SIG0 misc - doc, bounds checking, refactor tests
* expand documentation a little and tweak comments * add bounds checking in Verify() * refactor tests
This commit is contained in:
Andrew Tunnell-Jones
parent
deb8fe381f
commit
9862d7044a
43
sig0.go
43
sig0.go
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@ -2,7 +2,7 @@
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// SIG(0)
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// SIG0
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//
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// From RFC 2931:
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//
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@ -10,6 +10,10 @@
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// ... protection for glue records, DNS requests, protection for message headers
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// on requests and responses, and protection of the overall integrity of a response.
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//
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// Supported algorithms: DSA, ECDSAP256SHA256, ECDSAP384SHA384, RSASHA1, RSASHA256 and
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// RSASHA512.
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//
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// Signing subsequent messages in multi-message sessions is not implemented.
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//
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package dns
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@ -19,7 +23,6 @@ import (
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"crypto/ecdsa"
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"crypto/rand"
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"crypto/rsa"
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"fmt"
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"math/big"
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"strings"
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"time"
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@ -163,29 +166,34 @@ func (rr *SIG) Verify(k *KEY, buf []byte) error {
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adc, offset := unpackUint16(buf, 10)
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var err error
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for i := uint16(0); i < qdc && offset < buflen; i++ {
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// decode a name
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_, offset, err = UnpackDomainName(buf, offset)
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if err != nil {
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return err
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}
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// skip past Type and Class
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// Skip past Type and Class
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offset += 2 + 2
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}
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for i := uint16(1); i < anc+auc+adc && offset < buflen; i++ {
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// decode a name
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_, offset, err = UnpackDomainName(buf, offset)
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if err != nil {
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return err
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}
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// skip past Type, Class and TTL
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// Skip past Type, Class and TTL
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offset += 2 + 2 + 4
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if offset+1 >= buflen {
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continue
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}
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var rdlen uint16
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rdlen, offset = unpackUint16(buf, offset)
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offset += int(rdlen)
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}
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if offset >= buflen {
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return &Error{err: "overflowing unpacking signed message"}
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}
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// offset should be just prior to SIG
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bodyend := offset
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// Owner name SHOULD be root
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// owner name SHOULD be root
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_, offset, err = UnpackDomainName(buf, offset)
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if err != nil {
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return err
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@ -193,20 +201,21 @@ func (rr *SIG) Verify(k *KEY, buf []byte) error {
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// Skip Type, Class, TTL, RDLen
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offset += 2 + 2 + 4 + 2
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sigstart := offset
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offset += 2 + 1 + 1 + 4 // skip Type Covered, Algorithm, Labels, Original TTL
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// TODO: This should be moved out and used elsewhere
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unpackUint32 := func(buf []byte, off int) (uint32, int) {
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r := uint32(buf[off])<<24 | uint32(buf[off+1])<<16 | uint32(buf[off+2])<<8 | uint32(buf[off+3])
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return r, off + 4
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// Skip Type Covered, Algorithm, Labels, Original TTL
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offset += 2 + 1 + 1 + 4
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if offset+4+4 >= buflen {
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return &Error{err: "overflow unpacking signed message"}
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}
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var expire, incept uint32
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expire, offset = unpackUint32(buf, offset)
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incept, offset = unpackUint32(buf, offset)
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expire := uint32(buf[offset])<<24 | uint32(buf[offset+1])<<16 | uint32(buf[offset+2])<<8 | uint32(buf[offset+3])
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offset += 4
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incept := uint32(buf[offset])<<24 | uint32(buf[offset+1])<<16 | uint32(buf[offset+2])<<8 | uint32(buf[offset+3])
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offset += 4
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now := uint32(time.Now().Unix())
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if now < incept || now > expire {
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return ErrTime
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}
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offset += 2 // skip key tag
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// Skip key tag
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offset += 2
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var signername string
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signername, offset, err = UnpackDomainName(buf, offset)
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if err != nil {
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@ -215,7 +224,7 @@ func (rr *SIG) Verify(k *KEY, buf []byte) error {
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// If key has come from the DNS name compression might
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// have mangled the case of the name
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if strings.ToLower(signername) != strings.ToLower(k.Header().Name) {
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return fmt.Errorf("Signer name doesn't match key name")
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return &Error{err: "signer name doesn't match key name"}
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}
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sigend := offset
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hasher.Write(buf[sigstart:sigend])
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52
sig0_test.go
52
sig0_test.go
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@ -6,51 +6,39 @@ import (
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)
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func TestSIG0(t *testing.T) {
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keys := []struct {
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alg uint8
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rr *KEY
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pk PrivateKey
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}{{alg: DSA}, {alg: ECDSAP256SHA256}, {alg: ECDSAP384SHA384}, {alg: RSASHA1}, {alg: RSASHA256}, {alg: RSASHA512}}
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for i := range keys {
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keys[i].rr = new(KEY)
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keys[i].rr.Hdr.Name = AlgorithmToString[keys[i].alg] + "."
