code: func (k *IdentityKey) SecString() string {
  	buf := new(bytes.Buffer)
  	buf.Write(idSecPrefix)
  	buf.Write(k.SecBytes()[:32])
  
  	check := shad(buf.Bytes())[:ChecksumLength]
  	buf.Write(check)
  
  	return base58.Encode(buf.Bytes())
  }
docs: // SecString returns the string encoding of the secret key