IACR News item: 19 April 2015
Michael Düll, Björn Haase, Gesine Hinterwälder, Michael Hutter, Christof Paar, Ana Helena Sánchez, Peter S
ePrint Reportsoftware on three different popular microcontroller architectures. We consider a 255-bit curve proposed by Bernstein
known as Curve25519, which has also been adopted by the IETF. We optimize the X25519 key-exchange
protocol proposed by Bernstein in 2006 for AVR ATmega 8-bit microcontrollers, MSP430X 16-bit microcontrollers,
and for ARM Cortex-M0 32-bit microcontrollers. Our software for the AVR takes only 13 900 397 cycles
for the computation of a Diffe-Hellman shared secret, and is the first to perform this computation in less than
a second if clocked at 16 MHz for a security level of 128 bits. Our MSP430X software computes a shared secret
in 5 301 792 cycles on MSP430X microcontrollers that have a 32-bit hardware multiplier and in 7 933 296 cycles
on MSP430X microcontrollers that have a 16-bit multiplier. It thus outperforms previous constant-time ECDH
software at the 128-bit security level on the MSP430X by more than a factor of 1.2 and 1.15, respectively. Our
implementation on the Cortex-M0 runs in only 3 589 850 cycles and outperforms previous 128-bit secure ECDH
software by a factor of 3.
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