According to the World Health Organization, the world’s illegal drug market is $30 billion. It is estimated that one in ten medicines in middle-income and low-income developing countries is counterfeit. People who take such medication lose money and put their health and life at serious risk.

Substandard drugs are dangerous. Falsified and substandard drugs, which could contain inactive ingredients, active ingredients but in the wrong dosage, or potential contaminants, could be lethal.

Blockchain is an electronic cryptographic ledger that follows a decentralized network model—instead of storing all information in one database such as in conventional cloud-based applications, the information is distributed and synchronized duplication (or double spending) by allowing nodes to verify true information. Once verified, information is added to the hash value of a previous block, and the new sequence (i.e., previous hash + newly verified information) is hashed to form a new block using a cryptographic (i.e., one-way) hash function.

A cryptographic hash value is a string of non-readable letters and numbers of consistent length representing information subjected to a hash algorithm. Each hash value is unique to the information from which it was derived. These characteristics, in addition to the network forcing continuous synchrony across all nodes, make blockchain immutable and tamper-resistant. Although cryptographic hashing is one-way, the decrypted information can be rehashed and compared with the stored hash value in the ledger.