-		binary.LittleEndian.PutUint32(b[j:], v)
-		j += 4
-	}
-}
-
-func validateParams(N int, r int, p int) error {
-	if N <= 1 || N & (N - 1) != 0 {
-		return ErrBadN
-	}
-
-	if ((uint64(r) * uint64(p)) >= (1 << 30)) ||
-			r > maxInt / 128 / p ||
-			r > maxInt / 256 ||
-			N > maxInt / 128 / r {
-		return ErrParamsTooLarge
-	}
-
-	return nil
-}
-
 // Package scrypt implements the scrypt key derivation function as defined in
 // Colin Percival's paper "Stronger Key Derivation via Sequential Memory-Hard
 // Functions" (https://www.tarsnap.com/scrypt/scrypt.pdf).
@@ -325,39 +65,37 @@ func scrypt(
 	N int,
 	r int,
 	p int,
-	keyLen int,
+	outlen int,
 ) ([]byte, error) {
-	err := validateParams(N, r, p)
-	if err != nil {
-		return nil, err
-	}
-
-	xy := make([]uint32, 64 * r)
-	v  := make([]uint32, 32 * r * N)
-	b  := _PBKDF2Key(password, salt, 1, p * 128 * r, sha256.New)
-
-	for i := 0; i < p; i++ {
-		smix(b[i * 128 * r:], r, N, v, xy)
-	}
-
-	return _PBKDF2Key(password, b, 1, keyLen, sha256.New), nil
-}
-
-func SaltFrom(r io.Reader) ([]byte, error) {
-	buffer := make([]byte, saltMinLength)
-	_, err := io.ReadFull(r, buffer)
-	if err != nil {
-		return nil, err
+	passwordbuf := C.CBytes(password)
+	saltbuf     := C.CBytes(salt)
+	defer C.free(passwordbuf)
+	defer C.free(saltbuf)
+
+	outbuf := C.malloc(C.size_t(outlen))
+	defer C.free(outbuf)
+
+	rv := C.scrypt_kdf(
+		(*C.uint8_t)(passwordbuf),
+		C.size_t(len(password)),
+		(*C.uint8_t)(saltbuf),
+		C.size_t(len(salt)),
+		C.uint64_t(N),
+		C.uint32_t(r),
+		C.uint32_t(p),
+		(*C.uint8_t)(outbuf),
+		C.size_t(outlen),
+	)
+	if rv != 0 {
+		return nil, ErrInternal
 	}
-	return buffer, nil
-}
 
-func Salt() ([]byte, error) {
-	return SaltFrom(rand.Reader)
+	out := C.GoBytes(outbuf, C.int(outlen))
+	return out, nil
 }
 
 func Hash(password []byte, salt []byte) ([]byte, error) {
-	if len(salt) < saltMinLength {
+	if len(salt) < _SALT_MIN_LENGTH {
 		return nil, ErrSaltTooSmall
 	}
 
@@ -367,7 +105,7 @@ func Hash(password []byte, salt []byte) ([]byte, error) {
 		_N,
 		r,
 		p,
-		desiredLength,
+		_DESIRED_LENGTH,
 	)
 	if err != nil {
 		return nil, err
@@ -376,6 +114,19 @@ func Hash(password []byte, salt []byte) ([]byte, error) {
 	return hash, nil
 }
 
+func SaltFrom(r io.Reader) ([]byte, error) {
+	buffer := make([]byte, _SALT_MIN_LENGTH)
+	_, err := io.ReadFull(r, buffer)
+	if err != nil {
+		return nil, err
+	}
+	return buffer, nil
+}
+
+func Salt() ([]byte, error) {
+	return SaltFrom(rand.Reader)
+}
+
 func Check(password []byte, salt []byte, hash []byte) (bool, error) {
 	candidate, err := Hash(password, salt)
 	if err != nil {
@@ -392,8 +143,10 @@ func Main() {
 		fmt.Fprintf(os.Stderr, "Usage: scrypt PASSWORD SALT\n")
 		os.Exit(2)
 	}
+	password := os.Args[1]
+	salt     := os.Args[2]
 
-	payload, err := Hash([]byte(os.Args[1]), []byte(os.Args[2]))
+	payload, err := Hash([]byte(password), []byte(salt))
 	if err != nil {
 		if err == ErrSaltTooSmall {
 			fmt.Fprintln(os.Stderr, err)