Identity and access management in computer systems without the need for a central authority is provided. A user may create an identity on a blockchain, and generate a one-time pad of access passwords derived from repeated hashing of a master password and cryptographic salt. The user may publish a last access password from the one-time pad on the blockchain. The user may then provide proof of identify in response to an access challenge by revealing a prior access password from which the last access password is derived, and may receive a session token in response. The publishing of access passwords and receiving of session tokens may be associated with a transfer of tokens or digital credits of commercial value on the blockchain.