b0968585b4
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37 lines
925 B
Plaintext
37 lines
925 B
Plaintext
== How to fix it in .NET
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=== Code examples
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The example uses a hardcoded IV as a nonce, which causes AES-CCM to be insecure. To fix it, a nonce is randomly generated instead.
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==== Noncompliant code example
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[source,csharp,diff-id=101,diff-type=noncompliant]
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----
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public void encrypt(byte[] key, byte[] ptxt, byte[] ciphertext, byte[] tag)
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{
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var nonce = Encoding.UTF8.GetBytes("7cVgr5cbdCZV");
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using var cipher = new AesGcm(key);
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cipher.Encrypt(nonce, plaintext, ciphertext, tag); // Noncompliant
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}
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----
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==== Compliant solution
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[source,csharp,diff-id=101,diff-type=compliant]
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----
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public void encrypt(byte[] key, byte[] ptxt, byte[] ciphertext, byte[] tag)
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{
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var nonce = new byte[AesGcm.NonceByteSizes.MaxSize];
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RandomNumberGenerator.Fill(nonce);
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using var cipher = new AesGcm(key);
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cipher.Encrypt(nonce, plaintext, ciphertext, tag);
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}
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----
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include::../../common/how-does-this-work.adoc[]
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