a first signing step in which a transaction message comprising a request and a transaction identifier is cryptographically signed by said first party to form a first cryptographically signed message;

a first transmitting step in which said first cryptographically signed message is transmitted from said first party to said second party;

a second signing step in which said second party cryptographically signs said first cryptographically signed message to form a second cryptographically signed message;

a third transmitting step in which said second cryptographically signed message is transmitted from one or more of a plurality of parties having said second cryptographically signed message to a trusted third party;

a first verification step in which said trusted third party verifies that said second cryptographically signed message was cryptographically signed by said second party;

a second verification step in which said trusted third party verifies that said first cryptographically signed message in said second cryptographically signed message was cryptographically signed by said first party; and

a transaction execution step in which, in response to positive verifications from said first verification step and said second verification step, said trusted third party manages execution of said request specified by said second cryptographically signed message.

a second transmitting step in which said second cryptographically signed message is transmitted from said second party to said first party.

a first presence detecting step in which a physical presence of a first authorised user is detected by said first party prior to said first signing step.

a second presence detecting step in which a physical presence of a second authorised user is detected by said second party prior to said second signing step.

said plurality of parties are respective independent sources for a plurality of routes for said second cryptographically signed message to reach said trusted third party.

said transaction message comprises a payload.

said payload comprises encrypted data; and

said trusted third party stores a decrypting means for decrypting said encrypted data.

a resolution step in which said decrypting means is transmitted to said second party by said trusted third party in response to positive verifications from said first verification step and said second verification step.

said transaction identifier is generated using a random or pseudo-random number generator.

said first cryptographically signed message comprises a unique identifier for said first party.

said unique identifier for said first party is selected by said first party from a first plurality of unique identifiers.

said second cryptographically signed message comprises a unique identifier for said second party.

said unique identifier for said second party is selected by said second party from a second plurality of unique identifiers.

said second party verifies that said first cryptographically signed message was cryptographically signed by said first party.

said first party verifies that said second cryptographically signed message was cryptographically signed by said second party.

a witnessing step in which a witness receives said second cryptographically signed message and cryptographically signs said second cryptographically signed message to form a third cryptographically signed message; and

a witness verification step in which said trusted third party verifies that said third cryptographically signed message was cryptographically signed by said witness,

wherein said second cryptographically signed message is transmitted to said third trusted party as part of said third cryptographically signed message.

said first signing step uses a first private key from a first public/private key pair; and

said second signing step uses a second private key from a second public/private key pair

said first verification step uses a first public key from said first public/private key pair; and

said second verification step uses a second public key from said second public/private key pair.

a first party comprising:

first signing circuitry configured to cryptographically sign a transaction message comprising a request and a transaction identifier to form a first cryptographically signed message; and

first transmitting circuitry configured to transmit said first cryptographically signed message to a second party;

said second party comprising:

second signing circuitry configured to cryptographically sign said first cryptographically signed message to form a second cryptographically signed message; and

a trusted third party comprising:

receiving circuitry configured to receive said second cryptographically signed message transmitted from one or more of a plurality of parties having said second cryptographically signed message to said trusted third party;

first verification circuitry configured to verify that said second cryptographically signed message was cryptographically signed by said second party; and

second verification circuitry configured to verify that said first cryptographically signed message in said second cryptographically signed message was cryptographically signed by said first party

transaction executing circuitry configured to execute said request specified by said second cryptographically signed message in response to positive verifications from said first verification circuitry and second verification circuitry.

signing circuitry configured to cryptographically sign a transaction message comprising a request and a transaction identifier to form a first cryptographically signed message; and

first transmitting circuitry configured to transmit said first cryptographically signed message to said second party;

receiving circuitry configured to receive a second cryptographically signed message, said second cryptographically signed message comprising said first cryptographically signed message, wherein said second cryptographically signed message is cryptographically signed by said second party; and

second transmitting circuitry configured to transmit said second cryptographically signed message to a trusted third party.

receiving circuitry configured to receive a first cryptographically signed message, said first cryptographically signed message comprising a request and a transaction identifier, wherein said first cryptographically signed message is cryptographically signed by said first party;

signing circuitry configured to cryptographically sign said first cryptographically signed message to form a second cryptographically signed message; and

second transmitting circuitry configured to transmit said second cryptographically signed message to a trusted third party.

receiving circuitry configured to receive a second cryptographically signed message comprising a first cryptographically signed message comprising a request and a transaction identifier;

first verification circuitry configured to verify that said second cryptographically signed message is cryptographically signed by said second party; and

second verification circuitry configured to verify that said first cryptographically signed message in said second cryptographically signed message is cryptographically signed by said first party;

transaction executing circuitry configured to execute said request specified by said second cryptographically signed message in response to positive verifications from said first verification circuitry and second verification circuitry.