Copy code from x/golang/scrypt: get scrypt(), and also import tests

2 files changed, 601 insertions, 0 deletions

diff --git a/src/lib.go b/src/lib.go
index 911f273..14f4f33 100644
--- a/src/lib.go
+++ b/src/lib.go
@@ -1,12 +1,18 @@
 package gobang
 
 import (
+	"crypto/hmac"
 	"crypto/rand"
+	"crypto/sha256"
+	"encoding/binary"
 	"encoding/hex"
+	"errors"
 	"fmt"
+	"hash"
 	"io"
 	"log/slog"
 	"math/big"
+	"math/bits"
 	"os"
 	"runtime/debug"
 	"sync"
@@ -15,6 +21,7 @@ import (
 )
 
 
+
 // FIXME: finish rewriting
 //
 // lastV7time is the last time we returned stored as:
@@ -311,3 +318,286 @@ func FatalIf(err error) {
 func Main() {
 	fmt.Println(NewUUID().ToString())
 }
+
+
+/*
+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, salt []byte, iter, keyLen int, h func() hash.Hash) []byte {
+	prf := hmac.New(h, password)
+	hashLen := prf.Size()
+	numBlocks := (keyLen + hashLen - 1) / hashLen
+
+	var buf [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)
+		buf[0] = byte(block >> 24)
+		buf[1] = byte(block >> 16)
+		buf[2] = byte(block >> 8)
+		buf[3] = byte(block)
+		prf.Write(buf[: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]
+}
+
+// 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).
+
+const maxInt = int(^uint(0) >> 1)
+
+// blockCopy copies n numbers from src into dst.
+func blockCopy(dst, src []uint32, n int) {
+	copy(dst, src[:n])
+}
+
+// blockXOR XORs numbers from dst with n numbers from src.
+func blockXOR(dst, 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, 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, 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, N int, v, 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
+	}
+}
+
+// Key derives a key from the password, salt, and cost parameters, returning
+// a byte slice of length keyLen that can be used as cryptographic key.
+//
+// N is a CPU/memory cost parameter, which must be a power of two greater than 1.
+// r and p must satisfy r * p < 2³⁰. If the parameters do not satisfy the
+// limits, the function returns a nil byte slice and an error.
+//
+// For example, you can get a derived key for e.g. AES-256 (which needs a
+// 32-byte key) by doing:
+//
+//	dk, err := scrypt.Key([]byte("some password"), salt, 32768, 8, 1, 32)
+//
+// The recommended parameters for interactive logins as of 2017 are N=32768, r=8
+// and p=1. The parameters N, r, and p should be increased as memory latency and
+// CPU parallelism increases; consider setting N to the highest power of 2 you
+// can derive within 100 milliseconds. Remember to get a good random salt.
+func Scrypt(password, salt []byte, N, r, p, keyLen int) ([]byte, error) {
+	if N <= 1 || N&(N-1) != 0 {
+		return nil, errors.New("scrypt: N must be > 1 and a power of 2")
+	}
+	if uint64(r)*uint64(p) >= 1<<30 || r > maxInt/128/p || r > maxInt/256 || N > maxInt/128/r {
