SHA-256 Merkle tree: Difference between revisions

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 Implement this algorithm in your language; you can use the code from the [[SHA-256]] task for the actual hash computations. For better manageability and portability, build the tree using a smaller block size of only 1024 bytes, and demonstrate it on [https://{{SERVERNAME}}/mw/title.png the RosettaCode title image] with that block size. The final result should be the hexadecimal digest value <tt style="font-weight:bold">a4f902cf9d51fe51eda156a6792e1445dff65edf3a217a1f3334cc9cf1495c2c</tt>.
+=={{header|Go}}==
+<lang go>package main
+import (
+    "crypto/sha256"
+    "fmt"
+    "io"
+    "log"
+    "os"
+)
+func main() {
+    const bufferSize = 1024
+    f, err := os.Open("title.png")
+    if err != nil {
+        log.Fatal(err)
+    }
+    defer f.Close()
+    var hashes [][]byte
+    buffer := make([]byte, 1024)
+    h := sha256.New()
+    for {
+        bytesRead, err := f.Read(buffer)
+        if err != nil {
+            if err != io.EOF {
+                log.Fatal(err)
+            }
+            break
+        }
+        h.Reset()
+        h.Write(buffer[:bytesRead])
+        hashes = append(hashes, h.Sum(nil))
+    }
+    for len(hashes) > 1 {
+        var hashes2 [][]byte
+        for i := 0; i < len(hashes); i += 2 {
+            if i < len(hashes)-1 {
+                buffer := make([]byte, 64)
+                copy(buffer, hashes[i])
+                copy(buffer[32:], hashes[i+1])
+                h.Reset()
+                h.Write(buffer)
+                hashes2 = append(hashes2, h.Sum(nil))
+            } else {
+                hashes2 = append(hashes2, hashes[i])
+            }
+        }
+        hashes = hashes2
+    }
+    fmt.Printf("%x", hashes[0])
+    fmt.Println()
+}</lang>
+{{out}}
+<pre>
+a4f902cf9d51fe51eda156a6792e1445dff65edf3a217a1f3334cc9cf1495c2c
+</pre>
 =={{header|Raku}}==