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Questions tagged [umac]

UMAC is a family of message authentication codes defined in RFC 4418. UMAC supports 32-, 64-, 96-, and 128-bit tags. UMAC uses a PRF, typically instantiated with AES-128, to expand a short key into a long, 1–1.5 KiB, key for a large universal hash family to hash many messages, and encrypts each message's hash with a one-time pad generated by the PRF from a per-message nonce, in Carger–Wegman construction, to form the message's authentication tag.

UMAC is a family of message authentication codes defined in RFC 4418. UMAC supports 32-, 64-, 96-, and 128-bit tags. UMAC uses a PRF, typically instantiated with AES-128, to expand a short key into a long, 1–1.5 KiB, key for a large universal hash family to hash many messages, and encrypts each message's hash with a pseudorandom pad generated by the PRF from a per-message nonce, in Carger–Wegman construction, to form the message's authentication tag.

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Is this algorithm good enough for small radio messages?

This question is related to: How to implement security - authenticity/confidentiality/integrity for 6/14 bits radio messages? I am looking for a message that an attacker listening to the radio trafic will need at least 2 weeks to break it. I came…
Victor Iorinescu
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Is the NH hash family (from UMAC) AXU?

For any positive integer $k$, let $\boxplus_k$ be addition on $k$-bit unsigned integers and $\boxminus_k$ be subtraction on $k$-bit unsigned integers. Let $\operatorname{NH}_w((X,Y),(a,b)) = (a \boxplus_w X)\cdot(b \boxplus_w Y)$. For any binary…
jbapple
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How to implement security - authenticity/confidentiality/integrity for 6/14 bits radio messages?

I just took over two radio systems (using 433Mhz) - one communicates with 6 bit messages, one with 14 bit messages. Both have a lots of transmitters and one receiver (and, yes bits not bytes). For the first, 4 bits are used for the ID of the device,…
Victor Iorinescu
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How to look for implementations of universal hashing?

Being a physicist, I know very little about cryptography. In fact, the main two practical aspects I've learned so far are: Unless you're an expert, 1. Don't try to invent new cryptosystems and 2. Don't implement cryptographic algorithms yourself if…
Adomas Baliuka
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How to use the wiki UMAC example function?

I want to use the wiki UMAC example to protect the integrity of the communication between 2 devices. Unfortunately I am not quite sure of the meaning of the parameters and I don't want to get it wrong: The following C function generates a 24 bit…
John Rastem
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why is index "a non-negative integer less than $2^{64}$" in the KDF for UMACs?

https://www.rfc-editor.org/rfc/rfc4418#section-3.2.1 describes the parameters for KDF as follows: Input: K, string of length KEYLEN bytes. index, a non-negative integer less than 2^64. numbytes, a non-negative integer less than…
neubert
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