+		return nil, errors.New("scrypt: parameters are too large")
+	}
+
+	xy := make([]uint32, 64*r)
+	v := make([]uint32, 32*N*r)
+	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
+}
diff --git a/tests/lib_test.go b/tests/lib_test.go
index 797bb0f..cac0884 100644
--- a/tests/lib_test.go
+++ b/tests/lib_test.go
@@ -2,8 +2,13 @@ package gobang_test
 
 import (
 	"bytes"
+	"crypto/sha1"
+	"crypto/sha256"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
+	"hash"
+	"log"
 	"log/slog"
 	"reflect"
 	"testing"
@@ -51,3 +56,309 @@ func TestSetLoggerOutput(t *testing.T) {
 	fmt.Println(1)
 	// fmt.Println(e)
 }
+
+type pbkdfTestVector struct {
+	password string
+	salt     string
+	iter     int
+	output   []byte
+}
+
+// Test vectors from RFC 6070, http://tools.ietf.org/html/rfc6070
+var sha1TestVectors = []pbkdfTestVector {
+	{
+		"password",
+		"salt",
+		1,
+		[]byte {
+			0x0c, 0x60, 0xc8, 0x0f, 0x96, 0x1f, 0x0e, 0x71,
+			0xf3, 0xa9, 0xb5, 0x24, 0xaf, 0x60, 0x12, 0x06,
+			0x2f, 0xe0, 0x37, 0xa6,
+		},
+	},
+	{
+		"password",
+		"salt",
+		2,
+		[]byte{
+			0xea, 0x6c, 0x01, 0x4d, 0xc7, 0x2d, 0x6f, 0x8c,
+			0xcd, 0x1e, 0xd9, 0x2a, 0xce, 0x1d, 0x41, 0xf0,
+			0xd8, 0xde, 0x89, 0x57,
+		},
+	},
+	{
+		"password",
+		"salt",
+		4096,
+		[]byte{
+			0x4b, 0x00, 0x79, 0x01, 0xb7, 0x65, 0x48, 0x9a,
+			0xbe, 0xad, 0x49, 0xd9, 0x26, 0xf7, 0x21, 0xd0,
+			0x65, 0xa4, 0x29, 0xc1,
+		},
+	},
+	// // This one takes too long
+	// {
+	// 	"password",
+	// 	"salt",
+	// 	16777216,
+	// 	[]byte {
+	// 		0xee, 0xfe, 0x3d, 0x61, 0xcd, 0x4d, 0xa4, 0xe4,
+	// 		0xe9, 0x94, 0x5b, 0x3d, 0x6b, 0xa2, 0x15, 0x8c,
+	// 		0x26, 0x34, 0xe9, 0x84,
+	// 	},
+	// },
+	{
+		"passwordPASSWORDpassword",
+		"saltSALTsaltSALTsaltSALTsaltSALTsalt",
+		4096,
+		[]byte{
+			0x3d, 0x2e, 0xec, 0x4f, 0xe4, 0x1c, 0x84, 0x9b,
+			0x80, 0xc8, 0xd8, 0x36, 0x62, 0xc0, 0xe4, 0x4a,
+			0x8b, 0x29, 0x1a, 0x96, 0x4c, 0xf2, 0xf0, 0x70,
+			0x38,
+		},
+	},
+	{
+		"pass\000word",
+		"sa\000lt",
+		4096,
+		[]byte{
+			0x56, 0xfa, 0x6a, 0xa7, 0x55, 0x48, 0x09, 0x9d,
+			0xcc, 0x37, 0xd7, 0xf0, 0x34, 0x25, 0xe0, 0xc3,
+		},
+	},
+}
+
+// Test vectors from
+// http://stackoverflow.com/questions/5130513/pbkdf2-hmac-sha2-test-vectors
+var sha256TestVectors = []pbkdfTestVector {
+	{
+		"password",
+		"salt",
+		1,
+		[]byte {
+			0x12, 0x0f, 0xb6, 0xcf, 0xfc, 0xf8, 0xb3, 0x2c,
+			0x43, 0xe7, 0x22, 0x52, 0x56, 0xc4, 0xf8, 0x37,
+			0xa8, 0x65, 0x48, 0xc9,
+		},
+	},
+	{
+		"password",
+		"salt",
+		2,
+		[]byte {
+			0xae, 0x4d, 0x0c, 0x95, 0xaf, 0x6b, 0x46, 0xd3,
+			0x2d, 0x0a, 0xdf, 0xf9, 0x28, 0xf0, 0x6d, 0xd0,
+			0x2a, 0x30, 0x3f, 0x8e,
+		},
+	},
+	{
+		"password",
+		"salt",
+		4096,
+		[]byte {
+			0xc5, 0xe4, 0x78, 0xd5, 0x92, 0x88, 0xc8, 0x41,
+			0xaa, 0x53, 0x0d, 0xb6, 0x84, 0x5c, 0x4c, 0x8d,
+			0x96, 0x28, 0x93, 0xa0,
+		},
+	},
+	{
+		"passwordPASSWORDpassword",
