Formal verification of the W3C Web Authentication Protocol

International audienceThe science of security can be set on rm foundations via the formal verication of protocols. New protocols can have their design validated in a mechanized manner for security aws, allowing protocol designs to be scientically compared in a neutral manner. Given that these techniques have discovered critical aws in protocols such as TLS 1.2 and are now being used to redesign protocols such as TLS 1.3, we demonstrate how formal verication can be used to analyze new protocols such as the W3C Web Authen-tication API. We model W3C Web Authentication with the formal verication language ProVerif, showing that the protocol itself is secure. However, we also stretch the boundaries of formal verica-tion by trying to verify the privacy properties of W3C Web Authen-tication given in terms of the same origin policy. We use ProVerif to show that without further mandatory requirements in the speci-cation, the claimed privacy properties do not hold. Next steps on how formal verication can be further integrated into standards and the further development of the privacy properties of W3C Web Authentication is outlined

Biochemical and mass spectrometric characterization of human N-acylethanolamine-hydrolyzing acid amidase inhibition.

The mechanism of inactivation of human enzyme N-acylethanolamine-hydrolyzing acid amidase (hNAAA), with selected inhibitors identified in a novel fluorescent based assay developed for characterization of both reversible and irreversible inhibitors, was investigated kinetically and using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). 1-Isothiocyanatopentadecane (AM9023) was found to be a potent, selective and reversible hNAAA inhibitor, while two others, 5-((biphenyl-4-yl)methyl)-N,N-dimethyl-2H-tetrazole-2-carboxamide (AM6701) and N-Benzyloxycarbonyl-L-serine β-lactone (N-Cbz-serine β-lactone), inhibited hNAAA in a covalent and irreversible manner. MS analysis of the hNAAA/covalent inhibitor complexes identified modification only of the N-terminal cysteine (Cys126) of the β-subunit, confirming a suggested mechanism of hNAAA inactivation by the β-lactone containing inhibitors. These experiments provide direct evidence of the key role of Cys126 in hNAAA inactivation by different classes of covalent inhibitors, confirming the essential role of cysteine for catalysis and inhibition in this cysteine N-terminal nucleophile hydrolase enzyme. They also provide a methodology for the rapid screening and characterization of large libraries of compounds as potential inhibitors of NAAA, and subsequent characterization or their mechanism through MALDI-TOF MS based bottom up-proteomics

The endogenous cannabinoid anandamide produces delta-9-tetrahydrocannabinol-like discriminative and neurochemical effects that are enhanced by inhibition of fatty acid amide hydrolase but not by inhibition of anandamide transport.

Anandamide is an endogenous ligand for brain cannabinoid CB(1) receptors, but its behavioral effects are difficult to measure due to rapid inactivation. Here we used a drug-discrimination procedure to test the hypothesis that anandamide, given i.v. or i.p., would produce discriminative effects like those of delta-9-tetrahydrocannabinol (THC) in rats when its metabolic inactivation was inhibited. We also used an in vivo microdialysis procedure to investigate the effects of anandamide, given i.v. or i.p., on dopamine levels in the nucleus accumbens shell in rats. When injected i.v., methanandamide (AM-356), a metabolically stable anandamide analog, produced clear dose-related THC-like discriminative effects, but anandamide produced THC-like discriminative effects only at a high 10-mg/kg dose that almost eliminated lever-press responding. Cyclohexyl carbamic acid 3'-carbamoyl-biphenyl-3-yl ester (URB-597), an inhibitor of fatty acid amide hydrolase (FAAH), the main enzyme responsible for metabolic inactivation of anandamide, produced no THC-like discriminative effects alone but dramatically potentiated discriminative effects of anandamide, with 3 mg/kg anandamide completely substituting for the THC training dose. URB-597 also potentiated the ability of anandamide to increase dopamine levels in the accumbens shell. The THC-like discriminative-stimulus effects of anandamide after URB-597 and methanandamide were blocked by the CB1 receptor antagonist rimonabant, but not the vanilloid VR1 receptor antagonist capsazepine. Surprisingly, the anandamide transport inhibitors N-(4-hydroxyphenyl)-eicosa-5,8,11,14-tetraenamide (AM-404) and N-(3-furylmethyl)eicosa-5,8,11,14-tetraenamide (UCM-707) did not potentiate THC-like discriminative effects of anandamide or its dopamine-elevating effects. Thus, anandamide has THC-like discriminative and neurochemical effects that are enhanced after treatment with a FAAH inhibitor but not after treatment with transport inhibitors, suggesting brain area specificity for FAAH versus transport/FAAH inactivation of anandamide

MALDI-TOF MS/MS analysis of the hNAAA tryptic peptide T10-β after covalent modification.

<p>Tandem MALDI-TOF MS/MS spectra of the T10-β peptide (sequence: CTSIVAQDSR) demonstrates covalent modification of Cys126 by both AM6701 (Panel (A)) and <i>N-</i>Cbz-serine β-lactone (Panel (B)).</p

Mass of tryptic peptide containing Cys126 of hNAAA after covalent modification.

<p>T10-β peptides identified in the tryptic digest of untreated (control) and AM6701 or N-Cbz-serine β-lactone treated hNAAA samples.</p

Representation of the active site of hNAAA after treatment with <i>N-</i>Cbz-serine β-lactone.

<p>Homology model illustrates acylated catalytic nucleophile Cys126 after treatment with <i>N-</i>Cbz-serine β-lactone.</p

Representation of the active site of hNAAA after treatment with AM6701.

<p>Homology model illustrates thiocarbamylation of catalytic nucleophile Cys126 after treatment with AM6701.</p

Concentration dependent inhibition of purified hNAAA by three compounds.

<p>hNAAA was incubated with the compounds AM6701 (squares), <i>N-</i>Cbz-serine β-lactone (circles), and AM9023 (diamonds) for two hours in order to reach full inhibition before measuring activity. Panel (A). A radioactivity-based assay with [¹⁴C] PEA as substrate. Panel (B). A fluorescence-based assay with PAMCA as substrate. Representative curves are displayed.</p

Potencies of hNAAA inhibitors.

<p>The <i>k</i>_inact and <i>K</i>_I values for the covalent inhibitors were obtained as described in the Experimental Procedures. The IC₅₀ values were calculated after 2 hours preincubation of the enzyme and inhibitor before addition of the substrate. Values are averages ± SD of three independent experiments.</p