Patent Number: 
Section: claims

1. A computer implemented method for providing general data protection regulation (GDPR) compliant hashing in blockchain ledgers, the method comprising:receiving a first message from a user at a blockchain gateway device, wherein the first message comprises personal identification information (PII);performing, at the blockchain gateway device, a first hashing function on the first message to obtain a hash value of the first message;storing the hash value of the first message in a blockchain ledger;storing the first hashing function in an off-chain database;storing the first message in the off-chain databasesreceiving, at the blockchain gateway device, a request to delete the first message;arbitrarily selecting a second message that is different than the first message;calculating a second hashing function using the second message, wherein the second hashing function results in the same hash value;replacing the first message in the off-chain database with the second message;replacing the first hashing function in the off-chain database with the second hashing function; andstoring a GDPR compliant hash value of the message in the blockchain ledger. 2. The method of claim 1, wherein the personal identification information (PII) of the user is selected from social security numbers, mailing addresses, email addresses, phone numbers, IP addresses, login IDs, social media posts, digital images, geolocation data, biometric data, and behavioral data. 3. The method of claim 1, further comprising:requesting, by a data controller, a GDPR proof of compliance to the blockchain gateway device; andproviding the GDPR compliant message to the data controller in response to the request. 4. The method of claim 1, wherein the GDPR compliant message comprises a timestamp. 5. The method of claim 1, wherein the first hashing function and the second hashing function comprise a selected prime number. 6. The method of claim 1, wherein performing, at the blockchain gateway device, a first hashing function on the first message to obtain a hash value of the first message further comprises:selecting a prime number p and a primitive root g mod p;letting the first message be represented by a first residue m mod p;selecting a first hashing function as a second residue s mod p; andwherein storing the first message in the off-chain database comprises storing the first residue m mod p, storing the first hashing function in the off-chain database comprises storing the second residue s mod p, and storing the hash value of the first message in the blockchain ledger comprises storing the third residue v≡ms mod p. 7. The method of claim 6, further comprising:wherein receiving the request to delete the first message comprises a request to delete the first residue of m;wherein arbitrarily selecting a second message that is different than the first message further comprises selecting mnew mod p;wherein calculating a second hashing function using the second message, wherein the second hashing function results in the same hash value further comprises calculating snew≡vmnew−1 mod p; andwherein replacing the first message in the off-chain database with the second message further comprises replacing m in the off-chain database with mnew;wherein replacing the first hashing function in the off-chain database with the second hashing function further comprises replacing s with snew. 8. The method of claim 6, wherein the prime number p and the primitive root g mod p can both be made public. 9. A blockchain gateway device for providing general data protection regulation (GDPR) compliant hashing in blockchain ledgers, the system comprising:a processor; andone or more memory devices storing computer-executable instructions that, when executed with the processor, cause the system to at least:receive a first message from a user, wherein the first message comprises personal identification information (PII);perform a first hashing function on the first message to obtain a hash value of the first message;store the hash value of the first message in a blockchain ledger;store the first hashing function in an off-chain database;store the first message in the off-chain database;receive a request to delete the first message;arbitrarily select a second message that is different than the first message;calculate a second hashing function using the second message, wherein the second hashing function results in the same hash value;replace the first message in the off-chain database with the second message;replace the first hashing function in the off-chain database with the second hashing function; andstore a GDPR compliant hash value of the message in the blockchain ledger. 10. The system of claim 9, wherein the personal identification information (PII) of the user is selected from social security numbers, mailing addresses, email addresses, phone numbers, IP addresses, login IDs, social media posts, digital images, geolocation data, biometric data, and behavioral data. 11. The system of claim 9, wherein the one or more memory devices storing computer-executable instructions that, when executed with the processor, cause the system to further:receive a request from a data controller for GDPR proof of compliance; andprovide the GDPR compliant message to the data controller in response to the request. 12. The system of claim 9, wherein the GDPR compliant message comprises a timestamp. 13. The system of claim 9, wherein the first hashing function and the second hashing function comprise a selected prime number. 14. The system of claim 9, wherein the one or more memory devices storing computer-executable instructions that, when executed with the processor, cause the system to further perform a first hashing function on the first message to obtain a hash value of the first message further comprises computer-executable instructions to:select a prime number p and a primitive root g mod p;let the first message be represented by a first residue m mod p;select the first hashing function as a second residue s mod p; andstore the first residue m mod p as the first message;store second residue s mod p as the first hashing function; andstore third residue v≡ms mod p as the hash value. 15. The system of claim 14, wherein the one or more memory devices storing computer-executable instructions that, when executed with the processor, further comprises computer-executable instructions to:receive a request to delete the first residue of m;select a second message that is different than the first message as mnew mod p;calculate a second hashing function using the second message, wherein the second hashing function results in the same hash value, as snew≡vmnew−1 mod p; andreplace the first message in the off-chain database with the second message by replacing m in the off-chain database with mnew;replace the first hashing function in the off-chain database with the second hashing function by replacing s with snew. 16. The system of claim 14, wherein the prime number p and the primitive root g mod p can both be made public. 17. One or more non-transitory computer-readable media having computer-executable instructions for performing a method of running a software program on a computing device for providing general data protection regulation (GDPR) compliant hashing in blockchain ledgers, the method comprising, the computing device operating under an operating system, the method including issuing instructions from the software program comprising:receiving a first message from a user at a blockchain gateway device, wherein the first message comprises personal identification information (PII);performing, at the blockchain gateway device, a first hashing function on the first message to obtain a hash value of the first message;storing the hash value of the first message in a blockchain ledger;storing the first hashing function in an off-chain database;storing the first message in the off-chain database receiving, at the blockchain gateway device, a request to delete the first message;arbitrarily selecting a second message that is different than the first message;calculating a second hashing function using the second message, wherein the second hashing function results in the same hash value;replacing the first message in the off-chain database with the second message;replacing the first hashing function in the off-chain database with the second hashing function; andstoring a GDPR compliant hash value of the message in the blockchain ledger.