+		"saltSALTsaltSALTsaltSALTsaltSALTsalt",
+		4096,
+		[]byte {
+			0x34, 0x8c, 0x89, 0xdb, 0xcb, 0xd3, 0x2b, 0x2f,
+			0x32, 0xd8, 0x14, 0xb8, 0x11, 0x6e, 0x84, 0xcf,
+			0x2b, 0x17, 0x34, 0x7e, 0xbc, 0x18, 0x00, 0x18,
+			0x1c,
+		},
+	},
+	{
+		"pass\000word",
+		"sa\000lt",
+		4096,
+		[]byte {
+			0x89, 0xb6, 0x9d, 0x05, 0x16, 0xf8, 0x29, 0x89,
+			0x3c, 0x69, 0x62, 0x26, 0x65, 0x0a, 0x86, 0x87,
+		},
+	},
+}
+
+func testHash(t *testing.T, h func() hash.Hash, hashName string, vectors []pbkdfTestVector) {
+	for i, v := range vectors {
+		o := gobang.PBKDF2Key([]byte(v.password), []byte(v.salt), v.iter, len(v.output), h)
+		if !bytes.Equal(o, v.output) {
+			t.Errorf("%s %d: expected %x, got %x", hashName, i, v.output, o)
+		}
+	}
+}
+
+func TestWithHMACSHA1(t *testing.T) {
+	testHash(t, sha1.New, "SHA1", sha1TestVectors)
+}
+
+func TestWithHMACSHA256(t *testing.T) {
+	testHash(t, sha256.New, "SHA256", sha256TestVectors)
+}
+
+type scryptTestVector struct {
+	password string
+	salt     string
+	N, r, p  int
+	output   []byte
+}
+
+var good = []scryptTestVector {
+	{
+		"password",
+		"salt",
+		2, 10, 10,
+		[]byte {
+			0x48, 0x2c, 0x85, 0x8e, 0x22, 0x90, 0x55, 0xe6, 0x2f,
+			0x41, 0xe0, 0xec, 0x81, 0x9a, 0x5e, 0xe1, 0x8b, 0xdb,
+			0x87, 0x25, 0x1a, 0x53, 0x4f, 0x75, 0xac, 0xd9, 0x5a,
+			0xc5, 0xe5, 0xa, 0xa1, 0x5f,
+		},
+	},
+	{
+		"password",
+		"salt",
+		16, 100, 100,
+		[]byte {
+			0x88, 0xbd, 0x5e, 0xdb, 0x52, 0xd1, 0xdd, 0x0, 0x18,
+			0x87, 0x72, 0xad, 0x36, 0x17, 0x12, 0x90, 0x22, 0x4e,
+			0x74, 0x82, 0x95, 0x25, 0xb1, 0x8d, 0x73, 0x23, 0xa5,
+			0x7f, 0x91, 0x96, 0x3c, 0x37,
+		},
+	},
+	{
+		"this is a long \000 password",
+		"and this is a long \000 salt",
+		16384, 8, 1,
+		[]byte {
+			0xc3, 0xf1, 0x82, 0xee, 0x2d, 0xec, 0x84, 0x6e, 0x70,
+			0xa6, 0x94, 0x2f, 0xb5, 0x29, 0x98, 0x5a, 0x3a, 0x09,
+			0x76, 0x5e, 0xf0, 0x4c, 0x61, 0x29, 0x23, 0xb1, 0x7f,
+			0x18, 0x55, 0x5a, 0x37, 0x07, 0x6d, 0xeb, 0x2b, 0x98,
+			0x30, 0xd6, 0x9d, 0xe5, 0x49, 0x26, 0x51, 0xe4, 0x50,
+			0x6a, 0xe5, 0x77, 0x6d, 0x96, 0xd4, 0x0f, 0x67, 0xaa,
+			0xee, 0x37, 0xe1, 0x77, 0x7b, 0x8a, 0xd5, 0xc3, 0x11,
+			0x14, 0x32, 0xbb, 0x3b, 0x6f, 0x7e, 0x12, 0x64, 0x40,
+			0x18, 0x79, 0xe6, 0x41, 0xae,
+		},
+	},
+	{
+		"p",
+		"s",
+		2, 1, 1,
+		[]byte {
+			0x48, 0xb0, 0xd2, 0xa8, 0xa3, 0x27, 0x26, 0x11, 0x98,
+			0x4c, 0x50, 0xeb, 0xd6, 0x30, 0xaf, 0x52,
+		},
+	},
+
+	{
+		"",
+		"",
+		16, 1, 1,
+		[]byte {
+			0x77, 0xd6, 0x57, 0x62, 0x38, 0x65, 0x7b, 0x20, 0x3b,
+			0x19, 0xca, 0x42, 0xc1, 0x8a, 0x04, 0x97, 0xf1, 0x6b,
+			0x48, 0x44, 0xe3, 0x07, 0x4a, 0xe8, 0xdf, 0xdf, 0xfa,
+			0x3f, 0xed, 0xe2, 0x14, 0x42, 0xfc, 0xd0, 0x06, 0x9d,
+			0xed, 0x09, 0x48, 0xf8, 0x32, 0x6a, 0x75, 0x3a, 0x0f,
+			0xc8, 0x1f, 0x17, 0xe8, 0xd3, 0xe0, 0xfb, 0x2e, 0x0d,
+			0x36, 0x28, 0xcf, 0x35, 0xe2, 0x0c, 0x38, 0xd1, 0x89,
+			0x06,
+		},
+	},
+	{
+		"password",
