# US 11,310,217 B2 · Using ephemeral URL passwords to deter high-volume attacks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,310,217 B2 - Document ID: US11310217B2 - Status: Granted - Kind: B2 - Application number: 16/124,728 - Filed: 2018-09-07 - Published: 2020-03-12 - Granted: 2022-04-19 - Earliest claimed: 2018-09-07 - Assignees: Paypal, Inc. - Applicants: Paypal, Inc. - Inventors: John Franco - Web page: https://patentgrep.com/patent/US11310217B2 ## CPC - H04L 9/3271: {using challenge-response} - H04L 63/083: {using passwords (cryptographic mechanisms or cryptographic arrangements for entity authentication using a predetermined code H04L9/3226)} - H04L 9/002: {Countermeasures against attacks on cryptographic mechanisms (network architectures or network communication protocols for protection against malicious traffic H04L63/1441)} - H04L 9/0643: {Hash functions, e.g. MD5, SHA, HMAC or f9 MAC} - H04L 9/3228: {One-time or temporary data, i.e. information which is sent for every authentication or authorization, e.g. one-time-password, one-time-token or one-time-key} - H04L 9/3242: {involving keyed hash functions, e.g. message authentication codes [MACs], CBC-MAC or HMAC} - H04L 63/0838: {using one-time-passwords} - H04L 63/126: {the source of the received data} - H04L 63/1441: {Countermeasures against malicious traffic (countermeasures against attacks on cryptographic mechanisms H04L9/002)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Methods and systems for using ephemeral URL passwords to deter high volume attacks is described. A request to access one of several protected URLs is detected from a client computing device. A URL password is received from the client computing device. The request is redirected to the protected URL upon determining that the received URL password is valid for the one of the several of protected URLs. ## Claims ### Claim 1 A system for protecting uniform resource locators (URLs) comprising: a non-transitory memory storing instructions; and one or more hardware processors coupled to the non-transitory memory and configured to read the instructions from the non-transitory memory to cause the system to perform operations comprising: detecting a first request to access a protected URL from a client computing device; providing, to the client computing device, a second request for a URL password, wherein the second request includes a nonce comprising a server-generated string; receiving, from the client computing device and in response to the second request, the URL password including a parameter computable by the client computing device using a hash-based computation, wherein the parameter, when used as a key in the hash-based computation on the nonce provided to the client computing device, enables a signature having a prefix associated with the protected URL to be produced by the client computing device; and redirecting the first request to the protected URL upon determining that the received URL password is valid for the protected URL by confirming the parameter used in the hash-based computation on the nonce results in the signature having the prefix. ### Claim 2 (depends on 1) The system of claim 1, wherein the hash-based computation is performed in response to a challenge-response problem provided in a codebook downloadable by the client computing device. ### Claim 3 (depends on 2) The system of claim 2, wherein the URL password is determined to be valid when i) the codebook is determined to not be expired, ii) the URL password is not found in a cache of previously used passwords, iii) the URL password is a proper response to the challenge-response problem, and iv) the challenge-response problem solved by the URL password is associated with the protected URL in the codebook that matches the first request. ### Claim 4 (depends on 2) The system of claim 2, wherein the challenge-response problem is associated with the protected URL. ### Claim 5 (depends on 2) The system of claim 2, wherein the challenge-response problem is a hash-based message authentication code (HMAC) operation. ### Claim 6 (depends on 1) The system of claim 1, wherein: the hash-based computation is a HMAC operation that uses a SHA-256 function as a hash function of the HMAC operation; and the parameter is a 256-bit value. ### Claim 7 (depends on 6) The system of claim 6, wherein the received URL password is validated when the system generates the signature having the prefix upon using the 256-bit value to sign the nonce with the SHA-256 function. ### Claim 8 A method for protecting URLs, the method comprising: detecting a request to access a protected URL from a client computing device; providing, to the client computing device, a nonce comprising a server-generated string; receiving, from the client computing device, a URL password based on a codebook downloaded by the client computing device, the URL password including a parameter computable by the client computing device using a hash-based computation, wherein the parameter, when used as a key in the hash-based computation on the nonce provided to the client computing device, enables a signature having a prefix associated with the protected URL to be produced by the client computing device; determining that the codebook on which the received URL password is based is not expired; determining that the received URL password is not found in a cache of previously used URL passwords; determining that the received URL password is valid for the protected URL by confirming the parameter used in the hash-based computation on the nonce results in the signature having the prefix; and redirecting the request to the protected URL. ### Claim 9 (depends on 8) The method of claim 8, wherein the hash-based computation is performed in response to a challenge-response problem provided in the codebook downloaded by the client computing device. ### Claim 10 (depends on 9) The method of claim 9, wherein the challenge-response problem is associated with the protected URL. ### Claim 11 (depends on 9) The method of claim 9, wherein the challenge-response problem is an HMAC operation. ### Claim 12 (depends on 11) The method of claim 11, wherein: the hash-based computation is a HMAC operation that uses a SHA-256 function as a hash function of the HMAC operation; and the parameter is a 256-bit value. ### Claim 13 (depends on 12) The method of claim 12, wherein the determining that the received URL password is valid includes generating the signature having the prefix upon using the 256-bit value to sign the nonce with the SHA-256 function. ### Claim 14 A non-transitory machine-readable medium having stored thereon machine-readable instructions executable to cause performance of operations comprising: detecting a first request to access a protected URL from a client computing device; providing, to the client computing device, a second request for a URL password, wherein the second request includes a nonce comprising a server-generated string; receiving, from the client computing device and in response to the second request, the URL password including a parameter computable by the client computing device using a hash-based computation, wherein the parameter, when used as a key in the hash-based computation on the nonce provided to the client computing device, enables a signature having a prefix associated with the protected URL to be produced by the client computing device; and redirecting the first request to access to the protected URL upon determining that the received URL password is valid for the protected URL by confirming the parameter used in the hash-based computation on the nonce results in the signature having the prefix. ### Claim 15 (depends on 14) The non-transitory machine-readable medium of claim 14, wherein the hash-based computation is performed in response to a challenge-response problem provided in a codebook downloadable by the client computing device. ### Claim 16 (depends on 15) The non-transitory machine-readable medium of claim 15, wherein the URL password is further determined to be valid when i) the codebook is determined to not be expired, ii) the URL password is not found in a cache of previously used passwords, iii) the URL password is a proper response to the challenge-response problem, and iv) the challenge-response problem solved by the URL password is associated with the protected URL in the codebook that matches the first request. ### Claim 17 (depends on 15) The non-transitory machine-readable medium of claim 15, wherein the challenge-response problem is associated with the protected URL. ### Claim 18 (depends on 14) The non-transitory machine-readable medium of claim 14, wherein the hash-based computation is a HMAC operation that uses a SHA-256 function as a hash function of the HMAC operation, and the parameter is a 256-bit value. ### Claim 19 (depends on 1) The system of claim 1, wherein the operations further comprise generating a byte array, wherein the nonce comprises the byte array. ### Claim 20 (depends on 18) The non-transitory machine-readable medium of claim 18, wherein the determining that the received URL password is valid for the protected URL includes generating the signature having the prefix upon using the 256-bit value to sign the nonce with the SHA-256 function.