It has been conventional wisdom that, for e-commerce to fulfil its potential, each party to a transaction must be confident about the identity of the others. Digital signature technology, based on public key cryptography, has been claimed as appropriate means to achieve this aim. Digital signatures do little, however, unless a substantial 'public key infrastructure' (PKI) is in place, such that parties know what is being authenticated, and what level of assurance is provided. Conventional PKI, built around the ISO standard X.509, has been, and will continue to be, a substantial failure. This paper examines conventional X.509v3-based PKI architecture, and identifies key deficiencies including its inherently hierarchical and authoritarian nature, its unreasonable presumptions about the security of private keys, a range of other technical and implementation defects, confusions about what it is that a certificate actually provides assurance about, and its inherent privacy-invasiveness. A model is presented that explains the naiveté of identity authentication, and how ecommerce needs to be baaed on ‘nyms‘ rather than ‘identifiers‘. Alternatives to conventional PKI are identified.