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sum.go
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sum.go
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package multihash
import (
"crypto/sha1"
"crypto/sha256"
"crypto/sha512"
"errors"
"fmt"
sha3 "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/crypto/sha3"
)
var ErrSumNotSupported = errors.New("Function not implemented. Complain to lib maintainer.")
func Sum(data []byte, code int, length int) (Multihash, error) {
m := Multihash{}
err := error(nil)
if !ValidCode(code) {
return m, fmt.Errorf("invalid multihash code %d", code)
}
var d []byte
switch code {
case SHA1:
d = sumSHA1(data)
case SHA2_256:
d = sumSHA256(data)
case SHA2_512:
d = sumSHA512(data)
case SHA3:
d, err = sumSHA3(data)
default:
return m, ErrSumNotSupported
}
if err != nil {
return m, err
}
if length < 0 {
var ok bool
length, ok = DefaultLengths[code]
if !ok {
return m, fmt.Errorf("no default length for code %d", code)
}
}
return Encode(d[0:length], code)
}
func sumSHA1(data []byte) []byte {
a := sha1.Sum(data)
return a[0:20]
}
func sumSHA256(data []byte) []byte {
a := sha256.Sum256(data)
return a[0:32]
}
func sumSHA512(data []byte) []byte {
a := sha512.Sum512(data)
return a[0:64]
}
func sumSHA3(data []byte) ([]byte, error) {
h := sha3.New512()
if _, err := h.Write(data); err != nil {
return nil, err
}
return h.Sum(nil), nil
}