COMPREHENSIVE SECURITY ANALYSIS

Comprehensive security analysis of two architectural approaches for implementing a digital signature system.

Security Parameter	Rating	Expert Explanation
Technical Complexity of Interception	EXTREMELY HIGH	Requires compromising a Certificate Authority or zero-day exploits
Time to Decrypt TLS 1.3	5-10+ YEARS	Modern 128-bit+ ciphers are practically unbreakable with current technology
Risk of Incomplete Interception	HIGH	Loss of even 1 byte of data renders all intercepted information useless
Selective Packet Interception	IMPOSSIBLE	Attacker cannot determine in advance which packets contain critical data
Practical Feasibility	0.001%	Available only to state-level attackers with unlimited resources

CONCLUSION: Interception and decryption of HTTPS in real-world conditions represents a theoretical threat with no practical significance for system security assessment.

Table 1: CRYPTOGRAPHIC SECURITY

Security Criterion	Server-side Approach	Client-side Approach
Private Key Protection	CONDITIONAL (temporary storage)	COMPLETE (not transmitted)
User Data Integrity	GUARANTEED	UNCONTROLLED
Resistance to MITM Attacks	HIGH (HTTPS)	HIGH (HTTPS)
Protection Against Identity Forgery	COMPLETE	ABSENT

Table 2: OPERATIONAL RISKS

Criterion	Server-side Approach	Client-side Approach
Mass Compromise	MEDIUM RISK	MINIMAL
User Data Loss	LOW	HIGH (formatting)
Legal Responsibility	CONTROLLABLE	UNCONTROLLABLE
Third-Party Trust	HIGH	LOW

Table 3: MULTI-SIGNATURE IMPLEMENTATION CAPABILITIES

Functional Aspect	Server-side Approach	Client-side Approach	Explanation of Limitations
Participant Coordination	✅ COMPLETE	❌ IMPOSSIBLE	Clients cannot coordinate the process among themselves without a central server
Original Integrity Guarantee	✅ GUARANTEED	❌ IMPOSSIBLE	No way to guarantee all participants are signing the identical document version
Signature Combination	✅ AUTOMATIC	❌ MANUAL	Collecting signatures from multiple participants requires manual file merging
Document Version Control	✅ CENTRALIZED	❌ ABSENT	Impossible to prevent signing of outdated document versions
Business Process Workflow	✅ SUPPORTED	❌ IMPOSSIBLE	Complex signing chains (Director→Accountant→Lawyer) are unfeasible
Legal Force of Multi-signature	✅ GUARANTEED	❌ QUESTIONABLE	Lack of process control casts doubt on legal significance

CRITICAL PROBLEMS WITH CLIENT-SIDE MULTI-SIGNATURE:

• ❌ Coordination Problem - absence of a single process coordinator
• ❌ Integrity Problem - inability to guarantee document identity for all participants
• ❌ Order Problem - lack of control over signing sequence
• ❌ Versioning Problem - risk of signing different document versions
• ❌ Scalability Problem - difficulty managing large numbers of participants

CONCLUSION: Multi-signature is a killer-feature that architecturally requires a server component. A purely client-side implementation is impossible for practical use in business processes.

Security Threat	Probability	Impact	Overall Risk	Priority
Client-side: Identity Forgery	HIGH	CRITICAL	CRITICAL	1
Client-side: Multi-signature Impossibility	100%	HIGH	CRITICAL	1
Client-side: Key Loss	MEDIUM	HIGH	HIGH	2
Server-side: Infrastructure Attack	MEDIUM	MEDIUM	MEDIUM	3
Server-side: Temporary Key Storage	LOW	MEDIUM	LOW	4
HTTPS Traffic Interception	EXTREMELY LOW	HIGH	MINIMAL	5

ADVANTAGES OF SERVER-SIDE APPROACH:

• ✅ Guaranteed Authenticity of user identification data
• ✅ Full Multi-signature Support for complex business processes
• ✅ Legal Protection for the service and end users
• ✅ Controlled Environment for performing critical cryptographic operations
• ✅ Easy Recovery in case of user data loss
• ✅ Third-Party Trust in created digital signatures

IRREMEDIABLE DISADVANTAGES OF CLIENT-SIDE APPROACH:

• ❌ Fundamental Vulnerability to user identity forgery
• ❌ Architectural Impossibility of implementing multi-signatures
• ❌ Absence of Legal Force in created digital signatures
• ❌ Impossibility of Trust from third parties and organizations
• ❌ High Operational Risks for end users
• ❌ Unlimited Duplication of user identifiers