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Adds test vectors to hashToCurve and expanders.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,147 @@ | ||
| package group | ||
|
|
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| import ( | ||
| "crypto" | ||
| "encoding/binary" | ||
| "errors" | ||
| "io" | ||
|
|
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| "github.com/cloudflare/circl/xof" | ||
| ) | ||
|
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| type Expander interface { | ||
| // Expand generates a pseudo-random byte string of a determined length by | ||
| // expanding an input string. | ||
| Expand(in []byte, length uint) (pseudo []byte) | ||
| } | ||
|
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| type expanderMD struct { | ||
| h crypto.Hash | ||
| dst []byte | ||
| } | ||
|
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| // NewExpanderMD returns a hash function based on a Merkle-Damgård hash function. | ||
| func NewExpanderMD(h crypto.Hash, dst []byte) *expanderMD { | ||
| return &expanderMD{h, dst} | ||
| } | ||
|
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| func (e *expanderMD) calcDSTPrime() []byte { | ||
| var dstPrime []byte | ||
| if l := len(e.dst); l > maxDSTLength { | ||
| H := e.h.New() | ||
| mustWrite(H, longDSTPrefix[:]) | ||
| mustWrite(H, e.dst) | ||
| dstPrime = H.Sum(nil) | ||
| } else { | ||
| dstPrime = make([]byte, l, l+1) | ||
| copy(dstPrime, e.dst) | ||
| } | ||
| return append(dstPrime, byte(len(dstPrime))) | ||
| } | ||
|
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| func (e *expanderMD) Expand(in []byte, n uint) []byte { | ||
| H := e.h.New() | ||
| bLen := uint(H.Size()) | ||
| ell := (n + (bLen - 1)) / bLen | ||
| if ell > 255 { | ||
| panic(errorLongOutput) | ||
| } | ||
|
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| zPad := make([]byte, H.BlockSize()) | ||
| libStr := []byte{0, 0} | ||
| libStr[0] = byte((n >> 8) & 0xFF) | ||
| libStr[1] = byte(n & 0xFF) | ||
| dstPrime := e.calcDSTPrime() | ||
|
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| H.Reset() | ||
| mustWrite(H, zPad) | ||
| mustWrite(H, in) | ||
| mustWrite(H, libStr) | ||
| mustWrite(H, []byte{0}) | ||
| mustWrite(H, dstPrime) | ||
| b0 := H.Sum(nil) | ||
|
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| H.Reset() | ||
| mustWrite(H, b0) | ||
| mustWrite(H, []byte{1}) | ||
| mustWrite(H, dstPrime) | ||
| bi := H.Sum(nil) | ||
| pseudo := append([]byte{}, bi...) | ||
| for i := uint(2); i <= ell; i++ { | ||
| H.Reset() | ||
| for i := range b0 { | ||
| bi[i] ^= b0[i] | ||
| } | ||
| mustWrite(H, bi) | ||
| mustWrite(H, []byte{byte(i)}) | ||
| mustWrite(H, dstPrime) | ||
| bi = H.Sum(nil) | ||
| pseudo = append(pseudo, bi...) | ||
| } | ||
| return pseudo[0:n] | ||
| } | ||
|
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| // expanderXOF is based on an extendable output function. | ||
| type expanderXOF struct { | ||
| id xof.ID | ||
| kSecLevel uint | ||
| dst []byte | ||
| } | ||
|
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| // NewExpanderXOF returns an Expander based on an extendable output function. | ||
| // The kSecLevel parameter is the target security level in bits, and dst is | ||
| // a domain separation string. | ||
| func NewExpanderXOF(id xof.ID, kSecLevel uint, dst []byte) *expanderXOF { | ||
| return &expanderXOF{id, kSecLevel, dst} | ||
| } | ||
|
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| // Expand panics if output's length is longer than 2^16 bytes. | ||
| func (e *expanderXOF) Expand(in []byte, n uint) []byte { | ||
| bLen := []byte{0, 0} | ||
| binary.BigEndian.PutUint16(bLen, uint16(n)) | ||
| pseudo := make([]byte, n) | ||
| dstPrime := e.calcDSTPrime() | ||
|
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| H := e.id.New() | ||
| mustWrite(H, in) | ||
| mustWrite(H, bLen) | ||
| mustWrite(H, dstPrime) | ||
| mustReadFull(H, pseudo) | ||
| return pseudo | ||
| } | ||
|
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| func (e *expanderXOF) calcDSTPrime() []byte { | ||
| var dstPrime []byte | ||
| if l := len(e.dst); l > maxDSTLength { | ||
| H := e.id.New() | ||
| mustWrite(H, longDSTPrefix[:]) | ||
| mustWrite(H, e.dst) | ||
| max := ((2 * e.kSecLevel) + 7) / 8 | ||
| dstPrime = make([]byte, max, max+1) | ||
| mustReadFull(H, dstPrime) | ||
| } else { | ||
| dstPrime = make([]byte, l, l+1) | ||
| copy(dstPrime, e.dst) | ||
| } | ||
| return append(dstPrime, byte(len(dstPrime))) | ||
