An arrangement for establishing a digital crypto group, the arrangement comprising: - a cryptographic engine configured to produce cryptoproducts from given input data, and - a receiving end and a transmitting end of a secure transport mechanism coupled to said cryptographic engine; wherein said cryptographic engine is configured to respond to receiving, through said secure transport mechanism, a first request containing a plurality of user identifiers by producing a cryptoproduct, and wherein said cryptographic engine is configured to respond to receiving, through said secure transport mechanism, a subsequent second request containing one of said plurality of user identifiers by transmitting said cryptoproduct through said secure transport mechanism; wherein said cryptoproduct is a digital crypto group that contains said plurality of user identifiers and at least one of: - a common cryptographic key for use in symmetric cryptography between users identified by said plurality of user identifiers, - user-specific and user-identifier-related public keys for use in asymmetric cryptography in communications between users identified by said plurality of user identifiers. - a cryptographic engine configured to produce cryptoproducts from given input data, and - a receiving end and a transmitting end of a secure transport mechanism coupled to said cryptographic engine; wherein said cryptographic engine is configured to respond to receiving, through said secure transport mechanism, a first request containing a plurality of user identifiers by producing a cryptoproduct, and wherein said cryptographic engine is configured to respond to receiving, through said secure transport mechanism, a subsequent second request containing one of said plurality of user identifiers by transmitting said cryptoproduct through said secure transport mechanism; wherein said cryptoproduct is a digital crypto group that contains said plurality of user identifiers and at least one of: - a common cryptographic key for use in symmetric cryptography between users identified by said plurality of user identifiers, - user-specific and user-identifier-related public keys for use in asymmetric cryptography in communications between users identified by said plurality of user identifiers. wherein said cryptographic engine is configured to respond to receiving, through said secure transport mechanism, a first request containing a plurality of user identifiers by producing a cryptoproduct, and wherein said cryptographic engine is configured to respond to receiving, through said secure transport mechanism, a subsequent second request containing one of said plurality of user identifiers by transmitting said cryptoproduct through said secure transport mechanism; wherein said cryptoproduct is a digital crypto group that contains said plurality of user identifiers and at least one of: - a common cryptographic key for use in symmetric cryptography between users identified by said plurality of user identifiers, - user-specific and user-identifier-related public keys for use in asymmetric cryptography in communications between users identified by said plurality of user identifiers. - a common cryptographic key for use in symmetric cryptography between users identified by said plurality of user identifiers, - user-specific and user-identifier-related public keys for use in asymmetric cryptography in communications between users identified by said plurality of user identifiers. <EOS>