+		"NaCl",
+		1024, 8, 16,
+		[]byte {
+			0xfd, 0xba, 0xbe, 0x1c, 0x9d, 0x34, 0x72, 0x00, 0x78,
+			0x56, 0xe7, 0x19, 0x0d, 0x01, 0xe9, 0xfe, 0x7c, 0x6a,
+			0xd7, 0xcb, 0xc8, 0x23, 0x78, 0x30, 0xe7, 0x73, 0x76,
+			0x63, 0x4b, 0x37, 0x31, 0x62, 0x2e, 0xaf, 0x30, 0xd9,
+			0x2e, 0x22, 0xa3, 0x88, 0x6f, 0xf1, 0x09, 0x27, 0x9d,
+			0x98, 0x30, 0xda, 0xc7, 0x27, 0xaf, 0xb9, 0x4a, 0x83,
+			0xee, 0x6d, 0x83, 0x60, 0xcb, 0xdf, 0xa2, 0xcc, 0x06,
+			0x40,
+		},
+	},
+	{
+		"pleaseletmein", "SodiumChloride",
+		16384, 8, 1,
+		[]byte {
+			0x70, 0x23, 0xbd, 0xcb, 0x3a, 0xfd, 0x73, 0x48, 0x46,
+			0x1c, 0x06, 0xcd, 0x81, 0xfd, 0x38, 0xeb, 0xfd, 0xa8,
+			0xfb, 0xba, 0x90, 0x4f, 0x8e, 0x3e, 0xa9, 0xb5, 0x43,
+			0xf6, 0x54, 0x5d, 0xa1, 0xf2, 0xd5, 0x43, 0x29, 0x55,
+			0x61, 0x3f, 0x0f, 0xcf, 0x62, 0xd4, 0x97, 0x05, 0x24,
+			0x2a, 0x9a, 0xf9, 0xe6, 0x1e, 0x85, 0xdc, 0x0d, 0x65,
+			0x1e, 0x40, 0xdf, 0xcf, 0x01, 0x7b, 0x45, 0x57, 0x58,
+			0x87,
+		},
+	},
+	/*
+		// Disabled: needs 1 GiB RAM and takes too long for a simple test.
+		{
+			"pleaseletmein", "SodiumChloride",
+			1048576, 8, 1,
+			[]byte{
+				0x21, 0x01, 0xcb, 0x9b, 0x6a, 0x51, 0x1a, 0xae, 0xad,
+				0xdb, 0xbe, 0x09, 0xcf, 0x70, 0xf8, 0x81, 0xec, 0x56,
+				0x8d, 0x57, 0x4a, 0x2f, 0xfd, 0x4d, 0xab, 0xe5, 0xee,
+				0x98, 0x20, 0xad, 0xaa, 0x47, 0x8e, 0x56, 0xfd, 0x8f,
+				0x4b, 0xa5, 0xd0, 0x9f, 0xfa, 0x1c, 0x6d, 0x92, 0x7c,
+				0x40, 0xf4, 0xc3, 0x37, 0x30, 0x40, 0x49, 0xe8, 0xa9,
+				0x52, 0xfb, 0xcb, 0xf4, 0x5c, 0x6f, 0xa7, 0x7a, 0x41,
+				0xa4,
+			},
+		},
+	*/
+}
+
+const maxInt = int(^uint(0) >> 1)
+
+var bad = []scryptTestVector {
+	{"p", "s", 0, 1, 1, nil},                    // N == 0
+	{"p", "s", 1, 1, 1, nil},                    // N == 1
+	{"p", "s", 7, 8, 1, nil},                    // N is not power of 2
+	{"p", "s", 16, maxInt / 2, maxInt / 2, nil}, // p * r too large
+}
+
+func TestKey(t *testing.T) {
+	for i, v := range good {
+		k, err := gobang.Scrypt([]byte(v.password), []byte(v.salt), v.N, v.r, v.p, len(v.output))
+		if err != nil {
+			t.Errorf("%d: got unexpected error: %s", i, err)
+		}
+		if !bytes.Equal(k, v.output) {
+			t.Errorf("%d: expected %x, got %x", i, v.output, k)
+		}
+	}
+	for i, v := range bad {
+		_, err := gobang.Scrypt([]byte(v.password), []byte(v.salt), v.N, v.r, v.p, 32)
+		if err == nil {
+			t.Errorf("%d: expected error, got nil", i)
+		}
+	}
+}
+
+func TestExample(t *testing.T) {
+	const expected = "lGnMz8io0AUkfzn6Pls1qX20Vs7PGN6sbYQ2TQgY12M="
+	// DO NOT use this salt value; generate your own random salt. 8 bytes is
+	// a good length.
+	salt := []byte{0xc8, 0x28, 0xf2, 0x58, 0xa7, 0x6a, 0xad, 0x7b}
+
+	dk, err := gobang.Scrypt([]byte("some password"), salt, 1<<15, 8, 1, 32)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	given := base64.StdEncoding.EncodeToString(dk)
+
+	assertEqual(t, given, expected)
+}