| } | ||
|
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| func mustWrite(w io.Writer, b []byte) { | ||
| if n, err := w.Write(b); err != nil || n != len(b) { | ||
| panic(err) | ||
| } | ||
| } | ||
|
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| func mustReadFull(r io.Reader, b []byte) { | ||
| if n, err := io.ReadFull(r, b); err != nil || n != len(b) { | ||
| panic(err) | ||
| } | ||
| } | ||
|
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| const maxDSTLength = 255 | ||
|
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| var ( | ||
| longDSTPrefix = [17]byte{'H', '2', 'C', '-', 'O', 'V', 'E', 'R', 'S', 'I', 'Z', 'E', '-', 'D', 'S', 'T', '-'} | ||
|
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| errorLongOutput = errors.New("requested too many bytes") | ||
| ) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,112 @@ | ||
| package group_test | ||
|
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| import ( | ||
| "bytes" | ||
| "crypto" | ||
| "encoding/hex" | ||
| "encoding/json" | ||
| "fmt" | ||
| "os" | ||
| "path/filepath" | ||
| "strconv" | ||
| "testing" | ||
|
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| "github.com/cloudflare/circl/group" | ||
| "github.com/cloudflare/circl/internal/test" | ||
| "github.com/cloudflare/circl/xof" | ||
| ) | ||
|
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| func TestExpander(t *testing.T) { | ||
| fileNames, err := filepath.Glob("./testdata/expand*.json") | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
|
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| for _, fileName := range fileNames { | ||
| f, err := os.Open(fileName) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| dec := json.NewDecoder(f) | ||
| var v vectorExpanderSuite | ||
| err = dec.Decode(&v) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| f.Close() | ||
|
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| t.Run(v.Name+"/"+v.Hash, func(t *testing.T) { testExpander(t, &v) }) | ||
| } | ||
| } | ||
|
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| func testExpander(t *testing.T, vs *vectorExpanderSuite) { | ||
| var exp group.Expander | ||
| switch vs.Hash { | ||
| case "SHA256": | ||
| exp = group.NewExpanderMD(crypto.SHA256, []byte(vs.DST)) | ||
| case "SHA512": | ||
| exp = group.NewExpanderMD(crypto.SHA512, []byte(vs.DST)) | ||
| case "SHAKE128": | ||
| exp = group.NewExpanderXOF(xof.SHAKE128, 0, []byte(vs.DST)) | ||
| case "SHAKE256": | ||
| exp = group.NewExpanderXOF(xof.SHAKE256, 0, []byte(vs.DST)) | ||
| default: | ||
| t.Skip("hash not supported: " + vs.Hash) | ||
| } | ||
|
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| for i, v := range vs.Tests { | ||
| lenBytes, err := strconv.ParseUint(v.Len, 0, 64) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
|
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| got := exp.Expand([]byte(v.Msg), uint(lenBytes)) | ||
| want, err := hex.DecodeString(v.UniformBytes) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
|
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| if !bytes.Equal(got, want) { | ||
| test.ReportError(t, got, want, i) | ||
| } | ||
| } | ||
| } | ||
|
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| type vectorExpanderSuite struct { | ||
| DST string `json:"DST"` | ||
| Hash string `json:"hash"` | ||
| Name string `json:"name"` | ||
| Tests []struct { | ||
| DstPrime string `json:"DST_prime"` | ||
| Len string `json:"len_in_bytes"` | ||
| Msg string `json:"msg"` | ||
| MsgPrime string `json:"msg_prime"` | ||
| UniformBytes string `json:"uniform_bytes"` | ||
| } `json:"tests"` | ||
| } | ||
|
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| func BenchmarkExpander(b *testing.B) { | ||
| in := []byte("input") | ||
| dst := []byte("dst") | ||
|
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| for _, v := range []struct { | ||
| Name string | ||
| Exp group.Expander | ||
| }{ | ||
| {"XMD", group.NewExpanderMD(crypto.SHA256, dst)}, | ||
| {"XOF", group.NewExpanderXOF(xof.SHAKE128, 0, dst)}, | ||
| } { | ||
| exp := v.Exp | ||
| for l := 8; l <= 10; l++ { | ||
| max := int64(1) << uint(l) | ||
|
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| b.Run(fmt.Sprintf("%v/%v", v.Name, max), func(b *testing.B) { | ||
| b.SetBytes(max) | ||
| b.ResetTimer() | ||
| for i := 0; i < b.N; i++ { | ||
| exp.Expand(in, uint(max)) | ||
| } | ||
| }) | ||
| } | ||
| } | ||
| } |
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