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Chaskey is never claimed to be a cipher.

While Chaskey is it self constructed as CMAC/OMAC with EvanMansour block cipher, afaik it was never claimed its building block (EM block cipher) is safe to be used as standalone building block for encryption. More over, cryptoanalyzes have sentences about "attaker has no way for chosen ciphertext attack".

May be I'm missing something? Can you point on investigations?

Wrong result if an instance is reused with a shorter message length

var mac = new ChaskeyCipher.Mac();	// instantiate a cipher in MAC mode
mac.set([1,2,3,4]);			// set the key
console.log(mac.sign(new Uint8Array(0))); 
console.log(mac.sign(new Uint8Array(0)));
console.log(mac.sign(new Uint8Array(17)));
console.log(mac.sign(new Uint8Array(0)));

prints the following:

Uint8Array(16) [164, 51, 219, 196, 236, 190, 42, 255, 44, 145, 84, 85, 202, 211, 40, 178]
Uint8Array(16) [164, 51, 219, 196, 236, 190, 42, 255, 44, 145, 84, 85, 202, 211, 40, 178]
Uint8Array(16) [206, 55, 154, 136, 95, 96, 215, 4, 30, 37, 59, 16, 223, 175, 215, 176]
Uint8Array(16) [89, 208, 133, 178, 254, 56, 60, 179, 61, 217, 110, 222, 43, 11, 187, 61]

I expect the last line to be

Uint8Array(16) [164, 51, 219, 196, 236, 190, 42, 255, 44, 145, 84, 85, 202, 211, 40, 178]

The reason is that the formatter object's byte buffer is not reset completely upon reset. It is filled with zeros instead of truncated to zero length.

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