Table 2.

Security requirements for different image sharing topologies

	Requirements	Central repository and distributed security	Distributed repository and central security	Distributed repository and distributed security
Data transformation	De-identification		Need consistent de-identification approach	Need consistent de-identification approach
	Research identifier		Need global identifier	Need global identifier
	Privacy preserving transformation		Consistent transformation	Consistent transformation
	Encryption		Encryption by each repository using same mechanism	Encryption by each repository using same mechanism
	Signature		Signature for each repository	Signature for each repository
	Honest Broker		Consistency between brokers critical	Consistency between brokers critical
Infrastructure	Policy management	Consistent policies in different systems and coordinate different systems		Consistent policies in different systems and coordinate different systems
	User identity management	Each organization manages own users		Each organization manages own users
	User role and attribute management	Cross-institutional roles important		Cross-institutional roles important
	Authentication	Authentication against local identity provider. Security token needs to be acceptable by all		Authentication against local identity provider. Security token needs to be acceptable by all
	Audit log management	Log may need to be managed by and potentially replicated at multiple sites. Log mining would require accessing multiple log repositories		Log may need to be managed by and potentially replicated at multiple sites. Log mining would require accessing multiple log repositories
	Trust management	Critical to have well established trust fabric between security components		Critical to have well established trust fabric between security components
Data access and movement	Authorization	May need to combine multiple authorization policies	Each repository needs to enforce authorization	May need to combine multiple authorization policies. Each repository needs to enforce authorization
	Delegation
	Audit logging	May need to log to multiple log management services		May need to log to multiple log management services
	Non-repudiation
	Transmission protection