124 lines
3.2 KiB
Go
124 lines
3.2 KiB
Go
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package timestamp
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import (
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"bytes"
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"fmt"
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"io"
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"net/http"
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"crypto"
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"crypto/rand"
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"crypto/x509/pkix"
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"encoding/asn1"
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"math/big"
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cms "github.com/InfiniteLoopSpace/go_S-MIME/cms/protocol"
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oid "github.com/InfiniteLoopSpace/go_S-MIME/oid"
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)
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// TimeStampReq ::= SEQUENCE {
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// version INTEGER { v1(1) },
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// messageImprint MessageImprint,
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// --a hash algorithm OID and the hash value of the data to be
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// --time-stamped
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// reqPolicy TSAPolicyId OPTIONAL,
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// nonce INTEGER OPTIONAL,
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// certReq BOOLEAN DEFAULT FALSE,
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// extensions [0] IMPLICIT Extensions OPTIONAL }
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type TimeStampReq struct {
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Version int
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MessageImprint MessageImprint
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ReqPolicy asn1.ObjectIdentifier `asn1:"optional"`
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Nonce *big.Int `asn1:"optional"`
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CertReq bool `asn1:"optional,default:false"`
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Extensions []pkix.Extension `asn1:"tag:1,optional"`
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}
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func newTSRequest(msg []byte, hash crypto.Hash) (TimeStampReq, error) {
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mi, err := NewMessageImprint(hash, msg)
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if err != nil {
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return TimeStampReq{}, err
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}
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return TimeStampReq{
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Version: 1,
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CertReq: true,
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Nonce: GenerateNonce(),
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MessageImprint: mi,
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}, nil
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}
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// GenerateNonce generates a new nonce for this TSR.
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func GenerateNonce() *big.Int {
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buf := make([]byte, nonceBytes)
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if _, err := rand.Read(buf); err != nil {
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panic(err)
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}
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return new(big.Int).SetBytes(buf[:])
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}
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// Do sends this timestamp request to the specified timestamp service, returning
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// the parsed response.
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func (req TimeStampReq) Do(url string) (TimeStampResp, error) {
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var nilResp TimeStampResp
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reqDER, err := asn1.Marshal(req)
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if err != nil {
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return nilResp, err
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}
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httpReq, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(reqDER))
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if err != nil {
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return nilResp, err
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}
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httpReq.Header.Add("Content-Type", contentTypeTSQuery)
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HTTP := http.DefaultClient
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httpResp, err := HTTP.Do(httpReq)
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if err != nil {
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return nilResp, err
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}
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if ct := httpResp.Header.Get("Content-Type"); ct != contentTypeTSReply {
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return nilResp, fmt.Errorf("Bad content-type: %s", ct)
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}
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buf := bytes.NewBuffer(make([]byte, 0, httpResp.ContentLength))
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if _, err = io.Copy(buf, httpResp.Body); err != nil {
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return nilResp, err
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}
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return ParseResponse(buf.Bytes())
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}
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//MessageImprint ::= SEQUENCE {
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// hashAlgorithm AlgorithmIdentifier,
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// hashedMessage OCTET STRING }
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type MessageImprint struct {
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HashAlgorithm pkix.AlgorithmIdentifier
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HashedMessage []byte
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}
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// NewMessageImprint creates a new MessageImprint, digesting msg using the specified hash.
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func NewMessageImprint(hash crypto.Hash, msg []byte) (MessageImprint, error) {
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digestAlgorithm := oid.HashToDigestAlgorithm[hash]
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if len(digestAlgorithm) == 0 {
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return MessageImprint{}, cms.ErrUnsupported
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}
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if !hash.Available() {
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return MessageImprint{}, cms.ErrUnsupported
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}
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h := hash.New()
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if _, err := h.Write(msg); err != nil {
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return MessageImprint{}, err
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}
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return MessageImprint{
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HashAlgorithm: pkix.AlgorithmIdentifier{Algorithm: digestAlgorithm},
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HashedMessage: h.Sum(nil),
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}, nil
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}
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