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provide a sample method to handle irregular ciphertext #90

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This commit is contained in:
emmansun 2022-10-30 09:46:09 +08:00
parent 57d01255e8
commit 0f0eec19d0
3 changed files with 31 additions and 6 deletions
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2
sm2/sm2.go
View File

@ -457,7 +457,7 @@ func unmarshalASN1Ciphertext(ciphertext []byte) (*big.Int, *big.Int, []byte, []b
)
input := cryptobyte.String(ciphertext)
if !input.ReadASN1(&inner, asn1.SEQUENCE) ||
(!input.Empty() && !subtle.ConstantTimeAllZero(input)) ||
!input.Empty() ||
!inner.ReadASN1Integer(x1) ||
!inner.ReadASN1Integer(y1) ||
!inner.ReadASN1Bytes(&c3, asn1.OCTET_STRING) ||

33
sm2/sm2_test.go
View File

@ -6,11 +6,11 @@ import (
"crypto/elliptic"
"crypto/rand"
"encoding/hex"
"errors"
"math/big"
"reflect"
"testing"
"github.com/emmansun/gmsm/internal/subtle"
"github.com/emmansun/gmsm/sm2/sm2ec"
"github.com/emmansun/gmsm/sm3"
"golang.org/x/crypto/cryptobyte"
@ -329,16 +329,41 @@ func TestEqual(t *testing.T) {
}
}
// a sample method to get frist ASN1 SEQUENCE data
func getFirstASN1Sequence(ciphertext []byte) ([]byte, []byte, error) {
input := cryptobyte.String(ciphertext)
var inner cryptobyte.String
if !input.ReadASN1(&inner, asn1.SEQUENCE) {
return nil, nil, errors.New("there are no sequence tag")
}
if len(input) == 0 {
return ciphertext, nil, nil
}
return ciphertext[:len(ciphertext)-len(input)], input, nil
}
func TestCipherASN1WithInvalidBytes(t *testing.T) {
ciphertext, _ := hex.DecodeString("3081980220298ED52AE2A0EBA8B7567D54DF41C5F9B310EDFA4A8E15ECCB44EDA94F9F1FC20220116BE33B0833C95D8E5FF9483CD2D7EFF7033C92FE5DEAB6197D809FF1EEE05F042097A90979A6FCEBDE883C2E07E9C286818E694EDE37C3CDAA70E4CD481BE883E00430D62160BB179CB20CE3B5ECA0F5A535BEB6E221566C78FEA92105F71BD37F3F850AD2F86F2D1E35F15E9356557DAC026A")
_, rest, err := getFirstASN1Sequence(ciphertext)
if err != nil || len(rest) != 0 {
t.FailNow()
}
ciphertext, _ = hex.DecodeString("3081980220298ED52AE2A0EBA8B7567D54DF41C5F9B310EDFA4A8E15ECCB44EDA94F9F1FC20220116BE33B0833C95D8E5FF9483CD2D7EFF7033C92FE5DEAB6197D809FF1EEE05F042097A90979A6FCEBDE883C2E07E9C286818E694EDE37C3CDAA70E4CD481BE883E00430D62160BB179CB20CE3B5ECA0F5A535BEB6E221566C78FEA92105F71BD37F3F850AD2F86F2D1E35F15E9356557DAC026A0000")
seq, rest, err := getFirstASN1Sequence(ciphertext)
if err != nil || len(rest) != 2 {
t.FailNow()
}
var (
x1, y1 = &big.Int{}, &big.Int{}
c2, c3 []byte
inner cryptobyte.String
)
ciphertext, _ := hex.DecodeString("3081980220298ED52AE2A0EBA8B7567D54DF41C5F9B310EDFA4A8E15ECCB44EDA94F9F1FC20220116BE33B0833C95D8E5FF9483CD2D7EFF7033C92FE5DEAB6197D809FF1EEE05F042097A90979A6FCEBDE883C2E07E9C286818E694EDE37C3CDAA70E4CD481BE883E00430D62160BB179CB20CE3B5ECA0F5A535BEB6E221566C78FEA92105F71BD37F3F850AD2F86F2D1E35F15E9356557DAC026A0000")
input := cryptobyte.String(ciphertext)
input := cryptobyte.String(seq)
if !input.ReadASN1(&inner, asn1.SEQUENCE) ||
(!input.Empty() && !subtle.ConstantTimeAllZero(input)) ||
!input.Empty() ||
!inner.ReadASN1Integer(x1) ||
!inner.ReadASN1Integer(y1) ||
!inner.ReadASN1Bytes(&c3, asn1.OCTET_STRING) ||

2
sm9/sm9.go
View File

@ -408,7 +408,7 @@ func DecryptASN1(priv *EncryptPrivateKey, uid, ciphertext []byte) ([]byte, error
)
input := cryptobyte.String(ciphertext)
if !input.ReadASN1(&inner, asn1.SEQUENCE) ||
(!input.Empty() && !subtle.ConstantTimeAllZero(input)) ||
!input.Empty() ||
!inner.ReadASN1Integer(&encType) ||
!inner.ReadASN1BitStringAsBytes(&c1Bytes) ||
!inner.ReadASN1Bytes(&c3Bytes, asn1.OCTET_STRING) ||