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keys[i].rr.Hdr.Rrtype = TypeKEY
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keys[i].rr.Hdr.Class = ClassINET
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keys[i].rr.Algorithm = keys[i].alg
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m := new(Msg)
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m.SetQuestion("example.org.", TypeSOA)
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for _, alg := range []uint8{DSA, ECDSAP256SHA256, ECDSAP384SHA384, RSASHA1, RSASHA256, RSASHA512} {
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algstr := AlgorithmToString[alg]
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keyrr := new(KEY)
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keyrr.Hdr.Name = algstr + "."
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keyrr.Hdr.Rrtype = TypeKEY
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keyrr.Hdr.Class = ClassINET
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keyrr.Algorithm = alg
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keysize := 1024
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switch keys[i].alg {
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switch alg {
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case ECDSAP256SHA256:
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keysize = 256
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case ECDSAP384SHA384:
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keysize = 384
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}
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pk, err := keys[i].rr.Generate(keysize)
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pk, err := keyrr.Generate(keysize)
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if err != nil {
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t.Logf("Failed to generate key for “%s”: %v", AlgorithmToString[keys[i].alg], err)
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t.Logf("Failed to generate key for “%s”: %v", algstr, err)
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t.Fail()
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continue
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}
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keys[i].pk = pk
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}
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m := new(Msg)
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m.SetQuestion("example.org.", TypeSOA)
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for _, key := range keys {
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if key.pk == nil {
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continue
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}
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algstr := AlgorithmToString[key.alg]
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now := uint32(time.Now().Unix())
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sigrr := new(SIG)
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sigrr.Hdr.Name = "."
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sigrr.Hdr.Rrtype = TypeSIG
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sigrr.Hdr.Class = ClassANY
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sigrr.Algorithm = key.rr.Algorithm
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sigrr.Algorithm = alg
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sigrr.Expiration = now + 300
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sigrr.Inception = now - 300
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sigrr.KeyTag = key.rr.KeyTag()
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sigrr.SignerName = key.rr.Hdr.Name
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mb, err := sigrr.Sign(key.pk, m)
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sigrr.KeyTag = keyrr.KeyTag()
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sigrr.SignerName = keyrr.Hdr.Name
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mb, err := sigrr.Sign(pk, m)
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if err != nil {
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t.Logf("Failed to sign message using “%s”: %v", algstr, err)
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t.Fail()
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@ -81,22 +69,22 @@ func TestSIG0(t *testing.T) {
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if rr == sigrrwire {
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id = "sigrrwire"
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}
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if err := rr.Verify(key.rr, mb); err != nil {
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if err := rr.Verify(keyrr, mb); err != nil {
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t.Logf("Failed to verify “%s” signed SIG(%s): %v", algstr, id, err)
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t.Fail()
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continue
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}
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}
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mb[13]++
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if err := sigrr.Verify(key.rr, mb); err == nil {
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if err := sigrr.Verify(keyrr, mb); err == nil {
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t.Logf("Verify succeeded on an altered message using “%s”", algstr)
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t.Fail()
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continue
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}
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sigrr.Expiration = 2
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sigrr.Inception = 1
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mb, _ = sigrr.Sign(key.pk, m)
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if err := sigrr.Verify(key.rr, mb); err == nil {
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mb, _ = sigrr.Sign(pk, m)
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if err := sigrr.Verify(keyrr, mb); err == nil {
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t.Logf("Verify succeeded on an expired message using “%s”", algstr)
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t.Fail()
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continue
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