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From: "Elliott, Robert (Servers)" <elliott@hpe.com>
To: Eric Biggers <ebiggers@kernel.org>,
	"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
	David Howells <dhowells@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Petr Pavlu <petr.pavlu@suse.com>,
	Daniel Gomez <da.gomez@kernel.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	"Jason A . Donenfeld" <Jason@zx2c4.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	"Stephan Mueller" <smueller@chronox.de>,
	Lukas Wunner <lukas@wunner.de>,
	"Ignat Korchagin" <ignat@cloudflare.com>,
	"keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
	"linux-modules@vger.kernel.org" <linux-modules@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v2 1/2] lib/crypto: Add ML-DSA verification support
Date: Wed, 26 Nov 2025 21:29:10 +0000	[thread overview]
Message-ID: <IA4PR84MB4011F4D5B7EF52901829AD94ABDEA@IA4PR84MB4011.NAMPRD84.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <20251126203517.167040-2-ebiggers@kernel.org>



> -----Original Message-----
> From: Eric Biggers <ebiggers@kernel.org>
> Subject: [PATCH v2 1/2] lib/crypto: Add ML-DSA verification support
...

> +++ b/lib/crypto/mldsa.c

> +} mldsa_parameter_sets[] = {
> +	[MLDSA44] = {
> +		.ctilde_len = 32,
> +		.pk_len = MLDSA44_PUBLIC_KEY_SIZE,
> +		.sig_len = MLDSA44_SIGNATURE_SIZE,
> +	},
> +	[MLDSA65] = {
> +		.ctilde_len = 48,
> +		.pk_len = MLDSA65_PUBLIC_KEY_SIZE,
> +		.sig_len = MLDSA65_SIGNATURE_SIZE,
> +	},
> +	[MLDSA87] = {
> +		.ctilde_len = 64,
> +		.pk_len = MLDSA87_PUBLIC_KEY_SIZE,
> +		.sig_len = MLDSA87_SIGNATURE_SIZE,
> +	},
...
> +	union {
...
> +		/* The commitment hash.  Real length is params->ctilde_len */
> +		u8 ctildeprime[64];
> +	};
...
> +	/* Recreate the challenge c from the signer's commitment hash. */
> +	sample_in_ball(&ws->c, ctilde, params->ctilde_len, params->tau,
> +		       &ws->shake);
...
> +	/* Finish computing ctildeprime. */
> +	shake_squeeze(&ws->shake, ws->ctildeprime, params->ctilde_len);
...
> +	/* Verify that ctilde == ctildeprime. */
> +	if (memcmp(ws->ctildeprime, ctilde, params->ctilde_len) != 0)
> +		return -EKEYREJECTED;

Is there any way to ensure that each ctilde_len value is <= 64
and <= the corresponding .sig_size value at compile time so there's
no risk of overflowing any buffers?


  reply	other threads:[~2025-11-26 21:29 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-26 20:35 [PATCH v2 0/2] lib/crypto: ML-DSA verification support Eric Biggers
2025-11-26 20:35 ` [PATCH v2 1/2] lib/crypto: Add " Eric Biggers
2025-11-26 21:29   ` Elliott, Robert (Servers) [this message]
2025-11-26 21:42     ` Eric Biggers
2025-11-26 20:35 ` [PATCH v2 2/2] lib/crypto: tests: Add KUnit tests for ML-DSA verification Eric Biggers

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