A coupon-minter is configured to perform operations including: generating a coupon comprising encrypted discount information, wherein the encrypted discount information is encrypted with a discount key; generating, for the coupon, a hashlock from a preimage; introducing the coupon to a blockchain in association with the hashlock, wherein the blockchain is configured to permit claiming of the generated coupon only upon receiving access to the preimage used to generate the hashlock. A store-manager configured to perform operations including: claiming, using the preimage, the coupon in the blockchain; encrypting the discount key with a clearing-house public key; updating the coupon with the encrypted discount key. A clearing-house-manager configured to perform operations comprising: detecting the store-manager's claiming of the coupon; decrypting the encrypted discount key with a clearing-house private key to re-generate the discount key; and decrypting the encrypted discount information with the preimage.