A
system for detecting unauthorized activity in
blockchain transactions, consisting of: a
data acquisition interface operationally connected to one or more
blockchain nodes and configured to receive
transaction data including transaction identifiers, address information, transfer values, and timestamps; a preprocessing unit consisting of a normalization circuit configured to transform heterogeneous
blockchain data into a standardized internal representation stored in a storage unit; a graph construction processor connected to the storage unit and configured to generate and maintain a directed transaction graph, with nodes representing blockchain entities and edges representing value transfers with associated attributes;a classification processor with
parallel computing circuitry configured to process the directed transaction graph using a variety of graph-based learning architectures, and a probabilistic modeling unit configured to compute higher-order dependencies between node features, structural relationships, and temporal attributes; an aggregation unit configured to combine the outputs of the classification processor to generate a
risk assessment indicating illegal activity for at least one node or edge of the transaction graph; an optimization processor coupled to the classification processor and configured to iteratively select feature sets and determine weighting parameters to be assigned to the aggregation unit based on a predefined performance target;a perturbation generation processor configured to create modified instances of the directed transaction graph by modifying at least one of the following properties: graph topology, temporal attributes, or transaction values; a robustness assessment unit configured to compute stability
metrics of the risk
score among the modified instances of the directed transaction graph; and a cryptographic processor consisting of post-
quantum cryptography circuits configured to secure the
system's
data transmission, storage, and audit logs.