Odd hash.Sum call flow

This product is not supported for your selected Datadog site. ().
Cette page n'est pas encore disponible en français, sa traduction est en cours.
Si vous avez des questions ou des retours sur notre projet de traduction actuel, n'hésitez pas à nous contacter.

Metadata

ID: go-security/hashsum

Language: Go

Severity: Error

Category: Error Prone

Description

When you use a hash function that implements hash.Hash, you need to use Write() to provide the data before calling Sum().

// Correct usage of hash.Hash
h := sha256.New()
h.Write(data)
sum := h.Sum(nil)
// 'sum' contains the SHA256 sum of 'data'

Since the Sum() member function takes a byte array as an argument, it is a common mistake to believe that this argument contains the data to be hashed. In reality, this argument contains some data to which the hash will be appended.

// Incorrect usage of hash.Hash
h := sha256.New()
sum := h.Sum(data)
// wrong: 'sum' contains 'data' followed by the SHA256 sum of an empty string

This rule detects these erroneous usages of hash.Hash.

Non-Compliant Code Examples

import "crypto/sha256"

func main() {
    out := make([]byte, 64)
    h := sha256.New()
    hashed := h.Sum(out)

    hashed := sha256.New().Sum(out)
}

Compliant Code Examples

import "crypto/sha256"

func main() {
    arr := []byte{1, 2, 3}
    out := make([]byte, 64)
    h := sha256.New()
    h.Write(arr)
    hashed := h.Sum(out)

    h2 := sha256.New()
    hashArr(h2, arr)
    hashed2 := h2.Sum(out)
}

func hashArr(h hash.Hash, b []byte) {
    h.Write(b)
}
https://static.datadoghq.com/static/images/logos/github_avatar.svg https://static.datadoghq.com/static/images/logos/vscode_avatar.svg jetbrains

Seamless integrations. Try Datadog Code Security

Datadog Code Security