[golang-dev] code review 10571043: crypto/sha1: provide a top-level Sum function (issue 10571043)

Reviewers: golang-dev1,

Message:
Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://code.google.com/p/go


Description:
crypto/sha1: provide a top-level Sum function
Makes it easy to ask the simple question, what is the hash of this data?

Please review this at https://codereview.appspot.com/10571043/

Affected files:
    M src/pkg/crypto/sha1/sha1.go


Index: src/pkg/crypto/sha1/sha1.go
===================================================================
--- a/src/pkg/crypto/sha1/sha1.go
+++ b/src/pkg/crypto/sha1/sha1.go
@@ -90,9 +90,13 @@
   func (d0 *digest) Sum(in []byte) []byte {
    // Make a copy of d0 so that caller can keep writing and summing.
    d := *d0
+ hash := d.checkSum()
+ return append(in, hash[:]...)
+}

+func (d *digest) checkSum() [Size]byte {
+ len := d.len
    // Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
- len := d.len
    var tmp [64]byte
    tmp[0] = 0x80
    if len%64 < 56 {
@@ -120,5 +124,13 @@
     digest[i*4+3] = byte(s)
    }

- return append(in, digest[:]...)
+ return digest
   }
+
+// Sum returns the SHA1 checksum of the data.
+func Sum(data []byte) [Size]byte {
+ var d digest
+ d.Reset()
+ d.Write(data)
+ return d.checkSum()
+}