package libnmdc import ( "encoding/base32" "errors" "strings" "github.com/cxmcc/tiger" ) // Base32 encodes the input slice in BASE32 string format without any trailing // padding equals characters. func Base32(input []byte) string { return strings.TrimRight(base32.StdEncoding.EncodeToString(input), "=") } // TTH returns the TTH hash of a string in raw byte format. Use the Base32() // function to convert it to normal string format. // This is a basic implementation that only supports content up to 1024 bytes in length. func TTH(input string) ([]byte, error) { // Short segments do not need to be padded. // Content above 1024 bytes needs tree handling (0x00 prefix for leaf nodes, // 0x01 prefix for hash nodes) but for content less than 1024 bytes, just // return the leaf hash // @ref http://adc.sourceforge.net/draft-jchapweske-thex-02.html if len(input) > 1024 { return nil, errors.New("TTH content exceeded 1024 bytes") } // Single leaf hash only leafHash := tiger.New() leafHash.Write([]byte("\x00" + input)) return leafHash.Sum(nil), nil }