# US 2019/0171827 A1 · Data security using high speed serial equalization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0171827 A1 - Document ID: US20190171827A1 - Status: Published application - Kind: A1 - Application number: 16/269,679 - Filed: 2019-02-07 - Published: 2019-06-06 - Earliest claimed: 2017-10-11 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Layne A. Berge; Benjamin A. Fox; Wesley D. Martin; George Zettles - Web page: https://patentgrep.com/patent/US20190171827A1 ## CPC - G06F 21/606: {by securing the transmission between two devices or processes} - G06F 21/75: by inhibiting the analysis of circuitry or operation - G06F 21/85: interconnection devices, e.g. bus-connected or in-line devices - H04L 25/03828: {Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties (partial response systems H04L25/497)} - H04L 63/0428: {wherein the data content is protected, e.g. by encrypting or encapsulating the payload} - H04L 25/03057: {with a recursive structure (H04L25/03031 takes precedence)} - H04L 25/03343: {Arrangements at the transmitter end} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A system includes a transmit equalizer to equalize a data stream using a set of transmit parameters to generate an input signal. The system further includes a communication channel to receive the input signal. The system further includes a receive equalizer to receive an output signal from the communication channel in response to the input signal and detect the data stream from the output signal using a set of receive parameters. The system additionally includes a controller to change the set of transmit parameters in response to a condition, where the transmit parameters, the receive parameters, and the condition are selected to both enable the receive equalizer to detect the data stream from the output signal and reduce the likelihood of an external circuit detecting the data stream from the output signal. ## Claims ### Claim 1 A system comprising: a transmit equalizer to equalize a data stream using a set of transmit parameters to generate an input signal; a communication channel to receive the input signal; a receive equalizer to receive an output signal from the communication channel in response to the input signal and detect the data stream from the output signal using a set of receive parameters; and a controller to change the set of transmit parameters in response to a condition; wherein the transmit parameters, the receive parameters, and the condition are selected to both enable the receive equalizer to detect the data stream from the output signal and reduce the likelihood of an external circuit detecting the data stream from the output signal. ### Claim 2 (depends on 1) The system of claim 1, wherein the condition is an expiration of a time interval. ### Claim 3 (depends on 1) The system of claim 1, wherein the condition comprises equalizing a portion of the data stream. ### Claim 4 (depends on 1) The system of claim 1, wherein the set of transmit parameters are non-optimal equalizer parameters. ### Claim 5 (depends on 1) The system of claim 1, wherein the transmit parameters are selected in response to characteristics of the communication channel. ### Claim 6 (depends on 1) The system of claim 1, wherein the transmit parameters are selected to vary an amplitude of the input signal. ### Claim 7 (depends on 1) The system of claim 1, wherein: the transmit equalizer is a feed-forward equalizer, the receive equalizer is a decision feedback equalizer, and the communication channel is a high speed serial communication channel. ### Claim 8 A method comprising: equalizing a data stream using a set of transmit parameters to generate an input signal; transmitting the input signal to a communication channel; receiving an output signal from the communication channel in response to the input signal and detect the data stream from the output signal using a set of receive parameters; and changing the set of transmit parameters and the receive parameters in response to a condition; wherein the transmit parameters, the receive parameters, and the condition are selected to both enable the receive equalizer to detect the data stream from the output signal and reduce the likelihood of an external circuit detecting the data stream from the output signal. ### Claim 9 (depends on 8) The method of claim 8, wherein the condition is an expiration of a time period. ### Claim 10 (depends on 8) The method of claim 8, wherein the condition comprises equalizing a portion of the data stream. ### Claim 11 (depends on 8) The method of claim 8, wherein the set of transmit parameters are non-optimal equalizer parameters. ### Claim 12 (depends on 8) The method of claim 8, wherein the transmit parameters are selected in response to characteristics of the communication channel. ### Claim 13 (depends on 8) The method of claim 8, wherein the transmit parameters are selected to vary an amplitude of the input signal. ### Claim 14 A system, comprising: a transmit equalizer to transmit an input signal having serial data to a communication channel, the input signal equalized in response to transmit equalizer parameters to cause an output signal detected from the communication channel in response to the input signal to have a distortion level greater than a minimum distortion level, the transmit equalizer parameters having values that change in response to a condition; and a receive equalizer to receive the output signal from the communication channel and to process the received output signal to retrieve the serial data, the receive equalizer parameters selected in response to the transmit equalizer parameters to reduce the distortion level. ### Claim 15 (depends on 14) The system of claim 14, wherein the condition is an expiration of a time period, the time period being shorter than a threshold time period for a circuit external to the system to determine external equalizer parameters to process the output signal to retrieve the serial data. ### Claim 16 (depends on 14) The system of claim 14, wherein the transmit equalizer parameters are selected based on characteristics of the communication channel to cause distortion level to reduce a likelihood of a circuit external to the system processing the output signal to retrieve the serial data. ### Claim 17 (depends on 14) The system of claim 14, wherein the transmit equalizer parameters are selected, based on characteristics of the communication channel, to cause the distortion level to increase an amount of time for a circuit external to the system processing the output signal to process output signal to retrieve the serial data. ### Claim 18 (depends on 14) The system of claim 14, wherein the transmit equalizer parameters are selected to vary a transmit level of the input signal. ### Claim 19 A method, comprising: equalizing serial data to provide an input signal to a communication channel in response to at least two sets of transmit equalizer parameters, the at least two sets of transmit equalizer parameters selected to cause an output signal detected from the communication link in response to the input signal to have signal quality less than a threshold signal quality; receiving the output signal from the communication channel; and processing the output signal using a set of receive equalizer parameters to retrieve the serial data, the receive equalizer parameters selected to cause the signal quality to be greater than the threshold signal quality. ### Claim 20 (depends on 19) The method of claim 19, further comprising: selecting the threshold signal quality to cause an eye diagram of the received output signal to have a closed eye. ### Claim 21 (depends on 19) The method of claim 19, wherein equalizing the serial data comprises: equalizing a first portion of the serial data in response to a first set of transmit equalizer parameters of the at least two sets of transmit equalizer parameters for a first time period; equalizing, subsequent to the first time period, a second portion of the serial data in response to a second set of transmit equalizer parameters of the at least two sets of transmit equalizer parameters for a second time period, wherein a duration of first time period and the second time period are selected to reduce the likelihood detecting the serial data without the receive equalizer parameters. ### Claim 22 A System comprising: a transmit equalizer to equalize a data stream using a set of transmit parameters to generate an input signal; a communication channel to receive the input signal; a receive equalizer to receive an output signal from the communication channel in response to the input signal and detect the data stream from the output signal using a set of receive parameters; and a controller to change an amplitude of the input signal in response to a condition; wherein the amplitude of the input signal and the condition enable the receive equalizer to detect the data stream and reduce the likelihood of an external circuit detecting the data stream. ### Claim 23 (depends on 20) The system of claim 20, wherein the condition is an expiration of a time period. ### Claim 24 (depends on 20) The system of claim 20, wherein the condition comprises equalization of a portion of the data stream.