/
start.go
81 lines (73 loc) · 1.71 KB
/
start.go
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package hashchain
import (
"crypto/ed25519"
"crypto/rand"
"fmt"
"os"
"github.com/frankbraun/codechain/hashchain/linktype"
"github.com/frankbraun/codechain/util/base64"
"github.com/frankbraun/codechain/util/file"
"github.com/frankbraun/codechain/util/lockfile"
"github.com/frankbraun/codechain/util/time"
)
// Start returns a new hash chain with signature control list m.
func Start(filename string, secKey [64]byte, comment []byte) (*HashChain, string, error) {
// check arguments
exists, err := file.Exists(filename)
if err != nil {
return nil, "", err
}
if exists {
return nil, "", fmt.Errorf("hashchain: file '%s' exists already", filename)
}
// init
var c HashChain
c.lock, err = lockfile.Create(filename)
if err != nil {
return nil, "", err
}
c.fp, err = os.Create(filename)
if err != nil {
c.lock.Release()
return nil, "", err
}
// create signature
var nonce [24]byte
if _, err := rand.Read(nonce[:]); err != nil {
c.lock.Release()
return nil, "", err
}
pub := secKey[32:]
msg := append(pub, nonce[:]...)
if len(comment) > 0 {
msg = append(msg, comment...)
}
sig := ed25519.Sign(secKey[:], msg)
// create entry
typeFields := []string{
base64.Encode(pub),
base64.Encode(nonce[:]),
base64.Encode(sig[:]),
}
if len(comment) > 0 {
typeFields = append(typeFields, string(comment))
}
l := &link{
previous: emptyTree,
datum: time.Now(),
linkType: linktype.ChainStart,
typeFields: typeFields,
}
c.chain = append(c.chain, l)
// verify
if err := c.verify(); err != nil {
c.lock.Release()
return nil, "", err
}
// save
if _, err := fmt.Fprintln(c.fp, l.String()); err != nil {
c.lock.Release()
return nil, "", err
}
return &c, l.StringColor(), nil
}