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package sha1
import (
"encoding/binary"
)
// Size of a SHA-1 checksum in bytes.
const Size = 20
// BlockSize is the block size of SHA-1 in bytes.
const BlockSize = 64
// Sum returns the SHA-1 checksum of data.
func Sum(data []byte) [Size]byte {
n := len(data)
h := [5]uint32{0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476, 0xc3d2e1f0}
// Consume full blocks.
for len(data) >= BlockSize {
block(&h, data)
data = data[BlockSize:]
}
// Final block.
tmp := make([]byte, BlockSize)
copy(tmp, data)
tmp[len(data)] = 0x80
if len(data) >= 56 {
block(&h, tmp)
for i := 0; i < BlockSize; i++ {
tmp[i] = 0
}
}
binary.BigEndian.PutUint64(tmp[56:], uint64(8*n))
block(&h, tmp)
// Write into byte array.
var digest [Size]byte
for i := 0; i < 5; i++ {
binary.BigEndian.PutUint32(digest[4*i:], h[i])
}
return digest
}